4.6 L Variances

[Bray Hill]

I am trying to get some more info about the differences between the various 4.6 motors. Specificly the Thunderbird and Mustang. Any suggestions on good literature or websites would be appriciated.

And when the hell did they start making intake manifolds out of plastic?!!
Thanks in advance.

[Cobra01TT]

Um, Thunderbirds only had 3.9L V8's from Jaguar. Cobras have 4 valve/cylinder, Dual Over Head Cam Motors. GT's 2V, SOHC. Cobras have forged crankshafts. Different intake manifolds, and headers. 03+ Cobras have fully forged internals and lower compression. I haven't heard of a mustang having a plastic I.M. so I'm not quite sure what your talking about.

[76_cobra]

Originally Posted by Cobra01TT

Um, Thunderbirds only had 3.9L V8's from Jaguar. Cobras have 4 valve/cylinder, Dual Over Head Cam Motors. GT's 2V, SOHC. Cobras have forged crankshafts. Different intake manifolds, and headers. 03+ Cobras have fully forged internals and lower compression. I haven't heard of a mustang having a plastic I.M. so I'm not quite sure what your talking about.

uhhhhh....what he said yeah i've never heard of plastic intake manifolds either.

[StangNut86]

a lot of 4.6 guys end up switching to the Bullitt intake manifold, which is made of metal. the stock pieces on most GTs and such are indeed made of high-durability plastic.

this causes problems with coolant, which runs through the intake as we all know. it eats the manifold away eventually, or cracks it. a solution i've seen work is 2-part epoxy to hold the manifold shut. i dont' know how long that fix lasts, but it works.

[flex339]

plastic intakes have been on the 4.6's for awhile now. Saves weight and heat getting into the the a/f charge, but the idea of a bad backfire sounds kind of scary.

[GTStang]

I believe the 4.6 in GT's have always had the plastic intake manifold. The Bullit intake is not much of a performance improver especially when the cost is factored in. A lot of the gripes bout the plastic is just cause people are not use to it. The 1 major concern is how it holds up to Boost but so far it's not been a problem just a concern. I'm def not thunderbird expert but I do believe they had 4.6 in them the last few years like 94-96 before the stopped to make the new body style.

[Bray Hill]

Due to cobra01tt's responce I had to double check(Ive only had this car for a week and only checked to make sure it was a v8) and yes it is most definatly a 4.6.
My thought as far as the intake manifold goes, if I do a bit of head work how the hell will I hone the plastic (polymer) intake manifold. I own a glock and an H&K pistol so I am not new to the use of polymer's and can attest to their durability.
Furthermore, where can I find this bullit manifold. I could search for it but if you guys can tell me it would make things a lot simpler.
How well do the stock 4.6 manifolds flow (a flow rating would be nice if anyone knows)? Do they respond well to head modifacation?
Thanks.

[GTStang]

The biggest bottle neck is that lil metal box that bolts to the top of the polymer intake. First everybody use to port them by hand. I use to do them at my work for customers by hand but now C&L, TFS etc.., make a replacemnet unit that flows more CFM that the stock piece. Just ignore the Bullit intake not worth the time or effort. Go look at the P51 or maybe even the Riechhard Racing if your gonna S/C or wait cause more are coming everyday.

[Bray Hill]

Thanks, I appreciate the help.

[thunderbird muscle]

4.6s did come in thunderbirds i have a 95 with the 4.6 and its a great motor. Also the thunderbird actually had the 4.6 as its primary v8 before the mustang.