why doesn't somebody make a 2.5mm apex seal and find the happy medium? Is it possible?

 

Sure it's possible, but what's the point?

 

Arn't there problems with 2mm not handling enough and 3mm being to wide to seal properly? I thought it was a good idea

 

Handling enough what? You can easily run 25+ psi with 2mm seals with proper tuning. No apex seal is bulletproof.

 

then why do people run 3mm?

 

The same reason people ask about 6-speed transmissions when their 5-speed works just fine...

There's no real reason to run 3mm seals because 2mm seals are fine with proper tuning. The expense of having FD rotors machined for 3mm seals is a waste of money in my opinion.

 

do you know any reputable tuners,RE builders ect. in our area?

 

3mm seals are a older Mazda design. They changed to the 2mm for the 86 and later cars.

The reason some shops install 3mm seals in 2mm rotors is due to the fact that the 2mm grooves are beyond tolerances, either machine them out for 3mm seals or throw them away.

Remember the old school drag racer running 9s in his FD, Adam Sawartari? IIRC he ran 2mm seals.

 

Thats the answer I'm looking for! thanx.

 

Atkins or Pineapple (Oregon), probably. Stay away from Hayes Rotary.

 

Yeah I've heard about Hayes. Ive heard 50/50 about atkins and that pineapple only has good race engines. I'll probably end up going with atkins cause its so close. thanks for the info.

 

Yeah, the truth of the matter is that there are no really great rotary shops in the Northwest. For Washington, Atkins is about it, and I've heard my share of stories about their rebuilds too. That was one of the reasons I scrapped my 20B plans. I couldn't really trust anyone to rebuild the engine and didn't want to take the risk after what I went through with Hayes.

 

 

what about someone who can reliably tune a power fc by dyno locally

 

3mm & 2mm Apex seals will break at about the same rate even if it's tune "correctly". due to detonation or other obstacles.

 

Try Alex at Carb Connection in Kirkland. I don't know if he has experience with the Power FC specifically, but I know that he works with a lot of other car owners and various aftermarket systems.

 

Washington sucks sometimes. thanx

 

gotham racing does good rebuild work.

 

3mm will hold up better to detonation but the best way to prevent damaging them is proper tuning. If you don't detonate or preignite what are you going to hurt, nothing at all. Finding a very good tuner makes all the difference in the world. If you have good tuning skills run 2mm if your skills aren't to good use 3mm to cover yourself as an added safety measure.

 

No, they won't.

Do you really think that an additional 1mm (0.039") of thickness makes any difference? Detonation will destroy 3mm seals just as easily as 2mm seals.

 

Agreed! 3mm is a waste of time. They dont like revs either!

 

That's funny coming from a person who doesn't even have a rotary in their RX7. And I do have experience with both 3mm & 2mm apex seals detonating. A really harsh detonation at say 28psi boost will destroy any apex seal. The 3mm will hold up slightly better to minor detonations/misfires than 2mm but like I said before the only cure is to not detonate. I personally don't use the 3mm seals I've tried them before and the effort of getting the rotors machined is not worth it for me. Oh yeah a 396 in a '70 split bumper camaro twin turboed out is my dream. Yeah maybe on day but until then I'll have rotarys.

 

What exactly does that have to do with the current discussion? If I recall correctly, it did come with one originally.

Detonation is an uncontrolled burn resulting in vastly increased combustion chamber pressures. Detonation is, by definition, "harsh".

Any seal might hold up to a few pings, or it might not. Detonation will wipe out a 3mm seal just as readily as a 2mm seal, and even a 6mm seal (yes, rotary tuners have tried just about everything) isn't proof against detonation.

Well, at least you got that right.

 

Well, thanks Jim atleast we can agree on one thing.

 

Mazda tried to use 6mm seals in the 12a somewhere in the 70's.