[OxmanWI]

Just asking.....educate me please!

I have NPI heads just like the NPI 96-98 Mustang on my t-bird (go figure huh?). If I get PI heads from a 99+ Mustang that will bring my compression to 10:1 correct? I have a 6 psi supercharger from Allen and want to go with PI heads and get the Allen REV-1 PI runner manifold. My question is how can I compensate (get safer compression) for the compression with forced induction if I get the PI heads?

 

[Palmguy]

Why is it that you want PI heads? The answer to your question is to put a new engine in (increased piston dish with the PI heads brings the CR back down), although the 'better' answer may be to stick with the NPI heads, and maybe port them if you are looking for more performance than they're giving you now.

 

[OxmanWI]

Yeah I've been throwing that around too, can’t make up my mind on what I want to do. A P&P would be nice and throw in some better cams, just looking at the money issues with it right now. I could forge and take care of that...

Nice LS by the way

 

[Slowpoke]

What Allen kit do you have now? You dont need to change the Allen intake. I still have my non PI intake with the PI heads...Save yaself a few bucks there..You can port match yaself if you do that swap. Personally if its running good I'd leave it alone and save up to build a motor on the side. Stock 4.6 pistons dont like much boost anyhow whichever head you have...My stock PI motor with the 6psi Rev1 kit made 305-318rwhp(dependant on dyno sheet)And blew up 2 times!

 

[OxmanWI]

The t-bird 6 psi kit, yeah I know, just doing some brain stromen, I don't know what I want to do...thanks,

 

[Chris_Murder]

I've seen the carnage that occurs with forced induction, pi heads, and a stock bottom end, don't do it