I think the main problem with pneumatic VVT systems like the Cargine is their complexity - there are quite a few mechanical systems that can perform much the same tricks as the Cargine system (if indeed it does work as claimed) that are far simpler and consequently far more reliable. There is also the basic problem that a car left unused for some time may have lost its stored air pressure and have a flat battery etc. How would you get it running again? Cargine claim several "limp home" strategies - but presumably the main strategy would involve a tow truck. I would imagine all the current mechanical VVT system would have a limp home strategy - the main one being to act as a fixed timing system that is non-VVT.
Everybody seems to have glossed over the fact that the Cargine system needs a compressor and associated pipework etc. Presumably this is considered a mere detail - but it isn't. As an analogy - air spring systems (as in F1) are undoubtably superior at high RPM - but there are no production road-going equivalent systems (that I know of anyhow). Why isn't there any - apart from not being any better than steel springs at "normal" high RPM (not F1 RPM) there are the lack of stored air etc. problems, need for a compressor etc.
The disadvantages of the Cargine pneumatic system far outweigh any advantages it may have (and the advantages are debatable anyhow).
This is full of some of the weakest arguments I've ever read.
First - there are exactly none mechanical systems that offer the fully variable lift, duration and timing proffered by the Cargine system (assuming it works as advertised). You might want to spend the time reading that paper GG posted from the Cargine site - someone's PhD paper - that discusses the current offerings.
If your long-parked pneumatic valvetrain'd car has no air in the tank and a flat battery, you'd start it the same way you'd start any car I assume - a boost or a battery charger. Just like every other car. Worst case scenario, a boost and a connection to a compressor - perhaps your spare tire. It's not like it runs on compressed fairy farts - it's air. You note that it might limp home in non-VVT mode as if that's worse than any other limp-home mode in any current computer control system.
Why isn't the compressor a mere detail? Or the piping? Two lines connected to a valve cover that has a manifold cast into it. Oooohhhh...the insurmountable complexity! You point out that air springs
have no benefit to engines operating at typical passenger car speeds, but then use the "complexity" argument as the reason why it's not implemented. Have you ever looked at Porsche's Vario-Cam plus? Or the sequential turbocharged BMWs? Variable geometry manifolds, throttle-by-wire...an effin' compressor and some piping don't exactly set themselves apart as another level of complexity.
The disadvantages (a compressor and piping, imagined re-start problems after long periods of neglect and...oh yes, a non-VVT limp home strategy that we aren't sure even exists) outweigh throttle-less operation, fully variable valve lift, duration, overlap and timing, cylinder deactivation, deactivated cylinder as air-compressor, compressed air hybrid operation. I'm afraid I disagree as I would think most do, including the numerous companies including GM, Ford, Lotus and of course Cargine that have or are all pursuing it.