120R update and answers
#61
09-21-2010, 09:41 AM
Zach
#62
09-21-2010, 10:13 AM
Tourer
Join Date: May 2006
Location: Nebraska
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#63
09-21-2010, 02:59 PM
I don't want to debate it.
But I would like you to explain the scaling.
I may have mislabled in my post as you refer to graph one as auto scaling and graph 2 as forced scaling.
The first graph you post makes it appear that the torque curve peaks at 5000 rpm and the second graph shows the torque peaking at 3500. This is confusing. And I understand it has something to do with the scaling, I suspect it has to do with the graphing package embedded in the dyno software.
You state above that the curves do not have to cross at 5252. Does that mean depending on which scaling you choose, the torque will peak at different rpms?
Since you are a tuner, please explain to me why on first graph the torque peaks at one rpm and on second graph torque peaks at another rpm.
Thank you very much for your help on this subject.
But I would like you to explain the scaling.
I may have mislabled in my post as you refer to graph one as auto scaling and graph 2 as forced scaling.
The first graph you post makes it appear that the torque curve peaks at 5000 rpm and the second graph shows the torque peaking at 3500. This is confusing. And I understand it has something to do with the scaling, I suspect it has to do with the graphing package embedded in the dyno software.
You state above that the curves do not have to cross at 5252. Does that mean depending on which scaling you choose, the torque will peak at different rpms?
Since you are a tuner, please explain to me why on first graph the torque peaks at one rpm and on second graph torque peaks at another rpm.
Thank you very much for your help on this subject.
ok I dont have much time so I am going to give you a little info .
then let you think a little to figure it out. I think you have it half way figured out already.
this is what Ron Dickey at Axtell does to me when I ask him a question.LOL. seems to stay with you longer that way.
all the comments about 5250 and how hp/tq is arrived at is correct if the dynojet dyno measured it that way. but......
First it is important to have an understanding of how DynoJet gets their horsepower numbers. Power in mechanical terms is the ability to accomplish a specified amount of work in a given amount of time. By definition, one horsepower is equal to applying a 550 pound force through a distance of 1 foot in one second. In real terms, it would take 1 HP to raise a 550 pound weight up 1 foot in 1 second. So to measure horsepower, we need to know force (in pounds) and velocity (in feet per second). Dynojet's inertial dynamometer measures power according to the terms just described. It measures velocity directly by measuring the time it takes to rotate A heavy steel drum one turn. It measures force at the surface of the drum by indirectly measuring it's acceleration. Acceleration is simply the difference in velocity at the surface of the drum from one revolution to the next. The force applied to the drum is calculated from acceleration using Newton's 2nd law, Force = Mass * Acceleration. Since the mass of the drums is know and acceleration has been measured, Power (horsepower) can now be calculated. Torque is then calculated using the horsepower number: Torque = Horsepower * 5252 / RPM.
Now go back and look at those dyno sheets FHXS124 posted. notice the diff in hp/tq. when looking at the sheet that is in mph (speed) and the one in rpm's (engine speed) this should ring it home that dynojet uses acceleration to do it's hp/tq cal's.
I am not saying that we shouldnt auto scale. I was just saying that all dyno sheets dont cross at 5250 then someone said they did and they had never seen one that didnt,I just showed that they dont always. some dyno's dont have the ability to auto scale.
another note SE 6 Speed overdrive is not stock in 07 up bikes. 06 dyna is sorta a bastard child with it's one year run tranny. all 07 up cruise drive trannys are 1:1 final ratio...again ....the diff in gearing is in the primary.
sorry springer 3 if that makes your head spin (i guess that's what you meant when you posted the spining heads). I was wrong on your bike from the looks of the pic it is a 09. so the final gearing is 2.96 or 2.92 with the bigger rear sprocket vs 07/08 models
#64
09-21-2010, 05:01 PM
Club Member
Torque is then calculated using the horsepower number: Torque = Horsepower * 5252 / RPM.
I was just saying that all dyno sheets dont cross at 5250 then someone said they did and they had never seen one that didnt, I just showed that they dont always. some dyno's dont have the ability to auto scale.
I was just saying that all dyno sheets dont cross at 5250 then someone said they did and they had never seen one that didnt, I just showed that they dont always. some dyno's dont have the ability to auto scale.
If you know your math then you will see from that equation that:
RPM = Horsepower / Torque * 5252.
So when Horsepower and Torque are the same, RPM = 5252. QED. It's a fact of life!
You can show us as many graphs as you like that suggest otherwise, but they ain't showing true data.
#65
09-21-2010, 05:26 PM
Torque = Horsepower * 5252 / RPM.
If you know your math then you will see from that equation that:
RPM = Horsepower / Torque * 5252.
So when Horsepower and Torque are the same, RPM = 5252. QED. It's a fact of life!
