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The DFV is an internal combustion engine that was originally produced by Cosworth for Formula One motor racing. Named Four Valve because of the four valves per cylinder, and Double as it was a V8 development of the earlier, four-cylinder FVA (four valve type A engine), making it a Double Four Valve engine. Its development in 1967 for Colin Chapman's Team Lotus was sponsored by Ford. The engine was a 90°, (3.373 x 2.555 in) 2,992.98 cc V8, and produced over 400 bhp (408 bhp at 9,000 rpm, 270 ft·lbf (370 N·m) torque at 7,000 rpm was quoted) from the start, reaching over 500 bhp (510 bhp at 11,200 rpm was quoted) by the end of its remarkable Formula 1 career. The 1983 (3.543 x 2.316 in) 2,993.38 cc DFY variant gave 520–530 bhp at 11,000 rpm, 280 ft·lbf (380 N·m) torque at 8,500 rpm. For many years it was the dominant engine in Formula One, and it was also used in other categories, including CART, Formula 3000 and Sportscar racing.
In 1965, the Fédération Internationale de l'Automobile, that administered Formula One racing, agreed to raise the series' maximum engine capacity from 1.5 litres (92 cu in) to 3.0 litres (183 cu in) from 1966. Up until that point, Colin Chapman's successful Team Lotus cars had relied on power from fast revving Coventry Climax engines, but with the change in regulations Coventry Climax decided for business reasons not to develop a large capacity engine.
Chapman approached Keith Duckworth, previously a gearbox engineer at Lotus but now running his fledgling Cosworth company with Mike Costin, who commented that he could produce a competitive three-litre engine, given a development budget of £100,000.
Chapman approached the Ford Motor Company and David Brown of Aston Martin for funding, each without initial success. Chapman then approached Ford of Britain's public relations chief, former journalist Walter Hayes, with whom he had developed a close working relationship from the early 1960s. Since Hayes had joined Ford in 1962 the pair had already collaborated in the production of the successful Lotus Cortina, introduced in 1963. Hayes arranged dinner for Chapman with Ford employee Harley Copp, a British-based American engineer who had backed and engineered Ford's successful entry into NASCAR in the 1950s. Hayes and Copp developed a business plan, which was backed by Ford UK's new chairman Stanley Gillen, and approved by Ford's Detroit head office as a two-part plan:
- Stage one would produce a four-cylinder twin-cam engine for Formula Two.
- Stage two would produce a V8 engine for Formula One, by May 1967.
Formula One 
The project was revealed by Hayes in a PR launch in Detroit at the end of 1965, but the engine was not ready until the third race of the 1967 season, on the 4 June at Zandvoort, but its debut proved electric. Graham Hill, who was in the team at the specific request of Ford and Hayes, put his DFV-powered Lotus 49 on pole position by half a second, and team-mate Jim Clark stormed home to win. However, this dominant performance belied a serious fault in the timing gear. Clark took three more wins that season, but reliability problems left him third in the Drivers' Championship, 10 points behind Champion Denny Hulme. The progress of the engine was documented in a film produced by the Ford Motor Company's film section, entitled "Nine Days in Summer".
Initially, the agreement between Ford, Cosworth and Lotus was binding on all parties, and Ford as the funder had no plans to sell or hire the DFV to any other teams. However, it occurred to Hayes that there was no competition: the Ferrari engine was underpowered; the BRM complex and too heavy; the Maserati unreliable; the Honda overweight; while Dan Gurney's Weslake motor was powerful but unreliable. Only Brabham's Repco V8 engine provided a usable combination of power and reliability, but its age and design left little room for further improvement. Hayes concluded that Ford's name could become tarnished if the Lotus were to continue winning against only lesser opposition, and that they should agree to use the unit in other teams, and hence potentially dominate Formula One.
