[Monkey Boy]

An artilce in the June 5.0 says the non-PI heads aren't that bad. In fact, they actually outflow the PI heads on the intake side above .500 inches of lift! But, they suffer in the low lift range because of an emissions shroud around the intake valve and a poorly designed intake valve shape. The real culprits are the intake manifold and camshafts. If you compare Livernois stage 3 non-PI heads to their stage 3 PI heads, the non-PI heads outflow the PI heads on the intake side above .300 inches of lift. The only disadvantage the non-PI's have is on the exhaust side where they are spanked handidly by the PI heads. On an engine dyno, the non-PI heads with PI intake and Livernois cams made 335 hp @ 5,600 rpms while the same setup with PI heads made 351 hp @ 5,900 rpms. So, if you're thinking of a headswap, you may want to consider porting the stock heads as an alternative. This would be a great alternative to those who have a supercharged non-PI engine and are afraid of the high compression ratio you end up with in a headswap. You guys really ought to read this article.

[Mana4Real]

Someone posted something on this a couple days ago I thought... I really wanna hit the store and check out the article.

[hamburger beans]

i got some good head from 96-98 i will admit i have gotton better head in 99-04.Oh we are talking about car heads.Well i guess it counts if i got head in the car at the time.In my plymouth millgreen .Hell far the carol bernet show is on.Holla holla

[black04gt]

i got some good head from 96-98 i will admit i have gotton better head in 99-04.Oh we are talking about car heads.Well i guess it counts if i got head in

hahah! that made me laugh out loud at work...everyone is looking at me crazy right now...lol

[GTron]

I posted about this last week. You failed to mention that, according to the article, the plastic intake manifold on the 96-98 4.6 is the biggest problem. The internals are horrible. 35 hp was picked up by using Livernois adaptors that allow the plastic PI intake manifold to be used on the earlier heads. That was the only mod and it picked up that much power just by switching manifolds.

[dbs_11]

What other manifolds would you suggest to replace the stock plastic manifold?

[dbs_11]

Originally posted by dbs_11
What other manifolds would you suggest to replace the stock plastic manifold?

98 Silver GT, bbk intake, bbk 75mm, American Thunder Flo, Ford Racing wires, Ford Racing spring kit, 17inch Eagle Alloys, JL sound system

[GTron]

Like I said, Livernois makes adaptor plates that allow the plastic PI intake manifold ('99 and up) to be used on the earlier heads (96-98). The adaptor plates go between the head's intake ports and the runners on the intake manifold. The earlier heads have round ports where as the PI heads have rectangular ports. The adaptor plate allows for a smooth transition from the rectagular runner on the manifold to the round ports in the earlier heads. They also have to modify the plastic PI manifold by milling a certain amount off of the plenum mating surface for hood clearance reasons once the plates are installed. Buy the magazine and read the article as it goes into much more detail than I can on the boards. It's a great article and well worth reading if you have a 96-98 4.6