Mercedes-Benz M180
M130 engine of a 1971 280SL
Overview
Manufacturer	Daimler-Benz
Designer	Wolf-Dieter Bensinger[1]
Production	1951-1985
Layout
Configuration	Inline-6
Displacement	2.2 L; 134.0 cu in (2,196 cc) 2.3 L; 140.8 cu in (2,307 cc) 2.3 L; 139.9 cu in (2,292 cc) 2.5 L; 152.3 cu in (2,496 cc) 2.5 L; 154.1 cu in (2,525 cc) 2.8 L; 169.5 cu in (2,778 cc)
Cylinder bore	80 mm (3.15 in) 82 mm (3.23 in) 86 mm (3.39 in) 86.5 mm (3.41 in)
Piston stroke	72.4 mm (2.85 in) 72.8 mm (2.87 in) 78.8 mm (3.10 in)
Valvetrain	SOHC 2 valves x cyl.
Combustion
Fuel system	Solex or Zenith carburetors Bosch Mechanical or D-Jetronic fuel injection
Fuel type	Gasoline
Cooling system	Water cooled
Output
Power output	80–134 bhp (60–100 kW; 81–136 PS)
Chronology
Predecessor	Mercedes-Benz M153 engine (pre-war) Mercedes-Benz M189 engine (of M130)
Successor	Mercedes-Benz M110 engine (of M130) Mercedes-Benz M103 engine (of M123)

The Mercedes Benz M180 and the M127, M108, M129, M130, M114, M123 engines are single overhead camshaft inline-6 cylinder engine, that was used to power Mercedes-Benz vehicles from the early 1950s to the mid 1980s. Utilizing a reverse-flow cylinder head, staggered valve arrangement and rockers running off a single overhead camshaft driven by a duplex cam-chain it was available in both carbureted and fuel injected versions of different displacements from 2.2 to 2.8 litres.

Although it was introduced it the Frankfurt Motor Show in April 1951 in parallel to the M186 "big six", that engine family (M188, M198, M189) are of completely different design with little or no inter-changeability of parts.

The original design is a 2.2 L (2,196 cc; 134.0 cu in) single overhead camshaft inline-six cylinder engine introduced at the Frankfurt Motor Show in April 1951 to power the company's new 220 (W187). Utilizing a reverse-flow cylinder head and available in both carbureted and fuel injected versions, it had an "over-square" bore × stroke of 80 mm × 72.8 mm (3.15 in × 2.87 in), the first engine with a cylinder bore greater than its stroke that Mercedes had installed in a production car.

At the 1951 Frankfurt Motor show Mercedes also unveiled the larger 3.0-litre M186 "big six" inline-six to power its new flagship 300 (W186) Adenauer range. While sharing many design features such as, the engines were of completely different design with little or no inter-changeability of parts.^[2]

The M180 would also influence the design of Mercedes-Benz' OHC four cylinder motor, the M121 in 1955 sharing not only the architecture, but many of the components. In turn it will influence its diesel sibling the OM621 in 1958. These would evolve into the M115 and OM615 motors in 1968. The diesel range will continue to expand into a larger displacement OM616 in 1973 and the five cylinder OM617 in 1974.

In its original form, the first generation M180 I (180.920) had a "over-square" 80 mm × 72.8 mm (3.15 in × 2.87 in) geometry, for a 2196 cc overall displacement.

Powered by a dual downdraft Solex 30 PAAJ, with a 6.5 compression, it made 80 PS (59 kW; 79 hp) at 4600 rpm and 14.5 kg⋅m (142 N⋅m; 105 lb⋅ft) at 2500 rpm, with a piston speed of 11.1 & 6.1 m/s.

