Summer job

[americanjesus]

This summer I wanna do the PI intake and heads swap . Just wondering if the heads need to be modified or just the intake? Also woud P&P my 98 head be better then just stock PI heads? thanks

 

[stangGT97]

This summer I wanna do the PI intake and heads swap . Just wondering if the heads need to be modified or just the intake? Also woud P&P my 98 head be better then just stock PI heads? thanks

PI heads will bolt right up to your block, the intake just needs to have a tap for the 2nd coolant sensor. An easy way to do this is a T-fitting, or to use the crossover from your old intake (in my case, it was aluminum bc it was fixed by the recall). Porting your NPI heads (a very good port job) will outflow stock PI heads, while retaining the compression ratio. Bear in mind that if you had the PI heads ported, they would probably outflow NPIs, though there are cases where that isnt always true. Good luck!

 

[americanjesus]

why do the pi raise the compression, and what one will I get more power out of pi non ported or npi ported?

 

[mrvax]

I've heard these claims about non-PI ported flowing as well as PI non ported. I have yet to see dyno proven results. I've looked at both and frankly, I don't believe it.

The PI's raise compression b/c the chamber is smaller than non-PI; it was designed for slightly dished pistons. The result is a c/r of about 10.4:1.

Lastly, from dyno results I've seen, it's not worth the money to just port/polish PI heads for a N/A car. The gains are minimal. If PI heads are also treated to valve and chamber work, the results are very good. (Like Fox Lake heads.)

 

[americanjesus]

I would port the pi heads I would only port my stock heads because I wouldn't have to spend the money on the heads

 

[DropTopPony]

Are you staying NA or is a Supercharger in your future? If staying NA then PI heads are great. The added compression is a good thing. If your gonna get a blower then just keep your heads and have PI valves installed with a port job.