Direct injection: Introduction

With the N73B60 engine, direct injection technology is used for the first time on a BMW spark-ignition engine. Direct injection means that the fuel is injected under high pressure directly into the combustion chamber.

There are 2 concepts for spark-ignition engines with direct injection:

• Direct injection with  lean running: GDI engine (not used by BMW)

  Direct injection is used to reduce fuel consumption  in the part-load range.

  The disadvantage of direct injection with  lean running is the complex and expensive exhaust gas after treatment, which uses deNOx converters. The deNOx catalytic converter is a three-way catalytic converter with a special coating. Operation with the deNOx catalytic converter requires the use of sulphur-free fuel.

• Direct injection without  lean running: N73B60 engine

  Direct injection is used to increase power output  .

  The advantage of direct injection without  lean running is the use of exhaust gas after treatment with a conventional three-way catalytic converter. The three-way catalytic converter can be used with sulphurous fuel. On the N73B60 engine, the Valvetronic system is used to reduce fuel consumption in the part-load range. The disadvantages of direction injection with  lean running are thus avoided.

The combination of Valvetronic and direct injection (without lean running) allows low fuel consumption with high specific power output and high torque. Compared to the M73 engine, the N73 engine uses 3,6 % less fuel. Power output is increased by 87 kW to 327 kW and torque from 490 Newton-meters to 600 Newton-meters.

The N73B60 engine can be used all around the world as it does not require sulphur-free fuel.

The N73B60 engine will be installed for the first time in March 2003 in 760i/760Li (E65/E66) vehicles.

• > N73TU with introduction 09/2006

The N73TU satisfies the legal emissions limits, e.g. Euro 4 standard for Europe or LEV II for the USA (LEV: Low Emission Vehicle).

Measures on the direct injection system:

• MED 9.2.2 engine management system, based on ME 9.2.1 engine electronics