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  1. #1
    My Boats:
    1993 rinker 236, 502
    Join Date
    Jul 2008
    kandiyohi, mn

    502 mpi vs. 502 carb

    If i installed the fuel injection kit on my carbed 502 would it go from 390hp to 415hp? or is there other differences internally,cams , compression... my engine is a 93.

  2. #2
    My Boats:
    96 , cig top gun
    Join Date
    Aug 2005
    sint maarten
    maybe. for certain and beyond doubt, the injection will give you a more accurate fuel curve across the board. but having said that, the cam shaft on an injected motor is often different and certainly the cam timing is different. also... i have never done the calculation for the annular opening and flow rate thru the mpi system vs other carbs so it might not be an apples to apples comparison....

    but given that your carb and manifold as it sits gives you 390
    ( and assuming that is correct) , i believe you would have a much better motor with more power with a direct MPI exchange.

    but again, installing the injection is not like bolting on a new carb. it requires a painstaking and disciplined approach with all the I's dotted and Tee's crossed. no taped and twisted wires, no bad grounds, the right fuel pump (factory) and the right regulator ( factory) ... in short, a professional installation done to oem standards.

    if you do that you will be thrilled with the results, i believe.

    also... something often overlooked... on injected installations that use two motors, it is essential that each motor run off its own battery with no common + connection. you can run a dual battery switch and run "both" to start of as a war emergency but the sensor array runs off a 5v differential system... if you run both batts tied to both motors tied to both alternators etc, it is possible and very likely for the sensors to "talk" to each other and affect the "other" motor.

    and don't attempt this without the appropriate FACTORY workshop manual for that particular MPI in your hands before you start.

  3. #3
    Charter Member # 55 Charter Member Griff's Avatar
    My Boats:
    ..........32........... Active Thunder
    Join Date
    Oct 2000
    There are much easier ways to add 25hp. The cams are different and in order for the EFI to work coerectly you would need a cam change or ecm recal.

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