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Thread: Interest in new 3 cylinder drag rules..motor alterations and mixing manufacture parts

  1. #11
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    Based on the 56 OMC engine builds here in Canada a good drag motor would be oval port sleeves in a 1986 production cast block, mod 50 flywheel, Kevi baseplate and tuner, SST 60 gearcase with hooper billet carrier and 2 cylinder gears, a 12 1/2 X 24 thru hub Hill prop on a 13 foot Allison. Tuff to beat in 600 feet.
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  2. #12
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    so you would put oval port sleeves in a bridgeport block .

    what will you do about the the alloy bridge cast into the block itself. this would be visible with no sleeves in the block .(according to other on this site)...
    would you cut this wall of alloy out the block or leave it in.

    and why the cast block instead of the lost foam block, they are identical inside apart from a few glue lines, apart from the later cooling modifications made to the oval port block.

    what would be the benefit in changing blocks ?
    and the 2 cylinder gears being what ratio ? 2.42 or 1.86

  3. #13
    Administrator Ron Hill's Avatar
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    Default Powerabout Too Bad You Didn't Take OMC Over

    Quote Originally Posted by Powerabout View Post
    It would mean making new 3 cyl crank and see if you could swing that in 56 case?
    Thats the engine OMC should have made as yam just marched in with bigger triples and took tons of market
    I quote you, Powerabout, and I'm not sure you said it. But if OMC would have continued to make two stokes and sold them worldwide, (Meaning outside the USA) they'd never have gone broke. I think you said that to me on the phone one day.

    Seems, as I recall, my brother, asked Charlie Strang, why the 49 cubic incher was the way it was? And the answer wasn't what my expected. The answer was the NEW $100,000 mill wasn't large enough......It something that!!! My brother said, "Really?"

    Too bad, you didn't "Take Over" OMC, Powerabout. You could have made OMC Great........I'm not sure I'll use the word "AGAIN".

    I'd argue with you abut Yamaha. They took the WHOLE MARKET.
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  4. #14
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    Quote Originally Posted by filthy phill View Post
    so you would put oval port sleeves in a bridgeport block .

    what will you do about the the alloy bridge cast into the block itself. this would be visible with no sleeves in the block .(according to other on this site)...
    would you cut this wall of alloy out the block or leave it in.

    and why the cast block instead of the lost foam block, they are identical inside apart from a few glue lines, apart from the later cooling modifications made to the oval port block.

    what would be the benefit in changing blocks ?
    and the 2 cylinder gears being what ratio ? 2.42 or 1.86
    I would clean up the block and remove the bridge casting. The production block flows air better that the foam cast and even with the cooling mod to the foam cast, the production block is better. My thinking behind using the 2:42 gears is about hole shot, acceleration and 600 feet. The oval port motors running here have a big torque, low and mid range advantage over the bridge ports. A big diameter, big pitch prop turning slower will get out of the hole and accelerate faster with the 2:42 gears. You may need to repitch the 24 to 26 but if the motor is turn over 8000 for a second or two, it does not matter. Drag is about ET for 600 feet not speed reached at 600 feet. Only my opinion.

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    600 feet ? do you mean yards.

    600 feet is just 200 yards
    if its feet how long does it take for this race to be over ?

  6. #16
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    Quote Originally Posted by filthy phill View Post
    600 feet ? do you mean yards.

    600 feet is just 200 yards
    if its feet how long does it take for this race to be over ?
    Their current rules posted on this site have the distance at 660 feet.

  7. #17
    Team Member Roflhat's Avatar
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    Does anyone know of any smaller lower units that will fit the 70ces? It's quite a lot bigger than the 50hp, I think you could fit a 14" diameter prop on the 70

    Also maybe worth thinking about a modified tohatsu 50, you can bore them out and fit 40D 2 cylinder pistons (I think)

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    to fit small box on yamahaha do the same as most of the big boys, cut n shut.

    But why would you want a small gear case ?

  9. #19
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    One of the problems with going to a smaller gearcase is the size of the prop shaft. The smaller cases have smaller and weaker prop shafts. You run big diameter and pitch on those smaller shafts and they will break. Since it is only 660 feet you may find a larger case works better. You would likely run the prop shaft even with the bottom of the boat. The larger case will lift the stern. So what if it runs out of water, it can have a drink at the end of the run.
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  10. #20
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    Your dead right about large gearcase lifting the stern.
    My boat is a bit front heavy and not a light boat for its size, but I know the faster I go the more the stern lifts, even with a prop not known to be good stern lifter.
    the large area of the gearbox just wants to ride up on top of the water.

    There are a few videos on youtube showing larger gearcases being very good for surface running at almost 100mph.
    One video shows a large Honda with a big fat blunt gearcase riding happily on top of the water and staying on top nicely.

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