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Thread: 7.4 MPI vs. 454 MAG

  1. #1
    What is the difference. Has anyone out there done any hop-ups on this motor.

  2. #2
    Look at my reply in the 454 or 502 listing.
    The 310 hp motor is not a good motor for adding more hp to. It is a perfect motor as is. If you have one leave it along or get a mag 454. The interal parts will hold up to increases in hp. The old saying pay me now or pay me a whole lot later.

  3. #3
    Mike, Thanks for the info on the 7.4 MPI. I was thinking of just getting a less restrictive K&N to make it breath better. It has thru hull exhaust. Thought that it might be work the $. Let me know your thoughts.

  4. #4
    I pro-charged my 99 Baja 7.4 put close to 90 hours on it before blowing the head gasket if this is the some motor that you have find you a 454-502 mag and dont wast time or money on the 7.4 its just not worh it. Just my .02 cents worth.

  5. #5
    The best stock engine for superCharging is the 502 MAG. The internal parts are the best quality. Forged J & E pistons,Steel crank, ect..., It also has a compresion of 8.75:1, which is better for supercharging,all the other mercs have 9.0:1 or more compresion.
    And at 415 HP, it has alot of safe HP hidden in that block. When I was shoping for a SuperCharger for my 230SX. The folks at C & B Marine informed me that they had no problems superCharging the 502 Mag. But head gaskets on the 454's were common. That was due to the high stock comp. ratios. I eventualy went with a ProCharger set up.

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