Worth power?

FoxRod87 · Mar 25, 2008

I have a 96 GT and have some PI heads and cams and intake. Would I see any power by putting some comp cams in or should I just keep the PI cams cause I am not going to port the heads? I am also goin to put some shorty headers in while I have the heads off. I don't want longtubes. What kind of power will I be seeing on the dyno? With and without cams? and with and without ported heads? So what do you guys think I should do? Thanks.

CobraRed_96_GT · Mar 25, 2008

Ported heads + a stage I or II cam would be ideal, it'd also make it worth it to swap heads (instead of just +15 cfm) and would eliminate some of the compression increase you'd see which may be helpful for future boost?
Although, that's not for everyone - cams push up the powerband and so do ported heads. With that set-up and bolt on you'd see around 290rwhp but way up top. I went with slightly better flowing PI heads and stage I cams. It's worth it, but still i think it's a lot of work for the pay off even tho it's almost a necessity on an NPI stang. I say put on the pi heads with pi cams for dirt cheap, then save to build a supercharger, or buy a blower cam ahead of time and save yourself future labour. Either way that'll be the biggest pay-off

deftsound · Mar 25, 2008

you should look into longtubes....mine hang down less than a catted midpipe, the sound/power gains are more than worth it...

FoxRod87 · Mar 25, 2008

CobraRed_96_GT said:
Ported heads + a stage I or II cam would be ideal, it'd also make it worth it to swap heads (instead of just +15 cfm) and would eliminate some of the compression increase you'd see which may be helpful for future boost?
Although, that's not for everyone - cams push up the powerband and so do ported heads. With that set-up and bolt on you'd see around 290rwhp but way up top. I went with slightly better flowing PI heads and stage I cams. It's worth it, but still i think it's a lot of work for the pay off even tho it's almost a necessity on an NPI stang. I say put on the pi heads with pi cams for dirt cheap, then save to build a supercharger, or buy a blower cam ahead of time and save yourself future labour. Either way that'll be the biggest pay-off

What do you mean by, worth it to swap heads to eliminate some of the compression increase? I'm just not understanding what you are trying to tell me. Thanks.

ADRENLN · Mar 25, 2008

you will see a nice increase of power with the performance cams. i have a stage one cam. very miled but got a great power increase. i do have ported heads, but guys do just cams in pi heads unported all the time and get the same result.

Winters98GT · Mar 25, 2008

do not put in shorty headers! their worth zero, I thought the same thing when I did my headswap and the heads were off, and made the mistake twice. You are wasting your money on the shorty headers

I'd do a set of stage 1 or 2 cams. Id proboly stay away from the comps.

SaleenGT2001 · Mar 25, 2008

be sure to check for PTV clearance with big cams in PIheadson a non PI engine.

FoxRod87 · Mar 25, 2008

Winters98GT said:
do not put in shorty headers! their worth zero, I thought the same thing when I did my headswap and the heads were off, and made the mistake twice. You are wasting your money on the shorty headers

I'd do a set of stage 1 or 2 cams. Id proboly stay away from the comps.

So what is the power difference from the longtubes to the shortys. What is the best deal. Don't you have to take the headers off to pull the transmission out! Also in your sig are the dyno numbers with longtubes or shortys?

Winters98GT · Mar 25, 2008

FoxRod87 said:
So what is the power difference from the longtubes to the shortys. What is the best deal. Don't you have to take the headers off to pull the transmission out! Also in your sig are the dyno numbers with longtubes or shortys?

with, and without, the dyno changed less than 1hp, the curve was identical. It was a big waste.

My second headswap, I decided to put them on again sense the heads were off. didnt get any dyno numbers.

FoxRod87 · Mar 25, 2008

So with the PI headswap pullies and a K&N you put out 264 and 299 with stock manifolds. And then put on shortys and made 1 more HP. So how much power would Longtubes give you?

CobraRed_96_GT · Mar 25, 2008

FoxRod87 said:
What do you mean by, worth it to swap heads to eliminate some of the compression increase? I'm just not understanding what you are trying to tell me. Thanks.

im saying ported heads make the swap worth it instead of just a gain of 15cfm, and ported heads cause less of a compression increase because they have material taken out of them - so less compression is better suited for perhaps future supercharging or turbo charging

midnightcamaro · Mar 31, 2008

are you saying ported heads change compression ratio? hmm. the only thing thats changing is the flow of the air. there will be less pressure in exhaust port due to more room for the air out but it wont change compression. the only time any kind of porting will change compression is if they ported out the combustion chamber

Green&GoldGT · Mar 31, 2008

Lets get this straight. Swapping NPI heads for PI heads will increase your compression ratio. But if you port and polish the heads in the combustion chamber, your compression will be lowered but not by a large amount, less material means more volume. Most places that P&P modular heads will smooth out the combustion chamber, widen the chamber to enhance scavenging since the valve is close to the edge, and eliminate the "tongue" that is a chunk of metal. This increases flow(if done right) but decreases compression.

CobraRed_96_GT · Mar 31, 2008

Green&GoldGT said:
Lets get this straight. Swapping NPI heads for PI heads will increase your compression ratio. But if you port and polish the heads in the combustion chamber, your compression will be lowered but not by a large amount, less material means more volume. Most places that P&P modular heads will smooth out the combustion chamber, widen the chamber to enhance scavenging since the valve is close to the edge, and eliminate the "tongue" that is a chunk of metal. This increases flow(if done right) but decreases compression.

Right, there is a ledge that's for low rpm emissions - everyone takes it out for porting. that itself will low the compression slightly, and if you dont believe me that P&P'ing takes material out look at this: http://youtube.com/watch?v=l1SWFZ1rteI
This shows the tock ledges im talking about, mine are still on:

midnightcamaro · Apr 1, 2008

yea porting the chambers out will change compression slightly but i thought you were reffering to the runners.

CobraRed_96_GT · Apr 1, 2008

midnightcamaro said:
yea porting the chambers out will change compression slightly but i thought you were reffering to the runners.

you do work to both, who only ports the runners?

Worth power?

FoxRod87

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deftsound

Please ask me how much my supercharger cost

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