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having my 82 non turbo engine rebuilt with a p90 head

745 Views 6 Replies 4 Participants Last post by  heroe
Im seriously looking for a little advice for this build. My car currently has a p79 on it, and im wondering if it would be worth wild to go with the head change. I have heard the p90 has larger ports and feel this could give me a couple extra ponies if done right. Are the valves also larger? If im incorrect, please set me right. any advice on this NA build is welcome. thank you
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instead of buying a new head put that money towards the p79 build
just want to know if there are any performance differences between the 2. Im not paying much for the head anyway
you will see no power difference between the p79 and P90 heads.

same valves, same chambers, same intake ports. The P79 has round exhaust ports and liners but that doesn't hinder performance at mild and moderate levels.

For more power, I would invest in a megasquirt efi system, better exhaust system, and a little more camshaft (deltacams regrind with 260 degrees advertised)
Like the man said, swapping in a P90 will buy you nothing, unless you're getting really serious (big cam, big intake, etc. required for high-rpm power) and need porting (not necessary or desirable for a street build IMO).

An N47 head (or N42, but that would require a square-port exhaust manifold, as would a P90) from a 280Z will give you a substantial bump in compression ratio, from ~8.3:1 to 9.8:1. This should give a noticeable bump in performance. You will need to run premium fuel...

Or you could shave your P79 .080" and shim the cam towers to get a similar c.r. bump.

Should be good for10-15hp :)

Caveat: Some have reported having to back down ignition timing doing this. However I was able to run full advance (36deg all in) with a stock N42 head with a stock cam on my 3.1 at 10.25:1 CR. But as with everything, ymmv...
thank you guys.,... this was what i was wondering. Im kinda tied into buying the p90, so im going to have a valve job done on it and either save it for when i have the time and money for the turbo build or sell it.
Stand up to him. Tell him you dont need his stinking head. tell him the p79 is fine. dont be such a wuss.
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