Mitsubishi Astron engine

4G5

Manufacturer	Mitsubishi Motors
Also called	Astron
Production	1972–present

The Mitsubishi Astron or 4G5 engine, is a series of straight-4 internal combustion engines first built by Mitsubishi Motors in 1972. Engine displacement ranged from 1.8 to 2.6 litres, making it one of the largest four-cylinder engines of its time.

It employed a hemispherical cylinder head, chain-driven single overhead camshaft (SOHC) and eight valves (two per cylinder). United States passenger car versions had a small secondary intake valve referred to as the "Jet Valve". This valve induced swirl in the intake charge, enabling the use of leaner fuel/air mixtures for lower emissions. It was designed as a cartridge containing the valve spring and seat which simply screwed into a threaded hole in the head, similar to a spark plug but inside the cam cover. The rocker arms for the intake valve were widened on the valve end to accommodate the cartridge, which was equipped with a very soft valve spring in order to avoid wear on the camshaft intake lobe. Modifications to the head were thereby reduced as the Jet Valve negated the necessity for a three valve per cylinder design.^[1]

In 1975, the Astron 80 introduced a system dubbed "Silent Shaft": the first use of twin balance shafts in a modern engine. It followed the designs of Frederick Lanchester, whose original patents Mitsubishi had obtained, and proved influential as Fiat/Lancia, Saab and Porsche all licenced this technology.^[2]

The 4D5 engine is a range of four-cylinder belt-driven overhead camshaft diesel engines which were part of the "Astron" family, and introduced in 1980 in the then new fifth generation Galant. As the first turbodiesel to be offered in a Japanese passenger car, it proved popular in the emerging SUV and minivan markets where Mitsubishi was highly successful, until superseded by the 4M4 range in 1993. However, production of the 4D5 (4D56) continued throughout the 1990s as a lower-cost option than the more modern powerplants. Until now it is still in production, but made into a modern powerplant by putting a common rail direct injection fuel system into the engine.

4G51

The 4G51 displaces 1.85 L (1,850 cc).

Applications:

• 1973-1977 Mitsubishi Galant
• 1973-1975 Dodge Colt
• 1973-1975 Chrysler Galant
• 1977-1980 Chrysler Sigma

4G52

The 4G52 displaces 2.0 L (1,995 cc).

Applications:

• 1972-1975 Mitsubishi Galant GTO
• 1979-1989 Dodge Ram 50
• 1973-1987 Mitsubishi Sigma
• 1986-present Mitsubishi L300
• 1977-1981 Mitsubishi Celeste

4G54

The SOHC 8-valve 4G54 (also known as the G54B) displaces 2.6 L (2,555 cc), with bore × stroke at 91.1 mm × 98.0 mm. The G54B had heads with additional jet valves to improve emissions (MCA-Jet system). It was designed for longitudinal use in rear-wheel drive and all-wheel drive vehicles. It was equipped with a Hitachi two-barrel carburetor with a vacuum-operated progressive secondary, except for the turbocharged version and a version used in Australian Mitsubishi Magnas, which used fuel injection. This engine was also used on Chrysler's front-wheel drive K-cars and their derivatives from 1981 until 1987, when it was replaced by Chrysler's own 2.5 L engine. This engine was commonly paired with Chrysler's A470 3-speed automatic transmission on Chrysler vehicles. Chrysler sometimes marketed this engine as a "Hemi".

Specifications:

ECI-Multi

Multi-Point Fuel Injection

• 98 kW (131 hp) at 4,750 rpm (91 RON)
• 102 kW (137 hp) at 4,750 rpm (95 RON)
• 212 N·m (156 ft·lb) at 3,750 rpm (91 RON)
• 220 N·m (160 ft·lb) at 4,000 rpm (95 RON)
• Compression ratio: 9.2:1

Carburetor

Single two-Venturi downdraught carburetor

• 85 kW (114 hp) at 5,000 rpm (91 RON)
• 198 N·m (146 ft·lb) at 3,000 rpm (91 RON)
• Compression ratio: 8.8:1

