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germanbird writes: "Jalopnik has an interesting article up about Koenigsegg's Prototype Camless Engine. The engine uses pneumatic actuators rather than a cam to open and close the valves in the engine. The engineers behind this claim that it can provide "30 percent more power and torque, and up to 50 percent better economy" when applied to an existing engine designs. The article and some of the comments also mention that some work has been done with electromagnetic actuators to accomplish the same task. It may be a while before this tech is mature enough for passenger vehicles, but maybe if a racing series or two picked it up, it might give some of the manufacturers the opportunity to work the bugs out?
Not sure this is on topic for SoylentNews, but the article brought me back to my introduction to engineering course in college. One of my classmates was a car nut and I remember a discussion with an EE professor one day about the potential (or actually lack thereof due to performance issues) for using electric actuators to open and close valves."
(Score: 2, Informative) by drussell on Friday February 28 2014, @10:33PM
Yes, it's still a problem, and is the reason that many larger diesels (esp. stationary engines) have emergency air shutoff damper valves.
The burning of the diesel fuel (which can be halted by the electric fuel pump shutting off, some kind of mechanical fuel valve closing or even emergency hack to the fuel line with an axe) isn't the only possible cause for a runaway. It is true that if your rack hangs open or some other type of main fuel system failure causes the runaway, the regular fuel cutoff / anti-run-on device should cause the engine to stop when the key is turned off.
The more common reason for a diesel runaway, especially on turbo diesels, however, isn't fuel, it's engine oil. Whether it's pulled in due to a worn engine, overfilled crankcase, cracked block/head or most likely on a turbo, failure of a turbo shaft seal spewing engine oil into the intake side. The engine is now running on the crankcase oil instead of diesel. Shutting off the key won't help and there's many, many times more than enough oil in the crankcase to destroy the engine before it runs out.
The only surefire way to stop a runaway diesel is to block the air supply. This can be done either by covering the air intake completely with a book or block of wood or whatever, (usually only practical during service with easy access and air cleaner removed) or better yet, simply blasting the air intake area with a CO2 type fire extinguisher (NOT a dry chemical one, that would destroy the engine!) until the engine stops. Works like a charm. Most people who work on diesels know to have a CO2 type extingisher right handy in the shop, always ready for this purpose.
Personally, if I had a diesel vehicle, I'd carry one with me, just in case. (I have dry type extingushers in my vehicles, but if I had a diesel I'd have a CO2 for it also as well!)