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passenger car, it proved popular in the emerging SUV and minivan markets where Mitsubishi was highly successful, until superseded by the 4M4 range in 1993.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

Contents

4G51

The 4G51 displaces 1.85 L (1,850 cc).

Applications:

4G52

The 4G52 displaces 2.0 L (1,995 cc).

Applications:

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

Carburetor

Single two-Venturi downdraught carburetor

Applications:

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

48 kW (65 hp) at 4,200 rpm (SAE)
137 N·m (101 ft·lb) at 2,000 rpm (SAE)

Turbo (TC05 non-wastegated turbo)

Turbo (TD04 wastegated turbo)

62 kW (84 PS) at 4,200 rpm (DIN)[6]
64 kW (86 hp) at 4,200 rpm (SAE)
175 N·m (129 ft·lb) at 2,500 rpm (DIN)
182 N·m (134 ft·lb) at 2,000 rpm (SAE)

4D56

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

Non-Turbo

Non-intercooled Turbo (TD04 Turbo)

Intercooled Turbo (TD04 watercooled Turbo)

Intercooled Turbo (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

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)
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