punisher03

i was looking on ebay and i am lookoing at a cobra 4.6 or a 5.4 out of a f150
i want to now wich one has more power as is and wich one will handle the most power stock. thanks

califas_1987

32v cobra motor has more potential due to better heads.

punisher03

well my stock 4.6 is still good with only 40,090 miles on it what if i just put some 4 valve heads on it

DVS_Z28

go with the 4.6 4v

punisher03

what all would i need besides the heads and intake manifold

SVTeeshirt

the list for a 4v swap is a mile long, and as someone said before its rough to track down all the parts unless you found a complete package from someone who was about to do the swap but gave up. If you have a 2v with only 40k miles, mod that, you're gonna spend too much on either motor and be making less than what you could of on your 2v with the money invested. Mod the 2v(current motor).

punisher03

how much power can the bottom end of a two valve handle

SVTeeshirt

the general consenus is about 450whp.. i did however run into a guy at a carshow last week that has been running around 465whp for 3 years. Just make sure you find a good shop, a tune can make or break you. Unless the cobra engine is out of an 03/04 i doubt it is, the limits on the pistons and rods are about the same as your current car. The blocks and Cranks from the cobras are nearly indestructable but the rods still snap at about the same power levels as the GTs so theres really no point to buying that motor.

Sxynerd

Putting the 4v heads on your engine will lower your compression considerably. Which you'll end up loosing Hp because of it unless, you have some sort of F/I to make up for it.

If you're buying a full 4v motor make sure you're getting it complete with the main accessories, like Alternator, coolant crossover, water pump etc. Or you'll still get nickle and dimed like SVTee said.

As far as Hp, I think if you're over 430rw you should always be questioning it's longevity.