Oh I forgot to ask did you originally build the engine with RA springs or did you use the stock ones?

 

There are no RA 3mm springs. They do not make or supply them, to my knowledge. ONly 2mm springs. These are stock mazda 3mm springs.

 

Cool didn't know that!

 

are there any disadvantages to having RA 3mm springs in a daily driven FC with 31,xxx motor and n/a (going to be converted to turbo using the na block the way it is . . high 9.4 compression and all)

 

the ability of rotaryaviation seals are is not a question...

according to Dragon, Van and Iggy (okinawa) they have yet to see a set of RA seals break, and this include Van's rotors where detonation literally colapsed the seal seats. the seals came out of it, still reusable.

i think the possible abuse it causes to the chrome lining of the rotor housings would be more in question rather than its durability.

 

can you all imagine if Demetrious(reactive racing) did a 3 rotor conversion w/ his setup? good god!

 

rotaryresurection... can you take pics of the rotorhousings please

 

Of course there is. The possibility of improperly milled rotors, for one thing. Chattering at 8000+ rpms, increased friction/increased wear for a couple of more. For your typical street car/pump gas application, I don't think they are necessary.

Great post btw, Kevin. Firsthand accounts like this are great, seems like the RA seals are some stout *****

 

According to your profile, your a co-owner of Gotham racing. Doesn't gotham racing only use 3mm seals in their rebuilds?! If the problems you listed are of major concern, then why does Gotham use them?

-Alex

 

Sure am. Gotham uses whatever seals in the motors that the customer desires, although with appropriate input from the engine builder based upon each customer's specific application.

3mm seals have their uses, but they are not a gift sent down from the rotary gods, in my opinion.....they have their benefits and drawbacks just like anything else .

 

so no for a daily driven car, even if i premix . . .

 

there is no reason to use them in a daily driven car, so why go to the extra trouble? unless your rotors are out of spec...

pat

 

I think everyone is missing the real point behid the existence of 3mm seals to begin with. I'm actually related to tracy and laura crook, the founders of rotar aviation, and if the name doesn't explain it all, I guess I will. They put rotary engines in planes. To get a rotary in a plane, though, besides some size and shape mods, you need to be able to do 1 thing: make tons of power to spin a prop at super high rpms. Rotary engines are great for this though because they have what would be considered a limitless potential for tons of horsepower and high rpms. To create this, we're talkin serious turbocharging and various other power mods. With that in mind, it makes perfect sense to have some serious seals to withstand the high hp demand and constantly running at extremely high rpm's. I'm guessing about 10000+. In a car, you can only go for so long at 8000 rpms on a road, because they end, but in the air, at even higher rpms, there is no road and thus all out the whole time. They actually race their planes. So for extreme horsepower, high rpms for extended preiods of time, and racing, 3mm seals are what they needed to prevent having to change them in the air. Im off my soapbox now but just thought I'd fill you in on why they were designed and maybe it will help you figure out whether they're needed for your car.

 

Of course there is if the rotors aren't properly milled and installed. I know they do have a bit longer surface contact with the housings as well. I meant with them being properly installed. I can't give any input on either 2mm or 3mm because I have not had any experience with any yet. My engine is being built with 3mm seals and this will be a toy/weekend/track car. He praises the 3mm seals and I can't argue with someone that has been doing this much longer than I have.

 

I don't see what the huge deal is(2mm vs 3mm). I feel the real issue is whether to go with 2 piece seals vs 3 piece.

3mm 2 piece are stock seals for the 13b's in the GSL-SE. Those engines are damn near bullet proof and will easily last over 150k.

I've owned a 81 GSL. That engine lasted 150k before it blew because of cooling problems. The engine actually locked down during start-up.

I've owned an 84 GSL. That engine lasted 140k before it blew because of carbon lock breaking a seal. The plugs had over 25k on them because I forgot to change them. Doh!

Both of these engines could have easily lasted longer had it not been for my own stupidity. These engines also had 2 piece seals.

Just recently, the engine in my 91 vert blew at 140k. I bought the car with 75k miles on it back in 99 and it already had a rebuilt engine from Mazda in it. At the time it didn't make since for a NA rotary to need a rebuild so early. The paperwork showed that the old engine had low compression and had hard starting problems. Anyways I bought the car knowing it had only 10k on the rebuild. Now because of my past experience with rotaries I made sure that maintanence was my #1 priority. I changed the plugs and fuel filter every year or at 12k miles. Oil was changed at 3k. Coolant was flushed every 2 years and I used de-mineralized water. Hell I even flushed out my brake & clutch fluids. This engine "never" had any reliability problems or leaks what so ever which leads me to wonder why in the F*ck did this remanufactered NA engine only last another 70k? I haven't pulled it apart yet, but I know that the rear rotor has no compression.

Now the point I'm trying to make is, I feel that high mileage rotary's w/ 3 piece seals are a ticking time bomb. When the top piece of the apex seal (3-piece design) gets thinner from wear, it becomes more brittle. It doesn't have the same support as what a 2-piece design would have when it wears down. Thin & brittle is not a good recipe for longevity and reliability. The 91 vert (which was well maintained) had a 3 piece design and lasted only 70k before each rebuild! My 12A's (which had poor maintanence by comparison)had a 2 piece design and lasted nearly twice as long. Hmmmmmmmm! However my 3rd gen has 92k original miles and runs perfect. Even though I hardly never abuse it, do I expect it to last 150k? Nope!

Now I understand that there are more variables involved here but, I've seen too many 1st gens (12A or 13b)on the road with thier original engines pushing well 150k. I'm talking cars that are 20+ years old and still running. You compare that to all the NA second gens and the 1st gens have proven to last longer.

Now as far as 2mm VS 3mm! Boosted or NA, I feel the 3mm will be more durable in the long run because it will be less brittle and less prone to break than a 2mm seal at the same mileage. When I rebuild the engine in my vert, I will use RA 2mm if the rotors are within spec. If they are not, I will mill and use the 3mm.

 

i agree, the 3pc were a bad idea. they give slightly better compression, but definately limit engine life. thats why mazda discontinued them.

also, rxheaven, i think you overestimate the requirements for airplane engines. the power needed isnt much different from a car, its just that they run a constant rpm, rather than a throttled setup. most plane builders will NOT try to get huge amounts of power from an engine, because the #1 priority is reliability. if you blow an engine in a plane, it sucks.

planes generally run a conservative power level once they level off, they just use lots of power when taking off or climbing. 2/3 max speed is normal cruising speed, which means roughly 2/3 of engine power.

pat

 

Shhhhh. Keep it quiet about the NA 2nd Gens or that wacko with 430,000+ miles on his 89 GXL will chime in. That guy bought his car when it was two years old and has personally put over four hundred thou on it. He swears the S5 NA is bulletproof.

 

Bulletproof? Sheeiiiitttttttttttt!