The Formula F100 was a racing class that was open to lightweight sports cars powered by 1300cc Ford Kent engines. The short-lived series was around for just two years, in 1970 and 1971. The series was launched by Geoff Clarke and the Motor Racing Stables racing school. Clarke had previously launched the Formula Ford and thought the Formula F100 could be the sports car racing equivalent. The series specified lightly modified production engines and road tires were mandatory. Just as Formula Ford had proven to be an ideal training ground for senior single-seater formula's, it was hoped that Formula F100 would help train drivers for endurance, Can-Am, and the European 2-Litre sports car series.

Manufacturers who built cars for this series included Lotus, Beattie, Royale, Merlyn, and Nerus.

The first year of Formula F100 competition started slowly with few cars showing up to race. By the season's close, there were 12 cars on the grid. During the inaugural season, Ray Allen dominated early while driving his Royale RP4. After Nick Cole and his BMC-powered Nerus Silhouette started enjoying success, Allen changed engines. Les Leston of Formula 1 fame started to have success near the end of the season.

Tom Pryce in a Royale RP4, won eight of the twenty races for the 1971 season. The final race was at Brands Hatch on December 27th, 1971, and only one car showed up.

Nerus Engineering, an Essex-based company, specialized in the manufacturing of racing car components. When Formula F100 was announced, the company made the decision to build its own racing car. Their car was called the Nerus Silhouette F100, and only two examples were built. A third example was built up from spare parts. The body was designed by Lotus race engineer Cedric Seltzer. The entire drivetrain was located in a spaceframe chassis with aluminum panels. Power was from a 1300cc Ford Kent Crossflow engine derived from the Formula Ford 1600. Even though the engines were 300cc smaller, the cars were only slightly slower than Formula Ford. All of the Formula F100 cars were given spec Hewland transmission and rode on Firestone tires.

The first example built was raced by Nick Cole.

by Dan Vaughan