BMW’s new Shift Cam single-cylinder engine is expected to deliver higher fuel efficiency and reduced emissions
Engines with variable valve timing (VVT) and lift systems have been developed by various OEMs such as BMW, Honda and Ducati. Till now, VVT systems were largely used with larger capacity engines. In case of BMW, engines used with bikes like R 1250 boxer twins and the S 1000 RR have VVT.
Now a new patent reveals that BMW is planning to introduce the Shift Cam system with its 300cc single-cylinder engine. Another target could be C 400 GT, which also has a similar motor. However, the primary candidates to benefit from this upgrade will be G310R, G310GS and G310RR. The updated engine is likely to be shared with TVS as well for its 310cc Apache range.
BMW single-cylinder Shift Cam engine
As compared to Shift Cam system used in larger capacity BMW engines, the one to be used with the single-cylinder motor comes with a unique set of tweaks. Among the primary challenges is to make the Shift Cam system compact, so that it can fit inside the relatively smaller sized single-cylinder motor. This has resulted in some innovative tweaks to the single-cylinder motor.
Just as the name suggests, Shift Cam works by altering the cam timing as well as the valve lift. This is achieved by shifting the inlet camshaft so that one of the two cam profiles is always in contact with the inlet valves. The Shift Cam system is beneficial as it increases fuel efficiency and reduces emission in both low-rpm and high-rpm scenarios.
Basic idea of Shift Cam system is the same in case of the single-cylinder motor. However, there are some changes such as the compact size of the Shift Cam. BMW has been able to reduce the size by using a solenoid actuator that is placed between the two intake valves. Since it is a 4-valve engine, the size of camshaft can be based on conventional design principles.
Another innovation is a unique angle for the spark plug. This is necessary since the actuator is placed in the middle. As the whole camshaft slides, an extra idler gear has been provided. It connects the intake and exhaust cams. This is different from a direct chain drive that goes from the crankshaft to the camshafts.
Launch timeline not known
It may take some time to perfect the new Shift Cam single-cylinder setup. So, BMWs entry-level 310cc bikes are unlikely to get the updated engine anytime soon. Also, the manufacturing cost of this new engine is not known. Not all patents make it to production stage, as innovations need to have business viability for commercial applications.
In its current form, BMW’s 313cc, water-cooled, single-cylinder engine generates 34 hp of max power and 28 Nm of peak torque. It is mated to a 6-speed constant mesh gearbox. Performance numbers won’t change much with the upcoming Shift Cam single-cylinder engine.