The engine was combined with the chassis of the Mercedes-Benz 170S, which created the new W187 200 model.^[3]

• 220 W187.011 sedan from 04/07.1951 – 05.1954
• 220 W187.012 cabriolet A 04/08.1951 – 04.1954
• 220 W187.013 cabriolet B  04/07.1951 – 05.1953
• 220 W187.023 coupe 12.1953 – 04.1954

In June 1954 the new W180 Ponton was released, and as the chassis code suggests, the engine was designed for this very car. The M 180 II (180.921) had a higher compression ratio (7.6 to 1) and an upgraded carburettor pair (Solex 32 PAATJ). The W180 initially came only as a sedan, meaning that production of the two-door W187 continued, and they also got the new motor. After the engine was upgraded to the third generation .924 (see below), the older motor would power the new hybrid W105 that premiered in sync.

It made 85 PS (63 kW; 84 hp) at 4800 rpm and 16 kg⋅m (157 N⋅m; 116 lb⋅ft) at 2400 rpm (at piston speeds of 11.6 and 5.8 m/s).

• 220a W180.010 sedan 03/06.1954 - 04.1956
• 220 W187.023 coupe 04.1954 - 07.1955
• 220 W187.012 cabriolet A 04.1954 - 08.1955
• 219 W105.010 sedan 03.1956 - 08.1957

In August 1957 the compression ratio was raised to 8.7. It now made 90 PS (66 kW; 89 hp) at 4800 rpm and 17 kg⋅m (167 N⋅m; 123 lb⋅ft) at 2400 rpm (at piston speeds of 11.6 and 5.8 m/s).

• 219 W105.010 sedan 08.1957 - 07.1959

In March 1956, the 220a (W180) model was split into a hybrid W105 219 which retained the second generation .921 motor (see above). The W180 was now re-badged as the 220S and it now featured the third generation engine. The M 180 III (180.924) kept the 7.6 compression ratio, but was now fed by a pair of compound Solex 32 PAJTA.

It made 100 PS (74 kW; 99 hp) at 4800 rpm and 16.5 kg⋅m (162 N⋅m; 119 lb⋅ft) at 3500 rpm (at piston speeds of 11.6 and 8.5 m/s).

•  220S W180.010 sedan 03.1956 - 08.1957  
•  220S W180.037 coupe 10.1956 -  08.1957    
• 220S W180.030 cabriolet  07.1956 - 08.1957

In August 1957 compression was raised to 8.7. The engine now made 106 PS (78 kW; 105 hp) at 5200 rpm and 17.5 kg⋅m (172 N⋅m; 127 lb⋅ft) at 3500 rpm (with respective piston speeds at 12.6 and 8.5 m/s).

• 220S W180.010 sedan 08.1957 - 08.1959
• 220S W180.037 coupe 08.1957 - 10.1959
• 220S W180.030 cabriolet  08.1957 - 10.1959

In October 1958 Bosch Mechanical fuel injection, previously limited to the exclusive W188 300S and W198 300SL was made available for 220 series. The cars got a new chassis and model code: W128 220SE, and the engine, keeping the cylinder block was christened as the M127 I (127.980).

It was mechanically controlled by a multi-point injection system operates on an intermittent group injection scheme, with two pistons controlling a group of three cylinders each. The injection pump is mechanically driven, and mechanically controlled. The injection pressure is 15 atü (ca. 1570 kPa) equivalent to a BMEP of 11.1 kp/cm² (1.09 MPa). Daimler-Benz achieved this BMEP by using, in addition to the manifold injection, resonance effect induction, giving the engine a volumetric efficiency greater than 100 per cent.^[4]

It made 115 PS (85 kW; 113 hp) at 4800 rpm and 19.0 kg⋅m (186 N⋅m; 137 lb⋅ft) at 3800 rpm (at piston speeds of 11.6 and 9.2 m/s).

• 220SE W128.010 sedan 04/10.1958 - 08.1959
• 220SE W128.030 cabriolet 07/10.1958 - 08.1959
• 220SE W128.037 coupe 07/10.1958 - 08.1959

In August 1959 the new W111 Fintail car was released to succeed the W180 Ponton. Originally, production was limited to the sedans. The M180 and M127 all got performance updates.

