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I've been wondering this for quite a while, given that modern DFI systems for gasoline engines were developed along the lines of diesel engine principals.
First of all, unless I've missed something, why haven't gasoline engines used piezo injectors like diesel engines? And is there such a thing as a common rail gasoline DFI system? What are the possible hurdles to using such technology on gasoline engines?
I am no automotive engineer, but maybe it has something to do with the combustion qualities of gasoline vs. diesel? Diesel fuel tends not to burn as readily and you need high compression with no spark plug.
[QUOTE=Chernaudi;1017549]I've been wondering this for quite a while, given that modern DFI systems for gasoline engines were developed along the lines of diesel engine principals.
First of all, unless I've missed something, why haven't gasoline engines used piezo injectors like diesel engines? And is there such a thing as a common rail gasoline DFI system? What are the possible hurdles to using such technology on gasoline engines?[/QUOTE]
Most GM direct injection gas vehicles are common rail! My 2012 & 2013 Buick Lacrosses are common rail! The piezo injector question is basically what NSX said! The compression of a Diesel engine is to high for a standard injector! But the standard injector is much cheaper to make than a piezo injector, yet the standard injector is more than capable to handle the compression of a modern gas engine!
Indeed for petrol engines the common rail is becoming more common. Due to lower fuel pressures the gain from them is a lot less then on diesel engines though. The idea is basically that there is one high-pressure fuel line from the diesel tank to the rail and they are running at similar (very high!) pressures. That hardware is made to tight tolerances, so expensive. Piezo injectors are better, but also more expensive. As pressures are lower in a petrol engine there is simply no need and you can get away with cheaper injectors.