Defined 20b n/a semi p-port. 421rwhp

NoDOHC · 11-19-2010, 07:19 PM

I think that I misunderstand what a PP does for the Volumetric efficiency. I thought that they ran 125-130% VE at 9,000 RPM. My engine is making 102% VE at 7,700 RPM and making 160 WLb-ft (= 240Wlb-ft on a 20B) at 6500 rpm where it makes 98% VE.

I would expect the torque to be significantly better for an engine with better VE.

I also would have expected this engine to make about 8% higher torque/VE due to 9.7:1 vs 8.2:1 compression. This should put the torque output at 175 Wlb-ft / 100% VE for a 13B or 263 WLb-ft / 100% VE for a 20B. This is why I expected 280Wlb-ft out of it, I guessed 110% VE. Do you have a VE curve for that engine?

Your AFR is similar to mine, your timing is similar to mine (given the differences in Compression ratio).

This thread is scaring me, as I am beginning to worry that adding compression ratio adds enough flow resistance past the cusp in the housing to destroy any gains that are made by it (I have read that somewhere).

I will have to wait until spring to find out now (I will run my engine with 9.4:1 rotors instead of 8.2:1 rotors).

11-19-2010, 07:19 PM	#13
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin Posts: 855 Rep Power: 17	I think that I misunderstand what a PP does for the Volumetric efficiency. I thought that they ran 125-130% VE at 9,000 RPM. My engine is making 102% VE at 7,700 RPM and making 160 WLb-ft (= 240Wlb-ft on a 20B) at 6500 rpm where it makes 98% VE. I would expect the torque to be significantly better for an engine with better VE. I also would have expected this engine to make about 8% higher torque/VE due to 9.7:1 vs 8.2:1 compression. This should put the torque output at 175 Wlb-ft / 100% VE for a 13B or 263 WLb-ft / 100% VE for a 20B. This is why I expected 280Wlb-ft out of it, I guessed 110% VE. Do you have a VE curve for that engine? Your AFR is similar to mine, your timing is similar to mine (given the differences in Compression ratio). This thread is scaring me, as I am beginning to worry that adding compression ratio adds enough flow resistance past the cusp in the housing to destroy any gains that are made by it (I have read that somewhere). I will have to wait until spring to find out now (I will run my engine with 9.4:1 rotors instead of 8.2:1 rotors). __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic)