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Wikipedia / Mercedes-Benz M102 engine

The M102 family is a inline-four gasoline automobile engine family built by Mercedes-Benz from 1980 until 1995. It was the first of a new generation of modular engines that replaced the M115, a derivative of the M121 engine in production since 1955.

It would be complemented by the derived OM601 diesel engine in 1983 and the M103 six cylinder petrol and OM602 and OM603 five and six cylinder diesel engines in 1985.

This family of motors was a clean sheet design featuring thin walled cast iron cylinder block facilitating 30-40 kg reduction in weight, as compared to the predecessor. The 15 degree offset of the cylinder bank allowed for better engine balancing and more compact placing. The cylinder head featured a hemispherical cross-fire combustion chamber.

The M102 was the first 4 cylinder engine to feature multi-point fuel injection, and they would systematically replace the carburetor models towards the end of production. Later models added hydraulically adjusted valve lash and catalytic converters.

The M102 was also the first MB engine to introduce 4-valve per cylinder DOHC cylinder heads, originally developed by Cosworth for racing, they would power the 190E 2.3-16 and later the 2.5-16 performance versions.

Ultimately it would be replaced by the derived M111 engine, with the in-house developed DOHC cylinder heads in 1992-1993, though some models would continue to use the SOHC M102, particularly on the commercial W461 G-Wagen and the TN van until the mid-1990s.

1.8 and 1.7 litre

M102.910

Used in the W201 190E 1.8 from 1990 onwards (badged as 180E in Australia from 1991 to 1993). Displacement: . Power output: . Torque:

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M102.919

Downsleeved variant used in the W201 190E 1.7 from May 1992 onwards for export to Portugal only, where there was a major tax threshold at 1.75 litres. Displacement: . Power output: at 5500rpm. Torque at 3700rpm.

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2.0 litre carbureted

M102.920

The M102.920 was a 2.0L engine with an bore and stroke . Equipped with a Stromberg carburetor 175 CDT. Displacement: . Power output: . Swedish and Swiss market models developed at 5000rpm thanks to their stricter emissions regulations.

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M102.921

Similar to M102.920, but less power due to a different camshaft and different carburetor. Power Output:

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M102.922

An update of the M102.920 engine for use in the W124 chassis, Displacement: . Power output: .

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M102.924

Similar to M102.921, different carburetor, single-belt drive for alternator, power steering pump and air-conditioning compressor (where fitted). Hydraulic aided valvetrain. Power output: .

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M102.938

Low compression version of M102.921. Power output: .

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M102.939

Low compression version of M102.920. Power output: .

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2.0 litre fuel injected

M102.961

A 2.0L multi-point fuel-injected (KE-Jetronic) variation of the M102.921. An "E" was added to the model of the vehicle (standing for "einspritzung", the German word for fuel injection). This engine is identified by TSZ ignition and multiple belts for the alternator, power steering and air conditioning compressor (where fitted). Displacement: . Power output:

Application

M102.962

An update to the M102.961 introduced in 1985. This is identified by the EZL ignition system and a single accessory drive belt. Displacement: . Power output: .

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M102.963

2.0litre version with KE-Jetronic fuel injection. Displacement: . Power output:

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M102.964

2.0litre version with KE-Jetronic fuel injection for the W460 for Italian export. Displacement: . Power output:

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2.3 litre

M102.944

The M102.944 was a 2.3L version with a bore and the same stroke. Displacement was . It was powered by a Stromberg 175 CDTU carburetor and had a 7.2 compression ratio. Output: at 5300 RPM. Torque 174 Nm at 2000 RPM. It was used exclusively on the W460 G-wagen for extra-European export.

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M102.980

The M102.980 was a 2.3L version with a bore and the same stroke. Engine weight was . Used K-Jetronic fuel injection. Displacement: . Power output:

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M102.981

The M102.981 was a 2.3L version with a bore and the same stroke. Displacement: . Power output:

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M102.982

Similar to the M102.980 version, but with the newer KE-Jetronic system from Bosch. Displacement: . Power output:

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M102.985

An 8-valve M102 with a displacement of 2.3L used in the W201 chassis with KE-Jetronic fuel injection. Displacement: . Power output:

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16-valve

M102.983

A 16-valve version of the M102.985 with cylinder head designed by Cosworth.Displacement: . Power output: ; USA:

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M102.990

An update of the 16-valve version with increased capacity (2.5L) and stiffening ribs, still with a cylinder head designed by Cosworth. Displacement: . Power output:

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M102.991

An update of the 2.516-valve version, with shorter stroke and larger bore. H beam rods and piston cooling jets. Displacement: . Power output:

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M102.992

An update of the 102.991 version with removal of four crankshaft counterweights and even more stiffening ribs for higher RPMs. Single timing chain, oil pump with separate drive chain. Bigger intake manifold, camshaft and exhaust system. Higher compression ratio 10.5:1. Displacement: . Power output:

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Data accuracy

The M102 and M 103 engine family has with the M 104 E 30 a common piston stroke of 80.25mm. As only one decimal place is usually given, a large number of publications are in circulation with the incomplete specification of 80.2mm. This applies in particular to more recent publications after production was discontinued. As a result, the inaccurate figures of 1,996cc instead of the actual 1,997cc for the 2.0l engine and 2,298cc instead of 2,299cc for the 2.3l engine are sometimes listed.

There is no evidence anywhere that there are two crankshafts with different strokes.

See also

References