| Hart 420R/420S | |
|---|---|
| Overview | |
| Manufacturer |  Hart |
| Production | 1975–1980 |
| Layout | |
| Configuration | I4, naturally-aspirated |
| Displacement | 2.0 L (122 cu in) |
| Cylinder bore | 93.5 mm (3.68 in) |
| Piston stroke | 72.6 mm (2.86 in) |
| Cylinder block material | Aluminum alloy |
| Cylinder head material | Aluminum alloy |
| Valvetrain | 16-valve, DOHC, four-valves per cylinder |
| Combustion | |
| Fuel system | fuel injection |
| Output | |
| Power output | 290–305 hp (216–227 kW) @ 9500 rpm |
The Hart 420R and the Hart 420S are four-stroke, naturally aspirated, 2.0 L (120 cu in), four-cylinder engine, designed, developed and made by Hart Racing Engines, and tuned by Brian Hart, for Formula 2 and sports prototype racing applications, between 1975 and 1980. The 420R is based on the Cosworth FVA, while the 420S is based on the Cosworth BDG, with the design knowledge being taken and used on both. The Hart 420R F2 engine owes much to the Cosworth BDA series, being essentially an aluminium-block derivative using similar heads. Both the 420R and 420S were naturally-aspirated, 2-litre, 16-valve DOHC, fuel-injected, straight-four engines. Displacement is 1,994 cc (121.7 cu in), and maximum power output is between 290–305 hp (216–227 kW; 294–309 PS) at 9,500 rpm, with the motor being failsafe to just over 10,000 rpm. The bore is 93.5 mm (3.68 in), and the stroke is 72.6 mm (2.86 in).[1][2][3][4][5]
- ^ "Hart 420R Engine – primotipo…". primotipo...
- ^ "Hart 420S 2 litre Race Engine". racecarsdirect.com.
- ^ "Hartpower". Motor Sport Magazine.
- ^ "HART ENGINES". Garage 59.
- ^ Quiniou, Louis (April 16, 2014). "#Tech – The Cosworth BD engine".