Some months ago, I wrote about Cosworth in a history article as the company was instrumental in developing technology for road and race cars. This week’s article explores arguably their most famous product – the DFV engine. I have also written about the Repco 620 V8 that won several Formula 1 championships in the mid 1960s. Cosworth were a major competitor to Repco, Honda and Ferrari during the last four years of that decade.
Colin Chapman at Lotus wanted an engine that could be used as a stressed member of the chassis of his cars. He had been using Coventry Climax engines in Formula 1 and they had pulled out when the rules dictated a 3 litre capacity rather than 1.5 litres. Lotus had also had a long relationship with Ford for both road and race cars. So Chapman went to Ford to see if they could build a race only engine for the new rules. Ford then commissioned Cosworth to build an engine in conjunction with Lotus.
The heritage of the DFV starts in the late 1950s with the Ford Kent engine, a 1 litre overhead valve motor that was fitted to the Ford Anglia, Corsair and Cortina models. It was hugely successful in motor sport and Cosworth started to tune them for Lotus and other racers.
Cosworth’s contract with Ford started with the FVA, a Formula 2 engine of 1600cc based on the Kent. Cosworth redesigned the Kent to increase the capacity with a new head providing 16 valves with a double overhead cam on the 4 cylinder motor. It produced 225 hp out of the factory. The FVA was a successful motor even though it was a guinea pig for the bigger motor.
The DFV was born as the Double Four Valve, a 3 litre V8 with a double overhead cam putting out about 400hp. It was also wider than longer and specifically designed to have suspension components bolted directly to the aluminium block. As a stressed member of the car, it needed to provide support even though the heat of the engine would impact the size of the block. Heat expands materials and the aluminium block would grow slightly when hot which would affect the calculations of the suspension design.
With the width of the engine being larger than normal, it required the fuel tank to be repositioned in front of the engine, which had a secondary benefit of putting more weight in the centre of the car. Mike Costin (the Cos of Cosworth) did the initial testing in a Lotus chassis and found that the lightweight engine was a cracker even if it did have early problems with oil pooling in the head and other vibration issues.
Lotus built their “49” racing car around the engine and it had a dynamic start to its career with a pole and win in its first race, the Dutch Grand Prix during 1967. Lotus spent the rest of the year working with Cosworth to iron out the teething problems and as such didn’t get the championship – that went to a Brabham-Repco.
1968 saw the start of a 15-year dominance of Formula 1 with 155 wins as the engine was now available as a customer engine. It was typically matched to a Hewland gearbox. Apart from Lotus, other constructors like McLaren, Matra, Brabham, March, Tyrrell, Hesketh, Penske, Wolf, Shadow, Ligier & Williams have all won Formula 1 races with the DFV and in some years there were only two engines being used: the DFV and Ferrari. The engine provided power for 12 drivers championships and 10 constructors titles over its 15-year life.
The DFV spawned a number of variants: the DFX, DFY and the DFZ. The base motor was repurposed for sports car racing and for the North American single seaters series like Indycar (USAC and CART) and achieved more success on the west side of the Atlantic.