How can I get more power from a 525sc
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How can I get more power from a 525sc

  1. #1
    Senior Member Kylemenz1's Avatar
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    Default How can I get more power from a 525sc

    I know a bigger blower would do the trick but I was thinking of starting small. Pulleys, carb, intake? Anyone have a 525sc and have any ideas? Also what is the max hp that a Brovo I can safely handle? I have a drive shower but not sure if any internal work has been done.

    Thanks.

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  3. #2
    cfm
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    A bunch of years ago I was involved with intercoolers + larger pulley upgrade with a pair of 525SC's. I do not have the pulley parts #'s but remember we ran into an issue with style of pulley mounting. I believe there is a few different types over the years of the 525SC's.

    Best place for 525SC performance upgrading info is at offshoreonly.com There are a ton of 525SC and 575Sci owners over there.

    I did take notes when I tuned them.
    Module's total advance finishes at 4200rpm, not 3000rpm as others suggested to me. With superchillers and 7lbs boost I ended up at 102 square for carb jetting.

    Here's more info I gathered for the stock Merc configuration:


    454cid
    7.5:1 compression
    rectangle heads
    Holley Dominator 1050 carb (jetted 98 square + 6.5 high flow power valves front and rear )
    177 supercharger w/Dominator carb flange
    AC Delco MR41T spark plugs - gap .035"
    35° Total timing
    Premium fuel required. Merc suggests min 92 octane

    And following hyd flat tappet cam:
    Merc 400 / 420 / 425 / 525SC

    Crane Part#132561 Grind # H-228/312-2S-14 T1.2
    Duration at .004” : 298°, 296°
    Duration at .050”: 228°, 236°
    Lift with 1.7 rocker: .530”, .551”
    LSA 114°LSA
    ICL 109° ATDC , ECL 119° BTDC

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    It's what we do BDMarine's Avatar
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    We have done a fair amount of work and mods to those engines. The FIRST thing is to put a larger blower with two carbs. The little blower creates a ton of cylinder temp. and putting a smaller pulley to creat more boost only makdes this problem worse. They are border line with 91 as they are.
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    B & D Marine Performance
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  6. #4
    Senior Member Kylemenz1's Avatar
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    Default Wow thanks.

    Great info. thanks for all the help. How much blower can that motor handle?

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    Senior Member VDRIVERACING's Avatar
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    Dump a lot of money into it.

  8. #6
    It's what we do BDMarine's Avatar
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    Quote Originally Posted by Kylemenz1 View Post
    Great info. thanks for all the help. How much blower can that motor handle?
    If it were here we would put a 6-71 with (2) 750 DP Holleys. 5 lbs boost with the stock bottom end. 7 lbs if you run an inner cooler.... but the rods may want to find a new home outside the block if you run it hard for long periods.
    http://www.performanceboats.com//signaturepics/sigpic837_1.gif
    B & D Marine Performance
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