For the W111 220b, replacing the W105 219, the M 180 IV (180.940) was now fed with double Solex 34 PJCB. It made 95 PS (70 kW; 94 hp) at 4800 rpm and 17.2 kg⋅m (169 N⋅m; 124 lb⋅ft) at 3200 rpm (at piston speeds of 11.6 and 7.8 m/s).

• 220b W111.010 sedan 05./08.1959 - 08.1965

For the 220Sb, replacing the Ponton namesake, the M 180 V (180.941) had the enlarged compound Solex 34 PAJTA pair initially, but in July 1963 this was replaced with the Zenith 35/40 INAT with automatic choke.

It made 110 PS (81 kW; 108 hp) at 5000 rpm and 17.5 kg⋅m (172 N⋅m; 127 lb⋅ft) at 3500 rpm (at piston speeds of 12.1 and 8.5 m/s).

• 220Sb W111.012 sedan 05/08.1959 - 07.1965

For the 220SEb, with the additional, lower-case "b" to indicate that it was different from the Ponton sedan namesake it replaced, the M 127 III (127.982) was updated. As the W128, 2-door versions were still in production, they also got the new motor.

It made 120 PS (88 kW; 118 hp) at 4800 rpm and 19.3 kg⋅m (189 N⋅m; 140 lb⋅ft) at 3900 rpm (at piston speeds of 11.6 and 9.5 m/s).

• 220SEb W111.014 08.1959 - 08.1965
• 220SE W128.030 cabriolet 08.1959 - 11.1960
• 220SE W128.037 coupe 08.1959 - 11.1960

In it's final incarnation, the M 127 V / 127.984 was used to power the two door W111 220SEb models upon their release in early 1961. Output was the same as for the third generation of the M127.

• 220SEb W111.023 cabriolet 09.1961 - 10.1965
• 220SEb W111.021 coupe 09.1960 / 02.1961 - 10.1965

In summer of 1963, the new generation W113 Pagoda Roadster was showcased. Among the many novel features was a notably powerful engine. The power came not only from a 9.3 compression, 6-plunger fuel pump, but also from a 2-mm larger bore 82 mm × 72.8 mm (3.23 in × 2.87 in), increasing the displacement to 2.3 L (2,306 cc; 140.7 cu in). From the M 127 II's 127.981 number, one can deduce that development began in 1958.^[5][6]

It made 150 PS (110 kW; 148 hp) at 5500 rpm and 20.0 kg⋅m (196 N⋅m; 145 lb⋅ft) at 4200 rpm (at piston speeds of 13.3 and 10.2 m/s).

• 230SL W113.042 roadster 03/07.1963 - 01.1967

In July 1965, after the premiere of the 250 series W108, the W111 was kept in production, but now became a flagship of all the Fintail sedans as the lone 230S model. It was powered by the M 180 VIII / 180.947, which kept Pagoda’s block, but the 220Sb’s head, milled to make 9.0 compression.

It made 120 PS (88 kW; 118 hp) at 5400 rpm and 18.2 kg⋅m (178 N⋅m; 132 lb⋅ft) at 4000 rpm (at piston speeds of 13.1 and 9.7 m/s).

• 230S W111.010 sedan 07.1965 - 01.1968

The lesser W110 Fintail succeeded the departed 220 W111 as the 230, creating a hybrid model of a lower-priced body with the six-cylinder engine (much like the W105 219). The M 180 IX (180.945) had a 9.0 compression ratio but was powered by a pair of Solex 38 PDSI-2.

It made 105 PS (77 kW; 104 hp) at 5200 rpm and 17.7 kg⋅m (174 N⋅m; 128 lb⋅ft) at 3600 rpm (at piston speeds of 12.6 and 8.7 m/s).

