Quote:
Originally Posted by cmac2012
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It also occurs to me that they're talking about using compressed air to drive the valves downward, so in that case, having a regular supply of compressed air on board would be necessary. ....
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we can do compressed air at 100-300 psi, that's easy.
If they always need compressed air, now they need to either get an electric air compressor, or attach one to the motor...and if you run out of compressed air, your engine stops. maybe the parasitic drag of an air compressor wont be enough to worry about, or will be eclipsed by thermodynamic efficiency gains of variable valve timing (and higher rpms?) but it feels like the free lunch is getting costly.
and what to do with extra compressed air ? remember that if they put it in the engine, the ECU needs to be able to react fast enough to keep emissions in spec. They are probably capable of this now with existing twin turbo setups etc....but I see a pressurized air tank (with ???psi in it) needing a serious regulator, decent diameter pipe and good engineering to work in 2017.
I think the equation is PV=RT - that allows you to see how many
of air you get from a given of air at XX pressure.
hereafter- "?" means I'm not sure 
basic google: Looks like a basic 2.0L 4 cyl needs 150cfm to run if not supercharged. 300cfm would then give you 15psi of boost (? - Plenty?). Actually less boost because a NA engine intake is always at less-than-atmospheric pressure when running. but anything above 6 or 8 psi is a notable bonus. I'm way open to better facts/curves here.
https://www.chemicool.com/cgi-bin/gaslaws.pl
assume: temperature is held constant at 80F (it wont be, but my thermodynamics arent that good here either)
if you have a 10cu-ft air tank at 1000psi (70atm?), how long will you get 15psi of boost ?
If I'm doing this right, it has 805 moles of air in it, and when vented at 15psi/2atm- nets you 349 Cubic feet of air.
So if you had a 10cu-ft air tank at 1000psi, you could get a full minute at 10-15psi of boost. that's not insignificant.
Sorry for the mixing of 'Merican units
Maybe this isn't such a bad idea. surely I'm missing some physics somewhere (turbulent flow out of tank, friction losses, expensive 2" solenoid valves, fittings and piping in a civilian car that must be rated to 1000psi...
-John