5.7 MPI questions...?
 

I have a 02 5.7 MPI and was just curious what the HP limitations are on the stock heads...? meaning if I wanted to re cam where would I stop making hp due to restriction in the stock heads...?

the ecm is set up with the correct calibration from the OEM being a stock application., Whatever gets changed from the engine side one will have to calibrate a new tune for matching all that. Timing, rpms limits, fuel mapping, fuel pressure, octane of the fuel and so on.


Also possible the increases of HP and TQ the injectors might get maxed out for duty cycle. This , depending on how much those increases are and requirements of the fuel injectors..

I don’t know the answer to your question on where the heads max out at, but if I remember right the vortec heads need a special set of springs to go over .480 lift.

On the tune, check with mark boos at precision marine. He may have a tune he can give you the combo to run with.

Vortec Heads will require machining with any lift over about .480 as stated. A few years back I built an engine for a C18 Donzi with vortec heads. I started with a 2008 Mercruiser 6.2 Longblock, bored .30 new forged pistons at 9.6 to 1 a GM Performance parts hot cam kit and the Vortec heads that were on the 6.2 Had the heads reconditioned and had the machine work done to accommodate the springs and hardware that came with the kit. The Valve guides needed to be cut down , Spring seats cut, pushrod holes drilled to 7/16 (not for larger rods but for clearance due to higher lift). Topped it all off with a edelbrock performer RPM marine intake and 750 carb and it ran great. 12mph over the stock 260hp 5.7 If you want info on the heads you can google gm vortec 906 or 062

Being a 2002, and if its a MEFI and not 555 then there would be several, could even do it your self with MEFIBURN and AFR meter

Could also go from 5.7 to 6.2

What boat is it in? Not all boats are going to respond the same to a 50-75HP Increase. Most likely all of your increase will be at higher RPM without increasing the displacement. If you are in a heavy single engine, you may be disappointed.

. It in a 330 Sun Sport formula

. How do I know what I have..? Its a 2002 Formula SunSport 330 its a 5.7 mpi Horizon. Serial number begins with a 3

Not seeing a Horizon starting with a 3, the serial number would be a number, letter and then 6 more numbers exp: 0M123456

Now if its 0M3 something then its probably 555