RA finally got them in stock, so I'm ready to reassemble...



By the by, Laura at Rotary Aviation is a very nice lady who answered all my questions and even gave me a call when my seals were ready for purchase. Two thumbs up!

Next up, balancing the rotating assembly and getting the irons prepped for the stud kit.

w00! Progress!

 

you took it back apart?

why RA seals? IIRC, dont they eat housings?

 

It took itself apart.

RA seals seem to have the detonation resistance I want. A buddy of mine ran these seals and if they can put up with his abuse, I know they can put up with mine. He eventually detonated so hard he broke the front iron... The seals were intact when he took it apart.

I've heard the rumor that they eat housings, but I'm not terribly worried about it. I'm using JHB Cermet A housings with higher wear-resistance than stock and I plan to pre-mix heavier.

Honestly... I'm more worried about high-rpm chatter, and low-compression numbers than I am about housing wear.

 

I dont want to get you too far off topic but I had a 1/2 bridgea couple of years ago with the jhb cermet b(so i was told by the builder) in my opinion its garbage 10k km and there are massive flakes missing in seemingly random places(he never told me which apex seals he used), the engine never made over 90psi probably flaked away before i got to test good comp #s, When i brought it up with the builder he disapeared and did not honor warranty wich was supposed to be 1 year. I am actually seeing better results with my used housings factory chrome housings. I dont think i would build with cermet as you can get new housings for a similar/less price

 

A fellow Kentuckian, too. I have also been planning on running the JHB Cermet coated housings in my '84 13b. Are you boosting? I'd hope so, running the parts you are. Do you already have your housings, and what does the coating look like if so? Is the coating pliable enough to port-or will it stay together and survive if the exhaust ports are ported after the coating? That seems to be my only option if I choose to run these housings. BTW-those seals are beautiful-I'll have to investigate further...

The guy that posted above me apparently doesn't like the JHB housings, IMO I think he may have been ripped off. I hope so anyway, I plan on slightly abusing my engine and would expect wonders from them (the housings) if I do go that route. I would appreciate it if you could give me a few specs, some advice, etc. relating to these seals and housings, or other combinations that would be more reliable (i.e., over or close to 100,000 miles on low boost pressures). I don't want my engine to take itself apart or make me disassemble it for any reason prematurely. Good luck with the build-maybe this time she'll stay together! And thanks for any info you can give me...

-Adam Collins

 

Duh-it's in your sig. Sorry for asking you an obvious question... I feel very small now...

 

I can't even begin to express how bad of an idea it is to have coating done on the irons and rotor housings. I've not seen *one* engine with coating done on it last. They always seem to get ruined somehow w/ the coating coming off. It's just a bad idea.

The apex seals -- I don't think those are a good idea, either. If you are encountering engine knock (not detonation), then you're not using the right fuel for the load on the motor or there's something goofed with the setup somewhere. I used a set of the earlier Rotary Aviation 3mm apex seals and they scarred both of my rotor housings. I don't think they're a good idea for the engine. Alot of people have changed their minds about their enthusiasm of these seals and with good reason -- they seem to eat rotor housings and wear an engine out extremely early!!!!!

B

 

glad to see you're getting the engine back together. it's about time. seriously though, it's one of my favorite cars on the board. about the RA seals, i wish i could give you some useful input, but my seals are still fairly new - only about 700 miles on them and the engine is sitting in my garage now waiting for chassis. people go back and forth on these seals like cholesterol, so who knows what to think? also, it seems the masses have turned against JHB as well, not to say the masses are always right, but to me it seems like smoke - and you know what they say ... however, i still think you have the right stuff to make a reliable setup, so forge on. i do agree with BDC on one point though, there's something amiss with the tune if you're having combustion control issues.

refresh me on what ignition setup you're running again.

 

You're saying the JHB housings are crap? I need more feedback on them, but from what I had read and understood, in theory they sound even better than using new stock pieces or chrome-plated housings. The factory plates or coated the housings with chrome, which flakes and peels off. How much experience with "coated" housings do you have? Thanks for the info...

 

There's been a lot of speculation about the demise of my motor... Everyone seems to want to help diagnose the failure, which is cool but totally unnecessary. I was datalogging on the run that it popped, and I know exactly what happened! It was simply too much boost for the fuel setup I had. I've resolved the issue with a larger pump, fuel-tank baffle and pick-up, and larger AN lines. Contributing to the problem was the tendency towards boost creep, making it difficult to dial in boost pressure accurately with the manual boost controller. this is being resolved by a complete replacement of the manifold (and turbo at this point).

The only issue left unresolved at this point is the tendency of my parallel-rail setup to feed the lion's share of fuel to the rear-rotor. I'm increasing both volume and pressure of fuel entering the rails with the new hardware, and installing an EGT probe for each rotor. The plan is to use the EGT data to adjust injector trim to compensate for the difference in volume/pressure before and after the rear-secondary injector.

As for your question about ignition: I'm running a CAS from a TII, MSD 6AL, MSD coils, 8.5mm wires, and NGK 10's.

 

well, i trust and have faith in your ability. i mean you built this thing and got it this far, so that's all the testament i need. i can pipe down. i guess on my end, i feel attached to your car - kinda like i feel attached to Directfreak, Revhed, Max7, and some others. so i guess it's just a matter of waiting now and seeing what happens in version 2. i can't wait until the monster takes it's next breath though. hurry up already ...

 

I personally saw what RA seals did to what were a set of perfect rotor housings in less than 10,000 km, they had grooves in them much like a vinyl record. This is with an experienced builder/tuner/owner taking a chance on them and constantly running premix. I bought his engine and we ended up having to buy new housings (he treated me great and did a great build!). I run mazda seals in mine and it is what i recommend to anyone. As for aftermarket, I have heard Atkins are nice to the housing and forgiving. Now, the jhb coating. Mazda used this on their formula car, but they preheated the coolant and engine before running as there are expansion variables (according to my builder). I would only go with "new" housings and the price difference is not very much. just my 2 cents, good luck with whatever route you choose.

 

these seals are now for sale:

https://www.rx7club.com/showthread.php?p=7709062

 

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/detonation-%2A%2A%2Apicture%2A%2A%2A-572334/

check out that thread about the durability of atkins seals. good luck with the build.

 

No, I'm not saying they're crap. I'm saying doing coatings isn't a cut 'n dry thing when it comes to a dynamic engine environment. It could be that they're beneficial, but in my limited experience with them on plates and housings is that the coating flaked off in fairly short order. Granted, this was a couple years back and the process by either that company or another may've since been refined, but still -- this is stuff I think one should be very careful with. As a builder on the professional end of the spectrum, I wouldn't feel comfortable using coated housings on a customer's engine prior to using them on mine and then beating the crap out of the car for awhile. It's a test data thing; an evidential and empirical thing. In this case, I think the best thing to do would be to look for those that've used these coatings and ascertain their success or failure rate.

B

 

I ran Cermet A housings with OEM seals for a couple thousand miles. The motor had excellent initial and broken-in compression. I made several passes on slicks, and although eventually one was critically damaged due to detonation, neither showed any indication of peeling.

My experience has been overwhelmingly positive.

 

How many miles were on the ceramic-coated iteration of the engine before taking it apart?

B

 

I see exactly what you're saying. Thanks for the info, hopefully the technology has advanced enough for reliable products to be produced now as compared to a couple/few years ago because I believe I'll take my chances with the JHB pieces. If I do encounter a problem with them, or even if they take out a rotor or seal somehow in the process, I'll have an excuse to use the TII components.

Sorry to post off-topic, but I want to thank you for your info also. Good luck with this build!