page_title: Cosworth
section_title: DFV variants
hierarchical_section_title: Cosworth / Internal combustion engines / The DFV (Double Four Valve) / DFV variants
caption_attribution_description: A Cosworth DFX racing engine shown at Museum of American Speed in Lincoln, NE
context_page_description: Cosworth is a British automotive engineering company founded in London in 1958, specialising in high-performance internal combustion engines, powertrain, and electronics; for automobile racing and mainstream automotive industries. Cosworth is based in Northampton, England, with American facilities in Indianapolis, Shelby Charter Township, Michigan and Mooresville, North Carolina.
  Cosworth has collected 176 wins in Formula One as engine supplier, ranking third with most wins, behind Ferrari and Mercedes.
context_section_description: The DFV spawned a number of derivations.  In 1968; Cosworth created the DFV's first derivation, a 2,500 cubic centimetres (152.6 cu in) version for the Tasman Series, the DFW.  DFV to DFW conversion simply involved substitution of a short-stroke crank and longer connecting rods.
  One of the most successful and longest-lived projects of Cosworth has been its CART / Champ Car engine program.  In 1975; Cosworth developed the DFX, by destroking the engine to 2,650 cc (161.7 cu in) and adding a turbocharger, the DFX became the standard engine to run in IndyCar racing, ending the reign of the Offenhauser, and maintaining that position until the late 1980s.  Ford backed Cosworth with creating a new interim design for IndyCar racing in the late 1980s, the DFS, which merged DFR technology into the ageing DFX design, but it was eventually rendered obsolete by advancing technology.
  While designed as an F1 engine, the DFV was also used as in endurance racing, although its flat-plane crank design led to destructive vibrations putting stress on devices surrounding the engine, especially the exhaust system.  The first sports car to use a DFV, the Ford P68, failed to finish a single race because of repeated mechanical and electrical failures.  Despite this handicap the DFV won the 24 hours of Le Mans twice in its original 3.0 Litre form for Mirage and Rondeau, who were able to attain sufficient reliability by de-tuning the motor.
  The DFL for endurance racing was developed for the 1982 season to replace the DFV.  It came in two versions: one with 3,298 cc (201.3 cu in) and the other with 3,955 cc (241.3 cu in).  While neither competed well in the Group C (C1 Class) the former was adapted to the C2 Class (700 kg minimum weight, 55 Litres fuel, 5 refuelings/1000 km) starting in 1984.  During the latter half of the 1980s it was the most  popular motor for that class, with successful championship campaigns and five class wins at the 24 Hours of Le Mans.  The latter version's severe lack of reliability caused it to fall out of use by 1985.
caption: Cosworth DFX
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