Applications:

• 1978-1980 Plymouth Fire Arrow
• 1978-1983 Dodge Challenger/Mitsubishi Sapporo/Plymouth Sapporo
• 1978-1987 Mitsubishi Sigma
• 1979-1989 Dodge Ram 50
• 1981-1985 Dodge Aries/Plymouth Reliant
• 1982-1985 Chrysler LeBaron
• 1982-1985 Chrysler Town and Country
• 1982-1991 Mitsubishi Pajero
• 1982-1983 Dodge 400
• 1983-1984 Chrysler E-Class
• 1983-1985 Chrysler New Yorker/Dodge 600
• 1984-1987 Dodge Caravan/Plymouth Voyager
• 1982-1990 Mitsubishi Starion (turbocharger and fuel injection)
• 1984-1986 Dodge Conquest/Plymouth Conquest
• 1985 Plymouth Caravelle
• 1985-1996 Mitsubishi Magna (early carbureted, later EFI)
• 1986-1988 Mazda B2600
• 1987-1989 Chrysler Conquest
• 1987-1989 Dodge Raider
• 1991-1997 Mitsubishi Pajero China market version

4G55

The 4G55 displaces 2.3 L (2,346 cc).

4D55

Displacement - 2.3 L (2,346 cc)
Bore - 91.1 mm
Stroke - 90.0 mm
Fuel Type - Diesel
Valves per cylinder - 2^[3][4][5]

Non-Turbo

• Power - 55 kW (75 PS) at 4,200 rpm (JIS)^[6]

48 kW (65 hp) at 4,200 rpm (SAE)

• Torque - 147 N·m (108 ft·lb) at 2,500 rpm (JIS)

137 N·m (101 ft·lb) at 2,000 rpm (SAE)

• Engine type - Inline 4 cylinder SOHC
• Compression ratio - 21:1 (384 P.S.I. )

• Applications

• 1980-1983 Mitsubishi Galant Σ/Eterna Σ
• 1982-1986 Mitsubishi Pajero
• 1982-1986 Mitsubishi Delica/L300

Turbo (TC05 non-wastegated turbo)

• Power - 60 kW (80 hp) at 4,000 rpm (SAE)
• Torque - 169 N·m (125 ft·lb) at 2,000 rpm (SAE)
• Engine type - Inline 4 cylinder SOHC
• Compression ratio - 21:1 (384 psi)^[7]

• Applications - 1980-1983

Turbo (TD04 wastegated turbo)

• Power - 70 kW (95 PS) at 4,200 rpm (JIS)^[6]

62 kW (84 PS) at 4,200 rpm (DIN)^[6]

64 kW (86 hp) at 4,200 rpm (SAE)

• Torque - 181 N·m (133 ft·lb) at 2,500 rpm (JIS)

175 N·m (129 ft·lb) at 2,500 rpm (DIN)

182 N·m (134 ft·lb) at 2,000 rpm (SAE)

• Engine type - Inline 4 cylinder SOHC
• Compression ratio - 21:1 (384 psi)^[3][4][5]

• Applications:

• 1980-1983 Mitsubishi Galant Σ/Eterna Σ
• 1980-1984 Mitsubishi Galant Λ/Eterna Λ
• 1982-1986 Mitsubishi Pajero
• 1985-1987 Ford Ranger
• 1983-1985 Dodge Ram 50

4D56

Displacement - 2.5 L (2,476 cc)
Bore - 91.1 mm
Stroke - 95.0 mm
Fuel type - Diesel

Non-Turbo

• Power - 51 kW (68 hp) at 4,200 rpm
• Torque - 142 N·m (105 ft·lb) at 2,500 rpm
• Engine type - Inline 4 cylinder SOHC
• Fuel system - Distribution type jet pump
• Compression ratio - 21:1

Non-intercooled Turbo (TD04 Turbo)

