Mitsubishi 3G8 engine

The Mitsubishi 3G8 engine is a range of three-cylinder powerplant from Mitsubishi Motors, introduced in the fifth generation of their Mitsubishi Minica kei car. In common with other contemporary engines in the class, it could be specified with many advanced technologies despite its diminutive size, including multi-valve cylinder heads and double overhead camshafts. The top-of-the-line Dangan ZZ variant was also the first kei car to benefit from turbocharging. In 1987 Mitsubishi was the first manufacturer to supercharge a kei vehicle, and in 1989 became the world's first production car to feature five valves per cylinder, ahead of similar developments by Bugatti, Audi, Ferrari and Toyota.[1][2]

Mitsubishi 3G8 engine
Overview
ManufacturerMitsubishi Motors
Production1987–present
Layout
ConfigurationStraight-3
Displacement548 cc (33.4 cu in)
657 cc (40.1 cu in)
796 cc (48.6 cu in)
1,061 cc (64.7 cu in)
Cylinder bore
  • 62.3 mm (2.45 in)
  • 65 mm (2.56 in)
Piston stroke
  • 60 mm (2.36 in)
  • 66 mm (2.60 in)
  • 80 mm (3.15 in)
Block materialCast iron
ValvetrainSOHC, DOHC
Compression ratio8.5:1, 9.8:1, 10.0:1
Combustion
SuperchargerOn 1987-1990 models
Turbochargerwith air-to-air intercooler (on 1989-1990 models)
Fuel systemCarburetor
Electronic fuel injection
Fuel typeGasoline
Cooling systemWater cooled
Output
Power output22–47 kW (30–64 PS; 30–63 hp)
Torque output41–89 N⋅m (30–66 lb⋅ft)

Its 3G81 three-cylinder engine has a displacement of 548 cc (33.4 cu in) and features three intake valves and two exhaust valves incorporated into each cylinder. The valves are controlled by twin overhead camshafts through roller cam followers on finger rockers with hydraulic automatic lash adjusters. Gasoline is electronically injected through triple-jet nozzles (also a technological first). The water-cooled turbocharger operates through an air-to-air intercooler. The ignition timing advance is also controlled electronically, and a knock-sensing system is included.[1]

Originally a 550 cc (34 cu in) engine, it was enlarged to 660 cc (40 cu in) in 1990 following changes in the class regulations. The four-cylinder 4A3 engine is derived from the 3G8, sharing its 72 mm (2.8 in) bore pitch.[3]

3G81

Displacement — 548 cc (33.4 cu in)
Bore — 62.3 mm (2.45 in)
Stroke — 60 mm (2.36 in)
Fuel type — Unleaded regular gasoline

Single carb (1987)
  • Engine type — Inline three-cylinder SOHC
  • Compression ratio — 9.8:1
  • Fuel system — Single down-draft carburettor
  • Power — 22 kW (30 PS; 30 hp) at 6500 rpm
  • Torque — 41 N⋅m (30 lb⋅ft) at 3000 rpm

Single carb Supercharger (1987-1990)
  • Engine type — Inline three-cylinder SOHC
  • Compression ratio — 8.5:1
  • Fuel system — Single side draft carburetor with supercharger.

Double carb (1989)
  • Engine type — Inline three-cylinder SOHC
  • Compression ratio — 9.8:1
  • Fuel system — two-barrel down-draft carburettor
  • Power — 24 kW (33 PS; 32 hp) at 6500 rpm
  • Torque — 42 N⋅m (31 lb⋅ft) at 4000 rpm

DOHC (1989)
  • Engine type — Inline three-cylinder DOHC 15-valve
  • Compression ratio — 10.0:1
  • Fuel system — ECI multiple
  • Power — 34 kW (46 PS; 46 hp) at 7500 rpm
  • Torque — 46 N⋅m (34 lb⋅ft) at 5500 rpm

Turbo (1989)
  • Engine type — Inline three-cylinder DOHC 15-valve intercooled turbo
  • Compression ratio — 8.5:1
  • Fuel system — ECI multiple
  • Power — 47 kW (64 PS; 63 hp) at 7500 rpm
  • Torque — 75 N⋅m (55 lb⋅ft) at 4500 rpm

3G82

Displacement — 796 cc (48.6 cu in)
Bore — 65 mm (2.56 in)
Stroke — 80 mm (3.15 in)
Engine type — Inline three-cylinder SOHC 6 valves
Power — 33 kW (45 PS; 44 hp) at unknown rpm

This was built only for the Taiwanese market Mitsubishi Towny (Minica) and Minicab 800, from 01.87 - 11.88. Most specifications are unknown.

3G83

Displacement — 657 cc (40.1 cu in)
Bore — 65 mm (2.56 in)
Stroke — 66 mm (2.6 in)
Fuel type — Unleaded regular gasoline

Double carb (1990)
  • Engine type — Inline three-cylinder SOHC
  • Power — 29 kW (39 PS; 39 hp) at 6000 rpm
  • Torque — 51 N⋅m (38 lb⋅ft) at 4000 rpm
  • Fuel system — two-barrel down-draft carburettor
  • Compression ratio — 9.8:1

DOHC (1990)
  • Engine type — Inline three-cylinder DOHC
  • Compression ratio — 9.8:4
  • Fuel system — ECI multiple
  • Power — 38 kW (52 PS; 51 hp) at 7500 rpm
  • Torque — 56 N⋅m (41 lb⋅ft) at 5700 rpm

Turbo (1990)
  • Engine type — Inline three-cylinder DOHC 15-valve intercooled turbo
  • Compression ratio — 8.5:1
  • Fuel system — ECI multiple
  • Power — 47 kW (64 PS; 63 hp) at 7,500 rpm
  • Torque — 96 N⋅m (71 lb⋅ft) at 4,500 rpm

4G82

Displacement — 1,061 cc (64.7 cu in)
Bore — 65 mm (2.56 in)
Stroke — 80 mm (3.15 in)
Engine type — Inline four-cylinder SOHC
Power — 43 kW (58 PS; 58 hp) JIS at 5,500 rpm
Torque — 9.1 kg⋅m (89 N⋅m; 66 lb⋅ft) at 3,500 rpm[4]

Of the same dimensions as the 3G82 but with a fourth cylinder, this was built in Taiwan by CMC (China Motor Corporation). Used in the Mitsubishi Varica (LWB version of fourth generation Mitsubishi Minicab).

See also

References
  1. "A baby that sprints: tiny Mitsubishi engine blasts off with five valves". Ward's Auto World (April 1989).
  2. "Mighty Minica ZZ-4" Archived 2012-12-30 at Archive.today, Michael Knowling, Autospeed, issue 353, October 19, 2005
  3. "軽自動車用の4気筒エンジン" [Kei four-cylinder engines]. a-design-for-life (in Japanese). 2014-09-27. Archived from the original on 2019-07-08.
  4. Mitsubishi Varica New Tone 1100 (catalog). Old Car Manual Project. 1991. Retrieved 2010-10-12.
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