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K24madness K24madness is offline
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Join Date: Mar 2009
Posts: 158
I know this is an old thread but I have some input. I have a 993NA 11.2 CR running 6 psi of boost. It was built by prototech in Florida. The previous owner use to run 93 pump gas. I had protomotive retune it for 100 oct. The powerband is awesome!!! Compared to my previous 993tt with K24 hybrids (hence the screen name) at 600hp x 600tq this setup is much more fun!! While only about 450hp the fun factor is greater because of better throttle response and driveabilty.

The block is stock!!

I am tearing it apart this winter and upgrading the rods. While apart I am thinking of changing out the cast pistons. I would like to stay with the high CR low boost setup.

I read a lot about this on the web. Effective CR varies with cams and other volumetric efficiencies. I plan to use the apexi AVCR to vary boost in order to limit cylinder pressure. By decreasing boost at the motors torque peak (peak efficiency) and adding it when the efficiency falls you can flatten the torque curve out and not exceed the limits of the motor.

Peak cylinder pressure limits will be dictated by fuel, ambiant temp, oil contamination, and head design.
Old 11-14-2009, 09:27 AM
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