car of choice in Australian Formula 1 and Formula Mondial during the early to mid-1980s. Roberto Moreno drove an RT4 to win the Australian Grand Prix in 1981, 1983, and the final AGP in 1984 before it became a round of the Formula One World Championship in 1985, while Alain Prost also drove one to victory in the 1982 Australian Grand Prix. Other F1 drivers to drive a Ralt RT4 in Australia during this period included Jacques Laffite and Andrea de Cesaris, as well as World Champions Alan Jones, Nelson Piquet, Keke Rosberg and Niki Lauda. The RT4, generally powered by a 1.6 litre, 4 cyl Ford BDA engine which produced around , also saw John Bowe win the Australian Drivers' Championship in 1984 and 1985, while Australian Ralt importer Graham Watson used one to win the 1986 championship. Works F2 cars In 1980, Honda asked John Judd's Engine Developments to develop an engine for Formula Two, which would be used by the works Ralt team. Tauranac had previously been associated with Honda through Brabham's introduction of the Japanese marque to F2 in the 1960s, while Jack Brabham had co-founded Engine Developments with Judd. Between 1980 and 1984, Ralt's works F2 cars carried the RH6 designation: the RH6/80 and RH6/81 were developments of the RT2 theme, while the RH6/82, RH6/83 and RH6/84 were further developed around a new honeycomb tub. The cars proved very successful, winning 20 championship races and the 1981, 1983 and 1984 championships with Geoff Lees, Jonathan Palmer and Mike Thackwell respectively. Formula 3000 cars In 1985, Formula Two was replaced by the new Formula 3000 category. Ralt's first F3000 car was the RB20, essentially a further development of the RH6/84 but fitted with a Cosworth DFV engine. (The 'B' in the designation stood for Bridgestone, Ralt's tyre supplier and major sponsor at the time.) The car won four races of the inaugural International F3000 Championship with Thackwell and John Nielsen. For 1986, the RT20 was developed - a cheaper, more economical car with a traditional aluminium tub that was easier to maintain. Honda returned as the engine supplier for the works team, while customers used Cosworths. The works team won one race with Thackwell, while Pierluigi Martini and Luis Pérez-Sala won four races between them in customer cars entered by the Italian Pavesi Racing team. The RT21 was a further development for 1987, again incorporating honeycomb