The Mitsubishi Astron or 4G5 engine, is a series of straight-4

Straight-4

The inline-four engine or straight-four engine is an internal combustion engine with all four cylinders mounted in a straight line, or plane along the crankcase. The single bank of cylinders may be oriented in either a vertical or an inclined plane with all the pistons driving a common crankshaft....

 internal combustion engine

Internal combustion engine

The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

s first built by Mitsubishi Motors

Mitsubishi Motors

is a multinational automaker headquartered in Minato, Tokyo. In 2009 it was the fifth-largest Japan-based automaker and the 17th-largest in the world measured by production...

 in 1972. Engine displacement

Engine displacement

Engine displacement is the volume swept by all the pistons inside the cylinders of an internal combustion engine in a single movement from top dead centre to bottom dead centre . It is commonly specified in cubic centimeters , litres , or cubic inches...

 ranged from 1.8 to 2.6 litre

Litre

pic|200px|right|thumb|One litre is equivalent to this cubeEach side is 10 cm1 litre water = 1 kilogram water The litre is a metric system unit of volume equal to 1 cubic decimetre , to 1,000 cubic centimetres , and to 1/1,000 cubic metre...

s, making it one of the largest four-cylinder engines of its time.

It employed a hemispherical cylinder head

Cylinder head

In an internal combustion engine, the cylinder head sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This joint is sealed by a head gasket...

, chain

Roller chain

Roller chain or bush roller chain is the type of chain drive most commonly used for transmission of mechanical power on many kinds of domestic, industrial and agricultural machinery, including conveyors, wire and tube drawing machines, printing presses, cars, motorcycles, and simple machines like...

-driven single overhead camshaft (SOHC) and eight valves

Poppet valve

A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. The shaft guides the plug portion by sliding through a valve guide...

 (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

Spark plug

A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed fuels such as aerosol, gasoline, ethanol, and liquefied petroleum gas by means of an electric spark.Spark plugs have an insulated central electrode which is connected by...

 but inside the cam cover. The rocker arm

Rocker arm

Generally referred to within the internal combustion engine of automotive, marine, motorcycle and reciprocating aviation engines, the rocker arm is a reciprocating lever that conveys radial movement from the cam lobe into linear movement at the poppet valve to open it...

s 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 shaft

Balance shaft

In piston engine engineering, a balance shaft is an eccentric weighted shaft which offsets vibrations in engine designs that are not inherently balanced...

s in a modern engine. It followed the designs of Frederick Lanchester

Frederick Lanchester

Frederick William Lanchester, Hon FRAeS was an English polymath and engineer who made important contributions to automotive engineering, aerodynamics and co-invented the field of operations research....

, whose original patents Mitsubishi had obtained, and proved influential as Fiat

Fiat

FIAT, an acronym for Fabbrica Italiana Automobili Torino , is an Italian automobile manufacturer, engine manufacturer, financial, and industrial group based in Turin in the Italian region of Piedmont. Fiat was founded in 1899 by a group of investors including Giovanni Agnelli...

/Lancia

Lancia

Lancia Automobiles S.p.A. is an Italian automobile manufacturer founded in 1906 by Vincenzo Lancia and which became part of the Fiat Group in 1969. The company has a long history of producing distinctive cars and also has a strong rally heritage. Some modern Lancias are seen as presenting a more...

, Saab

Saab

Saab AB is a Swedish aerospace and defence company, founded in 1937. From 1947 to 1990 it was the parent company of automobile manufacturer Saab Automobile, and between 1968 and 1995 the company was in a merger with commercial vehicle manufacturer Scania, known as Saab-Scania.-History:"Svenska...

 and Porsche

Porsche

Porsche Automobil Holding SE, usually shortened to Porsche SE a Societas Europaea or European Public Company, is a German based holding company with investments in the automotive industry....

 all licenced this technology.

The 4D5 engine is a range of four-cylinder belt

Timing belt

A timing belt, or cam belt , is a part of an internal combustion engine that controls the timing of the engine's valves. Some engines, such as the flat-4 Volkswagen air-cooled engine, and the straight-6 Toyota F engine use timing gears...

-driven overhead camshaft diesel engine

Diesel engine

A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

s which were part of the "Astron" family, and introduced in 1980 in the then new fifth generation Galant

Mitsubishi Galant

The first generation of the car, initially known as the Colt Galant, was released in December 1969. The design was dubbed "Dynawedge" by Mitsubishi, referring to the influence of aerodynamics on the silhouette. Three models were available, powered by the new 'Saturn' engine in 1.3 or 1.5 L ...

