Truth about NPI vs PI

[S281 #39B]

Camshaft lift: .473/.473-inch lift for 96'
Camshaft lift: .505/.534-inch lift for 01'

 

[Dalamar]

Here's some info from powerheads - where I got my PI's

"Pre 99 heads had small ports and valves, and large round 52cc chambers.
Camshafts in these heads were only .460’’ lift with short spring heights,
you CANNOT install high lift cams in these early heads."

I gained 95 HP, NA, average tune, high elevation.
THere are guys that have got 132 RWHP gain from PI heads, cams and a good tune.
That's more than you can get from most Superchargers on the NON PI's setup.
Case closed for me.


Another hyped up point about the PI swap is that the compression will go up!!!!!!!!!!! aaaaagh, noooooo.
SO WHAT. the modular loves high compression, It's a benefit.
If you get detonation, it is due to a bad tune.

 

[98GTSTANG]

I thought this was supposed to be a cheap upgrade. When you start talking about porting and polishing, you're getting into big bucks. Not to mention you have to find a place that has the anderson tool and can do it without pulling the engine to install the cams in the NPI heads. Unless you can do it yourself, the installation of PI heads is not that much more. The only real price difference is the cost of the heads. I was looking at doing this without the head swap, but if the engine is out of the car why not put the newer heads in?

 

[S281 #39B]

for that money just buy a blower

 

[Dalamar]

A lot of poeple say that...
If you only want 50-80 HP gain, ya just get a blower.


If you want more, theres more to it than that.
I've posted up a thread on it, check it out:
http://www.sn95forums.com/forum/index.php?topic=1292.new#new

 

[Dalamar]

I was looking at doing this without the head swap, but if the engine is out of the car why not put the newer heads in?

I agree.

 

[97vertstang]

isnt a blower at least 3k while ported pi heads and cams is also around 3k and
blower=80 hp
ported pi and cams=100+
if i had money theres no question on which one i would go with.

 

[S281 #39B]

I guess we all use different blowers for those little power jumps (50-80)

 

[VenomStang96]

my only question is about whcih heads to go with

 

[Adam]

my only question is about whcih heads to go with

Well the only 2 intakes that are a true bolt on to NPIs are NPI intake and that POS FRPP 2V way overpriced unit. Any other intake requires some "work" to bolt to NPI heads. All the newer intakes, blowers, etc are designed to go on the PI heads, so in my opinion its an easy choice. Kinda like buying a VCR today and expectiing to put cd's or DVD's in it IMO. ONLY my opinion though 8)

Adam

 

[jpajkos]

So I have a question. I have a 96 GT with a few bolt ons such as. Cold Air, Catted X pipe, flows, 75mm TB, Trick flow intake plenum, steeda pulleys and some 4.10 on my stock 2v. If I was to get new PI heads, intake, and cams how much of a power gain would i be expecting given I paid my local shop to tune it after the work was done?

 

[Dalamar]

Stock swap, 40-60 HP. maybe more with some of the supporting mods you have and a good tune.

More with cams, depends on the grind.

If you can afford it, I'd recommend doing cams.
What you also have is a huge potential to get more power with the addition of a blower.
NPI, you're very limited past 350 HP or so.

More info here if you feel like reading.
http://www.sn95forums.com/forum/index.php?topic=1292.0


I had catback, 75mm TB, and gained 95 rwhp with ported PI's and cams - high elevation, average tune and an auto,

 

[jpajkos]

Cams were going to be my next mod. Then the intake. My question is would I be able to run a Power adder like a supercharger if I had no PI heads? What sites should I look at for upgraded parts?

 

[Dalamar]

Yes you can just do the cams. you'll have to weigh out if it's worth the work and cost.
depends on your long term goals.

I'd say do it all at once if you can.

I suggest you read the link I posted above, there's cam info, intake swap info, links to sites that sell the stuff, and other things for you to consider.
Post up in there with specifics if you want.

 

[BOOSTED98GT]

The PI cam and intake swap also provides decent power gains absent the draw backs associated with the PI head and intake swap. Swapping PI cams and a PI intake on nPI Stangs results in a 30 – 35 RWHP gain. The cams alone result in a 13 – 16 RWHP gain and the intake results in a 15 -18 RWHP gain. The extra 10-15 on the PI head is the bump in compression with an added cost for the heads.


The benefits of this swap are lower costs, less labor, and the fact that you maintain stock compression ratios.

Just wanted to note a conflict of information. The PI swap does indeed increase compression by nearly a point to approximately 10.3:1.

-Boosted

 

[DropTopPony]

The PI cam and intake swap also provides decent power gains absent the draw backs associated with the PI head and intake swap. Swapping PI cams and a PI intake on nPI Stangs results in a 30 – 35 RWHP gain. The cams alone result in a 13 – 16 RWHP gain and the intake results in a 15 -18 RWHP gain. The extra 10-15 on the PI head is the bump in compression with an added cost for the heads.


The benefits of this swap are lower costs, less labor, and the fact that you maintain stock compression ratios.

Just wanted to note a conflict of information. The PI swap does indeed increase compression by nearly a point to approximately 10.3:1.

-Boosted

What he was referring to was just the PI intake and Cams swap...stating that the heads don't add much power but the bump in compression is what is making up the hp difference. So not using PI heads will maintain stock compression and cost less.

 

[BOOSTED98GT]

The PI cam and intake swap also provides decent power gains absent the draw backs associated with the PI head and intake swap. Swapping PI cams and a PI intake on nPI Stangs results in a 30 – 35 RWHP gain. The cams alone result in a 13 – 16 RWHP gain and the intake results in a 15 -18 RWHP gain. The extra 10-15 on the PI head is the bump in compression with an added cost for the heads.


The benefits of this swap are lower costs, less labor, and the fact that you maintain stock compression ratios.

Just wanted to note a conflict of information. The PI swap does indeed increase compression by nearly a point to approximately 10.3:1.

-Boosted

What he was referring to was just the PI intake and Cams swap...stating that the heads don't add much power but the bump in compression is what is making up the hp difference. So not using PI heads will maintain stock compression and cost less.

Gotcha, now I see it. Thanks.

 

[MyBoxersSayJoe]

so, technically, if i kept the npi heads and just did the cam and intake, could still run regular gas?

 

[Ender]

so, technically, if i kept the npi heads and just did the cam and intake, could still run regular gas?

Sure, the only reason people run premium after the PI swap is because the heads raise compression.

 

[MAXX RS4]

Just today I paid notice to my coolant crossover and noticed it was the aluminum one, so obviously it's been changed by the PO.

Now, how do I know whether or not I have the PI intake? I've seen the difference between the two when they're not on the engine, but what's a sure way to tell?

If I take a pic of my engine, could someone clue me in on what's different from stock? I'll go take a pic now.