The previous Brabham BT16 forerunner initially had a Cosworth SCA, BRM, or HolbayMAE engine. On 20 March 1965, at the Formula Two meeting at Silverstone, it was equipped with the Honda RA300E engine. Displacing 996.7 cc (60.82 cu in), the engine produced 135 bhp at 10,000 rpm.[3]
The BT18 was designed as a Formula 2 and Formula 3 racing car. The car had a space frame that was reinforced by load-bearing plates. Two cars, F2-18-66 and F2-19-66, were used by the factory Brabham team with revised Honda RA302E engines, which now gave 150 bhp at 11,000 rpm.[4] 32 were Formula 2 racing cars and designated BT18A. Six copies were equipped with a Cosworth SCA engine for private teams. A special version BT18B of 8 examples was fitted for the Honda Racing School with Ford Kent engines for the upcoming 1966 Formula Ford. A total of 46 examples of the BT18 (+A+B) were produced.[5][6]