Djseto

iTrader: (2)

I did it because my car was going to see track days. Literally did everything I thought I should to mitigate any risk of engine failures.

Djseto

iTrader: (2)

im confused at this statement ⬆️

did I say something to offend you? I simply stated that when I sent my rotating mass out to be balanced, I sent the new flywheel after the comment above that dynamic balancing goes out the door if you aren’t using the stock flywheel.

at this point I’m just hoping I have a real cause to my headache based on the two possible issues Steve Eckerich suggested based on all the information I told him during our hour long call along with his experience from seeing similar situations to mine. Whether he’s right or wrong is yet to be seen but he’s a fresh set of very experienced eyes who is going to help.

Howard Coleman

iTrader: (6)

"Mazda stopped static balancing the rotors"

for the last 3 years i have only built my spec motors from new blocks. being an overly inquisitive guy i always measure everything... both on incoming new blocks as well as the outgoing product. every incoming new Mazda motor has had rotors that weigh within 3 grams, generally ONE gram. i conclude Mazda does static balance the rotors. obsessing over a few grams is ridiculous since the rotors are constantly being filled w varying amounts of oil.

j9fd3s

iTrader: (3)

Even 20 grams out of 3900 grams is 0.005%. yes if you're racing, you balance to the gram because you can.
the guy who did my PP engine balance didn't want the clutch, he said those were already balanced. i really only did mine because i used a non standard combo, and its a 12A, so if i break it, i'm SOL...

j9fd3s

iTrader: (3)

i hope so too. this build started off on such a good note, its been sad to see it hasn't gone well.

BLUE TII

iTrader: (9)

Sorry for confusion, my post was a response to TeamRX8 regarding Daryl building 13B-MSP.

____
BLUE TII
Rotary Motoring
So that is actually "yes".

Mazda stopped static balancing the rotors *edit- for rx8 13B-MSP production* and switched to dynamic balancing the entire rotating assembly instead.

You replace the stock flywheel as Daryl does on a race engine and you lose the dynamic balancing.

_____
MY new crate 13B-REW still had static balancing machining. I simply idly wondered if they threw it on the 13B-MSP dynamic balancing rig as well.

A "proper" balance such as in race engine blueprinting or turbo assembly includes matching and static balancing each rotating part prior to dynamic balancing/vsr balancing the rotating assembly.

Mazda with the RX-8 decided the parts production tolerances were "close enough" through their rotor weight matching program that they would go straight to dynamic balancing.

BLUE TII

iTrader: (9)

you think he never balanced with the original flywheel

You are asking me if Daryl ever put a complete stock 13B-MSP rotating assembly on a dynamic balance rig and checked it against Mazdas allowable spec?

Edit- actually, the Mazda dynamic balance would best be done during the factory engine run-in phase to account for oil in rotors- so, thats probably when they do it.

I don't know, but I am going to say most likely not since that is an extra step and waste of time in the blue printing process.

Daryl and Mazda already know the proper way of balancing is to match parts, static balance and then dynamic balance.

Howard Coleman

iTrader: (6)

here's Daryl changing the mains on my Weber at the June Sprints/Road America. Daryl built my GT3 12A motors for 3 seasons. dry sump. SCCA lowered the choke size from 50 mm to 38. we still made 259 FWHP. rpm band for about 35 minutes was from 7,000 to 10,000. that's me on the right w the greasy hands. as usual. circa 1986.

Carlos Iglesias

iTrader: (6)

... it's how Roger Mandeville did the rotors on my race clearanced and balanced rotating assembly. The cool detail is that he stamps in the individual finished rotor weights on each one.


Mandeville rotating assembly weight-stamped rotors

TeamRX8

iTrader: (2)

I may need to install a breathalyzer on my phone that prevents me from committing another PUI offense …
.

aplscrambles

iTrader: (7)

My very first thought when I read your last post--"Man that dude had one too many beers before he typed that"


On another note--Really thinking dj is on the right track now. Rebalance or new rotors, different seals, different tune, AI, and consulting with some real long term racing experience. Sounds like a winning setup to me.

TeamRX8

iTrader: (2)

genuine thought, just might have expressed it with more care

regardless, you’ve come a long way baby …



.

.

