First US model to receive the new N20 2.0 liter four-cylinder TwinPower engine is the 2012 BMW Z4 sDrive28i. Unveiled on Monday during the press conference at BMW Manhattan, the revised Z4 made its public debut today at the 2011 New York Auto Show.
The 2.0 liter engine found in Z4 sDrive28i combines highpressure direct-injection and BMW’s VALVETRONIC intake control. With 240 horsepower and 260 lb-ft of torque, it offers more power and torque than BMW’s normally aspirated 3.0-liter inline-6 that it replaces in the Z4 sDrive30i. Maximum output of 240 horsepower is achieved at 5,000 rpm, 1,500 rpm lower than in the normally-aspirated 3.0-liter inline six. The peak torque of 260 lb-ft comes on stream at just 1,250 rpm.
The 4-cylinder engine with its all-aluminum crankcase is lighter and more compact than a 6-cylinder engine of equivalent power. The turbocharger is a twin-scroll system. The exhaust streams leaving the two pairs of cylinders are kept completely separate as they flow through the exhaust manifold and the turbocharger, taking a spiral path to the turbine wheel.
This configuration results in very low exhaust back pressure at low engine rpm, and allows the energy of the exhaust gas pulses to be optimally managed and translated into powerful rotation of the turbine blades, without a delay in throttle response.
The highly-efficient and fairly powerful 4-cylinder will also make its way in other US-bound bimmmers, but no official word on which models will get it first. Our bet goes on the BMW 528i.
In the mean time, enjoy the beautiful Z4 in Atacama Yellow.