Outboard Engine GEAR RATIOS!

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Originally Posted by FORBESAUTO

I agree, my triton runs better on take off and top end with 2.0 gears and 27 pitch prop than with 1.87 gears and 25 pitch prop.

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im almost ready to put my 2-1 on. i know itll run better. ART

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Originally Posted by 90 5.0

Thats not entirely accurate, weight and motor style have a lot to do with it also.

I know at heavy weights my boat is faster in the 1/8th with a 2.0/22 than it is with a 1.87/20

on a triton we have we had a 225/1.75 and ran a 25p, we swapped motors and went to a 250/1.62. With the same 25p prop we could barely get out of the hole with a full load and livewells full of fish.
We had to go down to a 23 to get holeshot back and it fired out of the hole like a rocket, but then is on the limiter way too quick.
On that boat we cannot prop it to have a good holeshot and good top end with a 1.62 because of weight. But with a 1.75 we can.

Light boats are less effected by gears than heavy boats are because of the torque multiplication factor needed to get moving is less.

Its physics sorry.

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I THINK a 250 is lots heaver too that doesnt help but your right!

There are way to many variables to decide if one gear ratio is better than another. The major variable props. A 1.78 and a 20 is similar to a 1.87 and a 22. But however since no 2 props are the same even comparing same pitch same style out of exact same mold they still will be different. I think u can make any ratio work u just need the right prop for it.

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Originally Posted by Magcat 62

I THINK a 250 is lots heaver too that doesnt help but your right!

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225 opti to 250'opti same weight

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Originally Posted by bigbluechevy454

There are way to many variables to decide if one gear ratio is better than another. The major variable props. A 1.78 and a 20 is similar to a 1.87 and a 22. But however since no 2 props are the same even comparing same pitch same style out of exact same mold they still will be different. I think u can make any ratio work u just need the right prop for it.

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nope, not on all combos. Like I mentioned weight has a lot to do with it, getting a heavy boat up and moving the lower years help, even with a bigger pitch prop.

cars are the same way, have had heavy small block cars that needed a steeper gear and a taller tire to run right where a gutted car with same motor combo could get away with less gear and a shorter tire.

A light boat doesn't need as low of a gear to get moving so the effects are felt less, heavier the boat set up the more you notice.

Your not comparing apple to apples. Im talking about changing gear ratios on same boat with same motor. Your talking about 2 different cars. I get that. Lol. Some times u may need a lower or higher ratio to work with the tire size u run. But with props u can use same style and raise and lower pitch. Or work it a bit to over come a gear ratio change.

For A LOT of guys on this board, their boats are too light and they run too many r's to justify a 2:1. Who wants to be running 90 at 7k when they could be running 100. (And many are running big pitch props already, they can't go much higher to offset the 2:1)

I agree with that u have to change ratio due to limitations of the prop pitches in the style propeller u select. Thats why all the etec guys use sportsmasters in 1.62 to keep.the motors off the limiter becuase u cant get a big enough pitch.

Pretty sure everyone agrees it all depends on boat, setup, and what you're trying to accomplish. One size does not fit all. If it did we would all be running the same engines and setups. And it would boring as crap and wouldn't have these very interesting topics that started out as simple ratio to gear clarification. :cheers:

For most parts 2.1 just needs about 2 pitch sizes more than 1.87. But again pitch is a relative number on the blade.

This going in circles, make more power, turn more gear.

Problem is when you make more power for the most part will not be across full rpm range. Especially when you make significant hp increases it will be at a higher rpm and will lose some at really low rpm. So an extremely powerful engine could be a turd out the hole with tall gears and big prop and get spanked in a drag with much less powerful motor with lower rpm power band.

As stated so many variables into each and every combination u take what u got and make it work..less learned the expensive way. Seems for the most part ole mother merc knew what they where doing

Couldn't have been said better. Merc has the perfect balance figured out. Any time you modify something to improve one part you loose in another.

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Originally Posted by FORBESAUTO

Couldn't have been said better. Merc has the perfect balance figured out. Any time you modify something to improve one part you loose in another.

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So true. Best money spent it in props ive found

I'm gettin'ma gear in high gear, (Low Ratio), and headed for the Deer Blind!!!! :p