Astron
The Astron engine debuted in late 1974 in capacities ranging from 1.9 litres to 2.6 litres. It was the first engine to feature balance shaft technology, which was used to dampen rocking and vertical forces in the interest of smoothness.
The engine featured "hemispherical" combustion chambers and 8 valves per cylinder in overhead cam configuration. It was designed for use in rear-wheel and four-wheel drive vehicles.
The Astron was used in both passenger and commercial vehicles. It was also available in both petrol and diesel forms.
4G51
A 1.85 Litre Petrol engine with a displacement of 1855cc. It used a 81.0x90.0mm bore and stroke and was used in early Galants and Sigmas.
4G52
A 2.0 Litre petrol engine with a displacement of 1995cc. It used a 84.0x90.0mm bore and stroke. In Australia this engine was used in the Sigma, Scorpion, L200 and L300.
4G53
A petrol 2.4 Litre engine with a displacement of 2384cc. Using a 88.0x98.0mm bore and stroke it was used in the Challenger and Canter.
4G54
The basis for the later Astron II used in the Magna. A 2.6 Litre (2555cc) petrol engine which came in two variants. A standard compression (8.2:1) version and a high compression (9.5:1) version. It uses a 91.1x98.0mm bore and stroke.
In Australia, the standard compression version was used in GH-GK Sigma, Scorpion, Canter, Express, Pajero, Triton and Mazda B2600 (Ford Courier). The high compression version was used in some GK and GN Sigmas.
4D55
2.4 Litre diesel with a 2346cc displacement. Available with or without turbo. The 4D55 has a 91.1x90.0mm bore and stroke. In Australia this engine was used in the L200, L300 and Pajero.
4D56
2.5 Litre diesel with a 2476cc displacement. Available with or without turbo. Uses a 91.0x95.0mm bore and stroke and was fitted to the L300, Pajero and Triton.
| MITSUBISHI PETROL ENGINES | |
| 3 cylinder | |
| 3A9x | 3A90 3A91 3A92 |
| 4 cylinder | |
| Neptune | 4G41 4G42 |
| Orion | 4G11 4G12 4G13 4G15 4G17 4G18 4G19 G4ED |
| Sirius | 4G61 4G62 4G63 4G64 4G67 4G69 |
| Astron | 4G51 4G52 4G53 4G54 |
| Astron II | Original Revised |
| Saturn | 4G30 4G31 4G32 4G33 4G37 |
| 4G9x | 4G91 4G92 4G93 4G94 |
| 4A9x | 4A90 4A91 4A92 |
| 4B1x | 4B10 4B11 4B11T 4B12 |
| Inline 6 | |
| Saturn 6 | 6G34 |
| V6 | |
| 6G7x | 6G71 6G72 SOHC 12v 6G72 SOHC 24v 6G72 DOHC Early 6G74 Late 6G74 Ralliart 6G74 6G75 |
| 6A1x | 6A10 6A11 6A12 6A13 |
| 6B3x | 6B31 |
| V8 | |
| 8A80 | 8A80 |
