Torque, did someone mention torque. I like torque now that I forced myself to study “Newtons” and all that stuff!
These kind of things must be taken into consideration when talking torque vs. speed:
*Total Kart Weight
*Weight distribution
*Frontal Drag – Karts max width and max height
*Drag Coefficient - for hard surfaces it ranges from 0.25 (very aerodynamic) to 1.20 (not very aerodynamic). Most high performance karts without windshield and top are typically around 0.35 to 0.45.
*Gearing and tire size too.
There are plenty of programs “hidden-away” in the deep vaults of the Internet that let you fill in the blanks and they calculate Torque/Speed. The more you play around with the inputs, the more valuable information you can gain. One thing is figuring-out the answer to the above discussion on finding the motor that has the right amount of torque and will provide maximum acceleration of varying distances. (like perhaps a eighth of a mile!) It’s a lot easier if you use average acceleration (speed) instead of actual acceleration. Average acceleration is ending speed divided by 2. EX: 0 to 60 mph in 1/8th of a mile takes exactly the same time as driving 1/8th of a mile at 30 mph. (Sorry, perhaps I was the only person on earth that didn’t think about that before!)
Two interesting facts (at least I think so) effecting torque/speed that I found in the vaults (described in much more depth than I state here)
*Total “wasted torque” caused by the rotational inertia of motor and other drive components. Ex. If inertia of the motor results in it to rotate (even by a small amount) it takes away torque that should be delivered to the wheels! The force required to hold that rotation is much greater than one would think. Despite a popular belief, any opposite rotation of the motor housing does not increase the initial speed like a spring, it just wastes torque!
*Amount of Tire ballooning – change in tire diameter resulting from the tire spinning at high velocity. At high speeds, the centrifugal force causes the tire to expand. This increase in diameter can drastically change the top speed. (determined by width and hardness of rubber)
I apologize to all those that already knew all this, just got on one of my soap boxes again! (been a long time, you must admit)