A 275-bhp racing car has been developed for touring car racing. With the special model BMW 320si, a road-approved version with 173 bhp will also be built.
In-line engine, 4-cylinder
Displacement: 1999 cm3
Power output: 127 kW / 173 bhp at 7000 rpm
Engine management system: MEV9.2 (same as N46)
without Valvetronic
The structure of the cylinder head essentially corresponds to that of the S54 engine. Die gliding drag arms are geometrically identical to those on the S54 engine but they have a DLC coating (Diamond light Carbon). In the same way as on the S54 engine, the valve clearance is set using small adjustment plates in the upper spring cup.
The crankcase ventilation is integrated in the cylinder head cover. The crankcase ventilation is regulated by a partial vacuum and heated electrically.
In the same way as on the N45B16 engine, a stepless double VANOS is used.
The N45B20S is equipped with a thermal oil level sensor. The oil level check takes place electronically. The function of the oil level check and display of the oil level are the same as on the other engines in the E90.
The variable intake system corresponds to that in the N46.
A suction-jet pump is used for the brake power assistance in the same way as on the N45B16.