Was the P90 a turbo only head? I've seen p90 heads on a few z cars here in Aus, and since we never got Turbo zeds, Nissan may have used them in NA cars at some point. I dont think someone would go to all the trouble of finding a P90 and not using it on a turbo engine.

I got confused, I was thinking there was a 90a and 90b. Thanks for the correction guys.

I got an early E88 square port off of a 72 240Z, had N42 IN&EX valves fitted and put the lof of it on my fresh 81 F54 L28.

Using only a stock L24 cam for the moment I noticed a little bit of detonation at WOT from 5000 to redline and bumped my main air jets on my triple Mikuni 44s up by one size and that did the trick.

No complaints. Runs strong. Night and day difference from the old L24 of course.

-e

Currently running an N42, shaved by about 25 thou and cam tower shims, using stainless valves and race springs on a 300 duration cam, chambers are matched to 40 CC

Car pulls very well, has a nice torque and HP curve, topping out at 250 Hp

I’m not an expert on engines. Not at all, so tell me why an E31 head is more desirable. It has to do with the cambers, valves?

But why does people write “E31 having small valves” if they are desirable? I would say the more power you want out of an engine the bigger the valves you need.

I have on my car an E31 with 6-2 header and a L28 in the barn an. The camshaft is on my wish list.