•  230 W110.011 sedan 07.1965 - 07.1966

In July 1966 Mercedes-Benz opted to give the W110 230 the full power package of the W111 230S. The M 180 X / 180.949 now had the compound Zenith 35/40 INAT pair.

It made 120 PS (88 kW; 118 hp) at 5400 rpm and 18.2 kg⋅m (178 N⋅m; 132 lb⋅ft) at 4000 rpm (at piston speeds of 13.1 and 9.7 m/s).

• 230 W110.011 sedan 07.1966 - 01.1968

With the launch of the new /8 cars for 1968, the vehicles also had redesigned engines (the M114 below and the M115 four cylinder counterpart). The sole exception of the W114 230 model, which kept the old motor going, the M 180 V 23 / 180.954. For greater reliability and cooling, the piston bore was reduced by ¼ of a mm, displacement becoming 2.3 L (2,292 cc; 139.9 cu in), whilst the Zenith 35/40 INAT pair got the automatic choke. It was kept going past the 1973 facelift, and upon the conclusion of its production in autumn of 1976 wrapped up a 25 year story of the original M180.

It made 120 PS (88 kW; 118 hp) at 5400 rpm and 18.2 kg⋅m (178 N⋅m; 132 lb⋅ft) at 3600 rpm. (13.1 & 8.7 m/s)

• 230/8 W114.015 sedan 09.1967 / 01.1968 - 08.1973
• 230/8 W114.017 lw sedan 08.1968 - 07.1973
• 230.6 W114.615 sedan 09.1973 - 11.1976
• 230.6 W114.617 lw sedan 08.1973 - 10.1976

The launch of the W108 in September 1965 created a new 250-series. This was accomplished by stroking the 2.3-litre M180 by 6 mm 82 mm × 78.8 mm (3.23 in × 3.10 in), increasing displacement to 2.5 L (2,496 cc; 152.3 cu in). A change from four to seven main bearings was necessary in order to smoothly handle the resulting increase in power. Larger capacity oil pump was also implemented, and the cylinder heads had larger ports and valve diameter size increase by 2 mm.

The M 108 I / 108.920 was the entry model keeping the latter fifth generation M180's (.941) twin 2 brl Zenith 35/40 INAT rack and the 9.0 compression ratio. It made 130 hp at 5400 rpm and 19.8 mkg at 4000 rpm (14.1 & 10.5 m/s).

• 250S W108.012 sedan 07/09.1965 - 03.1969

The fuel injected stablemate also got the a new code the M 129 I / 129.980. A mechanically controlled six-piston Bosch injector pump was implemented in place of the W111 220SE's M127's two plunger pump. The injectors were repositioned to give a more direct angle towards the inlet valve heads. The engine cooling fan received six blades instead of four and incorporated a viscous coupling which activated the fan only when engine speed exceeded 3,000 rpm or the radiator water temperature reached a preset limit. Initially it had a 9.3 compression ratio, but in 09.1966 this was raised to 9.5.

It made 150 hp at 5500 rpm and 22.0 mkg at 4200 rpm (14.4 & 11.0 m/s).

• 250SE W108.014 sedan 08/09.1965 - 01.1968
• 250SE W111.023 cabriolet 08/09.1965 - 12.1967
• 250SE W111.021 coupe 08/09.1965 - 12.1967

M 129 III / M129.982 was the designation given to the motor powering the W113 Pagoda 250SL, with the same performance as the .980.

• 250SL W113.043 roadster 11/12.1966 - 01.1968

Generally speaking the M129 motor turned out to be controversial and short lived. Even though the crankshaft had seven bearings, the cylinder were still asymmetrically spaced in pairs, causing uneven cooling to reach between each pair. This was not a problem on the M127 in 2.3 litre version, but the stroked motor now made a top piston at 14.4 m/s at peak power (as opposed to the 13.1 m/s on the 2.3), which caused excessive stress and led to premature failure. To adjust for this Mercedes-Benz redesigned the cylinder block with symmetrical cylinder bores. This created two new engines, the M114 for the present 2.5 displacement and a bored out M130 (see below).

