Hirth HM 508
# Hirth HM 508

The Hirth HM 508 was an air-cooled, eight-cylinder, 60° cylinder bank angle inverted-V aircraft engine built in Germany in the 1930s. It had a bore and stroke of 105 mm × 115 mm (4.1 in × 4.5 in) and developed 210 kW (280 hp) at 3,000 rpm.

## Variants

### HM 508C

    270 PS (266 hp; 199 kW)

### HM 508D

    280 PS (276 hp; 206 kW) at 3000 rpm

### HM 508E

    150 kW (200 hp)

### HM 508H

    180 kW (240 hp), low fuel consumption variant, with centrifugal supercharger geared at 3.86:1 crankshaft speed for long-range record breaking aircraft.

## Applications

* Ambrosini S.7
* Gotha Go 146
* Gotha Go 149
* Heinkel He 116
* IMAM Ro.63
* Messerschmitt Bf 108
* Siebel Fh 104
* Weserflug We 271 Experimental aircraft

## Specifications (HM 508D)

Data from Flugzeug-Typenbuch. Handbuch der deutschen Luftfahrt- und Zubehör-Industrie 1944, Jane's fighting aircraft of World War II, Jane's all the World's Aircraft 1938

### General characteristics

* Type: 60° V-8, inverted air-cooled piston engine
* Bore: 105 mm (4.13 in)
* Stroke: 115 mm (4.53 in)
* Displacement: 7.96 L (486 cu in)
* Length: 1,292 mm (50.87 in)
* Width: 683 mm (26.89 in)
* Height: 815 mm (32.09 in)
* Dry weight: 222 kg (489 lb) dry, unequipped

             241 kg (531 lb) wet, equipped

### Components

* Valvetrain: 1 inlet and 1 exhaust under-valve per cylinder driven by pushrods and rockers
* Supercharger: Centrifugal supercharger geared at 4.47:1 crankshaft speed
* Fuel system: 2x Pallas-Zenith 65 VAH2 carbutettors
* Fuel type: 87 Octane gasoline
* Oil system: Pressure system for crankshaft, pistons and reduction gear at 1.5–2.5 atm (22.04–36.74 psi; 1.52–2.53 bar): splash lubrication for camshaft and supercharger
* Cooling system: Air-cooled
* 1x Double Bosch magneto

### Performance

* Power output:

   * 280 PS (276 hp; 206 kW) at 3,000 rpm (5 minutes) at sea level

   * 258 PS (254 hp; 190 kW) at 2,920 rpm (30 minutes) at sea level

   * 225 PS (222 hp; 165 kW) at 2,790 rpm (max. continuous) at sea level
* 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: 0.005 kg/PSh (0.011 lb/(hp⋅h); 0.007 kg/kWh) at max continuous
* Power-to-weight ratio: 1.266 PS/kg (0.566 hp/lb; 0.931 kW/kg)
* B.M.E.P.: 10.2 atm (10.3 bar; 150 psi)
* Reduction gear: Stoekicht sun and planet gears 0.666:1
