Airboat reduction

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Airboat reduction

Postby virginialuther12 » Tue Feb 21, 2017 5:36 am

Recently I have bought a 16' panther airboat and currently rebuilding (Panther rebuild thread soon to follow when I'm finished). I have a doubt that what belt reduction I should buy. I have a 350 HP 5.3 liter 05 Vortec Chevrolet truck motor that I am going to put on it with a 70 inch 3 blade whisper tip prop. What ratio belt reduction should I get for this motor/prop combination?
Please help me?

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Re: Airboat reduction

Postby firefight-n » Tue Feb 21, 2017 5:54 am

Get your max RPM's for both your engine and the prop and you can figure it out from there. You may want to consider a larger prop.

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Re: Airboat reduction

Postby seakin355 » Tue Feb 21, 2017 7:59 am

Call Century Drive Systems at 814-677-7100. Ask for Rob. He should be able to recommend what you need.

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Re: Airboat reduction

Postby Deano » Tue Feb 21, 2017 9:22 am

Firefight-n is exactly right. He has given you the two largest variables to be resolved.
He is additionally correct about your prop, you will likely need more.
While calling Rob may not be a bad idea, you need first to talk to Patti @ Whirlwind about the prop.

If you legitimately need help, there is plenty here.
Be aware though . . . that placing links in your first post only serves to
make you look like a troll, and not a particularly bright one at that. :roll:
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
- Carl Sagan

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Re: Airboat reduction

Postby One Eyed Gator » Tue Feb 21, 2017 12:05 pm

I would say you will need more prop, but I could be wrong.

LSmatt runs a 5.3 with a 76" 3 blade R with 2:1 belt, not sure where it is set. . I have built 3 boats with 5.3's: 1 with 2:1 Precision and a 81.5 2 blade R set just over mark 1, 2nd one had an L33 5.3 with a 2.55 ballistic it turns a 80" 3 blade maximus set at 10.2 degree and the last one is a 2.68 turning a 79" 3 blade R set near the 3rd pitch mark.

Hope this helps.

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Re: Airboat reduction

Postby CarMotorBarge » Wed Feb 22, 2017 3:02 am

Which LS 5.3 motor do you have? Have you done any upgrades? I don't know of a 2005 5.3 that made 350 HSP from the factory.

Assuming that you have the stock truck cam that peaks HSP around 5,300 RPMs, I would go with the 1.774 ratio and here is why. The prop you have needs to turn 2,800 to 3,000 RPMs at the prop. 3,000 multiplied by 1.774 equals 5,322. This means that turning your engine at its max HSP around 5,300 will turn the prop at 3,000 RPMs. There is no advantage to going above the max HSP.

Assuming that you have the stock truck cam, the 2.0 ratio doesn't make any sense because the engine drops HSP above 5,300. With the 2.0 ratio, you would have to turn the motor 6,000 RPMs to turn the prop 3,000.

Also I agree with everybody that you probably need more prop. One option to address this is to buy a new longer hub and reuse the 3 blades you have. Patti should be able to help with this.
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