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Thread: Mercruiser MPI max HP?

  1. #1
    I'm considering future boat options and wondering if I have a mercruiser stock 454 with MPI and I want to build about 500 HP in a couple of years will the Injection be usable or will I be canning it in favor of a carb and intake. I would prefer to run the injection setup if possible.

  2. #2
    I don't think you would have any problems getting 500hp out of that package. Good heads, a bigger cam and headers should put you there. There are a number of shops that post on hot boat that have experiance with tweaking the mpi's.

  3. #3
    Alum heads or cast??????

  4. #4
    So not sure at all what the details would on the motor in the future. I'm really just trying to decide if the FI setup has additional value for me if I'm comparing 2 otherwise comperable boats. Or if I would end up having to dump it to build 500HP. I would prefer to keep the injection if possible.

  5. #5
    JMI but...
    1) The 454 MPI is a good solid motor, It would not take a lot to get 500-550 reliable HP out of it. Computer is tuneable.
    2) Fuel injection is nice in that you turn the key, it starts, keeps running and idles. Cold engine, hot engine, 4,000 ft above sea level, winter whatever. However if it fails, it usually will be dead, you cant really do anything about it on the water. Carb problems will usually just make it run crappy. But Merc has their stuff together as far as engine management goes. (btw, how many trouble free hours do you have on it)

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