I'm sure it has been asked here before but here goes. I have 2000 model 7.4L 454 MPI's. I believe this is called a Gen 6 engine. I've heard the heads on this engine are adequate enough for hp upgrades. Is that true? Also i've heard both ways but is the crank cast or steel and are the main bearing 2 bolt or 4 bolt?

That motor has a 4 bolt main block, cast crank, cast pistons, oval port cylinder heads. A few guys here on OSO have added superchargers to this motor.

I have a 1998 7.4 MPI. Yes, it has cast pistons and cast crank. Therefore limit RPM`s to 5000. The heads are "Vortec" heads from GM. They are very good heads for a mild engine. For your money, a ProCharger is best investment, I just can`t afford one!

Outlaw -

The guy I recently bought my boat from installed a Procharger on a stock 7.4 and drove it for 4 years with no problem. Just use low boost and good fuel and you should be fine. Where in IL are you located? What wateray are you on??/

the heads on your motor are great for marine use, they could use larger valves/ the bottom end is ok if you keep the rpms under 5k. the problem with this motor is the fuel injection, its diffent than the magnum version and doent flow as well. you can get more power buy going to a 750 carb good intake , cam change, some head work and a gill exhaust. you may be able to get around 375 hp out of it . Ive heard these heads have a hot spot on them when super charging, procharger type would be the only type I would think about a roots style is asking for trouble.