Originally Posted by jefftang04

Hi All,

I just recieved My C38R unit. Will be replacing the C38-81 on my GTM Stage 1.5 kit in February.

Currently I'm doing 450whp and 380lbft at 10PSI. Will update with results once the system is running.

a few points:
1) The inlet is 3" as compared to 2.5' for the C38-81
2) From my calculations current C38-81 is drawing 80+ HP at peak (85mm pulley)
3) If you were to run the C38R at peak rpm it will draw up to 130hp. This will affect the pulley system requirements. currently my system is running 8PK instead of the
stock 7pk. Still, it barely meets the needs of 130hp. i believe 10pk would be needed to maintain the same belt change interval.
4) The C38R (7:1) has a different gear ratio as compared to the C38-81 (6:1) ratio so the pulley size will definitely change.
5) Because of the pressure ratio (assuming rest of the system is the same) IAT will increase by about 25degC so upgrading IC might be unavoidable.

Thanks all