Story of a cursed rotary
09-07-22, 10:18 PM
#1
Story of a cursed rotary
Short version of my story:
bought 50k mile FD, overboosted from failing vac lines popped apex seals. Bought a new motor from Ray Crowe and had Howard Coleman build it with Ianetti Seals then put an 8374, Haltech 1500 and Greddy V mount on it.
fast forward a bit and I had a local shop dyno tune the car with a break-in tune. They pulled 343hp at 10psi wastegate.
i decided to look through the tune and found that the split timing had negative numbers. Haltech has a split map that has “ignition retard” so a negative number would effectively be advance. Amateur and dangerous. Luckily I put very few easy miles on the car.
After the car was warm one day I tried a compression check and the rear rotor was quite low. 60ish after correction on Rotary tester.
two days later, cold, compression back up to above 100 on all faces.
Maybe there was some fuel on the seals and I messed up the test? While this seemed likely I have encountered the problem again but this time on the dyno.
i found a better tuner (Shawn) and used a friends shop dyno and after tuning for about an hour the compression in rear rotor is again low on all faces consistently. (~30psi). Argh.
I have a sneaking suspicion that tomorrow morning the compression will return to normal.
Warped I seals?
I will update tomorrow with new compression numbers.
What an interesting ride so far. It’s been 2 years since popping the first motor. And now I’m looking at buying another motor from Ray. Argh.
I have nothing but good things to say about Howard Coleman who has been the most helpful person in the rotary world. What a great guy to put up with my lack of knowledge in the beginning and problems Im having now.
Recently Ive started working with Tuned By Shawn and so far he has been an extremely valuable resource.
I will not mention the original tuner yet since Im not sure how I am going to handle that yet.
Stevo
bought 50k mile FD, overboosted from failing vac lines popped apex seals. Bought a new motor from Ray Crowe and had Howard Coleman build it with Ianetti Seals then put an 8374, Haltech 1500 and Greddy V mount on it.
fast forward a bit and I had a local shop dyno tune the car with a break-in tune. They pulled 343hp at 10psi wastegate.
i decided to look through the tune and found that the split timing had negative numbers. Haltech has a split map that has “ignition retard” so a negative number would effectively be advance. Amateur and dangerous. Luckily I put very few easy miles on the car.
After the car was warm one day I tried a compression check and the rear rotor was quite low. 60ish after correction on Rotary tester.
two days later, cold, compression back up to above 100 on all faces.
Maybe there was some fuel on the seals and I messed up the test? While this seemed likely I have encountered the problem again but this time on the dyno.
i found a better tuner (Shawn) and used a friends shop dyno and after tuning for about an hour the compression in rear rotor is again low on all faces consistently. (~30psi). Argh.
I have a sneaking suspicion that tomorrow morning the compression will return to normal.
Warped I seals?
I will update tomorrow with new compression numbers.
What an interesting ride so far. It’s been 2 years since popping the first motor. And now I’m looking at buying another motor from Ray. Argh.
I have nothing but good things to say about Howard Coleman who has been the most helpful person in the rotary world. What a great guy to put up with my lack of knowledge in the beginning and problems Im having now.
Recently Ive started working with Tuned By Shawn and so far he has been an extremely valuable resource.
I will not mention the original tuner yet since Im not sure how I am going to handle that yet.
Stevo
Last edited by goeatpaiste; 09-08-22 at 07:30 AM.
Popular Reply
01-24-23, 08:38 PM
Hello to everyone,
In particular Howard Colleman. Glad to see you are still at it, and a prominent figure in the board.
Been +/- 10 yrs. since my last post as an active member. Guess I reached that point in life were it just wasn't for me. No need to elaborate further.
Reason for this indulgence is several guys have reached out to me for my take on this matter.
For one, I've only experienced this issue 1 time back in '94 with a brand new freshly bought yellow Fd R-1 with only 800 miles on the clock.
Belonged to a local narco, who dropped the car off for a money no object build. Objective was 500+ daily driver with A/C and all power equipment a MUST !.
Took 4 attempts at getting it right and nearly a year before success on the 5th try.
Anyways, What I learned from that exercise:
a) This was a heat related problem specific to the rear Rotor.
b) OEM Apex Seals. Back in those days, no other choice for Steel Seals except Hurley out of England, plus I had no experience with them, so No Need to add another
UN-Known variable.
c) There was a Fuel Cut on #2 at 12psi or higher on the stock ECU. One I figured out a fix to delete.
Given upgrades:
I tried everything I new at the time to figure out what was happening.
This was THE very first Single Turbo in the country. No aftermarket kit's at the time.
2 Guys from GReedy flew down to Miami to have a look at the car.
Upgrades included:
Larger injectors from the get GO. 2x Supra Fuel Pumps. Custom Built Copper Radiator, Custom built IC. sized to fit between frame rails., Large Oil Coolers. Again size maxed out for available space. After market front bumper to maximize coolers space and ducting. External Oil Supply, (a race secret at the time), and what ever else I can't remember from 30 years back.
Same issues:
Broken Seals, Damaged Housings, Damaged Rotors, 1 blown Turbo from Apex flying out into Turbine. Nothing worked until the final analysis by process of elimination.
Mind you, through out the rebuilds I did major modifications.
All showed promise but still fell short of the goal.
- Machined Rotors for 3mm and used OE Seals from GSL-SE. Still broke.
- Dropped compression from Fd to S4. An obvious upgrade as all Turbo engines I had built to date were Low Comp. This had to work ! Right ? No Cigar.
My Daily was a Dave Kent Wide Body 7 left over from my IMSA GT-U days 12 inch wide Yocas AVS on 16" Epsilons. Turbo 6P block, Long Runner Custom Intake Blowing though a Weber Sidedraft and 4 additional Injectors via HKS AIC. for when on Boost, 20psi on 93 pump and 440 wheel with nearly same Torque. mind you, built this car in '87, and was Reliable as a Swiss Watch.
So the Low Comp thick wall Rotors with EFI should have been the answer ? NOT.
- Upgraded Fuel Line diameter to -10 from Surge Tank. forward .... Failed again.
Was not until walked away to analyze by build by process of elimination and function.
While scratching my head for what "COULD" cause this repeating problem, before the light turned on.
Mind you, my shop was in South Florida were it is scorching hot all year round.
The only Tell Tail Witness Mark (besides the physical damage of parts) was a full circle band of black gummy oily sud all the way around the circumference of the Rotor Housing's Trochoid Surface.
Like a long tacky skid mark all the way around the housing's surface.
Before Catastrophic damage occurred, as someone stated, car would be near impossible to start when HOT.
Hour later, or following morning car would start right up and run as hard as ever before performance began to drop off. Obviously Seals wrapped. Pull engine, take apart, and the perpetual black band all the way around in the center of the Housing. Reason why engine would start on tap when cold was because the circular band of the Oil/Carbon sud would get hard enough when cooled that the Apex seals could slide on and build compression.
This happened on every rebuild back to back until figured out the cause.
Now on to the subject of the I-Rotary Seals. ....
NOTE: I am a firm believer of eliminating any and all variables and focus exclusively on the
WITNESS MARKS. Damaged parts are the Symptoms, not the Cause. There is always something that is left behind. Sometimes it's obvious. Sometimes its not, Sometimes it's overlooked, passed by and taken for granted as part of the damage. That's why their called "Witness Marks"
By process of elimination, the issues these guys are having clearly shows it is NOT the I-Rotary Seals.
- If it didn't happen on the Front Rotor, by default CANNOT be the Seals as they were both exposed to the same conditions at the same time. ... PERIOD.
- It can not be a bad batch because again warpage would have manifested on both Rotors.
- Cannot be from lack of Premix because problem persist (with this small group of guys) regardless of amount of premix used. A little or a lot. Same issue.
- Since the I-Rotary Seal was introduced, well over 2 Thousand (2,000+) sets of seals have been sold world wide. Only less than 2 hands full of guys have this problem. What is the COMMON DENOMINATOR ?
Simple math equates to less than 0.005% of users have this issue.
Can you guys pronounce that ? Five One-Thousands of 1 percent. ... Seriously ???
Yes, their IS a common denominator, and it's NOT the I-Rotary Seals.
Through the years, I've used and kept notes on every Apex Seal that has come and gone.
IMHO, Nothing else comes close in compression or longevity.
It is very easy to point the finger and pass blame.
Way toooo many external factors at building Big Power Rotaries.
Reason why few are successful and World Renowned and the many are Not.
Lets assume these boys "assemble" the PERFECT engine, with everything brand new. Everything.
I say "Assemble" because from my point of view, 90%+ of engine guys today are assemblers. Not Builders. Everything from port work to Rotor machining is sent out.
Balancing is another subject. Has to be send out because it requires specialized equipment and Knowledge. Lots of it. Majority of my latter work has been correcting other shops balance work,
Today even the butcher at the local Supermarket is a Rotary Engine Balancing Expert.
For argument's sake, Lets eliminate the engine it's self and just look at outside variables,
Parts, People and Shops, Things normally taken for granted.
- Tuner,
- Exhaust Manifold and back pressure,
- Turbine sizing
- Engine Management
- Sensors, and Injector calibration.
- All Coolers Duct Work.
- Water Pump. (My Favorate)
- Even collapsing Hoses under engine acceleration.
All these factors by default are even MORE Important that the engine it's self.
- A good Tune, makes a mediocre engine run good and live long. On the other hand a mediocre Tune makes the very best engine run crappy and short lived.
- A poorly designed Ext. Manifold can adversely effect back pressure on one Rotor, and not the other.
- Too tight a Turbine Housing will choke the engine and elevate back pressure and EGT's
- Engine Managemet can and will have a mirage of influences on performance and reliability.
- Sensor and Injector calibration is HUGE factor. If ECU is not calibrated to Sensors and Injectors the Tune is GARBAGE.
- Heat Exchanger efficiency is governed by the Ducting, Radiator, Oil Coolers, or IC. Don't matter.
Ducting is more important than physical size of coolers themselves. The biggest, baddest coolers won't do squat if ducting is not functional mainly on extracting heated Air. For those who don't know: Duct outlet is far more important than inlet. At speed, Air will "get in" by the sheer force of vehicle velocity, i will get in. If trapped, and cant get the heat out, might as well not have coolers
- Water Pump. I say my favorite because it is the single most overlooked part of the puzzle and taken for granted. The Water Pump is responsible for the life of the engine under EVER CHANGING and STRESSED conditions. The Water Pump has to be matched to Thermal Loads in both capacity and Flow . Every Impeller of any type ie: V-8, Rotary, Boat, Turbo Charger, Does NOT matter. Has an operating range in witch maximum efficiency is generated. Too Slow and not enough GPM, Too Fast, goes into Cavitation. When Cavitation occurs in a cooling system, Catastrophe follows.
