Uncovering the Mysteries of Dragster Tyres: Distortion and Energy Recovery

[wolram]

When watching the tyres on a top fuel dragster one can see them under going massive distortion, is this distortion lost energy or is it recovered some time in the run.

The tyre (winds up) as well as grows in dia.

 

[turbo]

There are trade-offs, as you can well imagine. One of my friends was the US champion in his class for a couple of years, and he was really anal about tire pressure when we went to the track. He ran his rear tires at 3-4 psi usually, and to avoid spinning his rims out of the tires on take-off, he drilled many holes in the rims and screwed long sheet-metal screws through the rims into the beads of the tires. Low tire pressure translates to maximum contact-patch area, which means a good launch off the line. It does no good to throw a ton of horsepower at the track only to have the rear tires break free and spin.

I have pictures of Steve's car with the sidewalls of the slicks looking all twisted and distorted (and the car pulling a 2' + wheel-stand off the line). Assuming little or no slip, most of that distortion translated into forward acceleration. His car is a 340 Duster, and people would come to the pits to see if he had shoe-horned a big Hemi into the car. Nope! Just a perfectly balanced and tuned 340. BTW, if you look at a piston and rod assembly from a small-block Chevy and compare that to the sheer mass of similar parts from a Mopar car, you'd think Steve was insane to try to make his car competitive in that class.