All of the old-style BNRs used factory turbine wheels. The main diff from factory in the stage 2s was different compressor wheels. The new BNRs use totally new CHRAs.

Any updates?

Max/Batman,

Any new news that you guys can report? Max.... are you back together and running yet? Batman.... everything still running fine? Knock readings still low? What boost levels are you running now that I assume your breakin period is completed?

Inquiring minds want to know!

Tim

did the place where these were done say what the max temp was of this coating?

matt

I didn't ask. I don't know what the temps are inside the chamber anyway. I did talk to them about coating rotors in general. I guess they have done this for some road racing rotary engines over the years, though I think they were all NA. They were high-revving engines, though, which eased my mind a bit since I am concerned about the middle of the rotor face hitting the cusps in the housings.

I said that I was going to be using them in a moderately-high-powered turbo engine and they didn't seem concerned. I don't know if that's because they have done rotors for turbo engines before, or merely because they didn't know there is anything to worry about. I assume they have done pistons for forced induction cars before.

This is a bit of an experiment, and I don't know precisely how it will turn out. I really hope I don't get any rotor/housing contact or have chips of coating come off and mess up the housings or the turbine. On the positive side, perhaps I will get noticably better power than I expect on the dyno, better mileage, lower oil and/or water temps, a lower boost threshold, or a brighter smile. :D In reality, I think it will be difficult to positively attribute any particular effects to the coating. It is hard to draw conclusions from a sample size of one. I might just have to be happy that my car runs well, whatever the reasons might be. But maybe if I don't have any catastrophically bad results and do seem to have some positive results, other people might try it and see what happens.

-Max

I was told that contact or chipping of these coatings will not result in turbo damage
because it turns to dust when its either heated above the coatings max temp or chipped.
from what i understand or have been told the swain tech coatings are exclusive to them
and will not be available anywhere else for a couple more years. their coating for piston tops
and rotor faces are stable to a higher temp than other coatings.
I would love to know what other people are using and what the max safe temp are of the
coatings that are being used.
as for clearancing of the rotors, these coatings can add depending on how its applied
anywhere from 1/2 thou to 1 thou of an inch which i think should be compensated for before the
coatings are applied.
guess i will find out, I will be trying out a tbc of my own on some rotors which will go into a
motor for spring time, it will be interesting to see what differences i notice.

matt

I dont know if you are familir with this or if this is not the exact same thing that your after, but in this thread there is info about some company offering the same type of thing for all the parts not just the rotors.(in my eyes anyway). It is on page 16 to me, but i got the posts per page thing turned all the way up in my user cp, so i dont know what page it will be on for the rest of you.

forgot to link the thread. https://www.rx7club.com/showthread.p...&page=16&pp=40

Tim, BATMAN tells me that everything is running perfect.

He has 7000 miles on it so far and nothing has changed on the knock readings.

He still needs to tune the car right after new years.

More on the results later.

But for now the ceramic coating has his thumbs up.

Thanks for the reply Penguin!

Cheers,

Tim

No problem ;)

Maxcooper, any updates from your camp?

:batman:

I had a set of rotors ceramic coated back in 98 big increase in torque mid range,stand alone system,TO 4E single, water to air IC,extrude hone manis, 3.5" exhaust, blow the tires off at 70 mph in 3rd gear sideways, engine exploded at 100 miles twisted the housings a half turn, nothing salveged. I contribute it to of course to detonation the heat in chamber could not escape into the oil inside thr rotors,hence detonation, rotors were polished and coated low compression, also had NPG coolant in 98 , still have the car 87 TII, another FD 3rd gen engine. right now im wary of rotor coating but i have not forgoten the performance, WOW.

by the way checke out Pettit racing I believe they tried it out back then dont know how it worked out tho. coated rotors

hey a thought ocurred, duh, what if deton started to happen and the pressure pushed the apex seal coming up to firing ,away from the housing wall and fired off the mixture in intake phase way early, hy boost air fuel mix,sonic vibration or something like wierd that only rotarys can do . its called BLOW BACK.