TwinCharged RX7

iTrader: (14)

That's for sure. Car could have easily been a goner. Now everything is perfect except for the engine.

seckerich

Got a text to look at this thread and just wanted to add some information if it helps anyone with their problem. We have had rotors come in for inspection that have had apex seals warp multiple times like this build. Sometimes we find the rotors badly out of balance, as well as the entire assembly way off. But that is not the entire cause, and maybe just a side problem. Rotors have multiple thin spots near the apex seal area on the rotor face. Under high boost these can flex and move the wall of the apex seal groove. Many times this was done long before current owner had the parts. Drop a seal in the groove and check with feeler gauge and the clearance looks fine. Put the same rotor in a fixture and check with indicator and the groove is what is warped. Seal sticks for a second and the resulting blow by warps them quickly. In most cases we have enough metal left to straighten them out and solve the issue. Seemed to be some confusion in previous posts. Been many years since I was on this forum but looks like someone shared some very good information from Mr Drummond. Spot on.

Djseto

iTrader: (2)

☝️ smart guy and OG in the rotary world

TeamRX8

iTrader: (2)

thank you for your input.

I recently ordered an Xtreme Rotaries apex/side seal groove 2-sided diamond file just for this reason
.

ptrhahn

iTrader: (9)

I've heard a number of stories lately about balanced rotating assemblies (which are often sent out by builders to 3rd party vendors), not actually being balanced or not balanced correctly.

TeamRX8

iTrader: (2)

funny enough, this is from an article back in 2019:



.

Howard Coleman

iTrader: (6)

many of you have read this epic post in a related thread but for those that haven't...

GT1-20B:

"Hello to everyone,

In particular Howard Coleman. 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"

BLUE TII

iTrader: (9)

You have to measure your seal clearances with all seals in the rotor at operating height (not sprung out)- no newsflash there.

Corner seals in when you measure apex seal clearance and drag the feeler through the corner seal.

Side seals in on both sides of corner seals when you measure side seal clearance.

BLUE TII

iTrader: (9)

In rotaries the stuck apex seal phenomenon is called "spitback" phenomenon from the compression stroke pre-ignition it causes.

You can read up on Mazda's struggle with it in their Lemans program in primary (Mazda) source material.

It also causes extreme wear over the Leading spark plug rotor housing distortion as I adressed in the other "warped" seal dyno thread where the logs caught the spitback event.

-edit- sorry I already mentioned this in THIS thread regarding oil temps on dyno regarding apex seal clearance.

This thread is too long

seckerich

Good to see Howard is still on this forum sharing his knowledge.
So we got the rotors in from this build for inspection. We put them in our fixture on a surface plate and as suspected the apex seal grooves are very bad. Center 50- 60% is right on spec, but they are out almost .010" as you move toward the corner seal area. This means that 40% of any seal you install will not be supported over this length. Leading edge of seal groove is straight. No denting on faces near apex seal as we see on a lot of these, but they have seen some detonation in their life. Since I do not have the car or any other parts of the motor this is as far as I can go but different rotors are a minimum. Definitely not an apex seal issue.

BLUE TII

iTrader: (9)

So you are saying the apex seal slots are splayed out at either end from detonation causing loose corner seal pocket and apex seal binding in corner seal slot (as evidenced by the wear I pointed out on apex seal end).

Very common detonation damage any engine builder would catch using the FSM as his guide if it was present on engine pre- assembly inspection.

I have addressed this issue with a body hammer for the rotors and a punch for prying the corner seal Pockets on my own motors in a pinch (hahaha) which works if you get EVERYTHING back in spec instead of making it worse.

Just saying, not rocket science or anything we havent seen in rebuilds the last 50 years.

The other very obvious possibility is the rotors didnt go into the motor that way...

TeamRX8

iTrader: (2)

interesting … if the leading edge is straight then the outer trailing edge must be splayed or worn. Just curious about how that may occur.
.

seckerich

We are going to put these up on our CMM and check corner seal pockets just because we can. The corner seals fit well and our gauges to check them fit well. Not as obvious as you might think. May be a week or so, but I will post up anything cleared by owner. Don't be so quick to toss builder under the bus, he does good work. My one and only reason to post here is to share knowledge, not to bash anyone now, or in the future. It also bothered me that the seal was being blamed and I have used Iannetti seals since day one with zero issues ever. Francesco tosses more seals that do not meet his standards than most companies build.