In 1965 a new Grand Prix formula was announced and Dan Gurney decided to try to build his own 3-liter engines for the new regulations. Gurney commissioned a new engine from Weslake Engineering, a company run by Harry Weslake, the veteran engine designer who had worked with Jaguar in the 1930s and Vanwall in the 1950s. The 60-degree 48-valve V12 engine was designed by ex-BRM designer Aubrey Woods and had only one run on the dyno before it made its debut at Monza in September 1966. It was down on power but had a very smooth delivery. The engine reappeared at the US GP with Gurney driving and in Mexico with Bob Bondurant. Development continued over the winter and Gurney won the Race of Champions at Brands Hatch in March 1967 with Richie Ginther in the second car finishing third. The engines proved to be fairly unreliable but Gurney won the Belgian GP in June and finished third in Canada in August. Development of the engine continued through 1968 but at the end of the season Gurney ended the project and decided to concentrate on building successful Indycars in the United States.