Mitsubishi Astron engine
Mitsubishi G54B engine
ManufacturerMitsubishi Motors
Also called4G5/4D5
Displacement1.9–2.6 L (1,850–2,555 cc)
Cylinder bore84 mm (3.31 in)
88 mm (3.46 in)
91.1 mm (3.59 in)
Piston stroke90 mm (3.54 in)
95 mm (3.74 in)
98 mm (3.86 in)
ValvetrainSOHC 2 valves x cyl.
Compression ratio8.8:1-21.0:1
TurbochargerTD04, TD05 or TF035HL2 variable geometry with intercooler (on some versions)
Fuel systemCarburetor
Multi-point fuel injection
Throttle-body fuel injection
Indirect injection
Common rail Direct Injection
Fuel typeGasoline, Diesel
Cooling systemWater-cooled
Power output46–178 PS (34–131 kW)
Torque output137–400 N⋅m (101–295 lb⋅ft)
SuccessorSirius 4G64

The Mitsubishi Astron or 4G5/4D5 engine, is a series of straight-four 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 licensed this technology.

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passenger car, it proved popular in the emerging SUV and minivan markets where Mitsubishi was highly successful, until superseded by the 4M4 range in 1993.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 (1.85 liters)

The 4G51 displaces 1.9 L (1,850 cc).


4G52 (2.0 liters)

The 4G52 displaces 2.0 L (1,995 cc). Peak power for a 1975 Canter is 100 PS (74 kW), but power increased to as much as 125 PS (92 kW) for the twin-carb version fitted to the Galant GTO GSR and A115 Galant GS-II.

Used an 84 mm × 90 mm (3.31 in × 3.54 in) bore and stroke. In Australia this engine was used in the Sigma, Scorpion and L200.


4G53 (2.4 liters)

The SOHC eight-valve 4G53 displaces 2.4 L (2,384 cc), with bore & stroke at 88 mm × 98 mm (3.46 in × 3.86 in). Peak power is 110 PS (81 kW) at 5000 rpm,[3] as fitted to the Rosa bus or the Canter cabover truck. This engine shares its dimensions with the contemporary Fuso 4DR1 diesel engine.


4G54 (2.6 liters)

The SOHC eight-valve 4G54 (also known as the G54B) displaces 2.6 L (2,555 cc), with bore & stroke at 91.1 mm × 98 mm (3.59 in × 3.86 in). The G54B for the US market had a cylinder head with additional jet valves to improve emissions (MCA-Jet system). The engine was fitted to various Mitsubishi models from 1978 to 1997 and to the American Chrysler K-cars and their derivatives between 1981 and 1987. It was primarily set up longitudinally for use in rear-wheel drive and all-wheel drive platforms but also as a transverse engine in the front-wheel drive platform of the Mitsubishi Magna and Chrysler K platform. Chrysler commonly marketed the engine "Hemi," whereas the Australian-made version was marketed as the "Astron II" and featured "Balance Shaft" technology, which was subsequently licensed to Porsche and other automakers. The original engine featured a Mikuni two-barrel carburetor with a secondary vacuum actuator; later versions adopted EFI. Chrysler commonly paired this engine with its A470 3-speed automatic transmission; in Australia, Mitsubishi adapted it to a 5-speed manual transmission and its "ELC" (Electronic Control) 4-speed automatic transmission, featuring electronic overdrive. Chrysler eventually replaced the 4G54 with its own 2.5 L engine, whereas Mitsubishi replaced it with a 2.4 L engine codenamed 4G64.



Multi-point fuel injection


Single two-Venturi downdraught carburetor. 85 kW (114 hp) at 5000 rpm (91 RON), 198 N⋅m (146 lb⋅ft) at 3000 rpm (91 RON). Compression ratio: 8.8:1


4G55 (2.3 liters)

The 4G55 displaces 2.3 L (2,346 cc).