This ideal speed range is called the "Sweet Spot"
- Less than 1% of all engine builds I've seen in my 38 yrs.+ as a racer, builder, competitor, and supplier have a correct Drive ratio for Impeller Diameter, so to generate maximum Flow in GPM @ WOT. without over spinning and induce cavitation. All these Pretty Anodized Pulley Kits all over-spin WP's near engine red line. See were I'm going ?
Rotary engines have the worst surface to volume ration of ANY Internal Combustion Engine. Couple that with a 60 yr old cooling system designed for roughly 160 Hp.
Today we constantly DEMAND 3 to 5 times and more cooling from the same capacity and effective efficiency. So something needs to compensate and take up the slack.
It is IMPERATIVE to have the WP working at max efficiency @ WOT. and Thermal Load.
Electric WP's do a poor job of scrubbing away the boundary layer of coolant from the Rotor Housings particularly at the times when most heat is being generated. Electric WP's run fairly constant Flow vs. a correctly driven mechanical WP will respond by increase pressure and flow exactly when required by Speed and Load.
Electric WP's provide superior circulation at steady stage use. Highway and idle. in essence when great floe really is not needed. They DON'T offer the sudden Flow changes in volume required to SCRUB AWAY the tiny Air Bubbles that live in the pitted Water Jacket and little holes witch form in the Calcified Matter and debris that builds up on Water Jacket passages. These tiny Bubbles will live there un-disrupted for months at a time. Then suddenly one goes to the Dyno and does 5-7 pulls back to back at full throttle and boost. Engine block expands and contracts, these bubbles suddenly detach and migrate. Grow and travel. Eventually they travel to the WP's impeller. and if large enough, at this point the Impeller cavitates.
Entered a Thermal Runaway condition, were temperature flash and coolant will BOIL.
On extreme high boost racing engines I use both Mechanical and Electric Wp's. Each with their own specific job. They work together but perform, totally different functions on different areas of the block complementing each others strengths.
On Rotaries, there are 3 very specific sports were extreme heat is generated. 1st spot is just below the Leading Spark plugs. 2nd is right around the Exhaust Port. 3rd. is the Blowdown area between the (L) plug, and the Exhaust Ports. Localized Hot Spots are at their highest just below the (L) Plug. Hot enough to deform, and melt the Housing and crack / exfoliate the Chrome. Same but not quite as hot at and around the Exhaust Port, This is why it is SO IMPORTANT to Chanfer with large heavy Radius the closing edge of the Exhaust Port.
Under heavy Boost and Thermal load, both the vicinity around the Plugs and the Exhaust Ports deform sufficiently at the surface to cause the Apex seal to separate from the Housing. Anyone who's opened a few race engines has seen the witness marks emanating horizontally on both sides of the plugs, and on the closing edge of the exhaust port.
These 2 spots, combined with the Blowdown area between them hold sufficient surface heat that conduction into the Seal to is inevitable and absorbs the heat from the surface and naturally expands and grows while physically contained by the side Irons. Once it tries to grow it Bows because it cannot grow length wise, then when cooled remains warped.
If you look closely at the trailing edge (closing) of the exhaust ports, when ever experience a warped Apex Seal, you will see a matching mark on the top of the exhaust port. A simple explanation is the Seal TRIPS over the inward deformity at the top of the port. Like tripping over a side walk leaves a scrape on your shoe. In the unfortunate case when it happens take a close look.
________
Fuel Cut and it's effects on Rotaries.
Having come from a life of endurance racing, Fuel Cutting is a standard practice on race cars. Road Race, Endurance, Sprints, Club racing, Pro-Racing, What ever. All CIRCUIT Racing.
This has long been a Standard practice in road racing to save fuel. Fuel Stops are a critical strategy in road racing in general. Be it Sprints like in F1 or 24Hr. events as in IMSA and Le Mans.
It has NO PLACE in Street use or Drag Racing. We did it on Road Race cars with Iannetti Ceramic Seals because of of the none existing coefficient of friction, and before that we got away with it on Carbon Seals because of their self lubricating properties.
Just because the ECU offers the feature, It's not a requirement to use. Those who claim they know how to tune Rotaries, should know NOT to use this feature just because it's there.
There is no benefit. On the contrary. Fuel on De-Cell COOLS internals and washes surface heat away.
There is no lubrication of internals while under Fuel Cut condition.
Worse Case of fuel Cut is Off Throttle Overrun. Particularly in single drum Dynos like DynoJets
The sheer Inertia stored in these drums multiplied by the weight and rotational speed is enough to keep the engines spinning for over a minute from Full Boost @ WOT to Full Vacuum, Zero lubrication of Internals while PUSHED against engine rotational drag. Imagine the Friction of the Apex Seals against a SCORCHING HOT Surface ? Yes. Anyone can see how any seal will warp under these conditions. Reason why I harp on Water Pumps and Drive Speed to quickly scrub heat from surface.
Back in the early IMSA days, on Carburators, No EFI we used to run very large idle jets just to cool the Carbon Seals and internals to last a full 24 hours. The Carbon seals would wear at a rate of 0.004" per hour. By the 2/3 mark, engines literally had not enough spring tension to re-start. So we kept them running even of Fuel Stops ! ... Glory Days !!
Guys, I've spent way too long on this email.
Partly why I said at the top it was not really for me anymore.
In all my years of Racing, building, traveling all over the world, experiencing first hand success and failures, everything imaginable, the world of Drag Racers, the damage those guys produce. and the in between Street Racers. Honestly I believe I've seen and worked on the greater scope of set ups from every discipline than most. Well, not all. No Rallying or Mud, but most in the industry if not all. Everything from Street Racers to Pro-Import Drag Racers, to Professional and Club Club Racers. Here and abroad.
Because of these experiences and exposures I've seen the limits more often that not.
Lets stop blaming un-knows and instead dig deeper for answers. If not, I guarantee the same will repeat it's self.
Regards to all.
- 'c
In particular Howard Colleman. Glad to see you are still at it, and a prominent figure in the board.
Been +/- 10 yrs. since my last post as an active member. Guess I reached that point in life were it just wasn't for me. No need to elaborate further.
Reason for this indulgence is several guys have reached out to me for my take on this matter.
For one, I've only experienced this issue 1 time back in '94 with a brand new freshly bought yellow Fd R-1 with only 800 miles on the clock.
Belonged to a local narco, who dropped the car off for a money no object build. Objective was 500+ daily driver with A/C and all power equipment a MUST !.
Took 4 attempts at getting it right and nearly a year before success on the 5th try.
Anyways, What I learned from that exercise:
a) This was a heat related problem specific to the rear Rotor.
b) OEM Apex Seals. Back in those days, no other choice for Steel Seals except Hurley out of England, plus I had no experience with them, so No Need to add another
UN-Known variable.
c) There was a Fuel Cut on #2 at 12psi or higher on the stock ECU. One I figured out a fix to delete.
Given upgrades:
I tried everything I new at the time to figure out what was happening.
This was THE very first Single Turbo in the country. No aftermarket kit's at the time.
2 Guys from GReedy flew down to Miami to have a look at the car.
Upgrades included:
Larger injectors from the get GO. 2x Supra Fuel Pumps. Custom Built Copper Radiator, Custom built IC. sized to fit between frame rails., Large Oil Coolers. Again size maxed out for available space. After market front bumper to maximize coolers space and ducting. External Oil Supply, (a race secret at the time), and what ever else I can't remember from 30 years back.
Same issues:
Broken Seals, Damaged Housings, Damaged Rotors, 1 blown Turbo from Apex flying out into Turbine. Nothing worked until the final analysis by process of elimination.
Mind you, through out the rebuilds I did major modifications.
All showed promise but still fell short of the goal.
- Machined Rotors for 3mm and used OE Seals from GSL-SE. Still broke.
- Dropped compression from Fd to S4. An obvious upgrade as all Turbo engines I had built to date were Low Comp. This had to work ! Right ? No Cigar.
My Daily was a Dave Kent Wide Body 7 left over from my IMSA GT-U days 12 inch wide Yocas AVS on 16" Epsilons. Turbo 6P block, Long Runner Custom Intake Blowing though a Weber Sidedraft and 4 additional Injectors via HKS AIC. for when on Boost, 20psi on 93 pump and 440 wheel with nearly same Torque. mind you, built this car in '87, and was Reliable as a Swiss Watch.
So the Low Comp thick wall Rotors with EFI should have been the answer ? NOT.
- Upgraded Fuel Line diameter to -10 from Surge Tank. forward .... Failed again.
Was not until walked away to analyze by build by process of elimination and function.
While scratching my head for what "COULD" cause this repeating problem, before the light turned on.
Mind you, my shop was in South Florida were it is scorching hot all year round.
The only Tell Tail Witness Mark (besides the physical damage of parts) was a full circle band of black gummy oily sud all the way around the circumference of the Rotor Housing's Trochoid Surface.
Like a long tacky skid mark all the way around the housing's surface.
Before Catastrophic damage occurred, as someone stated, car would be near impossible to start when HOT.
Hour later, or following morning car would start right up and run as hard as ever before performance began to drop off. Obviously Seals wrapped. Pull engine, take apart, and the perpetual black band all the way around in the center of the Housing. Reason why engine would start on tap when cold was because the circular band of the Oil/Carbon sud would get hard enough when cooled that the Apex seals could slide on and build compression.
This happened on every rebuild back to back until figured out the cause.
Now on to the subject of the I-Rotary Seals. ....
NOTE: I am a firm believer of eliminating any and all variables and focus exclusively on the
WITNESS MARKS. Damaged parts are the Symptoms, not the Cause. There is always something that is left behind. Sometimes it's obvious. Sometimes its not, Sometimes it's overlooked, passed by and taken for granted as part of the damage. That's why their called "Witness Marks"
By process of elimination, the issues these guys are having clearly shows it is NOT the I-Rotary Seals.
- If it didn't happen on the Front Rotor, by default CANNOT be the Seals as they were both exposed to the same conditions at the same time. ... PERIOD.
- It can not be a bad batch because again warpage would have manifested on both Rotors.
- Cannot be from lack of Premix because problem persist (with this small group of guys) regardless of amount of premix used. A little or a lot. Same issue.
- Since the I-Rotary Seal was introduced, well over 2 Thousand (2,000+) sets of seals have been sold world wide. Only less than 2 hands full of guys have this problem. What is the COMMON DENOMINATOR ?
Simple math equates to less than 0.005% of users have this issue.
Can you guys pronounce that ? Five One-Thousands of 1 percent. ... Seriously ???
Yes, their IS a common denominator, and it's NOT the I-Rotary Seals.
Through the years, I've used and kept notes on every Apex Seal that has come and gone.
IMHO, Nothing else comes close in compression or longevity.
It is very easy to point the finger and pass blame.
Way toooo many external factors at building Big Power Rotaries.
Reason why few are successful and World Renowned and the many are Not.
