Did you know that bmw was the first to offer....

[DC52E55]

Absolute bullshit list. S class had the ABS before 1979.

[KenH]

I fail to understand why a world-class company with world-class products would feel the need to put together such a dubious (and in some cases dishonest) set of claims.

[bruce.augenstein@comcast.]

Originally Posted by bmstyle71

"Because the intake valves now have the ability to move from fully closed to fully open positions, and everywhere in between, the primary means of engine load control is transferred from the throttle plate to the intake valvetrain. By eliminating the throttle plate's "bottleneck" in the intake track, pumping losses are reduced, fuel economy and responsiveness are improved"

So how are pumping losses actually reduced? As far as I know, a cylinder starving for air is a cylinder starving for air, whether the bottleneck occurs at the throttle plate or the valve. That cylinder then robs power from whatever cylinder is firing at the time, becasue it will take more power to draw the piston down against a partial vacuum.

No?

Bruce

[bruce.augenstein@comcast.]

Originally Posted by Radiation Joe

With fixed valve opening durations, pumping is most efficient through limited rpm ranges. Even with VANOS the rpm range is still limited. At other engine speeds, flow can proceed for a short time in the wrong direction (reversion). This is made worse during part throttle because the high vacuum maintained in the manifold increases the reversion effect. It takes energy to reverse this flow. By limiting the valve duration to a period when intake pressure/momentum ensures positive flow in the desired direction, this reversion energy is conserved.
I also used to wonder how this saved pumping energy, because the engine still creates a vacuum in the cylinder at part throttle. It wasn't until I considered reversion that it made sense. There's probably a better explanation on the internet somewhere. I'm just pulling this out my butt.

I wasn't aware that the technology provided for variable valve duration as well as lift. That's a plus, from my point of view, but still doesn't explain how pumping losses are reduced.

As far as reversion goes, it really isn't a bad thing. Nowadays, you need to mix exhaust gas with the intake flow to keep flame front temps below 3500 degrees, where oxides of nitrogen are formed. The current state of the engineering art is to eliminate the EGR valve because you're deliberately allowing reversion.

Bruce

PS - I can't seem to find a good explanation from BMW on this.

[ModBargains.com]

Xenon headlights have been available for cars in Japan for way longer.

[KenH]

And Honda had an "on-board navigation" system on the Legend back in 1990, although it wasn't satellite based.

[synclastica_86]

Sure! Take some existing technology... let the in-house engineers put a few BMW touches on it ... then claim a BMW invention.