Formula 500

Formula 500 (F500) is a Sports Car Club of America (SCCA) and Midwestern Council of Sports Car Clubs (MCSCC) open wheel road racing class.

Formula 500 was originally introduced in the early 1980s as Formula 440 (F440), and is a closely regulated class. Several chassis manufacturers produce different designs to a tight dimensional ruleset. Engines are specified by the ruleset, and builders are not allowed to modify engine internals. Instead of traditional dampers and springs, F500 cars utilize a very simple elastomeric spring medium contained in a cylindrical canister. The rules state the elastomer must be 2" in diameter by 1" in thickness, but the design and implementation of the elastomeric springs (commonly called "pucks" by the competitors) is wide open. Additionally, each chassis manufacturer produces bodywork of their own design, which adheres to dimensional constraints. These regulations allow for very competitive racing at a relatively low cost, which rewards driver and car set-up skills.

Formula 500 cars are powered by a two-cylinder, water-cooled two-stroke engine. Modern cars use either the Rotax 494, or Rotax 493 originally produced for Ski-Doo snowmobiles. Older cars, mostly used for Solo events these days use the Kawasaki 440/A engine. The AMW 500L-85/250-2 R2c engine, while legal for use in Formula 500 racing, is rarely used these days.

The Kawasaki 440/A engine, produced by Kawasaki, is a 436 cc piston port engine utilizing 38 mm Mikuni VM series carburetors and a tuned dual exhaust. While this engine is no longer competitive in road racing, it is still widely used in Solo II and events. Like all F500 engines, except for the AMW, the Kawasaki was originally produced as a snowmobile engine. It has been out of production since the early 1980s. Parts for these engines are becoming more difficult to find.

The AMW 500L-85 engine, built by Two Stroke International was introduced to F500 in 1994. It is a 497 cc reed valve engine using twin 38 mm Mikuni SuperBN carburetors. To keep the performance of these larger, more powerful engines in line with prior engines, SCCA mandates the use of a spec Y exhaust manifold and single tuned pipe on the AMW engine. Unlike the other engines used in F500, the AMW engine is a derivative of a light aircraft engine. This engine is no longer in production, and is not supported by the manufacturer.

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