Lets assume these boys "assemble" the PERFECT engine, with everything brand new. Everything.
I say "Assemble" because from my point of view, 90%+ of engine guys today are assemblers. Not Builders. Everything from port work to Rotor machining is sent out.
Balancing is another subject. Has to be send out because it requires specialized equipment and Knowledge. Lots of it. Majority of my latter work has been correcting other shops balance work,
Today even the butcher at the local Supermarket is a Rotary Engine Balancing Expert.
For argument's sake, Lets eliminate the engine it's self and just look at outside variables,
Parts, People and Shops, Things normally taken for granted.
- Tuner,
- Exhaust Manifold and back pressure,
- Turbine sizing
- Engine Management
- Sensors, and Injector calibration.
- All Coolers Duct Work.
- Water Pump. (My Favorate)
- Even collapsing Hoses under engine acceleration.
All these factors by default are even MORE Important that the engine it's self.
- A good Tune, makes a mediocre engine run good and live long. On the other hand a mediocre Tune makes the very best engine run crappy and short lived.
- A poorly designed Ext. Manifold can adversely effect back pressure on one Rotor, and not the other.
- Too tight a Turbine Housing will choke the engine and elevate back pressure and EGT's
- Engine Managemet can and will have a mirage of influences on performance and reliability.
- Sensor and Injector calibration is HUGE factor. If ECU is not calibrated to Sensors and Injectors the Tune is GARBAGE.
- Heat Exchanger efficiency is governed by the Ducting, Radiator, Oil Coolers, or IC. Don't matter.
Ducting is more important than physical size of coolers themselves. The biggest, baddest coolers won't do squat if ducting is not functional mainly on extracting heated Air. For those who don't know: Duct outlet is far more important than inlet. At speed, Air will "get in" by the sheer force of vehicle velocity, i will get in. If trapped, and cant get the heat out, might as well not have coolers
- Water Pump. I say my favorite because it is the single most overlooked part of the puzzle and taken for granted. The Water Pump is responsible for the life of the engine under EVER CHANGING and STRESSED conditions. The Water Pump has to be matched to Thermal Loads in both capacity and Flow . Every Impeller of any type ie: V-8, Rotary, Boat, Turbo Charger, Does NOT matter. Has an operating range in witch maximum efficiency is generated. Too Slow and not enough GPM, Too Fast, goes into Cavitation. When Cavitation occurs in a cooling system, Catastrophe follows.
This ideal speed range is called the "Sweet Spot"
- Less than 1% of all engine builds I've seen in my 38 yrs.+ as a racer, builder, competitor, and supplier have a correct Drive ratio for Impeller Diameter, so to generate maximum Flow in GPM @ WOT. without over spinning and induce cavitation. All these Pretty Anodized Pulley Kits all over-spin WP's near engine red line. See were I'm going ?
Rotary engines have the worst surface to volume ration of ANY Internal Combustion Engine. Couple that with a 60 yr old cooling system designed for roughly 160 Hp.
Today we constantly DEMAND 3 to 5 times and more cooling from the same capacity and effective efficiency. So something needs to compensate and take up the slack.
It is IMPERATIVE to have the WP working at max efficiency @ WOT. and Thermal Load.
Electric WP's do a poor job of scrubbing away the boundary layer of coolant from the Rotor Housings particularly at the times when most heat is being generated. Electric WP's run fairly constant Flow vs. a correctly driven mechanical WP will respond by increase pressure and flow exactly when required by Speed and Load.
Electric WP's provide superior circulation at steady stage use. Highway and idle. in essence when great floe really is not needed. They DON'T offer the sudden Flow changes in volume required to SCRUB AWAY the tiny Air Bubbles that live in the pitted Water Jacket and little holes witch form in the Calcified Matter and debris that builds up on Water Jacket passages. These tiny Bubbles will live there un-disrupted for months at a time. Then suddenly one goes to the Dyno and does 5-7 pulls back to back at full throttle and boost. Engine block expands and contracts, these bubbles suddenly detach and migrate. Grow and travel. Eventually they travel to the WP's impeller. and if large enough, at this point the Impeller cavitates.
Entered a Thermal Runaway condition, were temperature flash and coolant will BOIL.
On extreme high boost racing engines I use both Mechanical and Electric Wp's. Each with their own specific job. They work together but perform, totally different functions on different areas of the block complementing each others strengths.
On Rotaries, there are 3 very specific sports were extreme heat is generated. 1st spot is just below the Leading Spark plugs. 2nd is right around the Exhaust Port. 3rd. is the Blowdown area between the (L) plug, and the Exhaust Ports. Localized Hot Spots are at their highest just below the (L) Plug. Hot enough to deform, and melt the Housing and crack / exfoliate the Chrome. Same but not quite as hot at and around the Exhaust Port, This is why it is SO IMPORTANT to Chanfer with large heavy Radius the closing edge of the Exhaust Port.
Under heavy Boost and Thermal load, both the vicinity around the Plugs and the Exhaust Ports deform sufficiently at the surface to cause the Apex seal to separate from the Housing. Anyone who's opened a few race engines has seen the witness marks emanating horizontally on both sides of the plugs, and on the closing edge of the exhaust port.
These 2 spots, combined with the Blowdown area between them hold sufficient surface heat that conduction into the Seal to is inevitable and absorbs the heat from the surface and naturally expands and grows while physically contained by the side Irons. Once it tries to grow it Bows because it cannot grow length wise, then when cooled remains warped.
If you look closely at the trailing edge (closing) of the exhaust ports, when ever experience a warped Apex Seal, you will see a matching mark on the top of the exhaust port. A simple explanation is the Seal TRIPS over the inward deformity at the top of the port. Like tripping over a side walk leaves a scrape on your shoe. In the unfortunate case when it happens take a close look.
________
Fuel Cut and it's effects on Rotaries.
Having come from a life of endurance racing, Fuel Cutting is a standard practice on race cars. Road Race, Endurance, Sprints, Club racing, Pro-Racing, What ever. All CIRCUIT Racing.
This has long been a Standard practice in road racing to save fuel. Fuel Stops are a critical strategy in road racing in general. Be it Sprints like in F1 or 24Hr. events as in IMSA and Le Mans.
It has NO PLACE in Street use or Drag Racing. We did it on Road Race cars with Iannetti Ceramic Seals because of of the none existing coefficient of friction, and before that we got away with it on Carbon Seals because of their self lubricating properties.
Just because the ECU offers the feature, It's not a requirement to use. Those who claim they know how to tune Rotaries, should know NOT to use this feature just because it's there.
There is no benefit. On the contrary. Fuel on De-Cell COOLS internals and washes surface heat away.
There is no lubrication of internals while under Fuel Cut condition.
Worse Case of fuel Cut is Off Throttle Overrun. Particularly in single drum Dynos like DynoJets
The sheer Inertia stored in these drums multiplied by the weight and rotational speed is enough to keep the engines spinning for over a minute from Full Boost @ WOT to Full Vacuum, Zero lubrication of Internals while PUSHED against engine rotational drag. Imagine the Friction of the Apex Seals against a SCORCHING HOT Surface ? Yes. Anyone can see how any seal will warp under these conditions. Reason why I harp on Water Pumps and Drive Speed to quickly scrub heat from surface.
Back in the early IMSA days, on Carburators, No EFI we used to run very large idle jets just to cool the Carbon Seals and internals to last a full 24 hours. The Carbon seals would wear at a rate of 0.004" per hour. By the 2/3 mark, engines literally had not enough spring tension to re-start. So we kept them running even of Fuel Stops ! ... Glory Days !!
Guys, I've spent way too long on this email.
Partly why I said at the top it was not really for me anymore.
In all my years of Racing, building, traveling all over the world, experiencing first hand success and failures, everything imaginable, the world of Drag Racers, the damage those guys produce. and the in between Street Racers. Honestly I believe I've seen and worked on the greater scope of set ups from every discipline than most. Well, not all. No Rallying or Mud, but most in the industry if not all. Everything from Street Racers to Pro-Import Drag Racers, to Professional and Club Club Racers. Here and abroad.
Because of these experiences and exposures I've seen the limits more often that not.
Lets stop blaming un-knows and instead dig deeper for answers. If not, I guarantee the same will repeat it's self.
Regards to all.
- 'c
09-08-22, 10:25 AM
#2
RX-7 Bad Ass
iTrader: (55)
Welcome to the warped seals club.
I've seen quite a few cases where the new I-Rotary seals have warped once you finish break-in and start putting down power. It exhibits as a drastic drop in compression.
@F1blueRx7 can chime in on this.
The good thing is it's JUST warped seals most likely. Everything else in the motor is fine. So, crack open the engine, new apex seals, done.
I have a great deal of respect for Francesco Ianetti but at this point I can't recommend those I-Rotary seals, too many cases I've seen first and second hand of warped seals. It could be a bad batch or something, but I have also seen recommendations when running them of a lot of premix, decal fuel cut turned off to constantly lubricate the seals, etc. - that's just crazy, it shouldn't need that much. There are other upgraded seals that don't require kid gloves.
Dale
I've seen quite a few cases where the new I-Rotary seals have warped once you finish break-in and start putting down power. It exhibits as a drastic drop in compression.
@F1blueRx7 can chime in on this.
The good thing is it's JUST warped seals most likely. Everything else in the motor is fine. So, crack open the engine, new apex seals, done.
I have a great deal of respect for Francesco Ianetti but at this point I can't recommend those I-Rotary seals, too many cases I've seen first and second hand of warped seals. It could be a bad batch or something, but I have also seen recommendations when running them of a lot of premix, decal fuel cut turned off to constantly lubricate the seals, etc. - that's just crazy, it shouldn't need that much. There are other upgraded seals that don't require kid gloves.
Dale
09-08-22, 03:08 PM
#3
Yeah I wouldn't run I-rotary seals in anything that's going to be driven on the street. Take a look at the instructions that come with the seals, that's entirely too much pre-mix to be putting in the chamber, additionally I-Rotary publicly states that their seals will warp if you use any type of Fuel cut on decel. Stick with OEM seals if you're not making huge power.
09-08-22, 10:03 PM
#4
I am starting to hear more about these seals having issue. Thank you for validating my thoughts.
I have heard that Adams seals (REC?) are fairly great and I may move to those. I am only shooting for 350-400whp to keep the car driveable so I am certainly not pushing anything too hard.
stevo
I have heard that Adams seals (REC?) are fairly great and I may move to those. I am only shooting for 350-400whp to keep the car driveable so I am certainly not pushing anything too hard.
stevo
Welcome to the warped seals club.
I've seen quite a few cases where the new I-Rotary seals have warped once you finish break-in and start putting down power. It exhibits as a drastic drop in compression.
@F1blueRx7 can chime in on this.
The good thing is it's JUST warped seals most likely. Everything else in the motor is fine. So, crack open the engine, new apex seals, done.
