Mercedes-Benz M130 engine

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The Mercedes Benz M130 Engine was the last and largest of the ‘mid-sized’ Single Over Head Camshaft (SOHC) straight-6 cylinder (inline) engines produced by Mercedes Benz. The ‘mid-sized six’ started life as the 2.2 litre M180 (2,197cc/133ci) which was unveiled at the Frankfurt Motor show in September 1951 alongside the new 3.0 litre M186 ‘big’ straight-6. These engines were used to power the 220 and 300 models of the 1951 Mercedes range. While sharing many design features such as, staggered valve arrangement and rockers running off a single overhead camshaft driven by a duplex cam-chain, the engines were of completely different design with little or no inter-changeability of parts.¹

[edit] The 'Big Six'

The 3.0 litre ‘big six’ was produced from 1951 until 1967 with no change in its 2,996cc displacement derived from a slightly under-square 85mm x 88mm bore and stroke. The various versions of the engine (M186 – M199) produced from 113 – 212 bhp as compression ratios rose and the number of carburettors multiplied or were replaced with fuel-injection. These engines powered the 300 Adenauer, 300S/Sc, 300SL, 300SE Fintail/Coupe/Cabrio (W111/112), 300SE/SEL (W108/109).²

[edit] M180 to M130

The ‘mid-sized’ six saw longer service with production ceasing after some 20 years in 1971. Its last home was fitted to the W108 280SE in M130E (130.980) fuel injected guise, and in M130V carburetted form, in the lower powered 280S and the smaller W114 250/8 (2.8).

The W108 would live on for a year longer powered by 3.5 and 4.5 litre V8 (M116/M117). However the next model 280SE W116 would use the new double-overhead camshaft (DOHC) M110 2.8 liter, with the W114 "Compact' initially using the older configuration carburetted OHC M114 2.5 liter engines.

The first M180 engine (180.920) displaced 2,195 cc (133ci) and was rated at 80hp. It powered the W187 220 Sedan, Coupe and Cabriolet (Type A and B) from 1951 – 1955, and the W105 219 from 1956 – 1959; the later M180.920 giving around 100hp for 220S. The W180 Ponton 6-cyinder 220 Sedans, Coupes and Cabriolets of 1955 -1959 benefited from the up-rated M180.924 which delivered 124hp. In 1958 Bosch mechanical fuel-injection was added to the 2.2 litre six and the engine, now giving 113 - 134hp, was redesignated M127. The M127 was fitted to the last of the Pontons, the rare 1958 W128 220SE of which less than 4000 were produced. The M127 would power the first series (1959-1965) of W111 ‘Fintail’ 220SE and 220SEb models, as would the carburetted M180 in the 220b and 220Sb. The addition of the lower case ‘b’ added to differentiate the Fintails from the earlier Pontons.

From 1965 the ‘New Generation’ or /8 models were introduced, with all W111/W112 sedans superseded by the new W108/109 chassis -apart from the W111 220b/Sb/SEb sedan which was continued up-rated to the 230S, produced up to 1968. All models in 1965 were given up-rated engines with the M180 being increased to 2,306cc by increasing the bore by 2mm for the 230 and 230S. The two door W111 coupes and cabriolets were continued right though to 1971. The higher specification W112 300 SE coupe and cabrios being discontinued in 1967 with the discontinuation of the 3 litre ‘big six’ engine. The gap left in the model line up by the departure of the 300 SE two doors being filled by the W111 280 SE coupe and cabriolet powered by the new 3.5 litre V8.

The new W108 250S and 250SE gained the new 2.5 litre (2,496cc) variant of the ‘mid size six’ the carburetted M108 and fuel-injected M129 as did the W111 250SE two door models. The extra capacity gained by lengthening the stroke by 6mm from 72.8mm to 78.8mm. The M129 fitted with a mechanically controlled six piston fuel injection pump The new long-wheelbase W109 300 SE sedan was initially powered by big M189 fuel-injected 3.0 litre six until its discontinuation, when in 1968 it was fitted with an enlarged version of the M129 the M130.

The M130 was the ultimate variant of the ‘mid sized six’ with a capacity of 2,778cc gained by increasing the bore to 86.5mm from the 82mm of the 2.5 litre engine while retaining the 78.8mm stroke. This represented the maximum practical enlargement of the engine given the limitations of the engine block as evidenced by the deletion of water passages between the cylinders.

[edit] References

¹ Six Appeal, Mercedes Enthusiast, May 2007, pp 52-58
² ibid