I'm still getting my car back together, but I'll post in this thread when I get it back. I don't expect to have any results that can be positively attributed to the coating, but we can make some guesses based on dyno charts and mileage. I am simultaneously encouraged and concerned by ronbros3's results. :) I am glad Batman hasn't reported any failures yet.

-Max

a correction to my reply, fingers type before brain is engaged ,about firing back past apex into the up coming compression phase can cause problems, also e-shaft flex or bend, rotors are not perpendecular and can touch the side housings then apex seals are not square in rotor, I believe shaft flex might occur around 350 to 400 ft. lbs , gives serius thought to center bearing e-shafts aftermarket. thanks RON

The apex seal floats on the spring(s) and should follow the rotor housing even when the rotor is slightly out of alignment, I think. The inertial forces from high RPM are likely to be greater than the forces the combusting chamber will make, though perhaps the forces of mucho-torque and mucho-RPM are different in a critical way. Rotors clearanced for high RPM use may help shaft flex alone is the problem.

I have heard of mega-power 13Bs bending the shaft enough to make the center of an uncoated rotor face (the "rim of the tub" so to speak) hit the cusp inside the rotor housing. The remedy there seems to be to take a little material off the rotor in the middle of the rotor face. The ceramic coating, though very thin, might be enough to increase the chances for contact to a critical degree. I think the clearance is something like 0.009" and the coating is said to be about 0.002" (warning: I pulled these numbers out of my ass and they might be completely wrong). It doesn't seem like the rotor hitting the cusp would "catch", but perhaps it creates enough of an upset in the motion (bounce off cusp, opposing rotor apex catches the cusp on the other side?) to be violently catastrophic. Maybe this is what happened to your motor, ronbros3. Was there any tell-tale damage to the rotor housing near the cusps? Or perhaps the rotor face showed some contact specifically in the middle of the face?

-Max

It seems that ceramic coating address a few issues:

1. The coating reduces heat soaking of the rotor face (or piston face for some). This should help reduce the heat on the rotor or piston face which in turn helps reduce the chances of said faces being the ignition point for "KABOOM." Also, by reducing the heat soak in the faces it helps reduce the load from the oil coolers.

2. Ceramic coating fills the small pores on the rotor face. This helps reduce the carbon build up on the rotor face. Carbon build up can attribute to KABOOM by being a ignition source (i.e. - red hot coals in a camp fire). Also the actual mass of the carbon build up may "inflate" the compresion ratios in the combustion chamber.

BATMAN has just recently notice that when he was driving the car in a VERY cold morning the intake temps were 10C while the water temp just settled at 80C. He boosted the car at 7psi~ and the knock readings shot up to 140. Everything checked out ok and those aviation apex seals seem to have held up nicely.

One more thing to add that BATMAN has noted:

While he was driving his car in the rain he noticed that there is less steam from the oil cooler as a result of rain and puddles splashing on the oil cooler.

Furthermore, he touched the surface of the oil cooler and noted that it was sligthly cooler to touch.

At this point there are just observations.

I'm glad Batman's engine is still running good. I built it about a year ago and haven't heard from him in awhile.

In person or on this forum?

It'll be interesting to see how well this effects your gas mileage. It seems that the single biggest thing killing the MPG on our cars is heat soak. Compared to a piston engine, ours run very hot, and it seems to be centralized in the engine. Coating the rotors should move that heat outwards so it can be picked up by the coolant. I've never owned a FD, but on my GXL, my water temperatures are usually pretty low (less then 1/4 on the guage normally) so it seems that a good deal of my cooling system is not realizing it's full potential.

On the other hand, it might not make that much difference. I'm sure Mazda attempted to coat the Renesis rotors and it probably didn't give good enough results to justify the costs, or it was too complicated of a process to make efficient production viable.

In person

For the mileage, the less heat that you lose to the oil and coolant, the better your mileage should be since you are harnessing more of the energy in the fuel to move the car. However, I don't know if the coating will make enough of a difference in that area to yield a noticeable result. It might be so small that you wouldn't really notice.

-Max

Nice post Batman, You've started something here. Love the lowered knock.