[Spridgets] calculating speed

Jim Johnson bmwwxman at gmail.com
Sat Oct 18 10:37:20 MDT 2008


Hey, David....

My engineering background tells me Dean and Duncan are on to something.
There will definitely be some tire circumference growth which changes the
tire diameter making it larger at higher speeds....  Where am I going wrong
with that thinking?  ;-)

Cheers!!
Jim

On Sat, Oct 18, 2008 at 6:13 AM, David Lieb <dbl at chicagolandmgclub.com>wrote:

> Go to:
>> http://bgsoflex.com/auto.html
>> Then scroll down on the left to rpm range program...
>> Here is a sample output.  The key item is to go measure your tire
>> diameter.
>>
>
> Since you already measured circumference, divide it by pi (3.1415) to get
> 20.69 as a diameter.
> with the 4.55 diff at 7000, that site indicates 95mph
> with the 4.22 diff at 7000, that site indicates 102mph
>
> Input Parameters Are the Following:
> Differential Gear = 4.55 to 1
> Transmission Gear = 1.00 to 1
> Tire Diameter (Inches) = 20.69
> Engine RPM = 7000
> Computation Results:
> Computed Vehicle MPH is 95
>
> Input Parameters Are the Following:
> Differential Gear = 4.22 to 1
> Transmission Gear = 1.00 to 1
> Tire Diameter (Inches) = 20.69
> Engine RPM = 7000
> Computation Results:
> Computed Vehicle MPH is 102 _______________________________________________
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-- 
Cheers!!
Jim


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