BMW Motorrad Introduces Boxer Engine With ShiftCam Variable Valve Timing
It’s the first VVT system ever in a BMW motorcycle.
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Variable valve timing isn't necessarily a new idea, but it is new to BMW motorcycles. With a freshly designed 1,254 cc two-cylinder flat engine, VVT is arriving in BMW bikes for the first time with an engineering feature called ShiftCam. This engine will be used in the updated 2019 models of the R1250GS adventure bike and the R1250RT sport touring motorcycle.
Essentially, it's a straight-forward VVT design. The intake camshaft has two lobes per valve and a sliding actuator determines which lobes are in use. The “part load cams” are in use when the engine is under light load and it switches to “full load cams” when the rider is demanding more juice. The part load cams use reduced valve lift to improve fuel economy and the full load cams maximize valve lift to deliver stronger performance. The engine can tell how open the throttle valve is and adjust the cam timing accordingly.
Along with the ShiftCam system and the bigger size over the 1,170 cc engine used in the outgoing 1200 models, another change to the engine includes staggering the order of the intake valves at different degrees. The idea is to get a more efficient burn inside the combustion chamber by giving the air-fuel mixture a swirling effect.
The results of these changes are 134 horsepower and 105.5 pound-feet of torque. That’s a decent bump in performance over the previous engine which made 123 hp and 92.2 pound-feet of twist. BMW is also claiming a slightly lower idle, reduced emissions, and a fuel economy improvement of four percent, partially thanks to ShiftCam. Four percent doesn’t sound like much, but it’s pretty impressive considering the bigger displacement and better performance numbers of the engine.
Enjoy this video from BMW Motorrad demonstrating its new engine accompanied by some rather dramatic music.
