I know a guy who has some 98gt ported heads. Can you use ported heads for a pi swap? He says the cam is in the heads.
ported heads
- Thread starter westgastang5.0Coyote
- Start date
98COBRA281
10 Year Member
well there not PI heads, there just ported NPI heads, i am going with ported npi's, and a good ported npi can flow as good as a pi heads, but it will not raise your compression....
CobraRed_96_GT
Active Member
This is true. "Stage II" and above may actually lower your compression a bit. I'm @ about 10.3:1 instead of 10.5:1 because of combustion chamber porting and CC matching
98COBRA281
10 Year Member
yeah i did quite a bit of chamber porting too, ive been watching the days waiting for you get that monster dyno'ed
98COBRA281
10 Year Member
CobraRed_96_GT
Active Member
He's talking about the intake manifold like the post above.
And it was on the dyno with not horrible results - just a totally impeded climb due messed tune. i hope to dyno this saturday if my tuner can get back to me with a tune by then based off my datalogging data.
98COBRA281
10 Year Member
Green&GoldGT
Member
Ported NPI's only flow better than ported pi's(in most comparable cases) in very low and high lift. Modular cams spend more time in the mid lift, so you want the heads to flow the best in your cams' range.
Just guessing, ported NPI flow better than Ported PI's above .550" lift. But more than likely your cams dont even lift that high. The Crower camshafts in my car have .581" lift gross, but that doesn't mean I'm going to buy Ported NPI's because they flow better at that high of lift. A cam barely spends any time at the higher lifts, but the cam will have a longer duration at mid lift from both sides of the lobe.
More CFM doesn't always mean more power. Especially considering how sensitive 2v heads are to big ports.
Hope this helps.
Just guessing, ported NPI flow better than Ported PI's above .550" lift. But more than likely your cams dont even lift that high. The Crower camshafts in my car have .581" lift gross, but that doesn't mean I'm going to buy Ported NPI's because they flow better at that high of lift. A cam barely spends any time at the higher lifts, but the cam will have a longer duration at mid lift from both sides of the lobe.
More CFM doesn't always mean more power. Especially considering how sensitive 2v heads are to big ports.
Hope this helps.
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