Ok so I read things about PI heads and NPI heads...whats the difference and wouldnt a police interceptor have PI heads.If not then whats the difference. How much power would we be talking if adding PI heads.

PI does not mean Police interceptor. It means Performance Improved. NPI means Non-Performance Improved. Mustangs got the PI heads, cams and intake in 1999. Panthers did not receive them until 2001. Putting them on a stock NPI engine will raise the compression ratio and require Premium gasoline. A cheaper solution that many have done is install the PI cams and intake on their stock engine. That is actually most of the HP improvement.

I know the PI doesnt mean police interceptor...so would i have to do anything else other then add the cams and intake?

Not really. A tune would optimize performance, though.

depends... what year, make and model do you have?? i'm almost certin 96+ ur ok. 96-98 mustang guys do this mod daily. i did the pi intake and cams. it was well worth it. i found used stuff, and total parts cost was under $200. i had to buy a bunch of tools to make it all happen (needed them anyway kind of thing).

so basically PI cams and PI intake manifold= PI engine? then whats the point of it having a higher compression? exactly how much power difference is there with the cams and intake vs the complete pi engine? does the PI ECU add anything or would a tuner be sufficient?

What makes a PI engine a PI engine is The PI Intake, Cams, and heads. Also, they have dished piston heads. The NPI engine doesn't have dished pistons.

Therefore, if you put the PI heads on the NPI motor,(non dished piston heads) it bumps the compression by making the combustion chamber smaller. Higher compression = higher cylinder pressure, and that in turns makes more power. One would have to put a higher octane fuel in though. At least 91, but some say 93. A tune wouldn't be required, but it would be suggested.

An NPI engine with PI cams, intake, and heads would out perform a stock PI engine. It would do that because the previously meantioned higher compression. But putting any sort of forced induction on the NPI motor with all the PI stuff would be out of the question. The Rods would tunnel their way out of the block, or you'd start blowing head gaskets.... or both, at the same time. Double FAIL!!!

So would adding forced induction on a NPI with the PI cams and Intake be good?

Tim

Yes, thats doable, just be aware the stock pistons and rods are not designed for that service.

NPI pistons still have a dish in the pston its just not as big of a dish as the pi pistons. The npi have a bigger combustion chamber on the heads and the pi's have the smaller combustion chamber and thats where the compression bump comes from the shallow dish npi piston and the smaller combustion chamber on the pi heads.

You can do that, but putting stock parts on a car is only gonna get you so far. If you bit and piece and engine together without a plan, you probably won't get as far as you would if you knew exactly what you wanted from the start. You get what you paid for. Aftermarket, when done right is way more worth it than making a frankenstine motor from stock parts with a blower on it.

how much does it cost to get a good set of rods and pistons, without install lol

to get a forged rotating assembly for the mod motor is about $1800-2300.