. As the first turbodiesel to be offered in a Japanese passenger car, it proved popular in the emerging SUV and minivan

Minivan

Minivan is a type of van designed for personal use. Minivans are typically either two-box or one box designs for maximum interior volume – and are taller than a sedan, hatchback, or a station wagon....

 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 1850 cc.

Applications:

• 1973-1977 Mitsubishi Galant
  Mitsubishi Galant
  The first generation of the car, initially known as the Colt Galant, was released in December 1969. The design was dubbed "Dynawedge" by Mitsubishi, referring to the influence of aerodynamics on the silhouette. Three models were available, powered by the new 'Saturn' engine in 1.3 or 1.5 L ...
  
  
• 1973-1975 Dodge Colt
  Dodge Colt
  The Dodge Colt and the similar Plymouth Champ and Plymouth Colt, were subcompact cars sold by Dodge and Plymouth from 1970 to 1994. They were captive imports from Mitsubishi Motors, initially twins of the rear-wheel drive Galant and Lancer families before shifting to the smaller front-wheel drive...
  
  
• 1973-1975 Chrysler Galant
• 1977-1980 Chrysler Sigma
  Chrysler Sigma
  The Chrysler Sigma is a version of the Mitsubishi Galant automobile that was built by Chrysler Australia in Adelaide from 1977. When Mitsubishi Motors Australia took over Chrysler Australia's manufacturing facilities in 1980, they renamed the vehicle the Mitsubishi Sigma...
  
  

4G52

The 4G52 displaces 1995 cc.

Applications:

• 1972-1975 Mitsubishi Galant GTO
  Mitsubishi Galant GTO
  The Mitsubishi Colt Galant GTO was first shown as the Galant GTX-1 showcar at the 1969 Tokyo Motor Show. Sales began in November 1970, when it was the flagship hardtop variant of Mitsubishi Heavy Industries's then-new Colt Galant sedan....
  
  
• 1979-1989 Dodge Ram 50
  Dodge Ram 50
  The Dodge Ram 50 was a compact pickup truck produced by Mitsubishi Motors and sold by the Chrysler Corporation from 1979 to 1993. Plymouth also received a version of the truck known as the Arrow Truck, sold from 1979 to 1982. This was Chrysler's belated answer to the Ford Courier from Mazda and...
  
  
• 1973-1987 Mitsubishi Sigma
  Mitsubishi Sigma
  Mitsubishi Sigma may refer to one of several vehicles manufactured by Mitsubishi Motors between 1976 and 1996:*The Mitsubishi Galant Σ , a version of the Mitsubishi Galant sedan built between 1976 and 1987...
  
  
• 1986-present Mitsubishi L300
• 1977-1981 Mitsubishi Celeste

4G54

The SOHC 8-valve 4G54 (also known as the G54B) displaces 2555 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

Longitudinal engine

In automotive engineering, a longitudinal engine is an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicle, front to back....

 use in rear-wheel drive and all-wheel drive vehicles. It was equipped with a Hitachi two-barrel carburetor

Carburetor

A carburetor , carburettor, or carburetter is a device that blends air and fuel for an internal combustion engine. It is sometimes shortened to carb in North America and the United Kingdom....

 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

Front-wheel drive

Front-wheel drive is a form of engine/transmission layout used in motor vehicles, where the engine drives the front wheels only. Most modern front-wheel drive vehicles feature a transverse engine, rather than the conventional longitudinal engine arrangement generally found in rear-wheel drive and...

 K-cars

Chrysler K platform

The Chrysler Corporation's K-cars were compact-to-midsize cars designed to carry six adults on two bench seats and were aimed not only to replace Chrysler's nominally-compact F-body Aspen and Volaré, but also to compete with intermediates like the Chevrolet Malibu and Ford Fairmont...

 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

Hemi engine

A Hemi engine is an internal combustion engine in which the roof of each cylinder's combustion chambers is of hemispherical form.- History :...

".

Specifications:

ECI-Multi

Multi-Point Fuel Injection
at 4,750 rpm (91 RON) at 4,750 rpm (95 RON) at 3,750 rpm (91 RON) at 4,000 rpm (95 RON)

• Compression ratio: 9.2:1

Carburetor

Single two-Venturi downdraught carburetor
at 5,000 rpm (91 RON) at 3,000 rpm (91 RON)

• Compression ratio: 8.8:1

Applications:

• 1978-1980 Plymouth Fire Arrow
• 1978-1983 Dodge Challenger
  Dodge Challenger
  The Dodge Challenger is the name of three different generations of automobiles marketed by the Dodge division of Chrysler.The first generation Dodge Challenger was a pony car built from 1970 to 1974, using the Chrysler E platform and sharing major components with the Plymouth Barracuda. The second...
  
