Mitsubishi Neptune engine

The Mitsubishi Neptune or 4G4 engine is a series of iron-block OHV inline-four engines built by Mitsubishi Motors from June 1971 to 1981.^[1] This was to be Mitsubishi's last OHV engine. The inability to clear new passenger car emissions rules for 1978 meant that the Neptunes were replaced by the 4G1 Orion. The Neptune continued to be built until 1979 for commercial vehicles, which suffered less restrictive environmental regulations and until about 1981 for other applications. Around 520,000 Neptune engines were built.^[1]

Neptune engine
Overview
Manufacturer	Mitsubishi Motors
Also called	4G4
Production	1971–1981
Layout
Configuration	Inline-4
Displacement	1.2–1.4 L (1,188–1,378 cc)
Cylinder bore	71 mm (2.8 in) 76.5 mm (3.01 in)
Piston stroke	75 mm (2.95 in)
Cylinder block material	Cast iron
Valvetrain	OHV 2 valves x cyl.
Compression ratio	9.0:1
Combustion
Fuel type	Gasoline
Cooling system	Water-cooled
Output
Power output	70–87 PS (51–64 kW; 69–86 hp)
Torque output	9.7–11.7 kg⋅m (95–115 N⋅m; 70–85 lb⋅ft)
Chronology
Predecessor	KE engine
Successor	4G1 Orion

4G41

Displacement — 1.4 L (1,378 cc)
Bore x Stroke — 76.5 mm × 75 mm (3.01 in × 2.95 in)
Power — 86 PS (63 kW; 85 hp) at 6,000 rpm (single carb)

95 PS (70 kW; 94 hp) at 6,300 rpm (Galant FTO, twin carb)

28 PS (21 kW; 28 hp) at 2,700 rpm in a 1972 FG15 forklift^[2]

Torque — 11.7 kg⋅m (115 N⋅m; 85 lb⋅ft) at 4,000 rpm (single carb)

8.6 kg⋅m (84 N⋅m; 62 lb⋅ft) at 2,000 rpm in a 1972 FG15 forklift^[2]

Applications

• Mitsubishi Galant
• 1971-1973 Mitsubishi Galant FTO
• 1971.10-1979.06 Mitsubishi Delica 75/1400^[3]
• Mitsubishi Forklift FG14, FG15

4G42

Displacement — 1.2 L (1,188 cc)^[4]
Bore x Stroke — 71 mm × 75 mm (2.80 in × 2.95 in)
Power — 70 PS (51 kW; 69 hp) SAE at 6,000 rpm
Torque — 9.7 kg⋅m (95 N⋅m; 70 lb⋅ft) at 4,000 rpm

Applications

• 1973.02-1975.10 Mitsubishi Lancer A71A^[4]
• 1973.09-1976.10 Mitsubishi Lancer Van A71V

See also

• List of Mitsubishi engines