At the end of 1967, Copp and Hayes gently explained to Chapman that he would no longer have monopoly use of the DFV and in August 1968 it was announced that the power unit would be available for sale, via Cosworth Engineering, to racing teams throughout the world. Hayes released the DFV initially to French team Matra, headed by Ken Tyrrell with Jackie Stewart as a driver. What followed was a golden age, where teams big or small could buy an engine which was competitive, light, compact, easy to work with and relatively cheap (£7,500 at 1967 prices or about £90,000 in 2005 money). The DFV effectively replaced the Coventry Climax as the standard F1 powerplant for the private (mostly British) teams.
Lotus, McLaren, Matra, Brabham, March, Surtees, Tyrrell, Hesketh, Lola, Williams, Penske, Wolf and Ligier are just some of the teams to have used the DFV. In 1969 and 1973 every World Championship race was won by DFV-powered cars, with the engine taking a total of 155 wins from 262 races between 1967 and 1985. The advent of ground effect aerodynamics on the F1 scene in 1977 provided a new lease of life for the now decade-old engine. The principle relied on Venturi tunnels on the underside of the car to create low pressure regions and thus additional downforce. Previously, teams running Ferrari and Alfa-Romeo flat-12 engines had enjoyed a handling advantage because of the low centre of gravity in such a configuration. However for ground effect, the wide-angle engine was completely the opposite of what was required: the cylinder heads protruded into the area where the Venturi tunnels should have been. In contrast, the V-configuration of the Cosworth engine angled the cylinders upwards and left ample space under the car for the necessary under-body profile.
The onset of the turbo era in the early 1980s put an end to the DFV's F1 activities, as even with modifications the 15-year-old engine could not hope to compete with the vast power being put out by the new 1.5-litre turbocharged engines. For a few years, between 1977 when Renault debuted the powerful but unreliable turbo engine and 1982 when the DFV-powered teams began to negotiate deals for turbo engines of their own, a competitive equilibrium was established. Michele Alboreto took the DFV's last F1 win in a Tyrrell at the Detroit Grand Prix in 1983, and Martin Brundle was the last person to race in F1 with a DFV, also in a Tyrrell at the Austrian Grand Prix in 1985.
Other formulae 
The DFV's success was by no means limited to Formula 1, with the engine being used in sportscar racing with some modest success. The design of the crankshaft caused vibrations that caused reliability problems in endurance racing. The first such vehicle to use the DFV was Ford's own P68, built as early as 1968. However, this car, and its derived sister the P69, failed to finish a single race. Seven years after it was introduced, the engine won the Le Mans 24 Hours twice, first in the Gulf-sponsored Mirage driven by Jacky Ickx and Derek Bell in 1975, then with the surprise winners Rondeau in 1980, driven by Jean Rondeau and Jean-Pierre Jaussaud.
The DFV was also the engine for which the Formula 3000 series was created in 1985, and thus it won every race that year. The DFV and its variants continued racing in F3000 for a decade, Pedro Lamy taking the last win for a DFV in top-class motorsport, at Pau in 1993, its 65th F3000 win in 123 races.
The first variant produced from the DFV was a reduced-capacity unit for the Australia and New Zealand-based Tasman Series races of 1968–69. The changes between the DFV and DFW specification were limited to a reduced stroke, taking capacity to 2491 cc and reducing power output to ~360 bhp. This was the smallest capacity variant of the DFV that was officially produced by Cosworth. The engine was a direct replacement for its DFV parent in Lotus's 49s. The small engine proved just as competitive as the larger version; and Jim Clark took four victories in 1968, followed by one win for Piers Courage and brace of victories for Jochen Rindt in 1969. After the demise of the 2.5L component of the Tasman Formula following the 1971 season, the four DFW engines were converted to DFV specification.
Formula One 
The DFV had three major upgrades over its life in the top formula, with the development of first the DFY and then the DFZ, followed by a major redesign to produce the final DFR type.
