Single Turbo RX-7's Questions about all aspects of single turbo setups.

Timing or AFR?

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Old 09-15-11, 08:11 AM
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After talking with a few at the track last night about what they heard from the pits when the motor let go, they said it was pretty violent. Since the motor was at 9000rpms and close or at the REV limiter, i assumed it was the rev limiter that caused the noise. But is what I really think happened is it detonated pretty bad. Three things played a part in the side seals burning like they did. One was running pump fuel at 25psi on a large bridge and 90mm t-body. Thinking easy 500rwhp. Then on top of that the AFR was 12.5. And last was the soft cut REV limiter. All three things happening at once causing it to detonate and collapse the rotor face just enough to cause the side seal to stick.

Thats my story and sticking to it

Last night at the track turned out to be a good one. No pump gas (C16/E85), added tons of fuel, raised the REV limiter to 9800, put my 28inch tall tires on to slow the rpms down and made a light pass (no burn out, no made shifting of the stock trans, no big launch) 10.9 at 130mph with a AFR in the 10.5 range.

Never know if it was a clearance problem. bad rotor is on the bench now. But motor does have the same front rotor installed. All we did was remove the rear plate, replace the rear rotor and re installed the rear plate and took it to the track. Different side seals were used but same apex seals and springs and corner seals/springs. Starts easy again and shows good vacuum. Happy camper.

Thanks
Old 09-15-11, 08:12 AM
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Originally Posted by Howard Coleman CPR
the speckled rotor bearings show clear evidence of alot of knock.

knock puts huge loads on the crank and generally the SSs on the opposite side of the stationary gear suffer most. the heat got to the supporting sideseal rail opposite the combustion chamber and locked them up. pretty common.

Old 09-15-11, 10:07 AM
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Good to hear your car is running again.
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