Over-rev
07-30-2007, 11:02 PM
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Over-rev
What happens to rotary that is over-reved? (As in a messed up down shift.) I know with a piston engine, if you over-rev, you can drop a valve, or spin a bearing, or bend a rod, etc. In a rotary, does the main shaft bend? That's the only thing I can think can happen and even that should take a lot of revs to bend with as thick as it is.
P.S. I'm talking internal. I know the accesories will usually give out before the motor.
P.S. I'm talking internal. I know the accesories will usually give out before the motor.
07-31-2007, 03:21 AM
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take this with the weight of a grain of salt....
it seems i read somewhere that our motors are balanced to spin up to something like 13,500rpms. anything more than that and vibration wil practically disentigrate the motor. now i've accidentally shifted to 2nd gear twice while redlining 3rd... both times: my dash lit up like a Xmas tree; ABS/TCS/DSC or something went apeshit trying to keep the rear end straight; and the tach jumped to what i guestimate would be around 11,000-11,500rpms.
scared the living shyte outta me both time, but i havent seen any negative effects yet. i dont know much about rotories, but i expected an early symptom would have been chatter from the seals(apex?) luckily *** seems well for the last 5-10K miles since.
it seems i read somewhere that our motors are balanced to spin up to something like 13,500rpms. anything more than that and vibration wil practically disentigrate the motor. now i've accidentally shifted to 2nd gear twice while redlining 3rd... both times: my dash lit up like a Xmas tree; ABS/TCS/DSC or something went apeshit trying to keep the rear end straight; and the tach jumped to what i guestimate would be around 11,000-11,500rpms.
scared the living shyte outta me both time, but i havent seen any negative effects yet. i dont know much about rotories, but i expected an early symptom would have been chatter from the seals(apex?) luckily *** seems well for the last 5-10K miles since.
07-31-2007, 03:13 PM
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07-31-2007, 04:00 PM
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I remember this being discussed a long way back. I also recall the 13K figure being thrown about but I wouldn't bet my engine on it. The things that start to go wrong, iirc, do include flex of the eccentric shaft. And if that flexes, then the rotors are no longer rotating in-plane, and start tearing up the side and apex seals, end plates, housing... yada yada
07-31-2007, 04:04 PM
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07-31-2007, 05:21 PM
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On my first track day last October at Road America I over revved the engine at least 5 times. When I say over rev I mean I downshifted to 2nd before I slowed down enough. The engine cut off fuel all 5 times. It was my first time on a course. Since then I have done 6 track days with no issues. Just don't make a habit out of it.
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