#### Gyro-nut

##### Gyro Blacksheep

Well, I think my CHT and EGT are shot.... so I purchased a discounted go-kart multigauge today. It has CHT/EGT/Tach (from sparkplug wire)/MPH.

I would like to use the Speedometer as my RRPM. Currently it's a prox which reads 2 magnets that spin inside a collar around the axle of the go-kart shaft.

My question is this: Is there a way to convert MPH to RRPM by manipulated the number of magnets/circumference of the 'tire'/ or combination of the two.

I used this formula:

m=speed

r (radius) = 18.3 inches

RPM = (1056*m)/(r^2*pi)

With this formula, it gave me almost a 1:1 curve MPH vs RPM

Am I doing something wrong? Is the formula correct??

If the formula is correct, why would 18.3 give me a closer 1:1 ratio than anything else??

Any help would be GREATLY appreciated.

Thanks to everyone on this forum for their assistance on various issues I've encountered trying to get this bird to fly