With the introduction of turbocharged engines towards the end of the 1970s, Cosworth's naturally aspirated DFV began to lose its predominance. In an attempt to recover some of the performance deficit Cosworth designer Mario Illien reconfigured the cylinder aspect ratio to allow the engine to rev more freely, and combined this with a narrow-angle valve set-up. The changes upped power output to ~520 bhp, but this was not sufficient to keep pace with the turbo cars at most tracks, and it was only through a modicum of luck that Michele Alboreto was able to take what would prove to be the DFV-family's final F1 victory, at the 1983 Detroit Grand Prix. The DFY lived on with back-marker teams until the end of the 1985 season, when Cosworth switched their efforts to supporting the new turbocharged Ford GBA V6.
The announcement at end of the 1986 season that turbocharged cars would be banned from 1989, and the introduction of the Jim Clark Cup and Colin Chapman Trophy championships for naturally aspirated cars for 1987, prompted Cosworth to revive their elderly engine design. This resulted in the DFZ, essentially an updated version of the final DFY design. However, the capacity increase for the new 3.5L naturally aspirated formula running alongside the 1.5L turbos in 1987 allowed Cosworth to increase the power output of the unit to ~560 bhp. The engine was intended as a temporary measure to tide smaller teams over into the new, non-turbo era from 1988 onwards. Tyrrell, AGS, March, Lola and Coloni chassis were all powered by Cosworth in 1987. Jonathan Palmer of Tyrrell eventually won the drivers' Jim Clark Cup, and his team took the constructors' laurels in the Colin Chapman Trophy. The engine remained in service with minor teams until the end of the 1988 season, when general release of the DFR engine made it obsolete.
From 1987 Benetton had been operating as the works Ford team. With the abandonment of turbocharging it was clear that the venerable DFV/Y/Z design was nowhere near being competitive with far newer offerings from Honda, Renault and Ferrari. To counter this, drastic changes were made for the DFR of 1988. Although superficially a DFV-design, almost the only feature carried over from previous versions into the DFR was the basic 90° V8 engine architecture. The DFR became available to all customers in 1989, with the Benetton team also using this engine until the 1989 French Grand Prix. The DFR struggled on until the 1991 season finally being eclipsed by the higher revving abilities of new pneumatic valve gear engines such as the HB, and was last used in that year's Australian Grand Prix by the Footwork, Fondmetal, Larrousse and Coloni teams, nearly a quarter of a century after the DFV's first race. By the time of its demise, continued improvement had pushed the DFR power output to nearly 630 bhp (470 kW), 60% higher than the original 1967 DFV.
North American series 
A 2.65L turbocharged version of the DFV was developed privately by the Vels Parnelli Jones team for the 1976 USAC season. Cosworth became involved in the project soon after, and the engine was henceforth known as the DFX. It went on to dominate American Indy car racing in much the same way the DFV had dominated Formula 1. The engine won the Indianapolis 500 ten consecutive years from 1978 to 1987, as well as winning all USAC and CART championships between 1977 and 1987. It powered 81 consecutive Indy car victories from 1981 to 1986, and 153 victories total. By the time it was replaced the DFX was developing over 840 bhp (630 kW).
In 1986 GM financed the British Ilmor firm to build a competitor to the DFX in American Indy car racing. Mario Illien's Ilmor-Chevrolet Indy V-8, which owed not little to the DFY of five years earlier, quickly took over dominance of the sport.
Ford responded by commissioning Cosworth to redesign the DFX to include a number of DFR improvements. In 1989, they introduced an updated "short stroke" version of the Indy car engine which would be referred to as the "DFS" ("S" for short stroke). The engine was fielded by two teams in its first season: Kraco Racing (Bobby Rahal) and Dick Simon Racing (Arie Luyendyk), and its development was an effort to regain dominance of the sport. At Indy, neither car qualified in the front two rows, but both started in the top ten. On race day, both drivers dropped out with engine failures. Rahal won one race in 1989 at the Meadowlands. However, the Kraco team merged with Galles at season's end, dropped the program, and switched to Chevrolets.
In 1990, the factory development was continued by Scott Brayton and Dominic Dobson, but neither won any races. The engine was utilized by other CART teams in 1991–1992, and was retired after the introduction of the Ford Cosworth XB with only one victory, that being Rahal's in 1989.