4D55 (2.3 liters diesel)

Displacement - 2.3 L (2,346 cc)
Bore x Stroke - 91.1 mm × 90 mm (3.59 in × 3.54 in)
Fuel Type - Diesel
Valves per cylinder - 2[6][7][8]


48 kW (65 hp) at 4200 rpm (SAE)
137 N⋅m (101 lb⋅ft) at 2000 rpm (SAE)

Turbo (TC05 non-wastegated turbo)

Turbo (TD04 wastegated turbo)

62 kW (84 PS) at 4200 rpm (DIN)[9]
64 kW (86 hp) at 4200 rpm (SAE)
175 N⋅m (129 lb⋅ft) at 2500 rpm (DIN)
182 N⋅m (134 lb⋅ft) at 2000 rpm (SAE)

4D56 (2.5 liters diesel)

Turbocharged and intercooled 4D56 engine in a 1991 Mitsubishi Pajero

Displacement - 2.5 L (2,477 cc)
Bore x Stroke - 91.1 mm × 95 mm (3.59 in × 3.74 in)
Fuel type - DIESEL

This engine is also built by Hyundai in South Korea, meaning it also sees use in some products made by their Kia subsidiary. Hyundai calls it the D4BA/D4BX (normally aspirated), D4BF (non-intercooled turbo), D4BH (intercooled turbo) .


Non-intercooled Turbo

Intercooled Turbo (TD04 Turbo)

Intercooled Turbo (TD04 water-cooled Turbo)

Also known as Hyundai D4BH[14]

Intercooled Turbo TF035HL2 (1st Generation DI-D)

Intercooled Turbo (2nd Generation DI-D)

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

With manual transmission

With automatic transmission

See also


  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. ^ a b Takayoshi, Seiji (高吉 誠司), ed. (2011-03-17), "トラックメーカーアーカイブ vol.2: 三菱ふそうのすべて [Truck Manufacturer Archive Volume 2: Everything Mitsubishi Fuso]", Camion (in Japanese), Tokyo, Japan: Geibun Mooks, no. 780, p. 65, ISBN 978-4-86396-112-8
  3. ^ Rosa (Brochure), Mitsubishi Motors Corporation, 1979, p. 8,
  4. ^ 自動車ガイドブック [Automobile Guide Book 1976/1977] (in Japanese), vol. 23, Japan: Japan Automobile Manufacturers Association, 1976-10-20, p. 286, 0053-760023-3400
  5. ^ Rohrbach, Hans U., ed. (1982), Internationaler Nutzfahrzeug-Katalog (Inufa) 1982 [International Commercial Vehicle Catalog] (in German), vol. 24, Solothurn, Switzerland: Vogt-Schild AG, pp. 104, 107
  6. ^ a b 1984 Mitsubishi Trucks Brochure
  7. ^ a b 1985 Mitsubishi Trucks Brochure
  8. ^ a b 1987 Ford Ranger Brochure
  9. ^ a b c Büschi, Hans-Ulrich, ed. (March 10, 1983). Automobil Revue '83 (in German and French). Vol. 78. Berne, Switzerland: Hallwag, AG. p. 388. ISBN 3-444-06065-3.
  10. ^ 1983 Mitsubishi Trucks Brochure
  11. ^ Heitz, Rudolf, ed. (1987). Auto Katalog 1988 (in German). Vol. 31. Stuttgart: Vereinigte Motor-Verlage GmbH & Co. KG. p. 202.
  12. ^ a b c "Thailand's top new 2009 2008 2007 2006 Mitsubishi Triton L200 exporter dealer 4x4 : top Mitsubishi used second hand car exporter : Exporter of New and Used L200 : World 4x4 Dealer and 4x4 Exporter". Jim 4x4. Retrieved 2012-01-27.
  13. ^ - Mitsubishi 4D56 Service Manual
  14. ^ "Hyundai Auto Tech, Inc".
  15. ^ a b "2009 2008 Mitsubishi Triton L200 Thailand Exporter export import on sale rhd lhd new used second hand 4x4 pickup SUV Soni Motors Thailand and Dubai's Top LHD Mitsubishi Triton exporter : Soni Motors Dubai -world's largest largest new Mitsubishi dealer and top used Mitsubishi dealer and exporter. Also top Toyota Vigo and Nissan Navara exporter". Retrieved 2012-01-27.
  16. ^ a b "Mike 4x4 Thailand - Thailand's Leading Used 4x4 Exporter - Selling Toyota Vigo, Mitsubishi Triton and Nissan Navara". Archived from the original on 2012-03-10. Retrieved 2012-01-27.
  17. ^ "StartLogic". Archived from the original on 2012-03-10. Retrieved 2012-01-27.
  18. ^ a b , Mitsubishi L200 (UK website)