Engine N54 And Engine N43: Notes

The new generation of 6-cylinder petrol engines (NG6) is being continued with an enhancement. With the new turbocharged 6-cylinder petrol engine N54 with direct fuel injection, BMW is once again entering the arena of turbo technology. In principle the description also applies to the new generation of 4-cylinder petrol engines.

Direct fuel injection of the 2nd generation (DI2) is used on the new turbocharged engine. The direct fuel injection (HPI: High Precision Injection) offers additional latitude for defining metering of injection flow volumes and regulating injection duration (multiple injection events, up to 3, depending upon engine rpm and load factor) and in defining mixture distribution within the combustion chamber. This enables a positive influence on the power output, engine torque, consumption and pollutant emissions. The mixture cooling by the directly injected fuel means the compression can be increased compared to a turbocharged engine with intake pipe fuel injection. This improves efficiency. The use of direct fuel injection creates a homogeneous mixture preparation in the entire combustion chamber. Homogeneous mixture preparation means that the fuel-air ratio is regulated stoichiometrically in the same way as for intake pipe fuel injection (Lambda = 1). ("Stoichiometrically" refers to a fuel-air ratio of 14.8 kilograms of air to 1 kilogram of fuel.) The homogeneous mixture preparation means that a conventional system for exhaust re-treatment can be deployed.

The bi-turbo concept makes an especially important contribution with its substantially quicker response to demand for increased power. Instead of a large exhaust turbocharger, two smaller units each supply three cylinders with compressed air. The major advantage of the smaller exhaust turbochargers is their low inertia torque. Even the smallest activation of the accelerator pedal module leads to an immediate pressure build-up in response. At the same time variable valve timing (double VANOS) provides optimal thermodynamic efficiency, furnishing increased torque at low engine speeds for enhanced flexibility.