Electric motor's rollout

[4tex]

forgive my ignorance, but just for interest sake. Is there a mathematical way to deduce the rollout of a electric motor? i personally brought a second-hand fantom superstock motor(a really old motor), in which it doesn't have any engine spec.it would be real handy if i could get the rollout so that i can tune my car properly.

4tex

[G10products]

Take the circumfrence of the tire, and divide by the final drive ratio.

[rcguy2477]

The rollout is how much the car moves for each rotation of the motor. The motor itself doesn't have a rollout number. Are you possibly talking about rpm of the motor?

[highroller]

Rollout is calculated by measuring tire circumference (2.24) multiplied by PI (3.14) divide by spur/pinion (125/30= 4.16666 or 4.17)
2.24 x 3.14 = 7.03 divided by 4.17 = 1.6858 or 1.69 rollout (this would be for direct drive cars)
For transmission cars
tire circumference x transmission ratio divide by gear ratio (spur/pinion)
2.2 x 3.14 = 6.9 x 2.25 (trans ratio) = 15.543 or 15.5 divided (83/24=3.458) 3.46 (gear ratio) = 4.479 or 4.48 rollout.

Motor rpm is then used to calulate the estimated speed, or rollout is used for certain motors to gear them to track layout based on power output. It is a Stock 27 turn motor could be a midnight2, paradox or another type. What color is motor can, endbell and what is stamped on end or endbell and output shaft end of motor.

[G10products]

You must mean diameter X Pi, which equals circumfrence. Circumfrence times pi means nothing, circumfrence divided by pi gives diameter, but thats irrelivant to rollout.

[highroller]

In most cases (pan car racing) the measurement is taken accross the tire with a set of caliper then multiplied by pi to get the exact diameter. Others just use a measuring tape. bypassing using Pi in the formula.