Mercedes-Benz M123 engine
The M 123 is a straight six -cylinder petrol engine from Daimler -Benz. Use he found from 1976 to 1984 in the models 250 and 250 T Series 123 He replaced the motors of the type M 180 and M 130 230.6 250 2.8 of the type series 114. Successor was the M 103, which was introduced in 1984 in the 124 series.
The motor is still essential features of the precursor. Then the crankshaft is mounted four times and the oil pump, fuel pump and distributor are driven by a shaft inclined at the front end of the engine, which in turn is driven through a sprocket and a Schraubenradpaar. On the other hand, the cylinders are no longer cast together in pairs, but the cylinder spacing is uniform. In the partition walls between the cylinders there is no cast cooling ducts, but the slots are sawn, are flowed through by cooling water.
The engine has a chain-driven overhead cam ( OHC ). The vertically hanging valves are actuated by rocker arms and are arranged in two rows. As with the M 115 makes the inlet and outlet on the right engine, and on the left side is a recessed in the cylinder head combustion chamber (with a flat piston crown ), in which the exhaust valve and the spark plug are. The remainder of the cylinder cross-section forms a squish area that the swirling mixture in the combustion chamber.
While the rest of the engine range was taken over from its predecessor, was just the M 123 is the only new development, the customers do not convince right. In 1979 the engine was upgraded with a power output of 95 kW ( 129 hp ) to 103 kW increased (140 hp). But especially after the launch of the new four- cylinder M 102 in the models 200 and 230 e the public interest fell sharply. The M 102 has almost everything better, even the gasoline consumption was considerably cheaper. The combination ( 250T ) was deleted in 1982, in the limo (250 ) of the engine to 1985 was available, but did not matter more in sales.
The complicated Solex carburettor is now regarded as relatively difficult to control. He is the carburetor of the previous model 280 W 114 functionally the same: a double carburetor. A set of mixing systems feeds three of the cylinders. A single set composed of a relatively small mixing system for idle speed and a second further opening system for the load operation at higher speeds. At idle and up to about one third load only the two smaller systems are mechanically addressed by the accelerator pedal; the second tubes are also open at high load and engine speed by vacuum unit. All four carburetor tubes (2 x 2) are supplied by a central float chamber with fuel. Despite the carburetor fuel supply flow and return line is also designed for this engine type as in fuel injection engines; this provides a cooling effect of the tank returning gasoline and so for a certain protection against vapor lock and it start causing problems in summer temperatures.
Shortly before the introduction of the first, working together with a catalyst and after lambda probe data electronically controlled carburettor (ca. 1986/87 ) was this model at four-pipe carburetor in about the most complex thing in the invention of the spray nozzle carburetor by Wilhelm Maybach after 80 years of development had become. When the oxygen sensors were needed for the three -way catalyst to control the Gemischfettigkeit, but this elaborate type of carburetor was already history and been replaced by fuel injection systems that are simpler in construction and can be easily maintained.
The joy of quiet operation was marred by a high gas mileage, but this engine was quite again significantly more economical than the 280 carburetor models ( the city traffic often more than 17 liters consumed ), reaching its most important development goal. Better but made it in every respect of the successor type M 103 from 1984, the produce in the variant with 2.6 liter displacement cheaper, lighter and consume much less fuel was, at higher engine output of 122 kW at first (166 hp) and 118 with Kat kW ( 160 hp ) and better revving against the comparatively sedate M 123 the smoothness of the M 103 was again significantly better, especially in the 2.6 -liter variant.
Use:
Data:
- Bore 86 mm, stroke 72.45 mm, capacity 2525 cm3
- Compression 8.7: 1
- Power 95 kW ( 129 hp ) at 5500 rpm
- Torque 196 Nm at 3500 rpm
- Maximum speed: 175 km / h
1979, the engine has been revised:
- Compression 9.0: 1
- Power 103 kW ( 140 hp ) at 5500 rpm
- Torque 200 Nm at 3500 rpm
In October 1981, the M 123 has been further revised to reduce consumption. The compression ratio by changing the combustion chambers in the cylinder head to 9.4: 1 increases; the other data remained the same. The internal motor type has been changed simultaneously from M to M 123 920 123 921.
- Mercedes- Benz engine