I have a great deal of respect for Francesco Ianetti but at this point I can't recommend those I-Rotary seals, too many cases I've seen first and second hand of warped seals. It could be a bad batch or something, but I have also seen recommendations when running them of a lot of premix, decal fuel cut turned off to constantly lubricate the seals, etc. - that's just crazy, it shouldn't need that much. There are other upgraded seals that don't require kid gloves.
Dale
I've seen quite a few cases where the new I-Rotary seals have warped once you finish break-in and start putting down power. It exhibits as a drastic drop in compression.
@F1blueRx7 can chime in on this.
The good thing is it's JUST warped seals most likely. Everything else in the motor is fine. So, crack open the engine, new apex seals, done.
I have a great deal of respect for Francesco Ianetti but at this point I can't recommend those I-Rotary seals, too many cases I've seen first and second hand of warped seals. It could be a bad batch or something, but I have also seen recommendations when running them of a lot of premix, decal fuel cut turned off to constantly lubricate the seals, etc. - that's just crazy, it shouldn't need that much. There are other upgraded seals that don't require kid gloves.
Dale
09-08-22, 10:05 PM
#5
I currently have 2oz/gal in the tank as I am still sorta breaking it in. No OMP.
I would imagine that is plenty of premix or at least enough to keep the seals happy.
i suppose not.
thanks
stevo
I would imagine that is plenty of premix or at least enough to keep the seals happy.
i suppose not.
thanks
stevo
Yeah I wouldn't run I-rotary seals in anything that's going to be driven on the street. Take a look at the instructions that come with the seals, that's entirely too much pre-mix to be putting in the chamber, additionally I-Rotary publicly states that their seals will warp if you use any type of Fuel cut on decel. Stick with OEM seals if you're not making huge power.
09-09-22, 08:25 AM
#6
RX-7 Bad Ass
iTrader: (55)
IMHO I would run an OMP on any street car. Premix is such a pain in the ***.
Yeah RA seals do fine.
Again, you are looking at a VERY straight forward rebuild to solve the problem. You have to pull and break open the engine again, which sucks, but the good thing is the parts in the engine to be replaced are few. Apex seals of course, and I'd probably go ahead and put new water seals and dowel pin O-rings, I just don't trust them after being used. That's pretty cheap parts-wise.
Dale
Yeah RA seals do fine.
Again, you are looking at a VERY straight forward rebuild to solve the problem. You have to pull and break open the engine again, which sucks, but the good thing is the parts in the engine to be replaced are few. Apex seals of course, and I'd probably go ahead and put new water seals and dowel pin O-rings, I just don't trust them after being used. That's pretty cheap parts-wise.
Dale
09-10-22, 08:58 AM
#7
OEM Seals will handle that power and not warp due to heat. They do of course break, not bend/warp in high power applications and take out the rotor and housing in the process.
Re: Premixing theory. (setting aside Dales point above) If you're using Fuel cut on decel, you are removing lubrication from the seals on off throttle events. Think about that. When you do a dyno pull the engine sees a long period of time with no oil lubricating the seals on deceleration after the pull. That was exactly where my i-Rotary seals warped. Had great compression before the dyno with 1000 break in miles, and 70-80 PSI evenly, on all rotor faces right after the dyno with maybe 6 pulls. We stopped after the engine made less power than the last pull when it should have been going up.
I have nothing but respect for Mr. Ianetti for the things he has done to progress the rotary engine in motorsports. He called me personally to apologize, and explain why he think the seals failed. I even sent the seals back to Paul at Mazmart to give to Ianetti, and there really are no hard feelings at this point over it, but I will not run those seals again in my engines. There are racing teams out there making huge power setting records, etc. But then there's at least 10 people I know of that have a story like mine. Now comes the chorus of "My I-Rotary seals are great and make huge power" comments.
Re: Premixing theory. (setting aside Dales point above) If you're using Fuel cut on decel, you are removing lubrication from the seals on off throttle events. Think about that. When you do a dyno pull the engine sees a long period of time with no oil lubricating the seals on deceleration after the pull. That was exactly where my i-Rotary seals warped. Had great compression before the dyno with 1000 break in miles, and 70-80 PSI evenly, on all rotor faces right after the dyno with maybe 6 pulls. We stopped after the engine made less power than the last pull when it should have been going up.
I have nothing but respect for Mr. Ianetti for the things he has done to progress the rotary engine in motorsports. He called me personally to apologize, and explain why he think the seals failed. I even sent the seals back to Paul at Mazmart to give to Ianetti, and there really are no hard feelings at this point over it, but I will not run those seals again in my engines. There are racing teams out there making huge power setting records, etc. But then there's at least 10 people I know of that have a story like mine. Now comes the chorus of "My I-Rotary seals are great and make huge power" comments.
Trending Topics
09-10-22, 06:11 PM
#8
I will have to check my tune but I am 99% certain that decel fuel cut was turned off.
I also have no logs at all indicating any significant knock events so Im about as baffled as could be.
also its only the rear rotor. Bizarre.
i will report back when the motor comes apart; likely next year.
stevo
I also have no logs at all indicating any significant knock events so Im about as baffled as could be.
also its only the rear rotor. Bizarre.
i will report back when the motor comes apart; likely next year.
stevo
The following users liked this post:
DaleClark (09-11-22)
09-19-22, 07:51 PM
#9
Racing Rotary Since 1983
iTrader: (6)
over 100 in the front and 60 in the rear.
clearly the front apex seals are fine and the rear are warped.
the fix focus should be on anything that is rotor specific rather than the brand of apex seals.
start with fuel injectors & ignition. if you don't find the problem in the rear rotor system and you
swap in another brand of apex seals you will again be looking at 100/60 in short order. and after that an LS, or better, a K24
F1blue RX7 makes some good points...
"OEM Seals will handle that power and not warp due to heat. They do of course break, not bend/warp in high power applications and take out the rotor and housing in the process."
dry humor, sort of like if you jump off a building you will have a nice view, before no view at all. i do totally agree re OE seals. they have no business in a single turbo app unless you want much of your motor and turbo in pieces. they just don't fit the app.
i also appreciate his candor re what apparently happened w his motor... decel fuel cut on a dyno is warped apex seals no matter what aftermarket brand if you are only pre-mixing.
i recently had one of my customer motors back for new seals after one dyno session. apex seals warped .004, compression around 70 on front and rear. apex seal brand REC. it could have been any brand since the tuner enabled decel fuel cut.
apex seal options in 2022 are way diff than back in the day. most seals warp rather than break. most seals are made of virtually the same material and most warp similarly if exposed to lack of lube. in a matter of minutes perhaps seconds. at 9000 rpm/3000 rotor rpm an apex seal exerts approx 10 pounds of force against the rotor housing. that force is focused on a contact area (part of the apex seal crown) that is beyond tiny... the rotor housing is about 3.15 inches width, the contact width on the apex seal is probably around .03 so the total area delivering the 10 pounds of centrifugal force is .09 of one square inch and going somewhere near 85 mph. no lube, pretty much instant death.
as most know, when Mazda debuted the Renesis they doubled the oil injection holes and later added a third. i prefer the linearity of premix. no doubt Mazda engineers fantasized about being able to get 2 cycle oil into the internals but the marketing guys told the engineers it was a no go as a $44,000 car should not be confused with a lawn mower. from a general perspective there really were no good options as to apex seal lubrication:
option A: pumping carbon filled 4 cycle oil directly on the apex seal and gunking up the rotor is not the ticket. rotors become crusted with a layer of carbon. glowing carbon can create pre-ignition and dished rotors. i have seen probably a hundred carbon crusted rotors with melted faces all due to pre-ignition which was generally caused by glowing carbon build-up..
option B: a small tank that you fill with 2 cycle oil run thru the EOP. that wasn't going to fly.
i am not necessarily posting to argue that I Seals are the best, rather that in the OP's case it was not the apex seal at fault so there should be no proper follow on conclusion that I Seals in this instance are bad. i have had good success w them as i have had with other metal seals. further, knowing about the extraordinary process that the I Seals metal undergoes before machining i would be surprised that there would be a "bad batch" as has bounced around the forum.
if there have been "10 people" that have had problems let's hear from each of them them.
everyone here is looking for the truth so we can make good decisions.
clearly the front apex seals are fine and the rear are warped.
the fix focus should be on anything that is rotor specific rather than the brand of apex seals.
start with fuel injectors & ignition. if you don't find the problem in the rear rotor system and you
swap in another brand of apex seals you will again be looking at 100/60 in short order. and after that an LS, or better, a K24
F1blue RX7 makes some good points...
"OEM Seals will handle that power and not warp due to heat. They do of course break, not bend/warp in high power applications and take out the rotor and housing in the process."
dry humor, sort of like if you jump off a building you will have a nice view, before no view at all. i do totally agree re OE seals. they have no business in a single turbo app unless you want much of your motor and turbo in pieces. they just don't fit the app.
i also appreciate his candor re what apparently happened w his motor... decel fuel cut on a dyno is warped apex seals no matter what aftermarket brand if you are only pre-mixing.
i recently had one of my customer motors back for new seals after one dyno session. apex seals warped .004, compression around 70 on front and rear. apex seal brand REC. it could have been any brand since the tuner enabled decel fuel cut.
apex seal options in 2022 are way diff than back in the day. most seals warp rather than break. most seals are made of virtually the same material and most warp similarly if exposed to lack of lube. in a matter of minutes perhaps seconds. at 9000 rpm/3000 rotor rpm an apex seal exerts approx 10 pounds of force against the rotor housing. that force is focused on a contact area (part of the apex seal crown) that is beyond tiny... the rotor housing is about 3.15 inches width, the contact width on the apex seal is probably around .03 so the total area delivering the 10 pounds of centrifugal force is .09 of one square inch and going somewhere near 85 mph. no lube, pretty much instant death.
as most know, when Mazda debuted the Renesis they doubled the oil injection holes and later added a third. i prefer the linearity of premix. no doubt Mazda engineers fantasized about being able to get 2 cycle oil into the internals but the marketing guys told the engineers it was a no go as a $44,000 car should not be confused with a lawn mower. from a general perspective there really were no good options as to apex seal lubrication:
option A: pumping carbon filled 4 cycle oil directly on the apex seal and gunking up the rotor is not the ticket. rotors become crusted with a layer of carbon. glowing carbon can create pre-ignition and dished rotors. i have seen probably a hundred carbon crusted rotors with melted faces all due to pre-ignition which was generally caused by glowing carbon build-up..
option B: a small tank that you fill with 2 cycle oil run thru the EOP. that wasn't going to fly.
i am not necessarily posting to argue that I Seals are the best, rather that in the OP's case it was not the apex seal at fault so there should be no proper follow on conclusion that I Seals in this instance are bad. i have had good success w them as i have had with other metal seals. further, knowing about the extraordinary process that the I Seals metal undergoes before machining i would be surprised that there would be a "bad batch" as has bounced around the forum.
if there have been "10 people" that have had problems let's hear from each of them them.
everyone here is looking for the truth so we can make good decisions.