In 1981 a variant of the DFV named the DFL (for long-distance) was produced specifically for use in the new Group C (and later C2) sports car racing categories. The engine was modified to a larger capacity of 3,298 cc (201.3 cu in) and evolved into a 3,955 cc (241.3 cu in) version. Both versions used wider bore and longer stroke dimensions than the standard DFV, and were tuned for reliable power during endurance events. The 3.9 L version proved unreliable but the 3.3 L engine found many uses during the mid-1980s, and was particularly successful in the C2 category, powering many privateers cars, mostly Spices and Tigas, to class victories around the world. The 3.9 L version never achieved the same success as its smaller sibling, but was used to power the famous Ford Supervan and Supervan 2 promotional projects as well as the Australian designed and built Romano WE84 in the Australian Sports Car Championship, which ran the 3.0 L DFV in the championship before upgrading to the 3.9 L DFL for the 1984 World Endurance Championship round at the Sandown Raceway in Melbourne.
Major successes 
DFV normally aspirated 3.0-litre 90° V8
Formula One Drivers' Champions (12):
- 1968 Graham Hill (Team Lotus)
- 1969 Jackie Stewart (Matra)
- 1970 Jochen Rindt (Team Lotus)
- 1971 Jackie Stewart (Tyrrell)
- 1972 Emerson Fittipaldi (Team Lotus)
- 1973 Jackie Stewart (Tyrrell)
- 1974 Emerson Fittipaldi (McLaren)
- 1976 James Hunt (McLaren)
- 1978 Mario Andretti (Team Lotus)
- 1980 Alan Jones (Williams)
- 1981 Nelson Piquet (Brabham)
- 1982 Keke Rosberg (Williams)
Formula One Constructors' Champions (10):
- 1968 Lotus
- 1969 Matra
- 1970 Lotus
- 1971 Tyrrell
- 1972 Lotus
- 1973 Lotus
- 1974 McLaren
- 1978 Lotus
- 1980 Williams
- 1981 Williams
Le Mans 24 Hours winners (2):
Formula 3000 Champions (6):
- 1985 Christian Danner (March Engineering)
- 1986 Ivan Capelli (March Engineering)
- 1987 Stefano Modena (March Engineering)
- 1988 Roberto Moreno (Reynard)
- 1992 Luca Badoer (Reynard)
DFX turbocharged 2.65-litre 90° V8
Indy 500 winners (10):
- 1978 Al Unser (Lola)
- 1979 Rick Mears (Penske)
- 1980 Johnny Rutherford (Chaparral)
- 1981 Bobby Unser (Penske)
- 1982 Gordon Johncock (Wildcat)
- 1983 Tom Sneva (March)
- 1984 Rick Mears (March)
- 1985 Danny Sullivan (March)
- 1986 Bobby Rahal (March)
- 1987 Al Unser (March)
USAC Champions (3):
CART Champions (9):
- 1979 Rick Mears (Penske)
- 1980 Johnny Rutherford (Chaparral)
- 1981 Rick Mears (Penske)
- 1982 Rick Mears (Penske)
- 1983 Al Unser (Penske)
- 1984 Mario Andretti (Lola)
- 1985 Al Unser (March)
- 1986 Bobby Rahal (March)
- 1987 Bobby Rahal (Lola)
- The Power and the Glory: A Century of Motor Racing by Ivan Rendall Published 1991 BBC Books ISBN 0-563-36093-3
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- Hilton, Christopher (2002) Ken Tyrrell – Portrait of a Motor Racing Giant p38 Haynes Publishing ISBN 1-85960-885-X
- EH.net How much is that worth today?
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- Hughes, Mark (2004) The Unofficial Complete Encyclopedia of Formula 1, p. 62, Lorenz Books, ISBN 0-7548-1509-9
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- Glick, Shav (24 May 1990). "11 Buicks Will Have a Race of Their Own in Indy 500". Los Angeles Times. Retrieved 13 October 2011.
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- Darren Galpin. (June 22, 1999) Customer power: the Cosworth DFV story. 8W.