Need help. Computer tuning 7.4 MPI

[RunninRed]

Hello all. Need some help. First things first.... Many of you know my boat. 1999 22 Zx, 454 MPI with a Whipple. Bought it from LittleGrizz back in March, been lovin it ever since. Boat is fast and fun. I get a solid 76-77 gps everytime out.

While its cold I would like to pull the motor and freshen it up. Nothing crazy. Here's what I have in mind.

New gaskets
New rings
New pistons, would like to bump comp. ratio to 9:1. Correct me if I'm wrong but its 8:1 stock??

New cam, convert everything to roller, and a bit more duration. I like the bumpy idle.

Just a general rebuild with the idea of adding a bit more power.

My question is how will my computer react to all this. I'm sure it will have to be adjusted, but how? By whom? etc...

Thanks in advance guys!
Greg

[The Hedgehog]

Does it have a mefi?

Mark Boos may have a cal for that. I would talk to him, get him to spec out a cam. You will probably want to put some o2 bungs in the exhaust for the final tuning.

Eddie Young does this type of work as well. You could just take it to him and turn it over. He stands behind his work. He did mine and won't stop until its done right. He did my 850. He also does boat tuning

[SilverBack]

Hello! I am pretty sure that Mark Boos did the tune on the boat that it has now. He does a great job! I like everything you are talking about doing with the freshen and the roller cam. I would not raise the compresion! If you want more performance just raise the boost!! I don't know if you are doing the engine yourself but I would let mark tune the engine on the dyno. You will be happy that you did!! He is the best around!

[SilverBack]

I just noticed that you listed your engine as a 454 MPI. I am not sure if that engine has a forged rotating assy. If it does not I think that I would put that on the top of my list of things to do!!

[mikev]

I agree forged internals if it doesnt already have them and I would not raise the compression ratio leave it stock and if anything crank up the boost a little more. Higher compression ratios and blowers don't play well together.

[BigGrizzly]

Running Red Mark boos did that computer after Wipple screwed it up 3 times. The only thing that probably may needs to be done is fuel pump pressure. Lil griz kept the RPMs low around 4600 to keep the durability up. Actually your compression may be lower because he used different heads then stock because the stock ones were prone to detonation. I have GPSed that boat at 81 once, right after he got it home from Mark Boos. It was set up to be safe. the bottom end has never been apart just the heads off. I beleive it is a roller block to begin with but can't remember.