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If you've got a shaved/sharpened edge on the apex seal, that's wear (which would cause localized heat). Gotta be wearing on something. Does this give credence to the "spark plug mountain" idea?
100%
People say "warped" but its not warped, its worn.
Measure the flatness of the back of the apex seals where the spring rides- still straight.
Put the apex seal back in the groove and rotate rotor in rotor housing around to the Leading spark plug. Note the angle of the apex seal and how the wear on the apex seal and rotor housing coincides.
Even OEM apex seals wear at this spot and Mazda says discard them when the wear reaches the crown of the apex seal (so light is revealed if you put two apex seals crown to crown.
Before the wear reaches the crown of the wear surface compession is not affected because the compression sealing is done on the other side of the apex seal crown. (Again, rotate your rotor in the rotor housing and have a look).
I do have an AST delete. I do believe my builder bought Atkins seal kit, whatever that includes. I burp the system quite meticulously, I dont know. My water temps never went past 90c. Do you really see a distortion hump along the leading plugs? I would expect more wear on the housing there, cracking.
BTW apex seals are beveled evenly across the entire seal. It is not focused in the middle. My plugs are 10's (denso equivalent).
Last edited by ArmenMAxx; Jan 31, 2023 at 01:26 AM.
The plates on that engine have definitely not been lapped, they've been surface ground. Wheel grit may have been selected to optimise material removal over surface finish too, unless the photography is playing tricks.
Not sure if there will ever be a proper sealing solution for these things, at least in turbocharged form. Pulled down the one here last year, odd, pronounced longitudinal wear on the seals, rather than the usual warping. Rotor housings were still good though!
2) Did you purchase inner coolant seals from Atkins?
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To me, it looks like you had an air pocket trapped at the coolant passage on the Leading plugs.
This is the hottest area of the rotor housing and exceeds the boiling point of coolant/water mix. Boiling occurs and without the AST (air separator tank) constantly bleeding the cooling system the vapor from the localized boiling event becomes trapped and increases to an air pocket.
Air does not conduct heat well so the issue is exacerbated. The Leading spark plug hump distortion becomes greater and excessively wears the apex seals (as you can see).
The Leading spark plug boss has the carbon shadow from the blow by when cold/normal operating temps and the apex seal has the wear spot in the middle.
To further this theory, is the flow direction of coolant such that this condition would make the front rotor worse than the rear? (normally its the rear rotor that wears out first).
the pics in post 94 raise significant considerations.
your motor has Atkins compression rings. you can tell by the (crucial) vertical protective walls being white. OE is a darkish tan.
while i continue to deal happily w Atkins for many of my build parts i have learned over the 20+ years that i need to be specific as to my parts requests.
i think it is laudable that Atkins (or anyone) continues to develop parts for our out of production motors. at some point in the future there (may) be no OE parts available.
of course "develop" is a process that can be quite dicey. there will be wins and losses.
Atkins has some wins... viton oil control rings. outer coolant seals, they also sell the OE Cosmo exhaust gaskets saving single turbo owners lots of $.
at the moment their compression rings are solidly in the "loss" category.
about a year ago i had occasion to disassemble a motor i had built as i didn't like the numbers from the compression table. to be clear, the motor had not run, it was assembled and then checked for compression.
as i removed the rear iron the compression ring caught my eye...
the puzzle joint had separated.
i have NEVER (200 motors) seen a separated puzzle joint and the motor hadn't even been run. the seal had also a number of squiggles in it, again a new phenomenom. finally, the barrier had separated from the inner core in some areas.
the compression ring might have been the most challenging and expensive project for Mazda. it has to be flexible, yet stand up to huge heat and pressure.
i will not use anything but OE compression rings.
Atkins, without disclosing to me, switched from OE comp rings to Atkins.
just to be clear, as long as there is disclosure i am all for product development. i don't want to be a part of the development. i still buy comp rings from Atkins but i specify OE.
my guess/hope is that they will make various changes and end up w a good product. eventually.
i do not like the looks of the comp rings in your motor. it is my speculation that your rings allowed communication between the HOT pressured combustion and the water jacket. this could have caused an especially hot spot which may have led to your problem.
you have a LOT of apex seal lift as evidenced by the "witness marks" / carbon on your housings. normally i see lift on the close of the exhaust port... you have lift, as well, on the open. and you have a ton of lift around your plugs. so your motor was running hot. this may not appear on your ECT as it is localised. it might be that the compression rings were the primary cause.
as has been previously mentioned, your seals are probably not warped. the daylight you see comes from a loss of material that corresponds with the lifted areas on the housing. the material is displaced from the crown to a ledge on the side of the crown...
i have mixed feelings re your engine builder's culpability as i didn't pick up on the comp ring seal switch either. i was fortunate that i had to take the motor apart.
i also don't like what i am seeing from the pics on your irons. i have never lapped an iron and i never will. the heat treatment for the surface of the iron is different in 3 areas. no way after lapping is that going to not be disturbed. all of the key items that ride on the irons are behind springs and have travel. unless an iron is blued or really rough i will pass on lapping, let alone grinding.
