BMW G 310 R to Get ShiftCam Single-Cylinder Engine

Motorcycles are increasingly adopting variable valve systems, and BMW's ShiftCam is a notable and straightforward solution compared to other current designs. This technology is already being utilised on the R 1250 boxer twins and the S 1000 RR's inline four stroke engine. BMW is now targeting its G-series single-cylinder range, which includes the G 310 R and G 310 GS. As evidenced by a new patent application, BMW seems to modernise its G- series with this innovation.

Do you know the mechanism of the BMW ShiftCam?

The ShiftCam system functions precisely as its name implies by shifting the inlet camshaft. Further, the camshaft allows the activation of one of two possible cam profiles to engage with the inlet valves. This alteration of the cam timing and valve lift offers the advantage of allowing the engine to utilise a more conservative cam profile at lower revolutions. 

Further resulting in less lift and increased gas velocity into the combustion chamber, thereby boosting torque at lower revolutions. 

Additionally, the low-revolution cam lobe features reduced timing advance and duration, resulting in a reduction of overlap (the time during which the inlet valves are open before the exhaust valves close). This reduction in overlap translates to a shorter period for unburned intake charge to escape into the exhaust, resulting in improved efficiency and lower emissions.

According to the patent drawings for the BMW ShiftCam system: A solenoid located at the centre of the intake cam. This Solenoid works on the spiral grooves to switch between the low-speed and high-speed cam profiles. 

At higher revolutions, the low-lift, short-duration cam profile is inadequate in getting enough air-fuel mixture into the combustion chamber within the limited window when the valve is open. Consequently, a more aggressive cam profile is activated by shifting the camshaft laterally. 

Further providing increased valve lift and duration, which allows for more air and fuel to enter the cylinder. It results in increasing peak power and maximum torque. 

As the engine's revolutions increase, the valve timing can be advanced, enabling the inlet valve to open earlier and increasing overlap without allowing sufficient time for unburned fuel to escape into the exhaust, ensuring that emissions and efficiency remain optimal.

Different Types of Variable Valve Timing and Lift

BMW's method of achieving cam-switching in their VVT system is different from other brands' solutions and is unique in the world of motorcycling. 

While the principle is the same as other cam-switching VVT systems, such as the Honda VTEC setup. It has been used on cars for over 30 years and on the VFR800 since 2002. BMW achieves this effect by sliding the camshaft to switch between lobes. The R 1250 model uses a slidable camshaft, while the S 1000 version features a slidable sleeve over a splined central section of the camshaft. 

The solenoids control the movement, pushing pins into a spiral groove machined into the camshaft, causing it to move to one side. The spiral groove ensures that the cam lobes swap over when the intake valve is closed, preventing any potential mechanical clash during the inlet stroke. 

In contrast, other VVT systems, such as those used on Ducatis, use oil pressure in chambers to vary the cam position relative to the driven sprocket. Ducati's VVT system features actuators on the intake and exhaust cams, controlled by solenoid valves and oil pressure, for more timing flexibility, but lift is not varied.

What's New in ShiftCam for the New Singles?

Although the basic concept is similar to the ShiftCam system in BMW's latest R 1250 and S 1000 engines. The single-cylinder engine in the new patent is more compact. 

To achieve this, the solenoid actuator is located between the two intake valves, allowing the camshaft to remain the same length as a conventional design. However, this positioning requires the spark plug to be installed at an angle. 

Additionally, because the entire camshaft is slidable, an additional idler gear is needed to connect the intake and exhaust cams. This is needed to have a direct chain drive from the crankshaft to the camshafts.

According to the patent, the newly developed engine is a single-cylinder. Currently, BMW only offers single-cylinder engines in the form of the G 310 range. This model is produced in India by TVS on behalf of BMW. The model includes the G 310 GS, G 310 R, and G 310 RR, as well as the C 400 scooters manufactured by Loncin in China. 

It is possible that the patent relates to any of these models, with the G-series models being the more likely candidates. However, it could also indicate that BMW is developing a completely new single-cylinder engine. Possibly a larger and higher-performance one, to bridge the gap between the G 310 bikes and the F-series parallel twins.

Do you know that TVS Motor appoints former JLR as Chairman and Ford engineer as CTO?

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