Engine selection

Automotive powered airboat discussion.
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Airboater76
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Engine selection

Post by Airboater76 »

Got a 16x8 gto deckover with a 82 in jx 3 blade prop wanting a new engine need opinions

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Deano
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Re: Engine selection

Post by Deano »

With over 60 views and no comments it is apparent that you have left out some pertinent information needed to arrive at an opinion;
The most important one being what gearbox ratio are you using (this is not generally a place where opinions are hard to come by :) ).
Your existing prop has a range where it happiest and most productive.
Your engine selection, and (just as importantly) its subsequent RPM range should compliment the prop's productivity requirements.
Without a known gear ratio there's not enough information to base an educated opinion on.

Stated differently, there are 3 variables that must all compliment each other to attain maximum results.

. Engine RPMs - the range where the engine produces the most power
. Propeller RPMs - the range where the prop produces the most thrust
. Gear Ratio - the link that bridges the gap between the differences in engine and prop requirements
With 2 of these variables in hand, a man can then solve for the third one.
Without 2 of these variables you simply can not.

Something else that would be relevant is Are you committed to building a new engine stand?
If not, what engine was the existing stand built for? Is there a reason you do not want to reuse it?

By most comparisons, a 16x8 Deck Over (of any flavor) with a rake would be considered on the heavier side
of the spectrum which is something else that is should be kept in mind while considering what engine will work best.
"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

Airboater76
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Re: Engine selection

Post by Airboater76 »

It has a 502 on it and a 2:1 belt drive I am up for whatever and Im wanted a new engine the 502 is getting old and wore out and it burns Over 150 gallons of gas in a weekend not ridding a lot just fishin inland

Airboater76
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Re: Engine selection

Post by Airboater76 »

And my rpm is 4K cruising and it will run around 30mph

unforgiven11B
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Re: Engine selection

Post by unforgiven11B »

What is your desired outcome? What are you wanting out of the airboat? Want more hp? Trying to run the hill? Power plants on airboats IMO are very specific to the application which you plan to utilize it. My boat for example is a 16x8 Diamondback 2:1 belt drive, 6.0L pcm/levitator. It’s not uncommon to run 100 miles or more when I go to the glades and burn nowhere close to 150 gals of fuel. No hill burner but tops out at 55mph and goes wherever I want. The newer levitator is 125 or more hp and over 100 lbs lighter. Wouldn’t be a good option for a tour boat but again we don’t know how you need or want the boat to perform.

SWAMPHUNTER45
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Re: Engine selection

Post by SWAMPHUNTER45 »

BBC 540 inch MAS engine
ratio change / 4 blade JX prop

The 502 is a standard stroke engine with an overbore the 540 is a .030 overbore with an additional .25 of stroke.

Stroke equates to usable power on an airboat platform. A properly built and geared 540 would be night and day from what you are currently running.


OR YOU COULD COME TO THE DARK SIDE AND PUT A BRANCH CADDILAC ON IT! :stirpot:

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kwanjangnihm
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Re: Engine selection

Post by kwanjangnihm »

Airboater76 welcome to SA! :salute:
We are all about spending your money sir! :toothy7:

What is your WOT (wide open throttle) with the setup now? the specs on the JX state 2450 as max rpm, so that's 4900 with your box.

Is the 502 stock or HO?
He'll cut your throat, baby, stick you in the back, drive off in your Cadillac.
He's more trouble than you think, he'll kill your sugar, leave you in the drink.

Airboater76
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Re: Engine selection

Post by Airboater76 »

Wide open is 5225 is max the 502 is bored .30

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