I'll agree on the irons. I had a set of lapped/re-nitrided irons eat the side/corner seals (because they were either over-hardened, and/or not re-lapped), and create a metallic chum that ate the apex seals too. I'd buy billet irons before I'd do that again.
@ArmenMAxx do you have a simple AST delete, or one of the ones with the expansion tank built in to the upper water hose mount?
I'll agree on the irons. I had a set of lapped/re-nitrided irons eat the side/corner seals (because they were either over-hardened, and/or not re-lapped), and create a metallic chum that ate the apex seals too. I'd buy billet irons before I'd do that again.
@ArmenMAxx do you have a simple AST delete, or one of the ones with the expansion tank built in to the upper water hose mount?
I have a simple AST delete on my car. Funny enough, it was the first mod I did back in 2007.
Howard, appreciate the information. Definitely concerning. I am relaying all this to my builder. It seems ours was crushed and flattened when assembling the motor vs degrading secondary to heat. Its interesting to me that hot combustion gases escaping into the water jacket would cause enough focal heat. Thoughts on my bent CAS contributing?
Last edited by ArmenMAxx; Jan 31, 2023 at 01:09 PM.
your CAS functionally should retard your timng somewhere around 3 degrees... just an est. i don't think it is much of an issue. your motor was really hot inside. normally you don't see lift at the exhaust open.
I wouldn't worry about that bent outer tooth. The outer tooth on the CAS acts like the 'camshaft' or 'TDC' signal for the ECU, it's not used for the ignition timing and it would only matter if it bent so far its location moved to the other side of the next inner tooth. The twelve inner teeth act like the 'crank' signal, their location is critical since they get referenced by the ECU for ignition timing. Luckily the outer ring makes them unlikely to bend.
Do be careful with the CAS sensors and bracket and mounting hardware, it's important those don't move or get damaged. If the wiring harness that plugs into the sensors is original, it will be old and fragile at this age.
awesome keep up updated
you end up getting a new mazda engine?
Yes, got lucky.
Just finished tuning, all seems well this time. We took it up to 23psi with water/meth. EGT's were 1100's in boost. Without water meth at 16psi EGT's were reaching 1600.
Car feels great. I dont have a picture, but we managed 455whp/401wtq final numbers at 22-23psi. Ill be running it at 20psi most of the time on streets and 18psi on the track. Power is low given the torque figures which I am working on figuring out yet at the same time I am just enjoying it as is for the time being. Feels like 500whp
The valley at 6.2k is suspect, I am curious if my old rotary extreme intercooler and my piping design is a limiting factor
@ArmenMAxx Did you tune for Water/Meth or just spraying it knowing you'll take some loss of power but knowing that if you are empty, you don't have to have a separate map/tune to compensate? Also, what PSI do you have your system starting to spray at?
I had similar issues with warping seals (iRotary and RA SuperSeals). We think we found the culprit which was apex seal grooves that were out of spec at the edges of my rotors. See you replied in my thread so you probably saw the photo.
@ArmenMAxx Did you tune for Water/Meth or just spraying it knowing you'll take some loss of power but knowing that if you are empty, you don't have to have a separate map/tune to compensate? Also, what PSI do you have your system starting to spray at?
I had similar issues with warping seals (iRotary and RA SuperSeals). We think we found the culprit which was apex seal grooves that were out of spec at the edges of my rotors. See you replied in my thread so you probably saw the photo.
Its functioning simply as a safety net to increase boost. My timing is not aggressive in general and not advanced for water/meth injection. I am using a SSD which is controlled by my haltech and begins trickling in at 12psi. I am using the new AEM nozzle but even at 23psi we are only at ~80% duty I believe. Its a lot flow.
I really do hope things work out for you this time around. I am following your thread.
Just finished tuning, all seems well this time. We took it up to 23psi with water/meth. EGT's were 1100's in boost. Without water meth at 16psi EGT's were reaching 1600.
