gear torque / shift point spreadsheet chart
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Joined: Mar 2005
Posts: 2,428
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From: CT, US
gear torque / shift point spreadsheet chart
So I decided to create a spreadsheet with my dyno chart info to chart out every gear to determine proper shift points for each gear. everything is automated, just need to input torque values at each rpm point, tire diameter, gear ratios, and final drive ratio and the spreadsheet does all the rest for you 
I only plotted 3800-7000 rpm because thats my spread for peak boost. proper shift point for fastest acceleration is where each line crosses, as this keeps actual wheel torque the highest. it's rather interesting to see the spread for each gear. and yes the labels are correct, it is in foot/pounds at the axle, but WITHOUT accounting for inertial losses, meaning 1st and 2nd gear are slightly higher then real world conditions. enjoy!
keep in mind I said I only plotted 3800-7000 rpm, which is why 1st gear begins at such a high speed, and 1st to 2nd transition happens at such a strange looking rpm spread
In case anyone wants access to the file, I'd be happy to send it to you. or if anyone wants to see their vehicle plotted you can just send me a detailed photo of your dyno chart
the car used here is my 1990 Prelude, built b21a1, 10.5psi from a super60 T3, d2a4 transmission, 215/40/17 tires.
comments, knowledge, constructive criticism, almost anything is welcome here
.
I only plotted 3800-7000 rpm because thats my spread for peak boost. proper shift point for fastest acceleration is where each line crosses, as this keeps actual wheel torque the highest. it's rather interesting to see the spread for each gear. and yes the labels are correct, it is in foot/pounds at the axle, but WITHOUT accounting for inertial losses, meaning 1st and 2nd gear are slightly higher then real world conditions. enjoy!keep in mind I said I only plotted 3800-7000 rpm, which is why 1st gear begins at such a high speed, and 1st to 2nd transition happens at such a strange looking rpm spread
In case anyone wants access to the file, I'd be happy to send it to you. or if anyone wants to see their vehicle plotted you can just send me a detailed photo of your dyno chart
the car used here is my 1990 Prelude, built b21a1, 10.5psi from a super60 T3, d2a4 transmission, 215/40/17 tires.
comments, knowledge, constructive criticism, almost anything is welcome here
.
Last edited by motoxxxman; Feb 26, 2016 at 09:08 PM.
Thread Starter
Honda-Tech Member
Joined: Mar 2005
Posts: 2,428
Likes: 11
From: CT, US
Re: gear torque / shift point spreadsheet chart
things to note, to clarify for those that dont fully understand the point of this:
I calculated it for axle torque, not actual tire surface torque. I can reconfigure it for tire surface torque at any time if I want, so I can better judge for traction purposes when comparing different size tires.
This is set up with my current street tires, which according to this chart break traction at about 1500 axle tq in temps around 35*F, much higher when temps increase.
The whole purpose of doing this was to calculate this:
shift points:
1-2 - whenever I can grab 2nd gear before hitting the rev limiter, way too much torque for full throttle, and such low gearing causes it to accelerate almost as fast as if I'm free revving in neutral
2-3 - 7000 (part throttle through peak torque area to maintain traction)
3-4 - 6600 (again part throttle through peak torque to maintain traction in colder weather)
4-5 - 6300
I calculated it for axle torque, not actual tire surface torque. I can reconfigure it for tire surface torque at any time if I want, so I can better judge for traction purposes when comparing different size tires.
This is set up with my current street tires, which according to this chart break traction at about 1500 axle tq in temps around 35*F, much higher when temps increase.
The whole purpose of doing this was to calculate this:
shift points:
1-2 - whenever I can grab 2nd gear before hitting the rev limiter, way too much torque for full throttle, and such low gearing causes it to accelerate almost as fast as if I'm free revving in neutral
2-3 - 7000 (part throttle through peak torque area to maintain traction)
3-4 - 6600 (again part throttle through peak torque to maintain traction in colder weather)
4-5 - 6300
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