pi swap vs porting npi cylinder heads

#2
You can find cheap used PI parts and getting your NPI heads ported from a good shop can run you alot of money. It all depends on what you want to do. If your staying NA then just swap to PI because the added compression is a benefit. If you plan on going supercharged/Turbo then having your heads worked by a shop like steen racing or renegade is a worthy long term investment.
 
#3
DropTopPony said:
You can find cheap used PI parts and getting your NPI heads ported from a good shop can run you alot of money. It all depends on what you want to do. If your staying NA then just swap to PI because the added compression is a benefit. If you plan on going supercharged/Turbo then having your heads worked by a shop like steen racing or renegade is a worthy long term investment.
Click to expand...

good advice, but if my car doesnt sell i may be staying N/A with npi heads i think i can drive it into the 12s with my intake manifold.

But really PI heads are prolly the way to go.
 
#5
on another not it would prolly be cheaper to do a PI swap because you can get the whole kit for like $1400 but there not ported but still flow way better than the NPI heads.

I am looking at around that just for a set of really nice NPI p&p heads and then around 5-600 for cams.

I would imagine the install would be a little easier with the NPI heads because you dont have to change intake manifolds but that would be an added upgrade to do is get a PI intake manifold on it as well so it would be about the same work.
 
#6
Dope 97GT said:
good advice, but if my car doesnt sell i may be staying N/A with npi heads i think i can drive it into the 12s with my intake manifold.

But really PI heads are prolly the way to go.
Click to expand...
Johny Langton has his NPI 97 TBird in the mid to low 12's NA! And its heavier then a mustang.
If you want really good p&p'd npi heads contact www.steenracing.com
If you want Great p&p'd npi heads contact Jim at Renegade Racing...send him your intake also and he'll port and clean that up also.
Look up member TGJ on SN..he has Renegade NPI heads and they flow as good as MPH st 2.5 PI's do. He can also modify the spring perch so you can run more aggressive higher lift PI cams like VT st 2's etc
 
#7
DropTopPony said:
Johny Langton has his NPI 97 TBird in the mid to low 12's NA! And its heavier then a mustang.
If you want really good p&p'd npi heads contact www.steenracing.com
If you want Great p&p'd npi heads contact Jim at Renegade Racing...send him your intake also and he'll port and clean that up also.
Look up member TGJ on SN..he has Renegade NPI heads and they flow as good as MPH st 2.5 PI's do. He can also modify the spring perch so you can run more aggressive higher lift PI cams like VT st 2's etc
Click to expand...

yeah i know i have contacted jim a couple of times but now i gotta make a decision of what im gonna do because i need a tranny in my car as well. Gearbanger told me about him.
 
#8
Dope 97GT said:
on another not it would prolly be cheaper to do a PI swap because you can get the whole kit for like $1400 but there not ported but still flow way better than the NPI heads.

I am looking at around that just for a set of really nice NPI p&p heads and then around 5-600 for cams.

I would imagine the install would be a little easier with the NPI heads because you dont have to change intake manifolds but that would be an added upgrade to do is get a PI intake manifold on it as well so it would be about the same work.
Click to expand...
Keep this in mind though....you could have your NPI's ported and refurbished as well as pick up a set of used stock PI cams and valve train for nearly what it would cost you to buy a complete PI swap kit (sans manifold)......at which point the NPI heads would be the better performers by a fairly significant margin, while still keeping the cost within reason.

The PI manifold will bolt to the NPI heads with nothing more than a set of PI gaskets and a few well placed dabs of RVT Black Silicone around the coolant areas......so don't let that scare you.

The aftermarket cams are going to cost you $600 no matter which set of heads you're working with, so keep that in mind when factoring out your budget. Also keep in mind that a set of cams is going to perform better with the above noted ported NPI’s than they would a set of untouched PI’s.

If big flow figures at all levels, while using a stock short block and keeping compression figures low is ones primary goal, then the right choice is always going to be the ported set of NPI's.

If a simple, strait swap, with higher compression numbers and factory limited flow potential, along with slightly lesser overall cost is what you're after then the PI's are where it's at!

…..and before anyone chimes in, yes the PI heads can be ported to perform as well as a set of ported NPI’s, but you’re got to add that additional cost to your pre-planned PI swap, which is going to affect the budget significantly. And when all is said and done…..when both heads have been ported to their fullest potential, they flow about the same anyway.
 
#9
Gearbanger 101 said:
Keep this in mind though....you could have your NPI's ported and refurbished as well as pick up a set of used stock PI cams and valve train for nearly what it would cost you to buy a complete PI swap kit (sans manifold)......at which point the NPI heads would be the better performers by a fairly significant margin, while still keeping the cost within reason.

The PI manifold will bolt to the NPI heads with nothing more than a set of PI gaskets and a few well placed dabs of RVT Black Silicone around the coolant areas......so don't let that scare you.

The aftermarket cams are going to cost you $600 no matter which set of heads you're working with, so keep that in mind when factoring out your budget. Also keep in mind that a set of cams is going to perform better with the above noted ported NPI’s than they would a set of untouched PI’s.

If big flow figures at all levels, while using a stock short block and keeping compression figures low is ones primary goal, then the right choice is always going to be the ported set of NPI's.

If a simple, strait swap, with higher compression numbers and factory limited flow potential, along with slightly lesser overall cost is what you're after then the PI's are where it's at!

…..and before anyone chimes in, yes the PI heads can be ported to perform as well as a set of ported NPI’s, but you’re got to add that additional cost to your pre-planned PI swap, which is going to affect the budget significantly. And when all is said and done…..when both heads have been ported to their fullest potential, they flow about the same anyway.
Click to expand...


Damn GearBanger, thats the best post/advise Ive seen from you. I totally agree with you, very rare but Im being honest...:D

Nohboy33, the PI head swap is very over rated. You can get within 10-15hp from the headswap just by doing the PI cam/intake swap.
Or you could spring for some Comp 268H's or VT stage 1's and be about 10-15hp over the headswap. Both without raising your compression, so if you want a s/c in the future it wont be an problem.
 
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