  /Mitsubishi Sapporo
  Mitsubishi Sapporo
  The Mitsubishi Sapporo name has been used on two derivations of the Mitsubishi Galant* 1978–1984 — This rear-wheel drive hardtop coupé was based on the third generation Galant. In Japan it was sold as the "Galant/Eterna Lambda", while European and South American export markets received...
  
  /Plymouth Sapporo
• 1978-1987 Mitsubishi Sigma
  Mitsubishi Sigma
  Mitsubishi Sigma may refer to one of several vehicles manufactured by Mitsubishi Motors between 1976 and 1996:*The Mitsubishi Galant Σ , a version of the Mitsubishi Galant sedan built between 1976 and 1987...
  
  
• 1979-1989 Dodge Ram 50
  Dodge Ram 50
  The Dodge Ram 50 was a compact pickup truck produced by Mitsubishi Motors and sold by the Chrysler Corporation from 1979 to 1993. Plymouth also received a version of the truck known as the Arrow Truck, sold from 1979 to 1982. This was Chrysler's belated answer to the Ford Courier from Mazda and...
  
  
• 1981-1985 Dodge Aries
  Dodge Aries
  The Dodge Aries is an automobile sold by the Chrysler Corporation from 1981-1989. It replaced the Dodge Aspen as Dodge's family car with "mid-size room" in a size and front-wheel drive format commonly associated with compact cars...
  
  /Plymouth Reliant
  Plymouth Reliant
  The Plymouth Reliant was one of the first two so-called "K-cars" manufactured by the Chrysler Corporation, introduced for the 1981 model year. The Reliant replaced the Plymouth Volaré/Road Runner, which was the short-lived successor automobile to the highly regarded Plymouth Valiant...
  
  
• 1982-1985 Chrysler LeBaron
  Chrysler LeBaron
  The Chrysler LeBaron was originally a classic luxury car of 1930s manufactured by Chrysler which competed with other luxury cars of the era such as Lincoln and Packard....
  
  
• 1982-1985 Chrysler Town and Country
  Chrysler Town and Country (pre-1990)
  The Chrysler Town & Country was a station wagon manufactured by Chrysler Corporation and sold under its flagship brand from 1941–1989. The model was also sold as a sedan, coupé, and convertible from 1947–1950 and as a convertible from 1982–1986....
  
  
• 1982-1991 Mitsubishi Pajero
  Mitsubishi Pajero
  The Mitsubishi Pajero is a sport utility vehicle manufactured by Mitsubishi Motors. It was named after Leopardus pajeros, the Pampas Cat which is native to the Patagonia plateau region of southern Argentina. However, since pajero is an offensive term for "wanker" in Spanish, alternative names have...
  
  
• 1982-1983 Dodge 400
  Dodge 400
  The Dodge 400 was Dodge's second K-car in the early 1980s. It was similar to the Chrysler LeBaron of the same era. The 400 was introduced for the 1982 model year, yet was renamed and added to the midsize Dodge 600 lineup just two years later.-1982:...
  
  
• 1983-1984 Chrysler E-Class
  Chrysler E-Class
  The Chrysler E-Class was a mid-size car produced by the Chrysler Corporation. Introduced in 1983 on a stretched version of the Chrysler K platform, the E-Class was a less expensive, less equipped version of the identical 1983 New Yorker. It was targeted at those who wanted Chrysler luxury, but...
  
  
• 1983-1985 Chrysler New Yorker
  Chrysler New Yorker
  The Chrysler New Yorker was a premium automobile built by the Chrysler Corporation from 1939–1996, serving for several years as the brand's flagship model. A model named the "New York Special" first appeared in the 1930s...
  
  /Dodge 600
  Dodge 600
  The 600 was Dodge's version of the Chrysler E-Class luxury car of the 1980s. It was introduced in 1982, as a 1983 model, as a small mid-size car on the Chrysler E platform and was discontinued after the 1988 model year. It was Chrysler's attempt to compete with the GM A-body, whereas the M-body...
  
  
• 1984-1987 Dodge Caravan
  Dodge Caravan
  The Dodge Caravan is a family minivan manufactured by Chrysler Group LLC and sold under its Dodge brand. Along with its nameplate variant, the Plymouth Voyager, the Caravan was introduced for the 1984 model year. In 1987, the Dodge Grand Caravan long-wheelbase model was introduced and sold...
  
  /Plymouth Voyager
  Plymouth Voyager
  In 1984, the Voyager name was applied to Plymouth's variant of Chrysler's all new minivan. This Voyager used the Chrysler S platform, which was derived from the K-platform . In addition to using a derived platform, the Voyager shared many components with the K-cars, most notably the interior...
  