• Power - 90 hp (67 kW) at 4,200 rpm
• Torque - 197 N·m (145 ft·lb) at 2,000 rpm
• Engine type - Inline 4 cylinder SOHC
• Fuel system - Distribution type jet pump
• Compression ratio - 21:1^[8]

Intercooled Turbo (TD04 watercooled Turbo)

• Power - 78 kW (104 hp) at 4,200 rpm
• Torque - 240 N·m (177 ft·lb) at 2,000 rpm
• Engine type - Inline 4 cylinder SOHC
• Rocker arm - Roller Follower type^[9]
• Fuel system - Distribution type jet pump (indirect injection)
• Combustion chamber - Swirl type
• Bore x Stroke - 91.1 x 95mm
• Compression ratio - 21:1
• Lubrication System - Pressure feed, full flow filtration

Intercooled Turbo (1st Generation DI-D)

• Power - 85 kW (114 hp) at 4,000 rpm
• Torque - 247 N·m (182 ft·lb) at 2,000 rpm
• Engine type - Inline 4 cylinder
• Fuel system - 1st Generation Common Rail Direct Injection (CRDi)
• Compression ratio - 17:1^[10][11][12]

Intercooled Turbo (2nd Generation DI-D)

• Power - 104 kW (139 hp) at 4,000 rpm
• Torque - 320 N·m (236 ft·lb) at 2,000 rpm
• Engine type - Inline 4 cylinder
• Fuel system - 2nd Generation Common Rail Direct Injection (CRDi)
• Compression ratio - 17:1^{[13][14][15][16]}

Intercooled Turbo (3rd Generation DI-D with variable geometry turbo)

With manual transmission

• Power - 131 kW (178 PS) at 4,000 rpm
• Torque - 400 N·m (295 ft·lb) at 2,000 rpm
• Engine type - Inline 4 cylinder
• Fuel system - 2nd Generation Common Rail Direct Injection (CRDi)
• Compression ratio - 16.5:1^[17]

With automatic transmission

• Power - 131 kW (178 PS) at 4,000 rpm
• Torque - 350 N·m (258 ft·lb) at 1,800 rpm
• Engine type - Inline 4 cylinder
• Fuel system - 2nd Generation Common Rail Direct Injection (CRDi)
• Compression ratio - 16.5:1^[18]

See also

List of Mitsubishi engines

References

1. ^ "Development of a New Combustion System (MCA-JET) in Gasoline Engine", Hirokazu Nakamura, Tsuneo Ohinouye, Kenji Hori, Yuhiko Kiyota, Tatsuro Nakagami, Katsuo Akishino, Yutaka Tsukamoto, SAE International, February 1978
2. ^ "Engine Smoothness", Mark Wan, AutoZine Technical School, 1998–2000
3. ^ ^{a b} 1984 Mitsubishi Trucks Brochure
4. ^ ^{a b} 1985 Mitsubishi Trucks Brochure
5. ^ ^{a b} 1987 Ford Ranger Brochure
6. ^ ^{a b c} Büschi, Hans-Ulrich, ed (March 10, 1983) (in German/French). Automobil Revue '83. 78. Berne, Switzerland: Hallwag, AG. p. 388. ISBN 3-444-06065-3. 
7. ^ 1983 Mitsubishi Trucks Brochure
8. ^ http://www.jim4x4.com/triton.html
9. ^ http://www.mitsubishilinks.com/fsm/pajero_fsm_printed-1990_engine_4D56-25-diesel.pdf - Mitsubishi 4D56 Service Manual
10. ^ http://www.jim4x4.com/triton.html
11. ^ http://samautogroup.com/triton.html
12. ^ http://www.mike4x4.com/triton.html
13. ^ http://www.jim4x4.com/triton.html
14. ^ http://www.unlawyer.net/?p=1699
15. ^ http://samautogroup.com/triton.html
16. ^ http://www.mike4x4.com/triton.html
17. ^ http://www.mitsubishi-cars.co.uk/l200/ , Mitsubishi L200 (UK website)
18. ^ http://www.mitsubishi-cars.co.uk/l200/ , Mitsubishi L200 (UK website)