260E M103 Engine Specs

by Harry Havemeyer
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The Mercedes Benz 260 E was a four-door sedan built on the W124 E-Class chassis between 1987 and 1991. The 260 E used Mercedes' M103 straight-six engine which was produced between 1985 and 1993. The iteration appearing in this specific model was the 2.6-L version of the M103, which was mechanically similar to the larger 3.0-L version that also appears in Mercedes models of similar vintage.


The 2.6-liter Mercedes Benz M103 engine is a straight-six, single-overhead camshaft design with two valves per cylinder. This power plant makes use of Mercedes' CIS-E (Continuous Injection System-Electronic) and has a bore of 82.9 mm and an 80.2 mm stroke.


Some models of the 2.6-L M103 came equipped with a factory-installed catalyst while others did not. This option has minimal effects on the performance of the engine but does affect performance nonetheless. The 2.6-liter with the catalyst installed produces 160 horsepower at 5,800 RPM and 162 ft.-lbs. of torque at 4,600 RPM. Without the catalyst, this power plant generates 166 horsepower at 5,800 RPM and 168 ft.-lbs. of torque.


In addition to being available in the 1987 through 1991 Mercedes Benz 260 E, the 2.6-liter M103 engine was also used in another W124 chassis, the 1990 through 1992 300 E 2.6. The 2.6-L M103 also came equipped on the W201 chassis in the 1987 through 1993 Mercedes Benz 190 E 2.6. Some world market W126 S-Class models also made use of the venerable power plant but are only available in the United States through gray-market importation.

Comparing the 2.6 L and 3.0 L

The Mercedes Benz 2.6-liter M103 was almost mechanically identical to its larger 3.0-liter stablemate. The only difference between the two engines was an increase in bore from 82.9 mm in the 2.6-L to 88.5 mm in the 3.0-L variant, smaller intake valves and a slightly different air box. The 3.0-L M103 with a catalyst produces 177 horsepower at 5,700 RPM and 188 ft.-lbs. of torque at 4,400 RPM while the version without the catalyst generates 185 horsepower at 5,700 RPM and 191 ft.-lbs. of torque at 4,400 RPM.

3.0 L Swapability

Due to the mechanical similarities between the 2.6-L and 3.0-L variants of the M103 engine, swapping them out between models is moderately easy as it's as simple as a bolt-on process, without any extra fabrication. Those seeking to gain a performance upgrade by swapping in the 3.0-L engine can find this larger power plant in the 1986 through 1993 W124 300 E, the 1988 through 1989 W124 300 CE, the 1988 through 1993 W124 300 TE, the 1989 through 1991 W126 300 SE, the 1989 through 1991 W126 300 SEL and the 1985 through 1989 R107 300 SL. It was also offered in the W463 G-Class SUV, but this model never made it to the United States other than through the gray-market.

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