daem0n

In a rotary engine, what determines the redline or max rpm? I saw a strengthened eccentric shaft that says it can handle up to 12k rpm. What other parts in a rotary engine would need to be strengthened?

wwilliam54

apex seals, oil pressure, stat gears, lightened rotors, clutch, flywheel, tranny, accesories, and ports that make it worthwhile

daem0n

but just talking engine - I would imagine the rotors and housings would be most prone to damage?...

wwilliam54

the apex seals will chatter and the e-shaft will bend letting the rotors gouge out the side plates

daem0n

So what kind of seals would be better suited? 3mm or are there some 2mm that should be able to handle the stress?

Project84

For racing engines (rotaries) that are used consistantly above 8,500 RPMs, there are procedures for providing more clearance between the housings and moving parts to prevent unwanted contact. Extra dowel pins can also be added to strengthen the block. It is also highly recommended (and mandated in all official racing organizations like the ITA or SCCA) that scattershields or kevlar shrouds of some kind be installed to prevent the clutch/flywheel from coming through the floor board and destroying everyone in the vehicle. Clutches have been known to come apart at RPMs exceeding 10,500.

There is no cheap, easy mod to allow you to rev higher so you can show your friends how high the tachometer in your RX-7 . Its a serious endeavor to do it safely.

daem0n

Yeah definitely not easy...and not worth it unless you need the higher rpm range. Just was wondering what was necessary for the engine to be strengthened enough to allow for it. Thanks for the info.

peejay

Loys of people use the Mazda production 2mm seals at stupid RPM with acceptable results.

3mm seal engines, uh, don't like RPM. Carbon-aluminum seals are a good idea, but then engine longevity goes out the window. (And don't think about forced induction)

daem0n

There's always a catch :P

wwilliam54

ceramics have all the advanteges of carbon and are reliable and last

but they are 1200$ a set

peejay

But they're a bit weaker than iron, IIRC.

There's not enough info on those, probably because not too many people buy them.

nevarmore

I'm not too familiar with the variance between materials in apex seals, however I do know what iron, steel, and ceramic mean to a knife.

Iron rusts. It is soft and will bend rather than break.

Steel rusts a bit less easily, it is not nearly as soft as iron so it holds its shape better. But it won't flex as much before it breaks.

Ceramic is very hard. It won't bend where iron or steel would, but if it gets pushed to hard it has no give. It will shatter rather than bending with stresses. It's breaking point is much higher than steel.

GUITARJUNKIE28

redline in a rotary is pretty much when it stops making power.

same for a piston engine....that and when the valves start to float

seanfd3s

your trans is limits it alot

GUITARJUNKIE28

why bother spinning a motor that fast?

turbos and forced induction in general is cool because you can get the power without spinning the motor into oblivion...

peejay

And it will spring back. And it would take a hell of a lot of "push" to break something that thick with that little leverage against it.

But it does shatter.

I'd rather have something give a little bit than snap and throw shrapnel everywhere...

And as someone wise here once said, there is NO MATERIAL IN THE WORLD that will not break. Detonation can and will break *anything*, since its forces are so much stronger than normal combustion.