what year 4.6s...
 

are better for running boost, sc or turbo? I thought a good tech thread would be a breakdown of the various years 4.6 engines and why some are better starting platforms for sc or turbo.

Re: what year 4.6s...
 

03-04 cobra eninges or coarse, because they come with forged goodies. Aside from that I would say the newer mach 5 speeds or 99+ cobras, because they have high flowing heads and a a forged crank. Next I would say 99+ gt's because the heads and intake out flow the 96-98. 96-98 would ahve to come last because, well basically the heads, intake, and cams suck.

dont know about 05's because I havent heard alot about them, but they make good stock power :shrug:

Re: what year 4.6s...
 

Obviously any of the 4Vs should respond better to boost. The '03 Cobra motor is a great longblock, but unless someone gives you one or you steal one from a warehouse, there are better alternatives for what it costs.

I think a '99/'01 aluminum block with '03/'04 heads, aftermarket cams or '03/'04 cams, forged internals, and a '99/'01 intake would make a great forced induction motor. But if we're talking about stock motors, I'd say either an '01 Cobra or '03/'04 Mach 1 motor would be the best bet.

As for 2Vs, I've heard a ported set of '96-'98 heads will actually outflow a set of ported PI heads. I'd replace the intake on either motor just because that plastic intake makes me nervous. The PI motor has much better cams though.

I think the 3V is going to be a great forced induction motor. Supposed to make torque like a 2V on the low end and scream on the top end like a 4V, and I would think that would only multiply once you add boost.

Re: what year 4.6s...
 

Actually, I have heard of some early failures of S/C and turboed Mach 1 motors.

I am not sure on the actual internal differences say to the 99/01 Cobras.

Obviously the crank and block are good to nearly 1000hp on Cobras. The rods and pistons are the weak point on 99/01 Cobras as well as all 2V's.

Re: what year 4.6s...
 

I'm pretty sure the Mach 1 has a higher compression ratio. Might be a downfall if you planned to run much boost.

Re: what year 4.6s...
 

If I am not mistaken, only the 5-speed machs come with a forged crank. Don't know of any other structural differences between them and the 99-01 cobra shortblock

Re: what year 4.6s...
 

:yup: There isn't a flexplate to bolt up to the Cobra crank, so the autos come with a GT crank. That's why the 5 spd cars have a 6800 rpm redline while the autos are closer to 5800. In all the comparisons I've seen, the 5 spds ran about .5 sec faster in the quarter.

Re: what year 4.6s...
 

:yup:

Also I have heard a set of PI heads/cams on a 96-98 block will have signifcantly higher compression than a PI longblock.

Re: what year 4.6s...
 

03-04 Cobras: Excellent
99-01 Cobras: OK. Rods and Pistons are the weak link. Windsor blocks used in some of the Cobras are a little weak.
96-98 Cobras: OK. Rods and Pistons are the weak link. Heads love Turbos or Centrifiguals.
Mach 1: See 99-01 Cobra except for Auto's

Re: what year 4.6s...
 

The pre-PI pistons aren't dished as much, so coupled with the smaller combustion chambers of the PI heads, you get a higher compression ratio.