The M 114 V 25 / 114.920 was the smaller displacement of the redesigned cylinder block with symmetrical cylinder spacing, keeping the rods and pistons of the M108. It also retained the Zenith stack and the 9.0 compression. It was offered on the flagship 250 model of the new /8 series.

It made 130 hp at 5400 rpm and 20.3 mkg at 3600 rpm (14.1 & 9.5 m/s)

• 250/8 W114.010 sedan 07/12.1967 - 05.1972
• 250C W114.021 coupe 10.1968 - 05.1972

In late 1968 Mercedes-Benz released the 2-door W114 coupe. Along with aforementioned .920 engine for the 250C, a sister 250CE model was released with the M 114 E 25 / 114.980 featuring the new electronically operated Bosch D-Jetronic, the first to receive the new technology.

It made 150 hp / 110 kW at 5500 rpm and 21.5 mkg at 4500 rpm (14.4 & 11.8 m/s)

• 250CE W114.022 coupe 10.1968 - 05.1972

The M114 will be replaced by the larger bore M130 in May 1972.

The symmetrical cylinder block of the M114 allowed for another expansion in displacement. This time the bore was increased by 4.5 mm to 86.5 mm × 78.8 mm (3.41 in × 3.10 in), resulting in a 2.8 L (2,778 cc; 169.5 cu in) displacement.This would be the maximum permissible size.

The carburettored version was the M 130 V 28 / 130.920 with a 9.0 compression, which would go into the 280S for the 1968 model year.

• 280S W108.016 sedan 11.1967 / 01.1968 - 09.1972

It would be replaced by the carburettor powered M110 DOHC engine in the W116 S-Class.

The M 130 E 28 / 130.980 was the fuel-injected version that superseded the M129 on the W108 sedans and W111 coupes and cabriolets

It made 160 hp at 5500 rpm and 24.5 mkg at 4250 rpm (14.4 & 11.2 m/s)

• 280SE W108.018 sedan 11.1967 / 01.1968 - 09.1972
• 280SEL W108.019 lw sedan 01.1968 - 04.1971
• 280SE W111.025 cabriolet 11.1967 / 02.1968 - 05.1971
• 280SE W111.024 coupe 11.1967 / 02.1968 - 05.1971

It would be replaced by the fuel injected DOHC M110 engine of the S-Class.

In parallel to solving the M108/M129 asymmetry, Mercedes-Benz also retired the 'Big Six' M189 engine that was still used to power the flagship 300 series.

The M 130 / 130.983 was slightly more powerful producing 170 hp at 5750 rpm 24.5 mkg at 4500 rpm

• 300SEL W109.016 sedan 12.1967 / 02.1968 - 01.1970

Production ceased after the launch of the M116 V8 engine, on the 300SEL 3.5 model, which was more suitable for the considerably price gap that the customer was willing to pay for the W109's air suspension.

The W113 Pagoda had the M 130 / 130.983 motor with more aggressive camshaft profiles.

It also made 170 hp at 5750 rpm and 24.5 mkg at 4500 rpm (15.1 & 11.8 m/s)

• 280SL W113.044 roadster 11.1967 / 01.1968 - 03.1971

It too will be replaced by the M110 powered R107 280SL.

When the W114 coupe was launched, exporting the car to had faced bureaucratic hurdles, namely to the newly introduced emission controls. To compensate for the power loss, for the 1969 MY, the US-destined 250C was instead sold with the larger M130 engine,. A year later the 250 sedan for 1970 MY would also have the 2.8 motor.

