BMW R1250 GS Yeni Boxer Motor 2-stage cam timing animation

[spacey1]

Pretty slick engineering... not variable valve timing per se, but, on the inlet valve camshaft only there is 2-stage valve lift and 2-stage valve timing.

Quite clever in it's execution. It looks to optimize air flow velocity into the cylinder at part and wide open throttle.

The engineering looks like it could prove robust over time too...

[spacey1]

Alpha Racing Variable Valve Timing for BMW R1200 boxer engine.

Alpha Racing Power Boxer: https://vvl.alpharacing.com/en/

Here's another version referred to as Variable Valve Lift from Alpha Racing that produces 146 ps.

It looks like it only operates on the inlet valves too. Another interesting feature is that there is no 'throttle butterfly' in the throttle.

This setup uses inlet valve lift and duration to control the air flow going into the engine.

Removing the throttle butterfly should equate to more wide-open-throttle power due to the fact that there is no impediment to air flow at the throttle.

[spacey1]

More detail about the 'Shift Cam' engine is getting around.

Quite clever really.

1. At part-throttle, they've staggered the two (2) stage one inlet cam lobes on each cylinder to promote 'swirl' in the combustion chamber.
This improves combustion; fuel economy; emissions; and torque at part-throttle.

2. And additionally because the first stage cams are targeted at part-throttle / low-power conditions, they've been able to lower the idle speed by 100 rpm, which should make 'em easier to get into first gear with less 'CLUNK'.

3. The second stage of the 'Shift Cam' targets wide-open throttle settings making big power.

4. There are now 2 injectors per cylinder.