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Old 02-28-2006, 06:11 AM   #1
moostang104314
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Stroke Size

I've been thinking a lot about bore and stroke lately and I was wondering if there was a correlation between the size of an engine's stroke and the amount of torque it produces? I figure a smaller stroke would move the crankshaft faster but wouldn't have the leverage to make a lot of torque. On the other hand wouldn't a longer stroke have more leverage and thus create more torque? Anybody know if there's a connection?
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Old 02-28-2006, 08:32 AM   #2
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This should be good.
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Old 02-28-2006, 10:04 AM   #3
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Quote:
Originally Posted by Wally
This should be good.

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Old 02-28-2006, 08:33 PM   #4
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well i could be wrong, but IN GENERAL--- yes, more stroke is more torque,
but there are plenty of other things that could completly change this.
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Old 03-01-2006, 02:51 AM   #5
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Quote:
Originally Posted by Wally
This should be good.

I've got the perfect answer .
------------
I am getting the impression there is an advocacy for stroking that will provide better torque. I guess people think that a bigger crank pin (moment arm) results in more engine torque?

Well guys the thing you must design to is BMEP. BMEP is proportional to torque output and maximum usually sits a little under the peak volumetric efficiency. And what things affect BMEP? Well burning fuel over a longer stroke and developing peak cylinder pressure at the wrong time sure as hell isn't going to increase the mean value is it, no Siree Bob.

Given a reference RPM, if you have had experience with cam selection you will know that it's profile will have a marked influence on BMEP. And we all know what a dog an engine becomes at lower revs if you open up an exhaust in isolation, reducing VE and thus BMEP, MBT, etc, etc.

So truth is if you increase your displacement you ideally should burn more fuel, which increases the power. How that power is handled in the form of pressure in the pots, is how much torque can be produced at whatever RPM.
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Old 03-01-2006, 03:31 AM   #6
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Quote:
Originally Posted by Godlaus
I've got the perfect answer .
------------
I am getting the impression there is an advocacy for stroking that will provide better torque. I guess people think that a bigger crank pin (moment arm) results in more engine torque?

Well guys the thing you must design to is BMEP. BMEP is proportional to torque output and maximum usually sits a little under the peak volumetric efficiency. And what things affect BMEP? Well burning fuel over a longer stroke and developing peak cylinder pressure at the wrong time sure as hell isn't going to increase the mean value is it, no Siree Bob.

Given a reference RPM, if you have had experience with cam selection you will know that it's profile will have a marked influence on BMEP. And we all know what a dog an engine becomes at lower revs if you open up an exhaust in isolation, reducing VE and thus BMEP, MBT, etc, etc.

So truth is if you increase your displacement you ideally should burn more fuel, which increases the power. How that power is handled in the form of pressure in the pots, is how much torque can be produced at whatever RPM.
ctrl-c, ctrl-v is your friend
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Old 03-01-2006, 04:18 AM   #7
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I can't even read this thread without my mind going to the gutter.
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Old 03-01-2006, 04:29 AM   #8
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Originally Posted by 97Talonchik
I can't even read this thread without my mind going to the gutter.
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Old 03-01-2006, 04:57 AM   #9
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Originally Posted by 97Talonchik
I can't even read this thread without my mind going to the gutter.
tsk tsk ... and coming from the only lady here too!
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Old 03-01-2006, 06:46 AM   #10
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Quote:
Originally Posted by Godlaus
I've got the perfect answer .
------------
I am getting the impression there is an advocacy for stroking that will provide better torque. I guess people think that a bigger crank pin (moment arm) results in more engine torque?

Well guys the thing you must design to is BMEP. BMEP is proportional to torque output and maximum usually sits a little under the peak volumetric efficiency. And what things affect BMEP? Well burning fuel over a longer stroke and developing peak cylinder pressure at the wrong time sure as hell isn't going to increase the mean value is it, no Siree Bob.

Given a reference RPM, if you have had experience with cam selection you will know that it's profile will have a marked influence on BMEP. And we all know what a dog an engine becomes at lower revs if you open up an exhaust in isolation, reducing VE and thus BMEP, MBT, etc, etc.

So truth is if you increase your displacement you ideally should burn more fuel, which increases the power. How that power is handled in the form of pressure in the pots, is how much torque can be produced at whatever RPM.


yeah, but that doesn't really answer his question.
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Last edited by Wally : 03-01-2006 at 10:53 PM.
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Old 03-01-2006, 01:38 PM   #11
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Originally Posted by windsonian
tsk tsk ... and coming from the only lady here too!
u forget there is also the supra girl.....
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