Prop & Gear Box Ratio Recommendations

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PistolPete
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Prop & Gear Box Ratio Recommendations

Postby PistolPete » Fri Dec 14, 2018 11:39 pm

My Son is putting a 14x 8 Alumitec boat together using a Gen 5 6.2l l86 Direct engine 420 hp 460 tq. stock. He wants to be able to run dry ground without any chance of getting stuck, would also like it to run top end about 60 -65 mph. What we were thinking after talking to water walker was 80" 3 blade falcon or Maximus 2.55 OX Box.
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CarMotorBarge
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Re: Prop & Gear Box Ratio Recommendations

Postby CarMotorBarge » Sat Dec 15, 2018 1:56 am

Ignore the torque curve on that dyno sheet. It tells you nothing useful when selecting gear ratio and prop. It just confuses people. The HSP curve tells you everything you need to know. I would run WOT at 5400 to 5600 RPM given that dyno sheet. Just have to experiment and find the setting you like.

Do you plan to do any performance upgrades in the future to the engine? What are you using for headers?

If you are planning performance upgrades that will cause the max HSP to occur at a higher RPM, you might want to consider a 2.68.

The Maximus blades are hard to beat when it comes to push on the hill. You should also be able to do 60 to 65 if the boat runs free enough.
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.88 Ox Box swinging 4 blade 83.5" R
GTO Rigging and B&S Tilt Trailer

SWAMPHUNTER45
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Re: Prop & Gear Box Ratio Recommendations

Postby SWAMPHUNTER45 » Sat Dec 15, 2018 9:49 am

If that is a take out or crate engine what are you planning to do with the ECM ?

PistolPete
Southern Airboat Member
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Joined: Tue Oct 02, 2018 7:24 pm

Re: Prop & Gear Box Ratio Recommendations

Postby PistolPete » Sat Dec 15, 2018 3:02 pm

Take out 26k have it programmed for stand alone and tuned

SWAMPHUNTER45
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Re: Prop & Gear Box Ratio Recommendations

Postby SWAMPHUNTER45 » Sat Dec 15, 2018 10:43 pm

That tune is important for sure.
Post pics as you build her

PistolPete
Southern Airboat Member
Posts: 27
Joined: Tue Oct 02, 2018 7:24 pm

Re: Prop & Gear Box Ratio Recommendations

Postby PistolPete » Sun Dec 16, 2018 10:02 pm

Ok this is what we are starting with a never used 2008 14 x 8 Alumitec boat. Got the motor Friday started ordering the parts we will need. we are going to make some changes to seating height.
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SWAMPHUNTER45
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Re: Prop & Gear Box Ratio Recommendations

Postby SWAMPHUNTER45 » Mon Dec 17, 2018 7:24 am

A new boat that sat unused for 10 years, that's a barn find!


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