Last edited by Howard Coleman; 09-26-22 at 05:34 PM.
The following 3 users liked this post by Howard Coleman:
01-16-23, 11:52 AM
#10
Racing Rotary Since 1983
iTrader: (6)
update:
i was able to disassemble the motor last week. prior to disassembly i did a comp test. the front was approx 115 and the rear was 62. there was no more than 3 psi variance on all 3 faces of each rotor. the corner seal springs were all at .17+ so no detonation.
the front 3 apex seals were Perfect... as in the best looking seals i have ever taken out of an engine that has been run. dead straight, beautiful crowns with zero pitting, zero ledging. all three
the rear 3 apex seals are (all) warped .003. they have ledging on both the leading and trailing edge of the crown. they show burned hydrocarbon on the upper sides next to the crown. lack of lube caused the heat which caused the ledging. solve the lube lack, solve the motor.
the actual analysis of condition of the apex seals without question removes the apex seal itself as the culprit for the motor failure. it also takes the timing mistake w the split out of the picture since the front rotor is perfect.
of course there is something seriously amiss here but it isn't the apex seals.
it has always been my contention that in 95% of the warped apex seal stories it is not the fault of the apex seal, rather it is heat and/or pressure that should not exist in a properly fixtured and tuned system. i am continuously blown away by the lack of appreciation for the amount of combustion chamber heat and pressure our 2 cycle rotaries generate. everything has to be right. 22 seasons of real racing taught me you do not ever do something 95%. the 5% will bite you.
i purposely spend too much time on my website making this point... executive summary for you:
examining 9 of the top power 2018 Supercars for rear wheel horsepower per cubic inch
average is 1.91 hp/cu inch
comparing to our 13BREW:
350 rwhp 2.19!!
400 2.5
450 2.81
500 3.13
550 3.44
600 3.75
a "lowly" 350 rwhp FD is creating more power per displacement than the average Supercar. consider what the Supercar has going for it: a combustion chamber created on a supercomputer so as to promote extremely efficient combustion.. (we have a long bath tub), extremely sophisticated/OE type ecu that anticipates (as in advance) detonation etc etc, FOUR CYCLE architecture as in every other TDC is a cooling cycle (we don't have that), big dollar 21st century hardware engineering -titanium rods etc etc. (we don't have that).
what we do have is an engine that, thanks to no valves and wonderful ports, outflows all of them. bolt on a turbo and it is really (too) easy to make tons of power.
Mazda stopped at 217 rwhp. our lowly 350 number is 61% more yet all of us consider this to be close to stock. not at all.
fortunately, over the 30 years since the FD emerged and w the advent of the internet proper paths have been forged.
but the key is you have to appreciate that no matter what power level you decide to visit there are certain things that must be done or you will have a motor needing repair.
many of the newer ECUs feature active knock response. Required. do you have it? is it enabled? at a certain knock level timing goes to zero. motor saved. i know because i have been there.
are you running AI? oh you don't need it as you are "only" making 350 hp. (see above)
i could get into IATs, my favorite subject, maybe another time.
getting back to the poor old apex seals, any brand, they are the scapegoat in this demanding chain of hardware-software. they actually are the victim.
this motor, while not necessarily representative of all apex seal situations, proves it clearly.
there is something existant in the rear rotor system that overheated the rear apex seals. overheat ANY apex seal and it will fail.
FWIW, I-Seals are my first choice and are in my new personal motor. one of the things that really caught my attention was the appearance of the apex seal crowns from this motor. unlike any seals i have seen other than OE. kind of a chromey shine with a total absence of micro pockmarks. clearly there is something special going on on the business end of these seals... again similar to OE... yet without the OE problem of tip breakage on detonation.
while I-Seals are my choice and recommendation i have used and would have no problem w REC, RXparts, E&J, and Goopy. i do not recommend Atkins due to tendency to break and an easily worn crown and OE simply because of breakage. the OE is awesome in certain narrow apps.
often, there are few easy answers...
not an answer: "broke apex seal A so switching to B."
in this particular motor the owner must I D and fix something that overheated the seal.
our motors, all our motors, are high strung thoroughbreds.
they will reward those who take them seriously and cause heartache to those who don't.
respect.
i was able to disassemble the motor last week. prior to disassembly i did a comp test. the front was approx 115 and the rear was 62. there was no more than 3 psi variance on all 3 faces of each rotor. the corner seal springs were all at .17+ so no detonation.
the front 3 apex seals were Perfect... as in the best looking seals i have ever taken out of an engine that has been run. dead straight, beautiful crowns with zero pitting, zero ledging. all three
the rear 3 apex seals are (all) warped .003. they have ledging on both the leading and trailing edge of the crown. they show burned hydrocarbon on the upper sides next to the crown. lack of lube caused the heat which caused the ledging. solve the lube lack, solve the motor.
the actual analysis of condition of the apex seals without question removes the apex seal itself as the culprit for the motor failure. it also takes the timing mistake w the split out of the picture since the front rotor is perfect.
of course there is something seriously amiss here but it isn't the apex seals.
it has always been my contention that in 95% of the warped apex seal stories it is not the fault of the apex seal, rather it is heat and/or pressure that should not exist in a properly fixtured and tuned system. i am continuously blown away by the lack of appreciation for the amount of combustion chamber heat and pressure our 2 cycle rotaries generate. everything has to be right. 22 seasons of real racing taught me you do not ever do something 95%. the 5% will bite you.
i purposely spend too much time on my website making this point... executive summary for you:
examining 9 of the top power 2018 Supercars for rear wheel horsepower per cubic inch
average is 1.91 hp/cu inch
comparing to our 13BREW:
350 rwhp 2.19!!
400 2.5
450 2.81
500 3.13
550 3.44
600 3.75
a "lowly" 350 rwhp FD is creating more power per displacement than the average Supercar. consider what the Supercar has going for it: a combustion chamber created on a supercomputer so as to promote extremely efficient combustion.. (we have a long bath tub), extremely sophisticated/OE type ecu that anticipates (as in advance) detonation etc etc, FOUR CYCLE architecture as in every other TDC is a cooling cycle (we don't have that), big dollar 21st century hardware engineering -titanium rods etc etc. (we don't have that).
what we do have is an engine that, thanks to no valves and wonderful ports, outflows all of them. bolt on a turbo and it is really (too) easy to make tons of power.
Mazda stopped at 217 rwhp. our lowly 350 number is 61% more yet all of us consider this to be close to stock. not at all.
fortunately, over the 30 years since the FD emerged and w the advent of the internet proper paths have been forged.
but the key is you have to appreciate that no matter what power level you decide to visit there are certain things that must be done or you will have a motor needing repair.
many of the newer ECUs feature active knock response. Required. do you have it? is it enabled? at a certain knock level timing goes to zero. motor saved. i know because i have been there.
are you running AI? oh you don't need it as you are "only" making 350 hp. (see above)
i could get into IATs, my favorite subject, maybe another time.
getting back to the poor old apex seals, any brand, they are the scapegoat in this demanding chain of hardware-software. they actually are the victim.
this motor, while not necessarily representative of all apex seal situations, proves it clearly.
there is something existant in the rear rotor system that overheated the rear apex seals. overheat ANY apex seal and it will fail.
FWIW, I-Seals are my first choice and are in my new personal motor. one of the things that really caught my attention was the appearance of the apex seal crowns from this motor. unlike any seals i have seen other than OE. kind of a chromey shine with a total absence of micro pockmarks. clearly there is something special going on on the business end of these seals... again similar to OE... yet without the OE problem of tip breakage on detonation.
while I-Seals are my choice and recommendation i have used and would have no problem w REC, RXparts, E&J, and Goopy. i do not recommend Atkins due to tendency to break and an easily worn crown and OE simply because of breakage. the OE is awesome in certain narrow apps.
often, there are few easy answers...
not an answer: "broke apex seal A so switching to B."
in this particular motor the owner must I D and fix something that overheated the seal.
our motors, all our motors, are high strung thoroughbreds.
they will reward those who take them seriously and cause heartache to those who don't.
respect.
Last edited by Howard Coleman; 01-17-23 at 06:18 AM.
01-16-23, 03:51 PM
#12
Rear rotor hot condition should have been illustrated with monitored EGT's correct? We did correct fueling quite a bit front and rear rotors with the haltech due to EGT discrepancies. Excessive heat to the LIM could be another factor but OEM twins and many single builds I see have terrible heat shielding to correlate with this. Mind you, I too am in the warped seal club.
01-16-23, 04:38 PM
#14
Racing Rotary Since 1983
iTrader: (6)
""fuel cut off is a NONO if u dint have an OMP?"
yes, you can warp seals in literally a few minutes. easy way to check is when you go off throttle your AFRs should read 9 to 13. if they read 20 you will be heading for a rebuild. (assuming no EOP)
"Rear rotor hot condition should have been illustrated with monitored EGT's correct?"
no. EGTs relate to combustion temps. you can have good egts and not be lubing your apex seal.
yes, you can warp seals in literally a few minutes. easy way to check is when you go off throttle your AFRs should read 9 to 13. if they read 20 you will be heading for a rebuild. (assuming no EOP)
"Rear rotor hot condition should have been illustrated with monitored EGT's correct?"
no. EGTs relate to combustion temps. you can have good egts and not be lubing your apex seal.
Last edited by Howard Coleman; 01-16-23 at 04:45 PM.
01-17-23, 03:17 PM
#15
""fuel cut off is a NONO if u dint have an OMP?"
yes, you can warp seals in literally a few minutes. easy way to check is when you go off throttle your AFRs should read 9 to 13. if they read 20 you will be heading for a rebuild. (assuming no EOP)
"Rear rotor hot condition should have been illustrated with monitored EGT's correct?"
no. EGTs relate to combustion temps. you can have good egts and not be lubing your apex seal.
yes, you can warp seals in literally a few minutes. easy way to check is when you go off throttle your AFRs should read 9 to 13. if they read 20 you will be heading for a rebuild. (assuming no EOP)
"Rear rotor hot condition should have been illustrated with monitored EGT's correct?"
no. EGTs relate to combustion temps. you can have good egts and not be lubing your apex seal.
For reference my original built motor with ALS seals did last 10+ years of hard use, including many track days mostly without water/meth injection. Working OMP with either no premix or occassional 0.5oz/gallon premix. Housings did show signs of some inadequate lubrication yet no warpage.
01-24-23, 08:38 PM
#16
Hello to everyone,
In particular Howard Colleman. Glad to see you are still at it, and a prominent figure in the board.
Been +/- 10 yrs. since my last post as an active member. Guess I reached that point in life were it just wasn't for me. No need to elaborate further.
