ported NPI > Pi ??

96 GT JOE · Sep 29, 2005

why doesn't anyone ever talk about the npi heads? i know they were restrictive from the factory but has anyone had their npi heads ported and polished? what about with aftermarket cams? i have a npi gt and i was going to do a pi swap, but recently i have been thinking about buying a pair of npi heads and having them p&p'd. throw in some good cams and a pi intake and i should be good to go?

- does anyone know of any good machine shops or tuning shops in the Central Florida area???

DropTopPony · Sep 29, 2005

renegade who is supposed to be awesome at porting NPI heads is in Florida i think, and blow by racing is in florida and they do P&P..then you can ship em to www.steenracing.com he does good work.
boss330racing is in florida.

tomustang · Sep 30, 2005

It's been debated before, what it comes down to it, ported NPI's can slightly outflow (few hp) stock PI's but it'll cost more than just picking up a set of PI's

TGJ · Sep 30, 2005

tomustang said:
what it comes down to it, ported NPI's can slightly outflow (few hp) stock PI's but it'll cost more than just picking up a set of PI's

That is a bunch of BS. Renegade Racing P&P NPI outflow P&P PI's, that is including Fox Lake Stg IIs, VT Stg IIs. It has been shown that they( NPI ) is making as much power as the P&P PI heads. Renegade Racing is located in Michigan. In fact it is cheaper to buy NPI and have them P&P then it is to buy PI's and have them P&Ped.

What it boils down to is, to pick a Compression ratio you want, choose the head that works best for you and go from there. NPI > PI in N/A application, PI > NPI with a super charger or turbo.

Orions98GT · Sep 30, 2005

TGJ said:
What it boils down to is, to pick a Compression ratio you want, choose the head that works best for you and go from there. NPI > PI in N/A application, PI > NPI with a super charger or turbo.

with pi heads on the npi engine, you will have higher comp with the PI heads making it better for N/A, and the NPI heads better for a blower/turbo on the stock npi block.

edbo · Sep 30, 2005

Very interesting thread, I was considering a PI swap, but I believe the ol' NPI P&P work has to be something to consider. Anyone know what intake manifolds are being installed to get the these NPI heads to rule?

CanadaStang · Sep 30, 2005

edbo said:
Very interesting thread, I was considering a PI swap, but I believe the ol' NPI P&P work has to be something to consider. Anyone know what intake manifolds are being installed to get the these NPI heads to rule?

I wouldn't be using the word "rule" but to get them perform about the same as the PI's you must use the PI intake. You'll also need to swap out the stock Non-Pi cams.

edbo · Sep 30, 2005

CanadaStang said:
I wouldn't be using the word "rule" but to get them perform about the same as the PI's you must use the PI intake. You'll also need to swap out the stock Non-Pi cams.

Okay, so maybe kick ass would be a better term. I know that the stock cams would have to go. I was just wondering if a regular PI intake would be a good match or if one should move up to a Bullitt intake.

CanadaStang · Sep 30, 2005

edbo said:
Okay, so maybe kick ass would be a better term. I know that the stock cams would have to go. I was just wondering if a regular PI intake would be a good match or if one should move up to a Bullitt intake.

Just go with the stock Pi intake. The bullit may give you a few extra ponies over the stock Pi but I think they are just too expensive to be a good alternative.
The nice thing about the Non-Pi heads, is that you can pick them up rather cheap, and you'll retain the stock compression incase you you decide to go with a S/C later on. You may want to check to see how much it would cost to get them P&P'd as well as the cost of cams [and springs if you go with the VT stage II's] before you decide to go that route as the are pricey.

TGJ · Sep 30, 2005

There is a few intake choices out there for intakes, if it will work on a PI, it will work for the NPI.

I can tell you Renegade will charge you approx. $2000.00 for Ported Assembled Heads, regardless of whether they are PI or NPI. Similar to what you would pay for from Fox Lake or VT. Just remember it is not just the port job you are paying for, you are getting the finest materials available in Renegade's Heads.

Now it has been raised about using an NPI stock block, then yes, the PI head will raise compression where the NPI won't. The PI head will always have a compression bump advantage over the NPI.

My comment was talking about building a motor, choose the compression level you want and go from there. Keeping in mind that the NPI head will have an advantage for a N/A application and the PI head will have an advantage for a S/C application. The reason being is that ported NPI's will out flow ported PI's on the intake side. Ported PI's out flow Ported NPI's on the exhaust side. This is comparing apples to apples, ported PI heads with the swirl dams in tact compared to ported NPI heads with swirl dams in tact.

ADRENLN · Sep 30, 2005

i think its a very close call once they are ported. judge it on the block u have and the compression you want and future plans. both are so close in flow numbers that it really dont matter.

Gearbanger 101 · Sep 30, 2005

The T-Bird/Cougar guys have been doing it for years. Actually, most of them are laughing their asses off because "most" mustang guys are so brainwashed into thinking they suck and so hell bent on PI heads, they don't realize the potential of their NPI castings and are letting them go on Ebay for peanuts.

tomustang · Sep 30, 2005

Gearbanger 101 said:
The T-Bird/Cougar guys have been doing it for years. Actually, most of them are laughing their asses off because "most" mustang guys are so brainwashed into thinking they suck and so hell bent on PI heads, they don't realize the potential of their NPI castings and are letting them go on Ebay for peanuts.

you suck

Gearbanger 101 · Sep 30, 2005

Maybe....but my motor is in better shape than yours.

TGJ · Sep 30, 2005

Gearbanger 101 said:
The T-Bird/Cougar guys have been doing it for years. Actually, most of them are laughing their asses off because "most" mustang guys are so brainwashed into thinking they suck and so hell bent on PI heads, they don't realize the potential of their NPI castings and are letting them go on Ebay for peanuts.

Quiet you, you are giving us away.

DropTopPony · Sep 30, 2005

TGJ said:
Quiet you, you are giving us away.

no need to worry, everyone is so against the NPI they will never buy into the fact they can flow just as well. I've been reading the t-bird/cougar boards for years to get tech info and guys like JL, K Danner etc have gotten great #'s with NPI heads. I only went PI myself because i got a great deal on the heads/cams/intake combo(400) I know a guy on another board who's been trying to sell a set of Livernois NPI P&P heads with Livernois cams and PI valves etc for 600 dollars with NO buyer yet..been @ 1 year now if those were PI he would have got a thousand easy.

hotmustang331 · Sep 30, 2005

NPI heads are really not the restriction and I have known that for a while. In stock form the NPI heads are really not too far behind the PIs...its the intake. I know P&Pd NPIs are about as good too.

Gearbanger 101 · Sep 30, 2005

Yeah...a set of PI valves and cams in a set of NPI head net nearly the same flow results as a stock PI head....and those are fairly inexpensive to obtain.

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