The Hart 420R and the Hart 420S are four-stroke, naturally aspirated, ,

four-cylinder engine The engine configuration describes the fundamental operating principles by which internal combustion engines are categorized. Piston engines are often categorized by their cylinder layout, valves and camshafts. Wankel engines are often categorize ...

, designed, developed and made by

Hart Racing Engines Brian Hart Ltd., also known as Hart and Hart Racing Engines, was a motor racing engine manufacturer that participated in 157 Formula One Grands Prix, powering a total of 368 entries. Founded in 1969 by British engineer Brian Hart, Hart initia ...

, and tuned by

Brian Hart Brian Roger Hart (7 September 1936 – 5 January 2014) was a British racing driver and engineer with a background in the aviation industry. He is best known as the founder of Brian Hart Limited, a company that developed and built engines for mot ...

, for

Formula 2 Formula Two (F2 or Formula 2) is a type of open-wheel formula racing category first codified in 1948. It was replaced in 1985 by Formula 3000, but revived by the FIA from 2009–2012 in the form of the FIA Formula Two Championship. The name re ...

and

sports prototype A sports prototype, sometimes referred to as simply a prototype, is a type of race car that is used in the highest-level categories of sports car racing. These purpose-built racing cars, unlike street-legal and production-based racing cars, are n ...

racing In sport, racing is a competition of speed, in which competitors try to complete a given task in the shortest amount of time. Typically this involves traversing some distance, but it can be any other task involving speed to reach a specific go ...

applications, between 1975 and 1980. The 420R is based on the

Cosworth FVA 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 (motorsport) and mainstream automotive industries ...

, while the 420S is based on the

Cosworth BDG Cosworth is a British automotive engineering company founded in London in 1958, specialising in high-performance internal combustion engines, powertrain, and electronics for auto racing, automobile racing (motorsport) and mainstream Automotiv ...

, with the design knowledge being taken and used on both. The Hart 420R F2 engine owes much to the

Cosworth BDA Cosworth is a British automotive engineering company founded in London in 1958, specialising in high-performance internal combustion engines, powertrain, and electronics for auto racing, automobile racing (motorsport) and mainstream Automotiv ...

series, being essentially an aluminium-block derivative using similar heads. Both the 420R and 420S were naturally-aspirated, 2-litre, 16-valve

DOHC An overhead camshaft (OHC) engine is a piston engine where the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion cha ...

fuel-injected Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines. All com ...

, straight-four engines.

Displacement Displacement may refer to: Physical sciences Mathematics and Physics * Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

is , and maximum power output is between at 9,500

rpm Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimensionl ...

, with the motor being failsafe to just over 10,000 rpm. The bore is , and the stroke is .

Background

With Ford's withdrawal from F2 in the mid-1970s, Hart began to concentrate on building their own designs. The first engine to bear the Hart name alone was the twin-cam, four-cylinder Hart 420R F2 unit, which appeared in 1976 and powered race-winning cars until the end of the decade. In 1978, the Toleman team agreed to a partnership program, with Toleman providing finance to develop further Hart engine designs. The fruits of this collaboration resulted in Toleman taking a one-two finish in the 1980 European Formula Two Championship. The Hart-tuned Ford FVA and BDA engines were successful in Formula Two, with Ronnie Peterson winning the European title with an FVA in 1971 and Mike Hailwood taking the same title in 1972 with a BDA. The arrival in F2 of BMW and Renault left Ford reluctant to increase its involvement, so Hart chose to develop his own F2 engine - the 420R - which was first raced in a Chevron sportscar in 1976. This engine was a race winner in F2 in 1977 and 1978. The off-season of 1978-79 brought the next step in the development of Brian Hart Limited, when the Toleman F2 team committed to providing finance for R&D. Toleman-Hart dominated the European F2 Championship in 1980, with Brian Henton and Derek Warwick finishing 1st and 2nd in the championship standings.

References

{{DEFAULTSORT:Hart 420 engine Straight-four engines