Reason for this indulgence is several guys have reached out to me for my take on this matter.
For one, I've only experienced this issue 1 time back in '94 with a brand new freshly bought yellow Fd R-1 with only 800 miles on the clock.
Belonged to a local narco, who dropped the car off for a money no object build. Objective was 500+ daily driver with A/C and all power equipment a MUST !.
Took 4 attempts at getting it right and nearly a year before success on the 5th try.
Anyways, What I learned from that exercise:
a) This was a heat related problem specific to the rear Rotor.
b) OEM Apex Seals. Back in those days, no other choice for Steel Seals except Hurley out of England, plus I had no experience with them, so No Need to add another
UN-Known variable.
c) There was a Fuel Cut on #2 at 12psi or higher on the stock ECU. One I figured out a fix to delete.
Given upgrades:
I tried everything I new at the time to figure out what was happening.
This was THE very first Single Turbo in the country. No aftermarket kit's at the time.
2 Guys from GReedy flew down to Miami to have a look at the car.
Upgrades included:
Larger injectors from the get GO. 2x Supra Fuel Pumps. Custom Built Copper Radiator, Custom built IC. sized to fit between frame rails., Large Oil Coolers. Again size maxed out for available space. After market front bumper to maximize coolers space and ducting. External Oil Supply, (a race secret at the time), and what ever else I can't remember from 30 years back.
Same issues:
Broken Seals, Damaged Housings, Damaged Rotors, 1 blown Turbo from Apex flying out into Turbine. Nothing worked until the final analysis by process of elimination.
Mind you, through out the rebuilds I did major modifications.
All showed promise but still fell short of the goal.
- Machined Rotors for 3mm and used OE Seals from GSL-SE. Still broke.
- Dropped compression from Fd to S4. An obvious upgrade as all Turbo engines I had built to date were Low Comp. This had to work ! Right ? No Cigar.
My Daily was a Dave Kent Wide Body 7 left over from my IMSA GT-U days 12 inch wide Yocas AVS on 16" Epsilons. Turbo 6P block, Long Runner Custom Intake Blowing though a Weber Sidedraft and 4 additional Injectors via HKS AIC. for when on Boost, 20psi on 93 pump and 440 wheel with nearly same Torque. mind you, built this car in '87, and was Reliable as a Swiss Watch.
So the Low Comp thick wall Rotors with EFI should have been the answer ? NOT.
- Upgraded Fuel Line diameter to -10 from Surge Tank. forward .... Failed again.
Was not until walked away to analyze by build by process of elimination and function.
While scratching my head for what "COULD" cause this repeating problem, before the light turned on.
Mind you, my shop was in South Florida were it is scorching hot all year round.
The only Tell Tail Witness Mark (besides the physical damage of parts) was a full circle band of black gummy oily sud all the way around the circumference of the Rotor Housing's Trochoid Surface.
Like a long tacky skid mark all the way around the housing's surface.
Before Catastrophic damage occurred, as someone stated, car would be near impossible to start when HOT.
Hour later, or following morning car would start right up and run as hard as ever before performance began to drop off. Obviously Seals wrapped. Pull engine, take apart, and the perpetual black band all the way around in the center of the Housing. Reason why engine would start on tap when cold was because the circular band of the Oil/Carbon sud would get hard enough when cooled that the Apex seals could slide on and build compression.
This happened on every rebuild back to back until figured out the cause.
Now on to the subject of the I-Rotary Seals. ....
NOTE: I am a firm believer of eliminating any and all variables and focus exclusively on the
WITNESS MARKS. Damaged parts are the Symptoms, not the Cause. There is always something that is left behind. Sometimes it's obvious. Sometimes its not, Sometimes it's overlooked, passed by and taken for granted as part of the damage. That's why their called "Witness Marks"
By process of elimination, the issues these guys are having clearly shows it is NOT the I-Rotary Seals.
- If it didn't happen on the Front Rotor, by default CANNOT be the Seals as they were both exposed to the same conditions at the same time. ... PERIOD.
- It can not be a bad batch because again warpage would have manifested on both Rotors.
- Cannot be from lack of Premix because problem persist (with this small group of guys) regardless of amount of premix used. A little or a lot. Same issue.
- Since the I-Rotary Seal was introduced, well over 2 Thousand (2,000+) sets of seals have been sold world wide. Only less than 2 hands full of guys have this problem. What is the COMMON DENOMINATOR ?
Simple math equates to less than 0.005% of users have this issue.
Can you guys pronounce that ? Five One-Thousands of 1 percent. ... Seriously ???
Yes, their IS a common denominator, and it's NOT the I-Rotary Seals.
Through the years, I've used and kept notes on every Apex Seal that has come and gone.
IMHO, Nothing else comes close in compression or longevity.
It is very easy to point the finger and pass blame.
Way toooo many external factors at building Big Power Rotaries.
Reason why few are successful and World Renowned and the many are Not.
Lets assume these boys "assemble" the PERFECT engine, with everything brand new. Everything.
I say "Assemble" because from my point of view, 90%+ of engine guys today are assemblers. Not Builders. Everything from port work to Rotor machining is sent out.
Balancing is another subject. Has to be send out because it requires specialized equipment and Knowledge. Lots of it. Majority of my latter work has been correcting other shops balance work,
Today even the butcher at the local Supermarket is a Rotary Engine Balancing Expert.
For argument's sake, Lets eliminate the engine it's self and just look at outside variables,
Parts, People and Shops, Things normally taken for granted.
- Tuner,
- Exhaust Manifold and back pressure,
- Turbine sizing
- Engine Management
- Sensors, and Injector calibration.
- All Coolers Duct Work.
- Water Pump. (My Favorate)
- Even collapsing Hoses under engine acceleration.
All these factors by default are even MORE Important that the engine it's self.
- A good Tune, makes a mediocre engine run good and live long. On the other hand a mediocre Tune makes the very best engine run crappy and short lived.
- A poorly designed Ext. Manifold can adversely effect back pressure on one Rotor, and not the other.
- Too tight a Turbine Housing will choke the engine and elevate back pressure and EGT's
- Engine Managemet can and will have a mirage of influences on performance and reliability.
- Sensor and Injector calibration is HUGE factor. If ECU is not calibrated to Sensors and Injectors the Tune is GARBAGE.
- Heat Exchanger efficiency is governed by the Ducting, Radiator, Oil Coolers, or IC. Don't matter.
Ducting is more important than physical size of coolers themselves. The biggest, baddest coolers won't do squat if ducting is not functional mainly on extracting heated Air. For those who don't know: Duct outlet is far more important than inlet. At speed, Air will "get in" by the sheer force of vehicle velocity, i will get in. If trapped, and cant get the heat out, might as well not have coolers
- Water Pump. I say my favorite because it is the single most overlooked part of the puzzle and taken for granted. The Water Pump is responsible for the life of the engine under EVER CHANGING and STRESSED conditions. The Water Pump has to be matched to Thermal Loads in both capacity and Flow . Every Impeller of any type ie: V-8, Rotary, Boat, Turbo Charger, Does NOT matter. Has an operating range in witch maximum efficiency is generated. Too Slow and not enough GPM, Too Fast, goes into Cavitation. When Cavitation occurs in a cooling system, Catastrophe follows.
This ideal speed range is called the "Sweet Spot"
- Less than 1% of all engine builds I've seen in my 38 yrs.+ as a racer, builder, competitor, and supplier have a correct Drive ratio for Impeller Diameter, so to generate maximum Flow in GPM @ WOT. without over spinning and induce cavitation. All these Pretty Anodized Pulley Kits all over-spin WP's near engine red line. See were I'm going ?
Rotary engines have the worst surface to volume ration of ANY Internal Combustion Engine. Couple that with a 60 yr old cooling system designed for roughly 160 Hp.
Today we constantly DEMAND 3 to 5 times and more cooling from the same capacity and effective efficiency. So something needs to compensate and take up the slack.
It is IMPERATIVE to have the WP working at max efficiency @ WOT. and Thermal Load.
Electric WP's do a poor job of scrubbing away the boundary layer of coolant from the Rotor Housings particularly at the times when most heat is being generated. Electric WP's run fairly constant Flow vs. a correctly driven mechanical WP will respond by increase pressure and flow exactly when required by Speed and Load.
Electric WP's provide superior circulation at steady stage use. Highway and idle. in essence when great floe really is not needed. They DON'T offer the sudden Flow changes in volume required to SCRUB AWAY the tiny Air Bubbles that live in the pitted Water Jacket and little holes witch form in the Calcified Matter and debris that builds up on Water Jacket passages. These tiny Bubbles will live there un-disrupted for months at a time. Then suddenly one goes to the Dyno and does 5-7 pulls back to back at full throttle and boost. Engine block expands and contracts, these bubbles suddenly detach and migrate. Grow and travel. Eventually they travel to the WP's impeller. and if large enough, at this point the Impeller cavitates.
Entered a Thermal Runaway condition, were temperature flash and coolant will BOIL.
On extreme high boost racing engines I use both Mechanical and Electric Wp's. Each with their own specific job. They work together but perform, totally different functions on different areas of the block complementing each others strengths.
On Rotaries, there are 3 very specific sports were extreme heat is generated. 1st spot is just below the Leading Spark plugs. 2nd is right around the Exhaust Port. 3rd. is the Blowdown area between the (L) plug, and the Exhaust Ports. Localized Hot Spots are at their highest just below the (L) Plug. Hot enough to deform, and melt the Housing and crack / exfoliate the Chrome. Same but not quite as hot at and around the Exhaust Port, This is why it is SO IMPORTANT to Chanfer with large heavy Radius the closing edge of the Exhaust Port.
Under heavy Boost and Thermal load, both the vicinity around the Plugs and the Exhaust Ports deform sufficiently at the surface to cause the Apex seal to separate from the Housing. Anyone who's opened a few race engines has seen the witness marks emanating horizontally on both sides of the plugs, and on the closing edge of the exhaust port.
These 2 spots, combined with the Blowdown area between them hold sufficient surface heat that conduction into the Seal to is inevitable and absorbs the heat from the surface and naturally expands and grows while physically contained by the side Irons. Once it tries to grow it Bows because it cannot grow length wise, then when cooled remains warped.
If you look closely at the trailing edge (closing) of the exhaust ports, when ever experience a warped Apex Seal, you will see a matching mark on the top of the exhaust port. A simple explanation is the Seal TRIPS over the inward deformity at the top of the port. Like tripping over a side walk leaves a scrape on your shoe. In the unfortunate case when it happens take a close look.
________
Fuel Cut and it's effects on Rotaries.
Having come from a life of endurance racing, Fuel Cutting is a standard practice on race cars. Road Race, Endurance, Sprints, Club racing, Pro-Racing, What ever. All CIRCUIT Racing.
