99black5spd

i researched this topic and really didnt find what i was looking for...i was wondering if any year cobra heads would fit on my 99 gt....anybody know?

Eagle2000GT

Its been done, but not easily. I've been told that you have to drill into the block to add additional bolts. You also have to replace pretty much the entire front of the motor, intake, and ECU. It's cheaper to just buy a 4v motor.

It depends on how far you intend to take your mods, but he only advantage that a 4v motor has if if you stay naturally aspirated. If you decide to get a power-adder (supercharger, turbocharger, or N2O) the motor is no longer limited by its ability to breath, but by its rods and pistons. All 4.6s (except the 03/04 terminator) have cask rods and pistons and are pretty much limited to the same maximum horsepower.

Fobra

.... yeah the 4v heads are worthless, who needs an extra 50 rwhp

indisposible_teens

Not to mention how much easier they gain power compared to a 2v in either N/A power or boosting it.

99black5spd

so you think that it is pointless to...so should i then just upgrade my heads now to aftermarket ones and change the crank/rods and pistons?.....thats what i originally was going to do...eventually when i have the money to do it...

cp51

it sucks to go through all the work and put in forged stuff and still use 2v heads. standard 4v heads flow much better than ported 2v heads. but it is gonna be a ton of work to swap em out. if ur gonna go through all the work to redo the internals, why not just look for a cobra motor to swap. it should be relatively easy, especially since u wont have to rebuild the entire motor.

Supercharged

Putting 4v heads does have it's benifits. Depending on the years of 2v & 4v you can get down to as much as 8.2:1 CR. This is an easy and cheap swap {[" IF "]} you already have the doner cobra engine with accesories.

Eagle2000GT

I don't think 4v are worthless. There isn't any doubt that 4v heads flow better than 2v and that they do respond a little better to boost. I'm just not sure its worth the cost to convert a 2v to a 4v when its really easy for a 2v to make 420 rwhp. I can get there with just a pulley change or headers. But, I have chosen to stay at 385 because my car is a daily driver.

I don't have unlimited budget but when its time to rebuild my little 2v motor, I been thinking about puttingin forged rods and pistons (the stock crank is good to 650 rwhp), headers and a mid-pipe, a THR intake, S/C cams and increasing the boost to 14#. I do not intend to change the heads because stock 2v heads are good to around 600 rwhp. I've floated this idea with a couple of engine builders. They thought I would also need a 8-rib belt and dual fuel pumps but getting to 535 rwhp is possible with just those changes (600 hp at the crank).

For the cost of changing a 2v to a 4v you can install a supercharger. S/C 2v > 4v. After that horsepower is limited to the rods and pistons. S/C 2v = S/C 4v. Until the bottom is forged, then you can definitely get more from a 4v. But that is above 600 hp. Forged S/C 2v < Forged S/C 4v.

cp51

that is a good point. taking ur word for the limit of the 2v being 600HP. it would be a lot asier with the 4v heads... hmmm... so the question is, is it worth forgin the engine and all that, or is it easier to buy a 03 cobra motor with it all done... i have a feeling its gonna come out to about the same when ur done... what decisions we must make... lol

Eagle2000GT

All it takes is money.