Mitsubishi Saturn engine
| 4G3 | |
|---|---|
| Overview | |
| Manufacturer | Mitsubishi Motors |
| Also called | Saturn |
| Production | 1969–1999 |
| Combustion chamber | |
| Cylinder block alloy | Cast iron |
This article is about the engine series produced by Mitsubishi Motors. For the engine series produced by the Saturn subsidiary of General Motors, please see Saturn I4 engine.
The Mitsubishi Saturn or 4G3 engine is series of overhead camshaft (OHC) straight-4 internal combustion engines introduced by Mitsubishi Motors in 1969, along with the Astron, Orion, and Sirius. Displacement ranges from 1.2 L to 1.8 L. The early versions have chain driven valvetrain while the later versions are belt driven and equipped with balance shafts.
The 4G30 displaces 1.3 L (1,289 cc). It is an 8-valve SOHC design with an aluminium head and iron block. The engine has five main bearings. Power was 87 hp.
Bore x Stroke: 2.87" x 3.03"
The 4G31 displaces 1.5 L (1,499 cc). It is an 8-valve SOHC design with an aluminium head and iron block. The engine has five main bearings. Power was 95-105 hp depending on which carburetor combo was used. An updated version with electronic central-point fuel injection was installed in Mirages and Lancers from 1986 on. A version for industrial use has 37 PS (27 kW) at 3000 rpm.
Bore x Stroke: 2.93" x 3.39"
In 1970, the 4G32 was introduced, and it displaces 1.6 L (1,597 cc). It is an eight-valve SOHC design with an aluminium head and iron block. The engine has five main bearings, a cross flow head and a single down draught carburetor. Firing order is 1-3-4-2. The GSR versions used two twin-barrel Mikuni-built Solex carburetors for a total of 110 hp (SAE).
A version with an early iteration of Mitsubishi's MCA lean-burn system (MCA-IIB), fulfilling the intermediate Japanese exhaust regulations for 1975, was called G32A. Those with the later, cleaner yet, "MCA-Jet" system were called G32B. Later, the G32B also came in a fuel injected, turbocharged model. For competition, a version of the 4G32 engine was made with a DOHC eight-valve cylinder head, and fitted with two twin-choke 40 mm Solex sidedraft carburettors.
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