Mercedes M112 engine

The Mercedes M112 engine is a V6 petrol engine, which was introduced in March 1997 in the E-class in the back of the W210 (W210 engines). He replaced the engine M104.

General information

The M112 engine is technically closely related to the M8 V113. For the most part, they were made at the same production sites and have many identical parts. Both have a light alloy cylinder block with cast liners made of Silitec (Al-Si alloy). The engine is equipped with one camshaft for each row of cylinders. Above the crankshaft is a balance shaft that rotates against the crankshaft at the same speed to reduce vibration.

The camshafts and balancer shaft are driven by a double roller chain. Like the M113, the M112 has two intake valves and one exhaust valve per cylinder, which are actuated by light metal roller rockers with a hydraulic slack adjuster.

The use of a single exhaust valve results in a smaller exhaust port area and thus less exhaust heat transferred to the cylinder head, especially when the engine is cold. Thus, the catalyst reaches its operating temperature faster. This is also facilitated by the thin sheet metal exhaust manifolds with double walls that absorb little heat.

Each combustion chamber has two spark plugs to the right and left of the exhaust valve. The arrangement of valves and plugs is symmetrical. Due to double ignition, the heat load on the piston increases, it is cooled by oil nozzles, injecting engine oil from below to the piston head.

The M112 engine was produced with a volume of 2,4 to 3,7 liters. We will consider the modifications in more detail below.

In 2004, the M112 was replaced by M272 engine.

Specifications М112 2.4

Engine displacement, cc	2398
Maximum power, hp	170
Maximum torque, N * m (kg * m) at rpm.	225 (23) to 3000 225 (23) to 5000
Fuel used	Petrol
Fuel consumption, l / 100 km	8.9 – 16.3
engine's type	V-shaped, 6-cylinder
Add. engine information	SOHC
Maximum power, h.p. (kW) at rpm	170 (125) to 5900
Compression ratio	10
Cylinder diameter, mm	83.2
The piston stroke, mm	73.5
Number of valves per cylinder	3

Specifications М112 2.6

Engine displacement, cc	2597
Maximum power, hp	168 – 177
Maximum torque, N * m (kg * m) at rpm.	240 (24) to 4500 240 (24) to 4700
Fuel used	Petrol Regular (AI-92, AI-95) Petrol Gasoline AI-95 Gasoline AI-91
Fuel consumption, l / 100 km	9.9 – 11.8
engine's type	V-shaped, 6-cylinder
Add. engine information	SOHC
Maximum power, h.p. (kW) at rpm	168 (124) to 5500 168 (124) to 5700 170 (125) to 5500 177 (130) to 5700
Compression ratio	10.5 – 11.2
Cylinder diameter, mm	88 – 89.9
The piston stroke, mm	68.4
CO2 emission in g / km	238 – 269
Number of valves per cylinder	3

Specifications М112 2.8

Engine displacement, cc	2799
Maximum power, hp	197 – 204
Maximum torque, N * m (kg * m) at rpm.	265 (27) to 3000 265 (27) to 4800 270 (28) to 5000
Fuel used	Petrol Regular (AI-92, AI-95) Petrol Gasoline AI-95
Fuel consumption, l / 100 km	8.8 – 11.8
engine's type	V-shaped, 6-cylinder
Add. engine information	SOHC
Maximum power, h.p. (kW) at rpm	197 (145) to 5800 204 (150) to 5700
Compression ratio	10
Cylinder diameter, mm	83.2 – 89.9
The piston stroke, mm	73.5
CO2 emission in g / km	241 – 283
Number of valves per cylinder	3 – 4

Specifications М112 3.2

Engine displacement, cc	3199
Maximum power, hp	215
Maximum torque, N * m (kg * m) at rpm.	300 (31) to 4800
Fuel used	Petrol
Fuel consumption, l / 100 km	16.1
engine's type	V-shaped, 6-cylinder
Maximum power, h.p. (kW) at rpm	215 (158) to 5500
Compression ratio	10
Cylinder diameter, mm	89.9
The piston stroke, mm	84
Number of valves per cylinder	3

Specifications M112 3.2 AMG

Engine displacement, cc	3199
Maximum power, hp	349 – 354
Maximum torque, N * m (kg * m) at rpm.	450 (46) to 4400
Fuel used	Gasoline AI-95 Gasoline AI-91
Fuel consumption, l / 100 km	11.9 – 13.1
engine's type	V-shaped, 6-cylinder
Add. engine information	SOHC, HFM
Maximum power, h.p. (kW) at rpm	349 (257) to 6100 354 (260) to 6100
Compression ratio	9
Cylinder diameter, mm	89.9
The piston stroke, mm	84
Supercharger	Compressor
CO2 emission in g / km	271
Number of valves per cylinder	3 – 4

Specifications М112 3.7

Engine displacement, cc	3724
Maximum power, hp	231 – 245
Maximum torque, N * m (kg * m) at rpm.	345 (35) to 4500 346 (35) to 4100 350 (36) to 4500 350 (36) to 4800
Fuel used	Petrol Gasoline AI-95
Fuel consumption, l / 100 km	11.9 – 14.1
engine's type	V-shaped, 6-cylinder
Add. engine information	DOHC
Maximum power, h.p. (kW) at rpm	231 (170) to 5600 235 (173) to 5600 235 (173) to 5650 235 (173) to 5750 245 (180) to 5700 245 (180) to 5750
Compression ratio	10
Cylinder diameter, mm	97
The piston stroke, mm	84
CO2 emission in g / km	266 – 338
Number of valves per cylinder	3 – 4

Mercedes M112 engine problems

The main problem of this engine is oil consumption, this is due to a number of factors:

• the crankcase gas recirculation system is clogged, the oil begins to squeeze out through the gaskets and seals (through the crankcase ventilation tubes, the oil also begins to press into the intake manifold);
• untimely replacement of valve stem seals;
• wear of cylinders and oil scraper rings.

It is also necessary to monitor the stretching of the chain (a resource of about 250 thousand km). If you notice in time, then replacing the chain (there are two of them) will cost from 17 to 40 thousand rubles, depending on the cost of spare parts. It is worse if you miss the moment of wear - in this case, the camshaft stars and the chain tensioner wear out, respectively, the repair will be several times more expensive.

Tuning M112

Tuning the stock naturally aspirated M112 is initially unprofitable, since a large increase with a minimum budget cannot be obtained, and serious improvements cost so much that it is easier to buy a car with an already compressor engine.

Nevertheless, there are compressor kits from the Kleemann company, created specifically for these engines. After installing the kit + firmware, you can get up to 400 hp at the output. (on a 3.2 liter engine).