  
• 1982-1990 Mitsubishi Starion
  Mitsubishi Starion
  The Mitsubishi Starion is a two-door, turbocharged four-cylinder rear-wheel drive four-seat sports car that was in production from 1982 to 1989. It was also marketed in North America as the Conquest under the Chrysler, Dodge, and Plymouth names; both the Starion and Conquest came to an end in 1989...
  
   (turbocharger and fuel injection)
• 1984-1986 Dodge Conquest/Plymouth Conquest
• 1985 Plymouth Caravelle
  Plymouth Caravelle
  The Plymouth Caravelle is a mid-size sedan that was originally a 1983 Canadian model. The Caravelle came to the United States in 1985 to replace the Chrysler E-Class. It was essentially identical to the concurrent Dodge 600. It was replaced by the Plymouth Acclaim in 1989...
  
  
• 1985-1996 Mitsubishi Magna
  Mitsubishi Magna
  The Mitsubishi Magna was a mid-size car offered between May 1985 and September 2005 by Mitsubishi Motors Australia Limited . Manufactured at the Tonsley Park assembly plant, Magna spanned three generations before being replaced by the Mitsubishi 380...
  
   (early carbureted, later EFI)
• 1986-1988 Mazda B2600
  Mazda B-Series
  The Mazda B-Series is a pickup truck, first manufactured in 1961 by Mazda Motor Corporation. From the first B-Series, Mazda has used the engine displacement to determine the name. Thus, the B1500 had a 1.5 L engine and the B2600 had a 2.6 L engine...
  
  
• 1987-1989 Chrysler Conquest
• 1987-1989 Dodge Raider
• 1991-1997 Mitsubishi Pajero
  Mitsubishi Pajero
  The Mitsubishi Pajero is a sport utility vehicle manufactured by Mitsubishi Motors. It was named after Leopardus pajeros, the Pampas Cat which is native to the Patagonia plateau region of southern Argentina. However, since pajero is an offensive term for "wanker" in Spanish, alternative names have...
  
   China
  China
  Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
  
   market version

4D55

Displacement - 2346 cc

Bore - 91.1 mm

Stroke - 90.0 mm

Fuel Type - Diesel

Valves per cylinder - 2

Non-Turbo

• Power - 55 kW at 4,200 rpm (JIS)

65 hp at 4,200 rpm (SAE)

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

101 ft-lb (137 N·m) 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 - 80 hp at 4,000 rpm (SAE)
• Torque - 125 ft-lb (169 N·m) at 2,000 rpm (SAE)
• Engine type - Inline 4-cylinder SOHC
• Compression ratio - 21:1 (384 psi)

• Applications - 1980-1983

Turbo (TD04 wastegated turbo)

• Power - 70 kW at 4,200 rpm (JIS)

62 kW at 4,200 rpm (DIN)

86 hp at 4,200 rpm (SAE)

• Torque - 181 N·m (134 ft-lb) at 2,500 rpm (JIS)

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

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

• Engine type - Inline 4-cylinder SOHC
• Compression ratio - 21:1 (384 psi)

• 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 - 2476 cc

Bore - 91.1 mm

Stroke - 95.0 mm

Fuel type - Diesel

Non-Turbo

• Power - 68 hp at 4,200 rpm
• Torque - 105 ft-lb (142.4 N·m) 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 at 4,200 rpm
• Torque - 145 ft-lb (196.6 N·m) at 2,000 rpm
• Engine type - Inline 4-cylinder SOHC
• Fuel system - Distribution type jet pump
• Compression ratio - 21:1

Intercooled Turbo (TD04 watercooled Turbo)

• Power - 104 hp at 4,200 rpm
• Torque - 177 ft-lb (240 N·m) at 2,000 rpm
• Engine type - Inline 4-cylinder SOHC
• Rocker arm - Roller Follower type
• 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 - 114 hp at 4,000 rpm
• Torque - 182 ft-lb (246.8 N·m) at 2,000 rpm
• Engine type - Inline 4-cylinder
• Fuel system - 1st Generation Common Rail Direct Injection (CRDi)
• Compression ratio - 17:1

Intercooled Turbo (2nd Generation DI-D)

• Power - 139 hp at 4,000 rpm
• Torque - 236 ft-lb (320 N·m) at 2,000 rpm
• Engine type - Inline 4-cylinder
• Fuel system - 2nd Generation Common Rail Direct Injection (CRDi)
• Compression ratio - 17:1

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

With manual transmission

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

With automatic transmission

• Power - 178 PS at 4,000 rpm
• Torque - 258 ft-lb (349.8 N·m) at 1,800 rpm
• Engine type - Inline 4-cylinder
• Fuel system - 2nd Generation Common Rail Direct Injection (CRDi)
• Compression ratio - 16.5:1