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Location:
Brisbane
Registered:
October 2002
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Location:
Brisbane
Registered:
November 2002
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Re: how to work out speed vs revs?????
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Sun, 14 March 2004 00:16
 
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I can't help you with the formula, however another way is to do 2000rpm in each gear and get your passenger to write down what speed you are doing.
For ease of maths divide it by 2, and you have the number of km/h per 1000rpm in each gear.
Then if your redline is (say) 6500rpm, multiply that figure by 6.5 and you'll have the maximum speed available.
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Location:
Newcastle
Registered:
May 2002
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Re: how to work out speed vs revs?????
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Sun, 14 March 2004 01:05
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I just wrote up a spreadsheet to do this. If you want it I can email it to you. It's pretty simple, but it gives you max speed in each gear and revs at speed. You put in the variables like max revs, tire width, profile, wheel radius, diff and gear ratios etc. It's pretty simple to do yourself. Otherwise
it goes like this:
Tyre circumference = pi x total diameter
Total diameter = sidewall x 2 + wheel diameter
Sidewall = tyre width x aspect/100
eg. for 195/50 R15, sidewall = 195(mm) x 50/100 = 97.5(mm)
Make sure units are the same! IE convert wheel diameter (usually in inches) to mm. IE x 25.4
Once you have the circumference you can then convert this to metres. Then you know distance/revolution (wheel) then you just multiply in the diff and gear ratio you want and then you should get a relationship between engine revs and distance travelled. Then you can work out what you want.
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Location:
Melbourne
Registered:
May 2002
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Re: how to work out speed vs revs?????
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Sun, 14 March 2004 02:40
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Bah who needs a formula when you can take it for a drive.
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Location:
New Zealand
Registered:
May 2002
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