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Thread: 1994 5.7 merc upgrades

  1. #1
    aldo_45030
    I have a 1994 searay br 200 w/5.7, w/4 brl carb, merc alpha 1 gen II and i am concidering some upgrades. What i want to know is there much gain in hp and speed to justify messing with a reliable motor. Questions are as follows:
    1. If i bump up to a higher rpm cam will the increase in hp offset the loss in low end torque. kids still tube need it to be family friendly.
    2. Is there an aftermarket intake manifold one would recommend?
    3. Is it difficult to install thru hull exhaust?
    4. anyone got some used stuff for sale cheap?
    5. Are there any online build projects similar to a hot rod build up in a car magazine?
    I would love to turn it into a sleeper..
    How about a recommended openbow 22 + boat with snap in and potty capable?

  2. #2
    jmherbert
    I think the best way is to pull the motor and turn it into a 383... but that might be out of your scope.
    You may have to pull the motor to change the camshaft, depends on if there is enough room or if your back bench is removeable. Your not going to get too much out of just a cam change, but if you change the cam and have head work done (or new heads such as aftermarket or vortech) you will net gains.
    An aftermarket exhaust system is the easiest way to get a few mph out of it.
    If you do all of the above, you could have a reliable 383 putting out 400+ hp, and with more torque everywhere. Head and cam improvements alone will make a good difference. Depends on what you are willing to invest in both time and money.
    The stock GM hi-rise intake is actually pretty good, the aftermarket stuff won't get you much, if any.

  3. #3
    77charger
    I have a 350 mag in my boat carb model.I thought about changing stuff also.I think iwill leave the cam alone in mine since it is a roller type.Probably just going to swap heads for the vortec ones.Mine already has a hi rise type which is a decent one.Dont want to be too hard on the drive either just want a lil more power
    Your best bet is like mentioned earlier going to a 383 stroker.Watch out with cam swaps alot og bigger cams will make peak power past your useable range with not much low end.Might look into heads also.The alphas are good for about 300hp after that who knows

  4. #4
    aldo_45030
    Thanks for the replies the 383 is not in the budget at this time. I am ASSuming since mine is not a mag it is a standard stock manifold. If i read it correctly an after market exhaust sounds to be the first step. At least it would sound good and i can see how the merc standard exhaust would be some what restrictive.
    Sounds like i had better just keep up my search for another boat.
    ANYONE KNOW OF A NICE USED PERFORMANCE OPENBOW IN THE CINCY AREA FOR SALE??????

  5. #5
    TIMINATOR
    The thru the prop exhaust WILL limit any HP gains, you must do the thru transom first. The alpha doesn't have the exhaust vents on the sides like a Bravo.Performer rpm air gap is IT!!! 750 AFB carb. Also compare your riser tops to the bigblock ones, earlier ones were smaller. The bigblock ones have a 3" outlet instead of the regular 2 3/8". Comp cams 280 will work awesome with these changes. We did this to a 24 Daytona with a 260 hp /350. The mph gain was awesome! Actually it went from 47 mph to 60!!!!! And why anyone would put a 350 in a 24 Daytona escapes me. We will keep it a smallblock, but plan to go between 383 and 434. The limit is the drive. TIMINATOR

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