[BakerFX4]

I can get my hands on a 4.6 2v core. Could i just go with forged rods and pistons since these are the weakest links? I just want to have a backup motor since i am putting this SC on my car. Are our factory heads very weak? i dont wanna spend much on a "extra" motor. ya know? Or would it be pointless to half way do it. Im not pushing my motor over 420 hp anyway. and if something was to happen to this one i would just drop another one in. Im not really looking for a 600 hp car at the moment. It is a daily driver so i wouldnt ever want more out of it than those numbers.

[TheBusher]

The stock crank is good to about 600 rwhp. If you only plan on going to 420 rwhp, then the crank will me fine. The pistons and rods can handle that much too, but it's reaching their limit. It would be safer to replace them. If you do eventually plan on making big power though, you might want to replace the crank now with the pistons and rods. It's so much easier then crackin' open the motor again just for a crankshaft...

[TheBusher]

Originally Posted by BakerFX4 Are our factory heads very weak?

What do you mean by this? The heads have really weak flow if that's what you mean. No real huge amount of stress is put onto the heads themselves so they don't need to be very "strong". The components that are contained in the valves are put under stress though (valves, springs, etc...) and need to be replaced when you start making big power or reving beyond 6200 rpm. For 420 rwhp the stock heads and components will be fine though.

[BakerFX4]

aight cool. Yeah im sure that im not going to ever go above 450 ever. i dont want to aim for 600 hp at all. I put alot of money in my FX4 Screw w/20's 36's and 9" lift. so the mustang cant be my only toy taking every bit of my money. ha

[TheUNZippee!]

Famous last words^

[SWEET2KSTANG]

the crank will hold well past 600, it will hold well past 800 if treated. the rods are the biggest thing, when they let go it usually isnt pretty. the pistons are just fine for all n/a or small power adder, it depends on how you set it up. the VE of the modular ford 2v heads is not great, the intake valve is only 1.75in and is primary restriction. with some work you can make them flow decent, but still limited. there is not any aftermarket head casting for the 4.6 either, all aftermarket heads are ford heads.