In April 1972, after the retirement of the W108 Mercedes-Benz opted to make the M130 powered W114 available on the home market, but as to not confuse with the M110 powered 280 and 280C models, that became available in parallel, MB kept the 250 badge and retired the M114 due to redundancy. ^[7]

The M 130 V 28 / 130.923 engine had a lower compression ratio 8.7, It made 130 hp / 96 kW at 5000 rpm and 22 mkg at 3200 rpm (13.1 & 8.4 m/s)

• 250C W114.023 coupe 07.1969 - 08.1973
• 250 W114.011 sedan 03/07.1970 - 08.1973
• 250C W114.623 coupe 08.1973 - 06.1976
• 250 W114.611 sedan 08.1973 - 07.1976

It would be replaced by the M123 engine on the W123 250 sedan. The W114 250C Coupe will not have a direct replacement, instead the C123 will have an entry level 230C model with the M115 four cylinder engine.

In 1975, upon the launch of the W123 Mercedes-Benz opted to rationalise the six-cylinder range. By this point the lineup represented a mix of the vintage M180 on the 230.6, the 2.8 ltre M130 on the 250 and the flagship 280 and 280 DOHC with the 2,7 litre M110.

Most of the 230.6 were sold to commercial customers for fleet cars. The shifting purchasing trends in the aftermath of the 1973 oil crisis caused the 250 series to fall in popularity. At the same time demand for the M110 powered vehicles, particularly in the W116 S-class and the SL and SLC 2 door versions was significantly larger than anticipated, due to customers electing the more economic entry models over the M116 and M117 powered V8 stablemates.

As the M130 and M110 shared the same tooling, Mercedes-Benz opted to retired the M130 completely and handover it's facilities to the M110. At the same time, the veteran M180 underwent a major design overhaul. The block kept the even spacing of the M130 and was adopted for the 86 mm bore, to optimised production by sharing the pistons with the M110. However, the stroke was shortened to just 72.4 mm. The result was a very oversquare 86 × 72.4 geometry, providing a 2.5 L (2,525 cc; 154.1 cu in) displacement.

The short stroke enabled Mercedes-Benz to keep the 4 pin crankshaft with large bearing journals with no counterweights. This resulted in a very smooth mid to high RPM, but at a cost of high fuel consumption. As was Intended, most of the customers were commercial fleet cars, particularly the stretched six-door taxicabs. Private sales were less successful, particularly after launch of the modular M102 in the 230E and 230TE in 1980, which offered equivalent performance, at lesser cost with superior economy. This led to a plummet of sales with the estate's early retirement in 1982.

Originally the engine had an 8.7 compression and made 129 hp at 5500 rpm and 196 Nm at 3500 rpm (13.2 & 8.4 m/s)

• 250 W123.026 sedan 07.1975 / 04.1976 - 09.1979
• 250 V123.028 lw sedan 09.1977 - 09.1979
• 250T S123.086 estate 09.1977/05.1978 - 09.1979

In September 1979 it got a power boost with a 9.0 compression, making 140 hp at 5500 rpm and 200 Nm at 3500 rpm (13.2 & 8.4 m/s)

• 250 W123.026 sedan 09.1979 - 12.1985  
• 250 V123.028 LWB sedan 09.1979 - 12.1985
• 250T S123.086 estate 09.1979 - 08.1982

In 1985, this engine was replaced by the modular M103 engine of the junior 2.6 litre displacement.

The final iteration of the engine was the M110 model, with a cross-fire DOHC 12 valve cylinder head with hemispherical combustion chambers. A reduced bore size, with resulting 86 mm × 78.8 mm (3.39 in × 3.10 in) dimensions, was to protect the cylinder walls from expected higher compression and RPM that would be permissible. Despite being covered in separate article, it sat atop the M130's cylinder block and can be considered as part of this engine family. It would be simultaneously the flagship of the mid-range W114 and W123 models, and the entry level of the W116 and W126 S-Classes, as well the R107 SL and C107 SLC, It's replacement will come in face of the modular M103 in the senior 3.0 displacement in 1985, but it will continue to be equipped on the W460 280GE G-wagen until 1991.

• Mercedes-Benz M186 engine
• List of Mercedes-Benz engines