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Thread: Gear Change

  1. #1
    Hi Guys,
    I am running a 378 Cleveland Stroker in my boat with an Argo 19% V-Drive. Cam operates 2500rpm to 6000rpm. Motor only reaching 5200rpm and about 70-75mph. I was wondering that if I changed to 14% or 15% gears would I rev out to 6000rpm and gain top end. Motor is between 500hp and 550hp, are 19% gears to high ?

  2. #2
    what size of prop are you running ,if you change gears your rpms will diff go up

  3. #3
    It is a 11" x 16" LUMBERG XPT, It was customised to suit my setup. It improved rpm's by about 300rpm and about 5 mph.

  4. #4
    V-Drive Tom
    Aussie, Yes, Lower the gear. The 14% is even a little too much.
    I don't think you will reach 6000 rpm with that change. Because you have little torque and small cubic inches you have to keep the gear lower so you can reach the top RPM that the engine is capable of.
    Is the boat going in circles or Dragging or just hot rod fun? TOM..

  5. #5
    Hi Tom,
    Yeah, Im just using it for a bit of hot rod fun, we also ski with the boat. It has no problems pulling skiers out of the water with the bigger v-drive.
    If I go to smaller gears what would you recommend ? Will it pull skiers out easier ? Will it improve topend ?

  6. #6
    anyone else have any to add or advice. I would really appreciate it

  7. #7
    V-Drive Tom
    Dale, I know that you have different gear ratios to with than we do.(yours being an Argo V-Drive)
    I think that the 14% will help pull skiers easyer. For most quickness out of the hole you will need to go down to 10 or 12%.
    Because you care about skiing and hot rodding, I think the 12% will work out good. Don't be nervous, Change it and try it! You'll Like It!! TOM..

  8. #8
    Cole Man II
    Dear Aussi Ski Racer,
    Tom is dead on as usual. Keep reducing that gear until you reach your 6k rpm. If you go to small and your spinning over the 6K your just throwing away horse power, back up some.
    Cole Man.

  9. #9
    Tom has covered it. Just do it.

  10. #10
    anyone else have any to add or advice. I would really appreciate it
    Let me get you the phone number of my friend in Melbourne. With a similar combination, he is running in the high 80's and low 90's. I know he does have more camshaft in the engine.
    I had a ride in the boat last year while I was there for the Southern 80, it really surprised me considering my experience in turbo and supercharged boats.

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