page_title: Judd (engine)
section_title: Yamaha partnership
hierarchical_section_title: Judd (engine) / Engine history / Formula One / Yamaha partnership
caption_attribution_description: 1993 Yamaha OX10A engine
context_page_description: Judd is a name brand of engines produced by Engine Developments Ltd., a company founded in 1971 by John Judd and Jack Brabham in Rugby, Warwickshire, England. Engine Developments was intended to build engines for Brabham's racing efforts, and became one of the first firms authorised by Cosworth to maintain and rebuild its DFV engines, but has since expanded into various areas of motorsport.
  Judd has provided engines for many major series, including Formula One and other smaller formula series, sports car racing, and touring car racing. They have been associated with manufacturers such as Yamaha, MG, Mazda and Honda, although they have mainly been a privateer-engine supplier.
context_section_description: Following Judd's withdrawal from Formula One in 1992, John Judd turned to Yamaha to continue production of his engines.  Using the Judd GV V10 as a base, Yamaha developed an all-new cylinder head and branded the motor as the OX10, for use by Tyrrell Racing in 1993.  Once again, Tyrrell were unable to score any points all season.  An improved OX10B for 1994 boosted Tyrrell's performance, as the team scored a podium and finished sixth in the Constructors' Championship.
  Rule changes in 1995 saw the OX10C (known by Judd as the HV) reduced to 3 litres, although the architecture of the engine was generally the same.  Tyrrell's performance fell off again however, as the team scored five points and finished eighth in the championship.  1996 saw the same points total from Tyrrell, although the new Yamaha OX11 (Judd JV) engine was an all-new design.  After 1996 Tyrrell switched to using Ford-branded engines.
  An updated C-Spec version of the OX11 was used by Arrows in 1997. Featuring a new bottom end, with changes consisting of a revised sump, crankshaft, oil pump and water pump; the OX11C had an extremely low centre of gravity (and a dry weight of 105 kg vs the Renault RS09's 121 kg) but was underpowered (708 bhp vs the RS09's 755 bhp) and most of all unreliable.
  Consequently, a D-Spec was introduced for the fourth race, at Imola, with significant improvements in the airflow management of the combustion chamber area, which permitted the OX11D to gain 20 hp, which along with superior Bridgestone tyres propelled Damon Hill to a second place at the Hungaroring, the 11th race of a year that otherwise was pretty lacklustre with Pedro Diniz's 5th place at the Nürburgring as a last high point before Yamaha consequently pulled the plug on the failing project.
caption: 1993 Yamaha OX10A engine, a variant of the Judd GV engine
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