Bill, it is governed by what ever association your running in. Some rules say 481 cu in and some (especially back in the day) say "'run what you brung". They have an 1850 lbs min. weight limit with a max of 100" wheel base and an 85" max. wheel track. No clutch or flywheel; the drive line hooks right to the crank shaft (more or less). The wings and suspension are all up to the builder. There aren't many classes left, in racing, where you can do that, anymore. One of the cool things is the wings that move up and down during corning and the driver can move it back and forward as the track changes, from the cockpit. Personally, I think these cars should be the ones running the Indy 500 instead of the Batmobiles that currently race there.