Engines especially designed for cars soon pushed the speeds to over 100 miles per hour. By the early 1950's they were going over 150 mph using the legendary Dooling 61 engine in a car that had ceased to look like anything on a big car track. Today they are going over 200 mph with Italian made engines in cars that look more like a bullet with the wheels inside the slim body. International competition is held with cars in five different classes depending upon engine size. The classes are 1 - 1.5cc (.09 cu in), 2 - 2.5cc (.15 cu in), 3 - 3.5cc (.21 cu in), 4 - 5cc (.29 cu in) and 5 - 10cc (.61 cu in). Running on an methanol - castor oil (80:20) fuel and using tuned exhaust pipes the engines peak out at over 44,000 rpm in the smallest class.
The cars run on a special circular track held to the center post by a wire tether. The person running the car stays on the outside of the track and the helper in the center assists the car off the line and stabilizes it until it reaches about 80 mph and then steps onto a small platform on the center pole until the car is shut off at the end of the run.
The cars and the engines are the most sophisticated of all the modeling hobbies. Because of the high speeds, the tracks are also sophisticated with a very flat running surface and extremely strong center post.
Ted Maciag (selection copied from AMRCA webpage)