I have acquired a few different types of heads and would like to know what motors they are off of, which are considered better and which work best on my cars. I have 4 all with L28 motors. A 73 with flat top pistons, SU's on a N42 with a header system. A 74 with flat top pistons, SU's on a N42 with a header system. A 75 with flat top pistons, fuel injection on what I feel was a poorly ported and polished N42 (could never get rid of the ping) balanced motor, lightened flywheel and a header system. A 77 assume stock pistons, fuel injection on a round port exhaust head with stock header. I have 2 E31 heads, 2 P90 heads and 3 N42 heads beside whats on the motors now. I was told that the P90 was the best out of the box by Nissan. Would like any info anyone has to offer. Thank-you, MC75Z.

http://www.geocities.com/zgarage2001/heads.html

http://www.geocities.com/zgarage2001/engine.html

The pinging on the 75 injected motor could be from compression not a poor head job. The head was most likely shaved raising the compression or the pistions could be domed. The head might be very nice, maybe a larger cam can relieve some of the compression stopping the pinging.

The p90 is said to flow the best but has a large combustion chamber yielding low compression. It cam be shaved .080 on an l28 to give higher compression then shim the cam towers to get the geometry right. It is a great head for a 3.2 stroker IMO. No shaving is needed and the motor would give around 10.5:1. I would like to get one.