Speed to RPM calculator
Posted: Mon Apr 04, 2005 8:53 am
Dave (from Wisconsin) gave me an Excel spreadsheet to help me guestimate what my RPMs would be at any given speed given a certain Overdrive and rear-end ratio. It was very limiting since all it's calculations were relatively hard coded.
I took the formulas the author used, and made the spreadsheet more dynamic so you can type in your specific tranny's OD ratio and rear-end ratio and the spreadsheet will re-calculate the values. In addition, I list about 5 different rear-end ratios so you can compare ratios with other ratios all at once.
http://students.kennesaw.edu/~cgrey/int ... ulator.xls
I left the old spreadsheet in the Excel file just for reference so you can see what I started with. I've tried to make good use of color to associate things that are related.
There's a big black banner with red text in there that lets you know any red text in the spreadsheet is a reference value, that when changed, will change the calculations of other things in the spreadsheet. I hope it's all self explainitory. For most users, the only parameters I expect to need to be changed are your particular OD ratio and tire diameter.
The tire diameter calculation section doesn't support inch init input such as 32"x16.5"rim. It is geared towards standard tire sizing methods like 255/60R16.
I haven't checked to see how accurate it is, however it appears accurate. If you find a bug, I'll see if I can fix it.
Enjoy, and let me know what you think...
I took the formulas the author used, and made the spreadsheet more dynamic so you can type in your specific tranny's OD ratio and rear-end ratio and the spreadsheet will re-calculate the values. In addition, I list about 5 different rear-end ratios so you can compare ratios with other ratios all at once.
http://students.kennesaw.edu/~cgrey/int ... ulator.xls
I left the old spreadsheet in the Excel file just for reference so you can see what I started with. I've tried to make good use of color to associate things that are related.
There's a big black banner with red text in there that lets you know any red text in the spreadsheet is a reference value, that when changed, will change the calculations of other things in the spreadsheet. I hope it's all self explainitory. For most users, the only parameters I expect to need to be changed are your particular OD ratio and tire diameter.
The tire diameter calculation section doesn't support inch init input such as 32"x16.5"rim. It is geared towards standard tire sizing methods like 255/60R16.
I haven't checked to see how accurate it is, however it appears accurate. If you find a bug, I'll see if I can fix it.
Enjoy, and let me know what you think...