[96GTNATE]

So the 97 Npi engine i bought has ported npi heads and the intake is ported to match. The engine its self only has 70k miles on it.

I also have some pi heads with new Patriot high load springs, new retainers, new keepers, etc....

I dont know what stage porting was done on the NPI heads so i will neeed to get them flowed to see if they flow better than my pi heads.

My question is, if the NPI heads flow better than the PI heads should i keep those on? Or should i go with the PI for the bump in compression?

Im getting the pistons notched for bigger cams as ill be adding cams to either application. I plan to stay N/A for this build

THANKS

[lilspanky9119]

let me know what you do with the pi heads if you decide not to throw them on

[SWEET2KSTANG]

the pi head will out flow the npi head in the lower lift values, and thats with the npi being ported if i remember right. the upper lift values will be the other way aroundm, and will exceed the pi's the more lift available to the npi's. its a personal preference with what head to go with as long as the npi head has a good port job.

[96GTNATE]

Originally Posted by lilspanky9119 let me know what you do with the pi heads if you decide not to throw them on

Will do! I should know for sure sometime this week

[lilspanky9119]

cool, I have been trying to get some cash together b/c a few people have offered me the heads but I dont know how fast I can get money together. My bills are high at the moment so ive been struggling for a little bit...really really sucks..guess thats what happens when your mom decides to move out..me and my dad are stuck with the morgage.

[97S281]

Originally Posted by lilspanky9119 cool, I have been trying to get some cash together b/c a few people have offered me the heads but I dont know how fast I can get money together. My bills are high at the moment so ive been struggling for a little bit...really really sucks..guess thats what happens when your mom decides to move out..me and my dad are stuck with the morgage.

Damn that sucks. At least your man enough to step up.

[97S281]

96GTNATE, Let me know if you decide to go with the p.i. heads. I might be interested in your Ported N.P.I.'s depending on how much work they have had done.

[jg42122]

I think it will depend on how the heads we're ported I have heard some guys say ported npi heads are better.

[KV007]

i wouldnt get rid of your ported npi, spend ur money elsewhere

[walt1120]

the ported npi's should flow better unless there barley ported. should take a run on the dyno just to see what your laying down too.

[tfofkyle]

i am almost positive that the last owner "port matched" your npi heads to the pi intake, which has been shown to sometimes hurt flow. id step up the the pi setup myself because its extremely rare to see a pair of properly ported npi heads (if they really were ported at all) and you better believe hed know all the details about the heads if they were really ported.

[lilspanky9119]

roughly how much would it cost to have NPI heads ported? And about how much performance increase will you see? I'm sure it wouldn't be much hp but some acceleration?

Sorry for questions, still learning

[fmxona500]

Originally Posted by walt1120 . should take a run on the dyno just to see what your laying down too.

Agreed! And if it's below the average mark of a pi swap, then you have before and after results.

[tfofkyle]

Modularheadshop NPI heads

$895 for stage 1 heads if you send in your npi cores.

you should really call nick at modularheadshop if you want real numbers, but heres a video of a 98 gt with npi heads that the guy ported by himself in his garage + mhs cams and supporting mods that's gunning for 11's:

YouTube - 98 gt 12.01@114

YouTube - 98 gt 12.01@114

i believe he hit around 330 rwhp with some awesome torque numbers.

[97S281]

Originally Posted by tfofkyle Modularheadshop NPI heads $895 for stage 1 heads if you send in your npi cores. you should really call nick at modularheadshop if you want real numbers, but heres a video of a 98 gt with npi heads that the guy ported by himself in his garage + mhs cams and supporting mods that's gunning for 11's: YouTube - 98 gt 12.01@114 i believe he hit around 330 rwhp with some awesome torque numbers.

Good info.

[lilspanky9119]

Would it be worth the savings to port NPI heads, or go with something different? What type of gains do you see?

Thanks 97s281

[tfofkyle]

if i had to do it all over again - id buy a pi longblock and throw on mhs blower cams and call it a day for my car (procharged setup soon) pi heads will always be superior for forced induction and trickflows are even better, but way too $$$. otherwise id pi swap on my stock bottom with the ported heads and custom cams. that should have you running in the 350 rwhp category just barely underneath the trickflow headswap guys and for several thousands less with a nice bump in compression (but i probably wouldnt supercharge it then)

theres really no reason to run ported npis unless youre trying to save money or do a hardcore budget na build. ported npis are best suited for an na setup, but you keep the same compression when you swap to ported npis on your stock block. nick recommends swapping to an aluminum 4v block thats been decked to really bump up the compression ratio, and then they can use their increased piston to valve clearance to run agressive intake centerline cams (their stage 1 cam is guaranteed to bend the intake valves in a stock pi head) which really boosts mid range torque.

only reason im an npi nutswinger is because i believe ill be able to max the limit of my bottom end on stock npi heads. 97stanger (on several other forums) laid down 392 rwhp/401 tq through a vortech blown/pi intake/pi cam setup with an *automatic* boost can overcome

[lilspanky9119]

well I know if you port the PI heads the compression ratio will be to high for f/i which I plan on doing in the future. I plan on doing LT's NPI ported heads, and cams. After all that I will be going f/i

[tfofkyle]

if forced induction is your final goal then consider a pi longblock like i said earlier. i would be curious as to how well ported npi heads would react to boost, however, especially with a set of blower cams.

[lilspanky9119]

I would go long block if I had the money lol I'm basically saving like $50 a week lol I have a lot of bills, and I have to help pay for the house since my mom left...kind of hard to put money aside.