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TrickyNicky

How much engine torque?

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TrickyNicky

Hey guys, My dad just asked today how much torque these boats put out relative to our outboard.

I know it's a night and day difference but I was curious what the difference would actually be. I estimated 3-5 times more.

Currently we have a Mercury Optimax 115hp. We'd be getting a LCR 320 or Monsoon 340.

I could not find official specs for any of these but did get a 375 lb/ft for LCR and 397 lb/ft for the monsoon from other forums. Nothing for the outboard.

Any comments guys?

EDIT: I know it depends on the prop but I though the engine driveshaft torque would supply a rough estimate.

Edited by TrickyNicky

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FIC

Hey guys, My dad just asked today how much torque these boats put out relative to our outboard.

I know it's a night and day difference but I was curious what the difference would actually be. I estimated 3-5 times more.

Currently we have a Mercury Optimax 115hp. We'd be getting a LCR 320 or Monsoon 340.

I could not find official specs for any of these but did get a 375 lb/ft for LCR and 397 lb/ft for the monsoon from other forums. Nothing for the outboard.

Any comments guys?

EDIT: I know it depends on the prop but I though the engine driveshaft torque would supply a rough estimate.

The stroke determins torque , most outboards are short stroke with little torque and higher hp.

Some of the newer 4 cycle engines might have longer stroke.

We call the 6.2l a stroker motor because of its longer stroke which in turn gives it a better hole shot when loaded up with ballast.

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UWSkier

LOTS more. Kindof an apples to oranges comparison due to the different power delivery methods. Put it this way. The big V8 inboard has more than twice as much torque as your outboard, is geared and propped lower, and has an optimized prop angle for strong holeshot and planing performance. Best thing to do is go drive one.

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TrickyNicky

LOTS more. Kindof an apples to oranges comparison due to the different power delivery methods. Put it this way. The big V8 inboard has more than twice as much torque as your outboard, is geared and propped lower, and has an optimized prop angle for strong holeshot and planing performance. Best thing to do is go drive one.

Oh ya I'm well aware that its a LOT more, as I've driven them. He should be finding out soon enough, on a new to us VTX. Yahoo.gif (Fingers crossed). I was just curious if anyone would have some numbers for me.

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Pistol Pete

Nicky,

Isn't the Optimax an oil injected 2 stroke?

It it is, you can't really compare motors side by side.

It'd be like comparing the tq. of a diesel to a gas motor.

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TrickyNicky

Nicky,

Isn't the Optimax an oil injected 2 stroke?

It it is, you can't really compare motors side by side.

It'd be like comparing the tq. of a diesel to a gas motor.

Yes it is Pete, I know I'm comparing apples to oranges, and am going to get an absurd result, just curious what the result may be? How much torque do you think that optimax makes? Couldn't find data for it online. And yes a diesel and gas torques comparison is unrealistic as well but when you buy your tow vehicle I'm sure you compare them both.

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Pistol Pete

Nicky,

Just get the Monsoon.

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TrickyNicky

Nicky,

Just get the Monsoon.

ROFL.gif I really needed that laugh, Slightly off topic, and yet you hit the nail on the head!Clap.gif I know what my decision would be but it's not my signature on the cheque.

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Pistol Pete

Well then,

tell your dad that Pistol Pete said get the Monsoon.

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NorCaliBu
Well then,

tell your dad that Pistol Pete said get the Monsoon.

And then tell him that the rest of TheMalibuCrew recommended that he not ignore Pistol Pete. :fingerwag:

:lol:

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CumminsBu

Try this formula and you should be in the ball park:

TQ = (HP X 5252)/ RPM

Pulled this out of an old engine book I have.

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TrickyNicky

Try this formula and you should be in the ball park:

TQ = (HP X 5252)/ RPM

Pulled this out of an old engine book I have.

Well that is a correct formula, But I'd still need to know the RPm where the most torque is being produced.

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Bobby Light

Well that is a correct formula, But I'd still need to know the RPm where the most torque is being produced.

Divide by the maximum RPM of your engine, this will get you very very close.

Edited by 06vlx

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Malibuswany

Don't worry about it and listen to Pete!

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Sandbagger

My guess is your torque will be close to your hp, so if you are 115 HP then somewhere around that for torque.

Max RPM on that motor is 5,000 to 5,750 so you get 115 x 5252 and divide by 5000 and get 120 foot lbs. (105 at 5750 RPMs).

Thats my guess.

Edited by Sandbagger

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Soon2BV

You need to know prop speed to determine the torque at the prop.

The equation above is correct.

If the engine to prop is geared all the way thru at 1:1, then the numbers above are close.

But if there is any speed reduction, then the torque at the prop will be higher.

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