Hirth HM 501
# Hirth HM 501

The Hirth HM 501 was a 6-cylinder air-cooled inverted in-line engine that was developed by Hirth Motoren GmbH in the late 1930s, from the 4-cylinder HM 500 and used principally on the submarine-born Arado Ar 231.

## Applications

* Arado Ar 231

## Specifications (HM 501A)

Data from Flugzeug-Typenbuch. Handbuch der deutschen Luftfahrt- und Zubehör-Industrie 1944

### General characteristics

* Type: 6-cylinder air-cooled inverted in-line aircraft piston engine
* Bore: 105 mm (4.13 in)
* Stroke: 115 mm (4.53 in)
* Displacement: 5.97 L (364.3 cu in)
* Length: 1,272 millimetres (50.1 in)
* Width: 485 mm (19.1 in)
* Height: 662 mm (26.1 in)
* Dry weight: 148 kg (326 lb) dry, unequipped

             155 kg (342 lb) wet, equipped

### Components

* Valvetrain: one intake and one exhaust under-head valve per cylinder actuated pushrods and rockers
* Fuel system: SUM 698/2 carburetor
* Fuel type: 80 octane gasoline
* Oil system: Dry sump with one pressure and two scavenge pumps
* Cooling system: Liquid-cooled, ethylene glycol

### Performance

* Power output:

   * 160 PS (158 hp; 118 kW) at 2,550 rpm for takeoff

   * 145 PS (143 hp; 107 kW) at 2,470 rpm (high performance) at sea level

   * 130 PS (128 hp; 96 kW) at 2,380 rpm (max. continuous ) at sea level
* Specific power: 26.8 PS/L (0.43 hp/cu in; 19.71 kW/L)
* Compression ratio: 6.2:1
* Specific fuel consumption: 0.220 kg/PSh (0.492 lb/(hp⋅h); 0.299 kg/kWh) at max continuous
* Oil consumption: 0.002–0.003 kg/PSh (0.004–0.007 lb/(hp⋅h); 0.003–0.004 kg/kWh) at max continuous
* Power-to-weight ratio: 1.075 PS/kg (0.481 hp/lb; 0.791 kW/kg)
* B.M.E.P.: 9.46 atm (9.59 bar; 139.0 psi)
