Thermodynamics and charge exchange of the new BMW six-cylinder engine

Abstract

The BMW in-line six-cylinder engine has been modified and introduced to production in the new BMW 3 Series model. Its major features include variable intake and exhaust camshaft timing, a new induction system with resonance charging, a turbulence-generating system in the intake ports and a new exhaust system with two closed-loop, coupled catalysts integrated into the exhaust manifold. The cam timing of both camshafts can be adjusted continuously within a range of 40° crank angle (CA) for the inlet cams and 25° CA for the exhaust cams. The turbulence-generating system supplies combustion air to the engine during part load operation and produces the necessary charge motion to run the engine with greater valve overlap at low loads and speeds. Its combination with variable camshaft timing results in lower fuel consumption and exhaust emissions that meet the LEV emission standard. In addition, the variable cam timing raises the torque curve of the unthrottled engine, particularly at low engine speed. The maximum values for torque and power output are unchanged, but maximum torque is reached 500 r/min earlier than with the previous engine.