The 4G91 uses a bore and stroke of 78.4mm ×77.5mm (3.09in ×3.05in) for a total displacement of 1.5L (1,496cc). With a 9.5:1 compression ratio and DOHC, four-valve-per-cylinder head and multi-point EFI, this engine produces 115PS (85kW; 113hp) at 6,000rpm and 135N⋅m (100lb⋅ft) at 5,000rpm.[1] The 4G91 was a short-lived model, mainly built between 1991 and 1995 and rarely seen in export markets. There was also a carbureted model, with 97PS (71kW; 96hp) at 6,000rpm and 126N⋅m (93lb⋅ft) at 3,500rpm.[1]
The 4G92 displaces 1.6L (1,597cc). It first appeared in the late-1991 Japanese-spec Mirage RS and Super R in DOHC form. The 4G92 is basically a version of the 4G91 with the bore increased to 81mm (3.19in). In the original DOHC 16V form it produces 120PS (88kW; 118hp). Later, a fuel-efficient SOHC version was added, but the 4G92 is best known in its high-performance MIVEC equipped DOHC version, which fully replaced "ordinary" DOHC in 1993. Power output was raised as high as 170PS (125kW; 168hp), as found in the JDM Mirage Cyborg-ZR and 1992 Lancer MR, making it one of the most powerful 1.6-litre naturally aspirated engines. A modular displacement (MD) version of the 4G92 MIVEC was also produced – MD is Mitsubishi's cylinder deactivation system which helps improve fuel consumption.
The 4G93 is a 1.8L (1,834cc) engine available in both SOHC and DOHC versions. Turbocharged variants are also produced. In mid 1996 Mitsubishi released a gasoline direct injection (GDI) version of the 4G93. This GDI model saw a production of over a million units though it was a heavy polluter therefore only sold in the Japanese market. A partially cleaned up version (with less power) was later sold in Europe, and was among the first of the modern GDI engines. It brought good fuel economy and, if well serviced, long engine life.
The 4G94 is a 2.0L (1,999cc) version built in Japan, used in the Mitsubishi Lancer. It has a cast iron engine block with Multi-point fuel injection and an aluminum SOHC cylinder head with forged steel connecting rods and four valves per cylinder. The 4G94 also comes in the GDI DOHC variant which can be found in the Mitsubishi Galant.
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