This has long been a Standard practice in road racing to save fuel. Fuel Stops are a critical strategy in road racing in general. Be it Sprints like in F1 or 24Hr. events as in IMSA and Le Mans.
It has NO PLACE in Street use or Drag Racing. We did it on Road Race cars with Iannetti Ceramic Seals because of of the none existing coefficient of friction, and before that we got away with it on Carbon Seals because of their self lubricating properties.
Just because the ECU offers the feature, It's not a requirement to use. Those who claim they know how to tune Rotaries, should know NOT to use this feature just because it's there.
There is no benefit. On the contrary. Fuel on De-Cell COOLS internals and washes surface heat away.
There is no lubrication of internals while under Fuel Cut condition.
Worse Case of fuel Cut is Off Throttle Overrun. Particularly in single drum Dynos like DynoJets
The sheer Inertia stored in these drums multiplied by the weight and rotational speed is enough to keep the engines spinning for over a minute from Full Boost @ WOT to Full Vacuum, Zero lubrication of Internals while PUSHED against engine rotational drag. Imagine the Friction of the Apex Seals against a SCORCHING HOT Surface ? Yes. Anyone can see how any seal will warp under these conditions. Reason why I harp on Water Pumps and Drive Speed to quickly scrub heat from surface.
Back in the early IMSA days, on Carburators, No EFI we used to run very large idle jets just to cool the Carbon Seals and internals to last a full 24 hours. The Carbon seals would wear at a rate of 0.004" per hour. By the 2/3 mark, engines literally had not enough spring tension to re-start. So we kept them running even of Fuel Stops ! ... Glory Days !!
Guys, I've spent way too long on this email.
Partly why I said at the top it was not really for me anymore.
In all my years of Racing, building, traveling all over the world, experiencing first hand success and failures, everything imaginable, the world of Drag Racers, the damage those guys produce. and the in between Street Racers. Honestly I believe I've seen and worked on the greater scope of set ups from every discipline than most. Well, not all. No Rallying or Mud, but most in the industry if not all. Everything from Street Racers to Pro-Import Drag Racers, to Professional and Club Club Racers. Here and abroad.
Because of these experiences and exposures I've seen the limits more often that not.
Lets stop blaming un-knows and instead dig deeper for answers. If not, I guarantee the same will repeat it's self.
Regards to all.
- 'c
In particular Howard Colleman. Glad to see you are still at it, and a prominent figure in the board.
Been +/- 10 yrs. since my last post as an active member. Guess I reached that point in life were it just wasn't for me. No need to elaborate further.
Reason for this indulgence is several guys have reached out to me for my take on this matter.
For one, I've only experienced this issue 1 time back in '94 with a brand new freshly bought yellow Fd R-1 with only 800 miles on the clock.
Belonged to a local narco, who dropped the car off for a money no object build. Objective was 500+ daily driver with A/C and all power equipment a MUST !.
Took 4 attempts at getting it right and nearly a year before success on the 5th try.
Anyways, What I learned from that exercise:
a) This was a heat related problem specific to the rear Rotor.
b) OEM Apex Seals. Back in those days, no other choice for Steel Seals except Hurley out of England, plus I had no experience with them, so No Need to add another
UN-Known variable.
c) There was a Fuel Cut on #2 at 12psi or higher on the stock ECU. One I figured out a fix to delete.
Given upgrades:
I tried everything I new at the time to figure out what was happening.
This was THE very first Single Turbo in the country. No aftermarket kit's at the time.
2 Guys from GReedy flew down to Miami to have a look at the car.
Upgrades included:
Larger injectors from the get GO. 2x Supra Fuel Pumps. Custom Built Copper Radiator, Custom built IC. sized to fit between frame rails., Large Oil Coolers. Again size maxed out for available space. After market front bumper to maximize coolers space and ducting. External Oil Supply, (a race secret at the time), and what ever else I can't remember from 30 years back.
Same issues:
Broken Seals, Damaged Housings, Damaged Rotors, 1 blown Turbo from Apex flying out into Turbine. Nothing worked until the final analysis by process of elimination.
Mind you, through out the rebuilds I did major modifications.
All showed promise but still fell short of the goal.
- Machined Rotors for 3mm and used OE Seals from GSL-SE. Still broke.
- Dropped compression from Fd to S4. An obvious upgrade as all Turbo engines I had built to date were Low Comp. This had to work ! Right ? No Cigar.
My Daily was a Dave Kent Wide Body 7 left over from my IMSA GT-U days 12 inch wide Yocas AVS on 16" Epsilons. Turbo 6P block, Long Runner Custom Intake Blowing though a Weber Sidedraft and 4 additional Injectors via HKS AIC. for when on Boost, 20psi on 93 pump and 440 wheel with nearly same Torque. mind you, built this car in '87, and was Reliable as a Swiss Watch.
So the Low Comp thick wall Rotors with EFI should have been the answer ? NOT.
- Upgraded Fuel Line diameter to -10 from Surge Tank. forward .... Failed again.
Was not until walked away to analyze by build by process of elimination and function.
While scratching my head for what "COULD" cause this repeating problem, before the light turned on.
Mind you, my shop was in South Florida were it is scorching hot all year round.
The only Tell Tail Witness Mark (besides the physical damage of parts) was a full circle band of black gummy oily sud all the way around the circumference of the Rotor Housing's Trochoid Surface.
Like a long tacky skid mark all the way around the housing's surface.
Before Catastrophic damage occurred, as someone stated, car would be near impossible to start when HOT.
Hour later, or following morning car would start right up and run as hard as ever before performance began to drop off. Obviously Seals wrapped. Pull engine, take apart, and the perpetual black band all the way around in the center of the Housing. Reason why engine would start on tap when cold was because the circular band of the Oil/Carbon sud would get hard enough when cooled that the Apex seals could slide on and build compression.
This happened on every rebuild back to back until figured out the cause.
Now on to the subject of the I-Rotary Seals. ....
NOTE: I am a firm believer of eliminating any and all variables and focus exclusively on the
WITNESS MARKS. Damaged parts are the Symptoms, not the Cause. There is always something that is left behind. Sometimes it's obvious. Sometimes its not, Sometimes it's overlooked, passed by and taken for granted as part of the damage. That's why their called "Witness Marks"
By process of elimination, the issues these guys are having clearly shows it is NOT the I-Rotary Seals.
- If it didn't happen on the Front Rotor, by default CANNOT be the Seals as they were both exposed to the same conditions at the same time. ... PERIOD.
- It can not be a bad batch because again warpage would have manifested on both Rotors.
- Cannot be from lack of Premix because problem persist (with this small group of guys) regardless of amount of premix used. A little or a lot. Same issue.
- Since the I-Rotary Seal was introduced, well over 2 Thousand (2,000+) sets of seals have been sold world wide. Only less than 2 hands full of guys have this problem. What is the COMMON DENOMINATOR ?
Simple math equates to less than 0.005% of users have this issue.
Can you guys pronounce that ? Five One-Thousands of 1 percent. ... Seriously ???
Yes, their IS a common denominator, and it's NOT the I-Rotary Seals.
Through the years, I've used and kept notes on every Apex Seal that has come and gone.
IMHO, Nothing else comes close in compression or longevity.
It is very easy to point the finger and pass blame.
Way toooo many external factors at building Big Power Rotaries.
Reason why few are successful and World Renowned and the many are Not.
Lets assume these boys "assemble" the PERFECT engine, with everything brand new. Everything.
I say "Assemble" because from my point of view, 90%+ of engine guys today are assemblers. Not Builders. Everything from port work to Rotor machining is sent out.
Balancing is another subject. Has to be send out because it requires specialized equipment and Knowledge. Lots of it. Majority of my latter work has been correcting other shops balance work,
Today even the butcher at the local Supermarket is a Rotary Engine Balancing Expert.
For argument's sake, Lets eliminate the engine it's self and just look at outside variables,
Parts, People and Shops, Things normally taken for granted.
- Tuner,
- Exhaust Manifold and back pressure,
- Turbine sizing
- Engine Management
- Sensors, and Injector calibration.
- All Coolers Duct Work.
- Water Pump. (My Favorate)
- Even collapsing Hoses under engine acceleration.
All these factors by default are even MORE Important that the engine it's self.
- A good Tune, makes a mediocre engine run good and live long. On the other hand a mediocre Tune makes the very best engine run crappy and short lived.
- A poorly designed Ext. Manifold can adversely effect back pressure on one Rotor, and not the other.
- Too tight a Turbine Housing will choke the engine and elevate back pressure and EGT's
- Engine Managemet can and will have a mirage of influences on performance and reliability.
- Sensor and Injector calibration is HUGE factor. If ECU is not calibrated to Sensors and Injectors the Tune is GARBAGE.
- Heat Exchanger efficiency is governed by the Ducting, Radiator, Oil Coolers, or IC. Don't matter.
Ducting is more important than physical size of coolers themselves. The biggest, baddest coolers won't do squat if ducting is not functional mainly on extracting heated Air. For those who don't know: Duct outlet is far more important than inlet. At speed, Air will "get in" by the sheer force of vehicle velocity, i will get in. If trapped, and cant get the heat out, might as well not have coolers
- Water Pump. I say my favorite because it is the single most overlooked part of the puzzle and taken for granted. The Water Pump is responsible for the life of the engine under EVER CHANGING and STRESSED conditions. The Water Pump has to be matched to Thermal Loads in both capacity and Flow . Every Impeller of any type ie: V-8, Rotary, Boat, Turbo Charger, Does NOT matter. Has an operating range in witch maximum efficiency is generated. Too Slow and not enough GPM, Too Fast, goes into Cavitation. When Cavitation occurs in a cooling system, Catastrophe follows.
This ideal speed range is called the "Sweet Spot"
- Less than 1% of all engine builds I've seen in my 38 yrs.+ as a racer, builder, competitor, and supplier have a correct Drive ratio for Impeller Diameter, so to generate maximum Flow in GPM @ WOT. without over spinning and induce cavitation. All these Pretty Anodized Pulley Kits all over-spin WP's near engine red line. See were I'm going ?
Rotary engines have the worst surface to volume ration of ANY Internal Combustion Engine. Couple that with a 60 yr old cooling system designed for roughly 160 Hp.
Today we constantly DEMAND 3 to 5 times and more cooling from the same capacity and effective efficiency. So something needs to compensate and take up the slack.
It is IMPERATIVE to have the WP working at max efficiency @ WOT. and Thermal Load.
Electric WP's do a poor job of scrubbing away the boundary layer of coolant from the Rotor Housings particularly at the times when most heat is being generated. Electric WP's run fairly constant Flow vs. a correctly driven mechanical WP will respond by increase pressure and flow exactly when required by Speed and Load.
