MILD THUNDER

iTrader: (3)

Question. Does anyone know what heads came on a 1999-2000 7.4L MPI (310HP)? Also, what type of cam (specs)? And, how much HP can the stock MPI system support? Looking for a 375-400HP recipe on a budget. I believe the heads should be the L29 vortec style?? Thanks

bobl

It has the Vortec heads(large oval). The cam is 206/211 duration @ .050 lift, .480/.483 lift. I've tried building this engine before. They just don't make any power with the stock EFI. I ported the heads, changed cams and reprogrammed the ECM. The boat only gained about 2-3 mph (so maybe 360-370 HP). I replaced the intake with an air gap and Holley carb and picked up another 5 mph.

anewway

iTrader: (1)

I have to second what Bobl said. I tried the same with my '98 7.4 MPI and spent a lot of money and a lot of time and very little to show for it.

I saw similar posts warning against it, but I went ahead with it anyhow, thinking there had to be a way to get to 400 hp without a lot of trouble, and it really was a waste of time and money.

jeffswav

Good info given to you so far. I started with the GenV carb version 7.4L BBC. The engine you have will work well for a long time and should be very dependable. However it was not designed for upgrading and has very limited HP potential. The heads will work fine with a little port work, however everything else sucks. I started with the penut port heads, now I have a set of 820 large ovals, pretty compairable to yours. I have a aftermarket Holley MPI kit with 42lb injectors & 1000CFM TB, EMI exhaust, forged stroker assembly, RMbuilder Roller Cam & valvetrain ect..... The list goes on, it will cost you a ton of money to get any real power out of it. Not trying to discourage you but get out your wallet if you want to go fast. If you deside to pull the trigger keep us in the loop and we can point you in the right direction.

Sledge Hammer

You could probably find a performance engine for sale here on the board for around $5,000 to $6,000 and sell yours for $2000 to $3000 and you would be money ahead and have more HP.