ABC Gnat

The ABC Gnat was a 45 hp (34 kW) flat, two-cylinder aero engine designed by British engineer Granville Bradshaw for use in light aircraft. The Gnat was built by ABC Motors, first running in 1916, production ceased in December 1918. 17 engines were built from an original order of 18.

Applications:
BAT Crow
Blackburn Sidecar
Eastchurch Kitten
Grain Kitten
Macchi M.16G
Sopwith Sparrow
Sopwith Tadpole

Specifications:

Gnat I
Type: 2-cylinder air-cooled flat-twin
Bore: 4.33 in (110 mm)
Stroke: 4.72 in (120 mm)
Displacement: 139.06 cu in (2.28 L)
Dry weight: 115 lb (52 kg)
Valvetrain: Overhead valve, two valves per cylinder
Fuel system: Single A.B.C. carburettor
Fuel type: Petrol (40-50 Octane rating)
Cooling system: Air-cooled
Power output: 45 hp (34 kW) at 1,920 rpm (takeoff power)
Specific power: 0.32 hp/cu in (14.9 kW/L)
Compression ratio: 3.8:1
Power-to-weight ratio: 0.4 hp/lb (0.6 kW/kg)