What is the limiting factor that keeps rotaries from revving past like 12k? rotating assembly weight? friction? just wondering because I would love to make my 82 12a SCREAM!!!!! thanks againfor any help

 

The main thing that is needed is balancing of the rotating assembly, although I am sure there are more things that would help. But why do you want to rev it that high except for cool points? You would need some serious porting, like peripheral ports, to even make power that high in the rev range.

 

^Agreed. There is no purpose except to impress high school friends and/or intentionally shorten engine life. I suppose that eventually fuel and intake tract restrictions will limit rpm.

 

I was just curious about it, not going to follow through with it right now

 

just curious, not going to do it right now, maybe later

 

to get your rotary to rev past 8k without blowing up...you need MONEY.

 

limiting factors (in no particular order)

1. budget
2. porting
3. rotating assembly
4. lubrication
5. budget
6. budget

budget is pretty self-explanatory. things get exponentially expensive when you're looking at an engine that will rev that high - that is assuming you could get it to rev much higher. this is where few moving parts start to be a drawback, no fancy tricks like pneumatic valves and such. making the engine physically capable of running crazy RPM will cost thousands of dollars in center bearings assemblies, fortified lubrication (dry sump), machine work to lighten and balance everything and of course, intake and exhaust tuning (because it should be obvious that there's no point to turn more RPM if the engine is not producing power there).

lubrication is kind of a twofold affair, too, because bearings will need more oil and pressure. however, the housings will also require attention - which more than likely means ceramic seals and either heavy premixing and/or some kind of steroid-enhanced MOP system.

actually, think about it this way ... take a long, hard look at the R26B engine and check out all the things that made it successful, then look at the fact that they didn't run it anywhere near the RPM you're inquiring about.

i won't go into the wisdom (or lack of it) of running crazy RPM since that was already covered by the members that have already posted.