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Discussion Starter #1
Which mathematical relation which links power and torque values where T= torque, P= power, V= throttle opening percentage, n= RPM?
 

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elo said:
Which mathematical relation which links power and torque values where T= torque, P= power, V= throttle opening percentage, n= RPM?
Not sure what you mean. Could it be...
ft. lbs.torque x RPM / 5250 = Horsepower?
 

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Discussion Starter #3
Which mathematical relation links power and torque values where T= torque, P= power, V= throttle opening percentage, n= RPM?

Is that better?
 

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Re: Re: No pics for this one!

elo said:
Which mathematical relation links power and torque values where T= torque, P= power, V= throttle opening percentage, n= RPM?

Is that better?
I might understand the formula but am not sure of the point or the useful application. Maybe for estimating fuel efficiency.:confused: The effect of "V" will be all over the place depending on "n". Unless "V" should be "percent of maximum flow" rather than "opening percentage".:confused: I'll wait for the answer.:D
 

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Re: Re: No pics for this one!

elo said:
Which mathematical relation links power and torque values where T= torque, P= power, V= throttle opening percentage, n= RPM?

Is that better?
No. I can't believe I have put this much thought into this. Unless I am missing something, Torque (which is a force) is the only measure of power among the listed variables. Throttle opening percentage is a percentage, RPM is a measure of rotational speed, of which torque is dependent upon.

To common sense it out, "Power" is a measure of torque, which depends on the RPM's, which depends on the amount of throttle applied. If that holds true, then for a given moment in time, P=T=n=V

My head hurts.
:confused: :cool: :D

*Edit*
I just realized you were talking HP, not simply "power". Disregard all above. Someone needs to be more specific in their wording :p
 

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I'm still waiting.:) My problem is "percentage of throttle opening" which I believe has to be "percentage of max. flow" to be at all useful. It could aid in figuring efficiency/fuel economy. There is nothing magical about the POSITION of a control valve that is predictable when the volume of the flow is all over the place (n). Example: at extremely low flow (idle), a small increase in opening position will effectively be max. flow for the RPM(n) because the open area is sufficient to allow an unrestricted flow based on the demand (n), whereas at middle RPM, a larger percent of motion will be required to give an unrestricted flow. At any time that an unrestricted flow occurs, that will be the max. power for that RPM. Any additional change in throttle position will give no change in any of the other outputs, so it tells nothing. Now, if it was a percent of maximum flow rather than position, it would correct for the unpredictable characteristics of the throttle valve positioning and that would be useable... for efficiency. The rest of it is standard HP calculation and with any two knowns, the third can be calculated. That's my story and I'm sticking to it.:)

Edit: After reading my own post, there would be a possible use for percent of opening if you were trying to test or tune the characteristics of an intake for partial throttle driveability and efficiency issues, but I think that's a reach. Why do I let the hook get such a set? Time to go riding... and deliver, of all things, a control valve to a power plant.:D REALLY.:D
 

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Okay, okay!

I was going to wait until Monday to post the answer, but you all seem to have put WAY too much thought into this to waste the weekend on.

The answer is: P=T·n·2Pi/60
as copied from the Ducati Tech Quiz at www.ducati.com.
 

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Re: Okay, okay!

elo said:
I was going to wait until Monday to post the answer, but you all seem to have put WAY too much thought into this to waste the weekend on.

The answer is: P=T·n·2Pi/60
as copied from the Ducati Tech Quiz at www.ducati.com.
Where is "V" in the answer?:confused: It's not there for the same reasons I mentioned. That was misleading which is why I was confused. It can't be used as a part of a formula because there is nothing constant or predictable about it.

I read that thing and it's an explanation of the HP formula and a primer in how to read a dyno graph. The reason for the difference in the HP formula (the answer) is that they're using metric units (torque in newton meters rather than foot lbs.) which changes the 5250 number to the Pi/60. It's the same formula but in metric units. The "V" isn't in the formula but was mentioned in the article describing the effect of a throttle position change on long stroke motor, showing the technical reason for the low end grunt felt by anyone who has ridden a high torque bike. Anybody see any different? I feel better now.:D It's still fun 'cause it makes you think... I think.:)

BTW, I had a nice 170 mile ride today and will have a better one tomorrow.:) Being a four banger, high windin' short stroker, I just make sure to have lots of "n" then crank in some "V" and it BOOGIES! Gotta' use "n" when you got no "T".:)
 
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