Armydad

Hey all,

If you were going to install a Vortec on a 98 GT, and only wanted 320-350 rwhp, is there any point in porting the npi heads. I am installing blower cams, so I am thinking that should suffice. I dont think it will gain enough to justify the time/money involved. Any thoughts?

pcs

porting will always help especially with a blower, but some people just swap to pi heads if they pull off the npi heads. in your case, the pi swap will increase your c/r which is not boost friendly though.

Mustang3GT07

I believe NPI ported heads flow better then ported PI heads.

Armydad

Thanks guys, well I know about the pi swap, I'm not doing it due to the increased C/R. I also know that the ported npi can flow as well as pis'. What I want to know is does anyone think there is a reason to port the heads if i am going FI and only want 320-350rwhp. My thinking is that with a blower, cams,pi manifold,exhaust, I should get around 320-350rwhp without porting. Do you guys also feel this is correct, or am I way off?

pcs

porting should help you reach that power level. i know on pi stangs with a blower and a few bolts ons they get around 350-380whp more or less depending on the boost and dyno. you should be close with the mods you listed w/o porting but porting is always a plus, especially to make good use of your cams.

Mustang3GT07

I would port them.

william_ace

i figured if you ported them and went with the blower cams that you would have more than 320 hp with FI. i was figuring more like 380 or so with all the bolt on mods. but i could be wrong

justinschmidt1

stock npi with 10 psi= around 300 rwhp
bolt ons npi +10 psi= 300-330 rwhp?
pi intake+10 psi= 330-350 rwhp?
pi intake+pi cams+ bolt ons+ 10 psi- 350-370 rwhp

Something like that man....ported heads should be worth like 20-30 rwhp with a blower setup

massred98gt

i think you should port them haha but increasing the amount of air the engine can pump through itself nets more hp. so why not port the npi heads if you have the funds. so instead of 320 rwhp you could get possiblly 350. i don't see a down side

98SN95

i have a set of npi heads i can sell you if your interested. i just finished my pi swap. before i bought the pi heads i re-lapped the valves and put new valve stem seals, there ready to go!