Car feels great. I dont have a picture, but we managed 455whp/401wtq final numbers at 22-23psi. Ill be running it at 20psi most of the time on streets and 18psi on the track. Power is low given the torque figures which I am working on figuring out yet at the same time I am just enjoying it as is for the time being. Feels like 500whp
The valley at 6.2k is suspect, I am curious if my old rotary extreme intercooler and my piping design is a limiting factor [/QUOTE
that's awesome power, stock ports? I hope one day to be there
1100 egt seems really cool! think I'm like 1500f
Power is low given the torque figures which I am working on figuring out
congrats on getting it running.
if its a flow limitation, its not too hard to find, for the IC you can put a boost gauge in front of it and see what the pressure drop is like. ~2-3psi is pretty normal.
you can do the same on the exhaust side too, ideally you'd do pre turbo AND post turbo, but post turbo is easier, again more than 2-3psi post turbo you're loosing
if you do pre turbo pressure, post turbo pressure AND EGT you can figure out where you are on the turbine map, which might be informative
I'd say you're on the right track, I feel like at that boost level on that turbo I've normally seen higher numbers though. But a flow restriction/inefficient IC could explain that as well as the high EGT's when not using water/methanol. Do you have any IAT data from before and after using the water/methanol? The EGT difference you are seeing using it is a true testament to the powers of AI though, that's fantastic. Congrats on getting it back up and running, nothing like falling back in love with your project after episodes of heartbreak with it!
Last edited by RotaryMachineRx; Mar 24, 2023 at 03:09 PM.
The new motor is street ported, xcessive LIM which is port matched, cooling mod "grooves" added to the housings by the plugs, E&J seals.
Air temps would drop significantly from 42c pre-run to ~15c after the pull. We dialed it back for a few reasons, too much water will kill power of course, but its scary to think the motor will be 100% dependent on AI in high boost. If something fails, so will the engine. I mean, will my haltech safety measure and closed loop AFR adjustments save me? Who knows
Adding a pre-post boost gauge is a great idea. Especially given I have a 3.5 inch downpipe & midpipe I think there is something bottlenecking flow. I hate how my charge IC pipe is perpendicular to my IC endtank. I have cracked my turbo side IC endtank twice which should clearly be a sign. I ended up reinforcing it with aluminum plates.
throwing this out there, it's been debated ad nauseum but you could try waterless coolant, Evans or your own mix.
It reduces or even eliminates hot spots and localized boiling keeping a better heat distribution within the block. This together with cold plugs (11+) in theory could reduce the leading spark plug mountain due to heat.
Also it can be run at reduced pressures.
the first thing that jumped off my screen was the location of your peak torque. 4600/4700. something is seriously wrong. peak Tq should be around 5700-6000 on a moderately ported motor. my ports produce peak Tq at 6250. you have a material flow restriction as rpm builds.
i added your numbers (after correcting to SAE) into my "Horsepower Under The Curve" Excel file. i have 88 dyno runs posted at 6 RPM levels and a total. highest total wins the race. the 6 data points are 5000 thru 7500. your total placed 38 from the bottom at 2436 total SAE HP. the range is from 1688 to 3530. your total power doesn't particularly interest me.
what is of interest is where your power is located. as you can see from a comparative between your power and the average distribution of power from 88 other dyno sheets more of your power is early.
this fits w the early Tq peak. your motor/system is fine til it runs into a wall. this is also why your peak power is off by a large amount... 23 psi w an 8374 should be on the other side of 500 and that is SAE not "Standard." correction (there about a 3% diff)
while it would be really easy to blame it on the IC, i do wonder if that would be the answer. normal ICs have a pressure drop of 1 to 4 psi. when you are looking for 50 hp and it is coming from an IC restriction the number would be very close to 10 psi. since you were able to put 23 psi through the motor i don't think the IC is the issue. further, IF the IC was the problem your IATs would have been horrendous.
as an aside, i doubt your IATs and the EGT change.
at 23 psi w an 8374 the output temp from the turbo is very close to 400 F. while a W/M AI slightly cools the IAT it would be in the 30/40 F range.
a very GOOD IC is 67% efficient without AI. (generally we don't see that high an E due to the limited space on our cars)
using your IAT number your IC is 117% Efficient.
400 F - 59 F (your 15 C reading)/400 F - 110 F IAT (at your air filter) = 117%.
removing the AI effect by adding 30 F to your IAT:
400 F - 89 F/400 F -110 F = 93% Efficient....
the best setups are about 67%
if we assume your IC is 67% efficient and the 30 F drop AI and solve for your IAT we find it is 176 F:
400 F -176/ 400-110 = 67% Efficiency
with AI, assuming a 400 F output from the turbo and 110 F near the filter and 67% IC Efficiency your IAT should be 176F
perhaps you are measuring IATs w a thermistor. i suggest you switch to an IAT thermocouple and you will have accurate data.
the other item that has me scratching my head is your 1100 F EGT.. going from 1600 F (quite reasonable) to 1100 F based on AI.
AI generally doesn't lower EGTs. timing and type of fuel legitimately change EGTs.
taking a step back your overall package looks very good. as often is the case a trip to the dyno raises more questions than answers.
it will be interesting to find the answers.
Last edited by Howard Coleman; Mar 26, 2023 at 02:22 PM.
