Pic. 1.11. Turbodiesel 2.9 L (flywheel side view). Here you can see the flywheel, exhaust turbocharger and elements of the exhaust system
Pic. 1.12. Turbodiesel 2.9 L (view from the side of the suction system)
Another model of a 5-cylinder engine - E 290 TD (in the domestic market OM 602) with a volume of 2.9 l (pic. 1.11 and 1.12) is the first direct injection diesel model for a Mercedes-Benz passenger car.
Diesel has 2 valves per combustion chamber. The nozzle is directly screwed into it. In a conventional prechamber system, fuel, so to speak, «stored» in the prechamber before self-igniting directly in the combustion chamber. The direct injection system differs from the prechamber by a significant reduction in fuel consumption. This is achieved by more efficient combustion of the fuel as it is under high pressure (up to 31 MPa) enters directly into the combustion chamber, where it immediately ignites under the action of hot compressed air of high pressure.
For the E 290 TD engine (OM 602) air is pre-compacted by exhaust gas turbocharger (similar to KKK or Garrett), is accelerated and fed into the swirl chamber of the cylinder head.
Pic. 1.13. 2.9L direct injection turbodiesel with exhaust gas turbocharger and charge air cooler
In addition, a charge air cooler is used (pic. 1.13), located in front of the radiator of the cooling system, which brings the temperature of the intake air to 80°C, thereby increasing the density of the air supplied to the combustion chamber.
The compact turbocharger is adjusted to achieve a maximum absolute pressure of 195 kPa at an engine speed of 1900 rpm-1. For turbo engines of previous models, when the car was started or the gas pedal was pressed sharply, a «turbo failure» - lack of incoming air. For the E 290 TD engine (OM 602) the compressor is adjusted so effectively that this disadvantage is practically not felt.
The start and quantity of injection is controlled by the EDS system (Elektronic Diesel Control), which has about 50 specified parameters. Numerous engine condition sensors monitor the change in parameters while driving and provide readings in the form of electrical signals to the EDC, which in turn issues a control command for the amount and order of injection.
EDC controls both the start of the engine and the idling speed and the amount of exhaust gases discharged for afterburning. The control is carried out according to the principle of just enough - EDC supplies the combustion chambers with as much fuel as necessary for optimal engine operation.
Pic. 1.14. Diesel 5-cylinder engine E 270 CDI
In June 1999, the new E 270 CDI inline 5-cylinder diesel engine replaced the E 290 TD. Engine E 270 CDI (pic. 1.14) has become a combination of optimal characteristics.
The power of the diesel engine E 270 CDI has increased by 31.5% compared to the previous model and reached 125 kW / 170 hp. at an engine crankshaft speed of 4200 min-1, and in the frequency range of 1600–2400 min-1, the torque increased to 370 Nm. The maximum speed of the car was 225 km/h, and the average fuel consumption (NEFZ) - 6.9 liters per 100 km.