The compression is the same for all the 99-04 motors as long as they still have the stock pistons, stock bore, and stroke. I believe its 9:4:1 for stock 99-04 Modular 4.6ltrs.
Yeah. You should be able to make 450rwhp safely with the stock compression level. Might want to ask jimfitzgerald what type of setup he's using. I know he's putting down mad power in his supercharged GT. He has all forged internals on the lower end and I think his compression is close to the stock setting.
Actually, I think the 99 and 00's have a little bit lower compression due to the different heads. Not sure how much the difference is on it though...just try searching or maybe someone will let you know.
thanks guys, i figured there might be a small difference because of the heads or somthing, but i dont think its enough to make a difference. ok im glad to hear that it should be ok, i dont want to change things that much from stock. dont mind using forged internals, but wanted engine spects to remain the same.
My advice is tell the place you buy the forged internals from what your plans are. They will advise you on what type of pistons to buy. Remember, compression has to do with how much air/fuel mixture is "compressed". This is why if you use "dished pistons" as opposed to "flat-top" pistons, there is more surface space in the cylinder and thus, the more air/fuel can be compressed within each cylinder. I recommend talking to CobraKiller(Tim) at Modular Ford Powerhouse. Talk to the guys at VTEngines and Modular Depot as well. They'll hook you up with exactly what you need for your application.