Mitsubishi Astron engine
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| 4G5 | |
|---|---|
| Manufacturer | Mitsubishi Motors |
| Also called: | Astron |
| Type: | Four cylinder |
| 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.
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.[1]
The 4D5 engine is a range of four cylinder 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passenger car, it proved popular in the emerging SUV and minivan markets where Mitsubishi was highly successful, until superseded by the 4M4 range in 1993.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.
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[edit] 4G51
The 4G51 displaces 1.85 L (1850 cc).
Applications:
- 1973-1977 Mitsubishi Galant
- 1973-1975 Dodge Colt
- 1973-1975 Chrysler Galant
[edit] 4G52
The 4G52 displaces 2.0 L (1995 cc).
Applications:
- 1972-1975 Mitsubishi Galant GTO
- 1979-1989 Dodge Ram 50
- 1973-1987 Mitsubishi Sigma
- 1986-present Mitsubishi L300
[edit] 4G54
The SOHC 8-valve 4G54 (also known as the G54B) displaces 2.6 L (2555 cc), with bore x stroke at 91.1 mm x 98.0 mm. Some had heads with additional jet valves to improve emissions. It was designed for longitudinal use in rear-wheel drive and all-wheel drive vehicles. It was equipped with a Hitachi 2-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 2.5 L engine. This engine was commonly paired with Chrysler's A470 3-speed automatic transmission on Chrysler vehicles.
Specifications:
[edit] ECI-Multi
Multi-Point Fuel Injection
- 98 kw (131 hp) at 4750 rpm (91 RON)
- 102 kw (138 hp) at 4750 rpm (95 RON)
- 212 nm (156 lb-ft) at 3750 rpm (91 RON)
- 220 nm (162 lb-ft) at 4000 rpm (95 RON)
- Compression ratio: 9.2:1
[edit] Carburetor
Single two-Venturi downdraught carburetor
- 85 kw (114 hp) at 5000 rpm (91 RON)
- 198 nm (146 lb-ft) at 3000 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
[edit] 4G55
The 4G55 displaces 2.3 L (2346 cc).
[edit] 4D55
Displacement - 2346 cc
Bore - 91.1mm
Stroke - 90
Fuel type - Diesel
[edit] Turbo
- Power - 62 kW (84 PS) at 4000 rpm
- Torque - 175 N·m (129 ft·lbf) at 2000 rpm
- Engine type - Inline 4 cylinder SOHC
- Fuel system - Diesel
- Compression ratio - 21:1 (384 P.S.I.)
[edit] 4D56
Displacement - 2476 cc
Bore - 91.1 mm
Stroke - 95.0 mm
Fuel type - Diesel
[edit] Non-Turbo
- Power - 51 kW (73 PS) at 4200 rpm
- Torque - 143 N·m (105 ft·lbf) at 2500 rpm
- Engine type - Inline 4 cylinder SOHC
- Fuel system - Distribution type jet pump
- Compression ratio - 21:1
[edit] Turbo
- Power - 63 kW (85 PS) at 4000 rpm
- Torque - 196 N·m (145 ft·lbf) at 2000 rpm
- Engine type - Inline 4 cylinder SOHC
- Fuel system - Distribution type jet pump
- Compression ratio - 21:1
[edit] Intercooled turbo
- Power - 77 kW (105 PS) at 4000 rpm
- Torque - 240 N·m (177 ft·lbf) at 2000 rpm
- Engine type - Inline 4 cylinder SOHC
- Fuel system - Distributor type injection pump
- Compression ratio - 21:1
[edit] Common rail intercooled turbo
- Power - 99 kW (134 PS) at 4000 rpm
- Torque - 314 N·m (232 ft·lbf) at 2000 rpm
- Engine type - Inline 4 cylinder DOHC
- Fuel system - Common rail direct injection
- Compression ratio - 17:1
Applications:
- 2005-present Mitsubishi Triton/L200/Strada
[edit] See also
[edit] References
- ^ "Engine Smoothness", Mark Wan, AutoZine Technical School, 1998–2000
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