Electric WP's provide superior circulation at steady stage use. Highway and idle. in essence when great floe really is not needed. They DON'T offer the sudden Flow changes in volume required to SCRUB AWAY the tiny Air Bubbles that live in the pitted Water Jacket and little holes witch form in the Calcified Matter and debris that builds up on Water Jacket passages. These tiny Bubbles will live there un-disrupted for months at a time. Then suddenly one goes to the Dyno and does 5-7 pulls back to back at full throttle and boost. Engine block expands and contracts, these bubbles suddenly detach and migrate. Grow and travel. Eventually they travel to the WP's impeller. and if large enough, at this point the Impeller cavitates.
Entered a Thermal Runaway condition, were temperature flash and coolant will BOIL.
On extreme high boost racing engines I use both Mechanical and Electric Wp's. Each with their own specific job. They work together but perform, totally different functions on different areas of the block complementing each others strengths.
On Rotaries, there are 3 very specific sports were extreme heat is generated. 1st spot is just below the Leading Spark plugs. 2nd is right around the Exhaust Port. 3rd. is the Blowdown area between the (L) plug, and the Exhaust Ports. Localized Hot Spots are at their highest just below the (L) Plug. Hot enough to deform, and melt the Housing and crack / exfoliate the Chrome. Same but not quite as hot at and around the Exhaust Port, This is why it is SO IMPORTANT to Chanfer with large heavy Radius the closing edge of the Exhaust Port.
Under heavy Boost and Thermal load, both the vicinity around the Plugs and the Exhaust Ports deform sufficiently at the surface to cause the Apex seal to separate from the Housing. Anyone who's opened a few race engines has seen the witness marks emanating horizontally on both sides of the plugs, and on the closing edge of the exhaust port.
These 2 spots, combined with the Blowdown area between them hold sufficient surface heat that conduction into the Seal to is inevitable and absorbs the heat from the surface and naturally expands and grows while physically contained by the side Irons. Once it tries to grow it Bows because it cannot grow length wise, then when cooled remains warped.
If you look closely at the trailing edge (closing) of the exhaust ports, when ever experience a warped Apex Seal, you will see a matching mark on the top of the exhaust port. A simple explanation is the Seal TRIPS over the inward deformity at the top of the port. Like tripping over a side walk leaves a scrape on your shoe. In the unfortunate case when it happens take a close look.
________
Fuel Cut and it's effects on Rotaries.
Having come from a life of endurance racing, Fuel Cutting is a standard practice on race cars. Road Race, Endurance, Sprints, Club racing, Pro-Racing, What ever. All CIRCUIT Racing.
This has long been a Standard practice in road racing to save fuel. Fuel Stops are a critical strategy in road racing in general. Be it Sprints like in F1 or 24Hr. events as in IMSA and Le Mans.
It has NO PLACE in Street use or Drag Racing. We did it on Road Race cars with Iannetti Ceramic Seals because of of the none existing coefficient of friction, and before that we got away with it on Carbon Seals because of their self lubricating properties.
Just because the ECU offers the feature, It's not a requirement to use. Those who claim they know how to tune Rotaries, should know NOT to use this feature just because it's there.
There is no benefit. On the contrary. Fuel on De-Cell COOLS internals and washes surface heat away.
There is no lubrication of internals while under Fuel Cut condition.
Worse Case of fuel Cut is Off Throttle Overrun. Particularly in single drum Dynos like DynoJets
The sheer Inertia stored in these drums multiplied by the weight and rotational speed is enough to keep the engines spinning for over a minute from Full Boost @ WOT to Full Vacuum, Zero lubrication of Internals while PUSHED against engine rotational drag. Imagine the Friction of the Apex Seals against a SCORCHING HOT Surface ? Yes. Anyone can see how any seal will warp under these conditions. Reason why I harp on Water Pumps and Drive Speed to quickly scrub heat from surface.
Back in the early IMSA days, on Carburators, No EFI we used to run very large idle jets just to cool the Carbon Seals and internals to last a full 24 hours. The Carbon seals would wear at a rate of 0.004" per hour. By the 2/3 mark, engines literally had not enough spring tension to re-start. So we kept them running even of Fuel Stops ! ... Glory Days !!
Guys, I've spent way too long on this email.
Partly why I said at the top it was not really for me anymore.
In all my years of Racing, building, traveling all over the world, experiencing first hand success and failures, everything imaginable, the world of Drag Racers, the damage those guys produce. and the in between Street Racers. Honestly I believe I've seen and worked on the greater scope of set ups from every discipline than most. Well, not all. No Rallying or Mud, but most in the industry if not all. Everything from Street Racers to Pro-Import Drag Racers, to Professional and Club Club Racers. Here and abroad.
Because of these experiences and exposures I've seen the limits more often that not.
Lets stop blaming un-knows and instead dig deeper for answers. If not, I guarantee the same will repeat it's self.
Regards to all.
- 'c
Last edited by GT1-20b; 01-25-23 at 01:12 PM.
The following 10 users liked this post by GT1-20b:
Carlos Iglesias (01-25-23),
cone_crushr (01-25-23),
DaveW (01-25-23),
Esser (01-25-23),
gracer7-rx7 (01-25-23),
and 5 others liked this post.
01-25-23, 07:07 AM
#18
Racing Rotary Since 1983
iTrader: (6)
Thank You for such a valuable post.
witness marks certainly point us in the right direction. my greatest frustration is the lateral marker at the close of the exhaust port. i have purposely never touched the close as i wanted to not increase overlap at the exhaust and i assumed the factory had attempted to do the very best as to the radius so as to decrease the inevitable lift. is there anything that can be done? no doubt the chatter marks after the close towards the top of the housing come not only from lift at the plugs but also at the exhaust close.
loved your comments about the need for exhaust flow out of the intercooler as well as engine coolant flow issue.
it is all about heat. .
witness marks certainly point us in the right direction. my greatest frustration is the lateral marker at the close of the exhaust port. i have purposely never touched the close as i wanted to not increase overlap at the exhaust and i assumed the factory had attempted to do the very best as to the radius so as to decrease the inevitable lift. is there anything that can be done? no doubt the chatter marks after the close towards the top of the housing come not only from lift at the plugs but also at the exhaust close.
loved your comments about the need for exhaust flow out of the intercooler as well as engine coolant flow issue.
it is all about heat. .
The following users liked this post:
DaveW (01-25-23)
01-25-23, 08:23 AM
#19
I like the part about the water pump being your favorite. Very interesting.
With todays technology though, can't one use a electric water pump and map control it via the ECU for RPM vs flow. That should effectively provide the rate change a mechanical water pump provides but also the benefits of electric.
With todays technology though, can't one use a electric water pump and map control it via the ECU for RPM vs flow. That should effectively provide the rate change a mechanical water pump provides but also the benefits of electric.
The following users liked this post:
DaveW (01-25-23)
01-25-23, 10:53 AM
#20
Racecar - Formula 2000
This relates to some things I have said in this and other forums:
Effective cooling at max power and RPM relies on keeping the coolant temperature as constant as possible throughout its entire flow path, i.e., into and out of the engine, into and out of the radiators. This means obtaining the highest coolant velocity possible w/o cavitation, either at the pump, or inside the engine at convoluted flow areas. So, high flow, and, if necessary, higher coolant pressures to prevent cavitation.
Effective cooling at max power and RPM relies on keeping the coolant temperature as constant as possible throughout its entire flow path, i.e., into and out of the engine, into and out of the radiators. This means obtaining the highest coolant velocity possible w/o cavitation, either at the pump, or inside the engine at convoluted flow areas. So, high flow, and, if necessary, higher coolant pressures to prevent cavitation.
Last edited by DaveW; 01-25-23 at 11:07 AM.
01-25-23, 11:15 AM
#21
Racing Rotary Since 1983
iTrader: (6)
cavitation is the name of the game for the water pump impeller. i don't think the same amount of engineering was applied to our impellers as to the suspension. maybe the accountants designed the impeller. Rick Engman fixed that. you can too by calling Mazmart.
Last edited by Howard Coleman; 01-28-23 at 08:56 AM.
The following users liked this post:
gracer7-rx7 (01-25-23)
01-25-23, 12:11 PM
#22
Rotor or no motor
iTrader: (24)
I put the oem waterpump back on and all my problems are gone. I had no cooling issues before i installed the "upgraded" pump and i have no cooling issues after removing it.
I reached out to MazMart to explain the situation and perhaps send it back to them to inspect it but yeah i was completely ignored which only adds salt to injury .
01-25-23, 12:23 PM
#23
I still don't understand why EWP would be a problem. Maybe a long time ago with older pumps and limited ecu, but you can get a nice OEM BMW pump which flows boatloads of water, and then variably control vs RPM and/or temperature it if there are issues like mentioned above regarding constant flow.
The following users liked this post:
R-R-Rx7 (01-25-23)
01-25-23, 01:14 PM
#24
I still don't understand why EWP would be a problem. Maybe a long time ago with older pumps and limited ecu, but you can get a nice OEM BMW pump which flows boatloads of water, and then variably control vs RPM and/or temperature it if there are issues like mentioned above regarding constant flow.
With modern engine management systems, EWP control is basically a non-issue. Even the most basic ECU boxes offer 3D table control (e.g. RPM + coolant temp or coolant pressure or other variable) to PWM control a pump motor. Some offer 4D or 5D control for even more flexibility. And if you're concerned about electrical failures (e.g., say the alternator fails to produce enough juice to run EWP) or mechanical failures (e.g., blow a coolant hose), it would be pretty easy to integrate fail-safe engine protection strategies right into the EWP controls.
Last edited by Pete_89T2; 01-25-23 at 01:53 PM.
The following users liked this post:
R-R-Rx7 (01-25-23)
01-25-23, 02:56 PM
#25
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,835
Received 2,603 Likes
on
1,847 Posts
^Agree, the only negative points I see today for a EWP setup is extra costs associated with it, the additional electrical load it would put on the car's electrical system and sourcing a pump motor that has proven OEM level reliability (i.e., finding a maker that will warranty it to last at least 100K miles under continuous duty operation).
With modern engine management systems, EWP control is basically a non-issue. Even the most basic ECU boxes offer 3D table control (e.g. RPM + coolant temp or coolant pressure or other variable) to PWM control a pump motor. Some offer 4D or 5D control for even more flexibility. And if you're concerned about electrical failures (e.g., say the alternator fails to produce enough juice to run EWP) or mechanical failures (e.g., blow a coolant hose), it would be pretty easy to integrate fail-safe engine protection strategies right into the EWP controls.
With modern engine management systems, EWP control is basically a non-issue. Even the most basic ECU boxes offer 3D table control (e.g. RPM + coolant temp or coolant pressure or other variable) to PWM control a pump motor. Some offer 4D or 5D control for even more flexibility. And if you're concerned about electrical failures (e.g., say the alternator fails to produce enough juice to run EWP) or mechanical failures (e.g., blow a coolant hose), it would be pretty easy to integrate fail-safe engine protection strategies right into the EWP controls.