You can show us as many graphs as you like that suggest otherwise, but they ain't showing true data.
If you know your math then you will see from that equation that:
RPM = Horsepower / Torque * 5252.
So when Horsepower and Torque are the same, RPM = 5252. QED. It's a fact of life!
You can show us as many graphs as you like that suggest otherwise, but they ain't showing true data.
you said
They do! It's basic arithmetic and applies to all engines. As has been pointed out the value is 5252rpm, which is a simple conversion factor or constant. Nothing, including a mouse, can move it! 
I just pointed out ,and showed you that not all dyno sheets auto scale.you said not even a mouse could move it. I showed you otherwise. not all dyno's auto scale. so they dont all cross at 5250 automatically.
it is still true data just that the scaling hasn't been done for you.
it is very useful info when tuning . that's a fact of life.at least tuning life. LOL
#66
09-21-2010, 06:15 PM
Tourer
Yep, I understand of that explanation.
Now I understand the graph!
It took me looking at it over and over again.
I have labeled the curves.
Maybe this will help others.
Late model bikes are 34/46 or 1.35, early model bikes are 25/36 or 1.44
That provides about a 6.5% reduction.
There must be a change in the secondary gearing, too.
Now I understand the graph!
It took me looking at it over and over again.
I have labeled the curves.
Maybe this will help others.
Late model bikes are 34/46 or 1.35, early model bikes are 25/36 or 1.44
That provides about a 6.5% reduction.
There must be a change in the secondary gearing, too.
Last edited by inverse121; 09-21-2010 at 06:51 PM. Reason: Labeled Curve and Scanned it
#67
09-23-2010, 03:18 PM
As strokerjlk has pointed out a graph does not have to cross at 5252.
The reason being the scaling on either side is simply different.
What is a fact is that no matter HOW you scale a graph, by definition ( math) Hp equals torque at 5252! They will always be the same(value on the Y axis), at that RPM. If they are not equal at 5252 then the calculation is wrong.
Scaling differences ( if two separate axis are possible) means they do not need to "cross" on a GIVEN graph, nor would you expect them to cross there if they are graphed on different scaling break points!
Many normal Hp and Torque graphs only have one "Y" axis so they will again ( given the math) always cross at 5252 when scaled the same or using the same axis.
And if you look at the “forced” scaling(the modified graph) where it is a different Y axis for hp and torque, you can still see that at 5252 the values of both are the same!
The reason being the scaling on either side is simply different.
What is a fact is that no matter HOW you scale a graph, by definition ( math) Hp equals torque at 5252! They will always be the same(value on the Y axis), at that RPM. If they are not equal at 5252 then the calculation is wrong.
Scaling differences ( if two separate axis are possible) means they do not need to "cross" on a GIVEN graph, nor would you expect them to cross there if they are graphed on different scaling break points!
Many normal Hp and Torque graphs only have one "Y" axis so they will again ( given the math) always cross at 5252 when scaled the same or using the same axis.
And if you look at the “forced” scaling(the modified graph) where it is a different Y axis for hp and torque, you can still see that at 5252 the values of both are the same!
Last edited by FBRR; 09-23-2010 at 03:23 PM.
#68
09-23-2010, 05:59 PM
As strokerjlk has pointed out a graph does not have to cross at 5252.
The reason being the scaling on either side is simply different.
What is a fact is that no matter HOW you scale a graph, by definition ( math) Hp equals torque at 5252! They will always be the same(value on the Y axis), at that RPM. If they are not equal at 5252 then the calculation is wrong.
Scaling differences ( if two separate axis are possible) means they do not need to "cross" on a GIVEN graph, nor would you expect them to cross there if they are graphed on different scaling break points!
Many normal Hp and Torque graphs only have one "Y" axis so they will again ( given the math) always cross at 5252 when scaled the same or using the same axis.
And if you look at the “forced” scaling(the modified graph) where it is a different Y axis for hp and torque, you can still see that at 5252 the values of both are the same!
The reason being the scaling on either side is simply different.
What is a fact is that no matter HOW you scale a graph, by definition ( math) Hp equals torque at 5252! They will always be the same(value on the Y axis), at that RPM. If they are not equal at 5252 then the calculation is wrong.
Scaling differences ( if two separate axis are possible) means they do not need to "cross" on a GIVEN graph, nor would you expect them to cross there if they are graphed on different scaling break points!
Many normal Hp and Torque graphs only have one "Y" axis so they will again ( given the math) always cross at 5252 when scaled the same or using the same axis.
And if you look at the “forced” scaling(the modified graph) where it is a different Y axis for hp and torque, you can still see that at 5252 the values of both are the same!
I knew you could explain it better then me.
#70
09-25-2010, 05:22 PM
