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Old 14 September 2006, 21:11   #1
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missing technical data

Does anyone know why torque never gets a mention with outboards, seems far more relevant to marine engines than BHP does ? not even the manufacturers talk about it ?
performance car brochures always link the two.

they obviously know how important it is,why use 2.5ltrs to get 150 bhp in an outboard when you can get the same figure from 1.0 in a bike engine

I would have thought lowdown grunt ina V8 car out of a corner was the same as holeshot?

This might be me missing something here,but i'm keen to know the torque figure of an engine and can't find it anywhere..
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Old 14 September 2006, 23:23   #2
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Quote:
Originally Posted by IBWET
Does anyone know why torque never gets a mention with outboards, seems far more relevant to marine engines than BHP does ? not even the manufacturers talk about it ?
performance car brochures always link the two.

they obviously know how important it is,why use 2.5ltrs to get 150 bhp in an outboard when you can get the same figure from 1.0 in a bike engine

I would have thought lowdown grunt ina V8 car out of a corner was the same as holeshot?

This might be me missing something here,but i'm keen to know the torque figure of an engine and can't find it anywhere..
That is SO scary - I was about to post EXACTLY the same question. I have been looking at the stats for the latest Suzuki 300hp and no mention of torque.

You can work out the torque from the following equation

Horsepower = Torque x rpm / 5252 or
Torque = Horsepower x 5252 / rpm

Things aren't that simple though - so much depends on how the torque is delivered and at what RPM. The curves are what you really need!!!

For example an old Scammel with only 200bhp and say 400ftlbs of torque could easily out pull a 400bhp 800ftlbs truck up a steep hill - would be a different story on a motorway drag though!!!
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Old 15 September 2006, 04:59   #3
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torque

It's as if they think it won't matter to anyone?..I,ve just picked an engine on a guess that it will produce the goods low down, based in cc's and HOPEING the curve is flat.

If the outboard market is so competative I think they are missing a huge selling point.

having been involved in motorsport, any tuner will tell you that bhp sells cars and torque wins races.

what amazes me more, is Suzuki of all people know that...strange.

I find it hard to believe all the marketing departments in these companies have missed this which brings me back to me having missed something?

Codprawn, I've read threads from some Technically knowledgeable people here so maybe we will get our answer .
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Old 15 September 2006, 05:10   #4
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Depends on the gearing though, dunnit.

Quote:
Originally Posted by codprawn
That is SO scary - I was about to post EXACTLY the same question. I have been looking at the stats for the latest Suzuki 300hp and no mention of torque.

You can work out the torque from the following equation

Horsepower = Torque x rpm / 5252 or
Torque = Horsepower x 5252 / rpm

Things aren't that simple though - so much depends on how the torque is delivered and at what RPM. The curves are what you really need!!!

For example an old Scammel with only 200bhp and say 400ftlbs of torque could easily out pull a 400bhp 800ftlbs truck up a steep hill - would be a different story on a motorway drag though!!!
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Old 15 September 2006, 06:01   #5
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torque

The whole point about torque is that ultimately (taken to extremes) you would'nt need any gearing.

In this though, a pitch that allows an extreme top speed usually stop the engine turning quickly enough at slow speed to pull / skiers also stress's the engine.

with big torque you get your cake and eat it.
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Old 15 September 2006, 06:14   #6
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Quote:
Originally Posted by IBWET
they obviously know how important it is,why use 2.5ltrs to get 150 bhp in an outboard when you can get the same figure from 1.0 in a bike engine
Reliability is one reason; if you run a high performance bike engine at WOT for a large part of its life you'd probably find it was a fairly short life, same for performance cars. Race engines often have a life expectancy of just a few hours, as an extreme example of that, and at the opposite end of the scale the engine in my Dad's Cessna was about 5.5 litres (5.something anyway) and produced 160hp - all for extreme reliability. And in 25 years the fan only stopped once so it must work

I agree with you though - I'm surprised they don't quote torque figures, it must be about the only engine industry anywhere which doesn't! A torquey engine would surely not "bog down" when you put a few lardy divers in the blunt end so it must be a selling point you would think.

It occurred to me recently when looking at Suzukis - the DF140 is only a whisker over 2 litres while the DF150 is 2.8something, I bet there is a big difference in the torque (and therefore power) outputs at say 2500rpm.

I suppose the bottom line is that more torque means bigger engine means more expensive, so it may be a better marketing ploy to get a buzzy engine producing lots of HP because it's cheaper to make and therefore a more competitive product if power is the number that goes up in big flashing lights?
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Old 15 September 2006, 07:52   #7
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This is good info. I am considering a Honda BF50. I have a buddy with an extra BF40 that he is willing to sell for a song. These 2 engines eigh the same and have the same displacement (different camshafts).

My knee-jerk reaction is why get a 40hp if it weighs just as much as the 50hp? (The boat I've got on order is rated for up to 60hp). If, however, the 40hp produces just as much (or maybe more) torque at a given engine rpm, maybe it would be every bit as fast (with the right prop) as the 50.

Are any of you familiar with the differences between these 2 engines?
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Old 15 September 2006, 08:28   #8
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torque

I thought the reliability issue had been addressed by limiting the rpm most of these engines have WOT max's of ,5500 maybe 6,000. I think mercury have dropped the ball with the Verado the, 150 is a forced 1.7 with all the stress that go with that (over 100 bhp/per ltr) but the weight has gone through the roof? Suzuki have got it right I think.
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