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Old 08-12-2011, 10:24 AM   #1
veinbar
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RPM Calculator

This is the best RPM Calculator that I have found on the internet. Fun to play around with and enter various gears and tire sizes. It helped me determine Which rear ratio, transmission, and tire size to go with...

http://www.chevellestuff.com/tools/rpm_calculator.htm

For example...
Old Setup: 275/60/15 tires + TH350 transmission + 3.08 Rear @ 70mph = 2600 RPM
New Setup: 275/60/15 tires + 700r4 transmission + 3.73 Rear @ 70mph = 2194 RPM
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Last edited by veinbar; 08-12-2011 at 10:32 AM.
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Old 08-12-2011, 10:59 AM   #2
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Re: RPM Calculator

Here's another gearing calculator build for dodge cars that I sue alot

http://www.squirrelpf.com/gearingcalc/index.php

this is another cool one for comparisons

http://www.fatboyraceworks.com/gears/index.php
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Old 08-13-2011, 03:42 PM   #3
hatzie
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Re: RPM Calculator

Several years ago I made an Excel sheet that calculates RPM & Speedo gears based on tire size and axle ratios.
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Old 08-15-2011, 10:11 AM   #4
veinbar
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Re: RPM Calculator

Quote:
Originally Posted by hatzie View Post
Several years ago I made an Excel sheet that calculates RPM & Speedo gears based on tire size and axle ratios.
Do you still have it? That would be great to circulate. I am not that great with excel.
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1976 Chevrolet Sport Van SWB; 355ci, TH350, 2.73 Open - Rape Free
1972 Oldsmobile Cutlass S; 455ci, TH400, 2.73 Open - SOLD (but I still claim to own it from time to time)
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Old 09-14-2011, 06:10 PM   #5
hatzie
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Re: RPM Calculator

Quote:
Originally Posted by veinbar View Post
Do you still have it? That would be great to circulate. I am not that great with excel.
Here ya go. This is in Excel 97-2003 format.

I'd put an unmolested copy in a safe place before you change any values.
All of the Blue and Red numerals can be changed by hand without affecting formulas.

You can hand enter the tire diameter in inches but it will overwrite the formula in that cell.

The speedometer driven gears are automagically calculated from the tire diameter and the axle ratio.

Enjoy.
Attached Files
File Type: zip RPM_Gear_Axle_Transmission_TransferCase.zip (18.7 KB, 37 views)
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Old 09-14-2011, 06:21 PM   #6
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Re: RPM Calculator

4lo.com is better, can factor in crawl ratios....
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Old 09-14-2011, 07:43 PM   #7
hatzie
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Re: RPM Calculator

Quote:
Originally Posted by b454rat View Post
4lo.com is better, can factor in crawl ratios....
Ummm... Overall Gear Ratio and Crawl Ratio are the same critter. Cells C19-C30 and C37-C48.

All green rows have the splitter engaged... "1S" is 1st gear with a range splitter.
The Low Range Table has RPMs with the transfer case in low range.

Try changing Cell D10 from 1 to the Klune V Extreme Gear Splitter ratio of 4.1
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