Please see the Official Rule Book for specifications in all classes.

Jeep
Must be a 4 cylinder American Jeep.

Air Cooled
Must be air-cooled. Usually powered by motorcycle or Volkswagen engines.

4 Cylinder
Must be 4 cylinders.

6 Cylinder
Must be 6 cylinders. V6 or straight 6.

V8 Stock
Must be stock V8 engine block according to manufacturer's specifications.

Modified 4WD
Must be driven by all 4 wheels. Engine of choice; big block Chevrolet modified with high performance parts.

Pro Modified
Same as above, except 2 wheel drive. These engines can develop nearly 1,000 horsepower.