Gazoline injection at TDC
Gazoline injection at TDC
(OP)
Why don't they make a gazoline engine that compresses only air and uses fuel injection at TDC (top dead center), just like in diesel? Looks tempting - high compression, better efficiency and so on. They even made a HCCI engine with lots of control problems that didn't stop them, so there must be a fundamental reason not to inject the gazoline at TDC. I tried very hard to find that reason on the web, but no result. Could anyone tell me? Thanks a lot in advance.





RE: Gazoline injection at TDC
Gasoline is not the right fuel for compression ignition
RE: Gazoline injection at TDC
RE: Gazoline injection at TDC
RE: Gazoline injection at TDC
RE: Gazoline injection at TDC
And, back when there was a thought of using gasoline-direct-injection in lean-burn mode, some of them *would* inject sometime into the compression stroke under some operating conditions.
But, emission regulations (primarily NOx) killed the idea of lean-burn gasoline direct injection. If you are going to use stoichiometric direct-injection, there is little purpose to injecting it late. Might as well inject it early and give it more time to vaporize.
You COULD theoretically still use lean-burn gasoline direct injection, if you use the newer de-NOx catalysts that the diesels are doing. But, that's expensive. If you are going to make a gasoline engine as expensive as a diesel engine because of the exhaust aftertreatment, you might as well go all the way and use a diesel engine running on diesel fuel.
RE: Gazoline injection at TDC
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I drive an Audi with an FSI engine in it and it will pull cleanly from 1200rpm in top gear, foot to the floor. Wouldn't consider it particularly economical though.
Harry
www.tynevalleyplastics.co.uk
RE: Gazoline injection at TDC
RE: Gazoline injection at TDC
All Mitsubishi current production engines with "GDI" are direct injection - mostly outside North America. I think they were first to production with this.
There is a version of the GM Ecotec 4-cylinder with direct injection in current production.
The BMW 335i uses gasoline direct injection.
Honda, Mercedes, Mazda are others that I can think of, off the top of my head, that have current-production direct injection gasoline engines although not all are in North America.
RE: Gazoline injection at TDC
Heavy oils have to be "upgraded " to diesel and upgraded further to produce gasoline.
Bill
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"Why not the best?"
Jimmy Carter
RE: Gazoline injection at TDC
The type of DI used in the Mitsubishi GDI and VAG FSI are termed first-generation side-injector wall- or air-guided systems. BMW is the first I know of to put the state-of-the-art spray-guided system with centrally-mounted piezo injectors (not too far removed from Diesels!) to series production in its "High Precision Direct Injection" system. It's really quite a neat piece of work. Hardly a European OEM doesn't have a development project for spray-guided DI, even DI pioneer VAG has such a program to follow their highly successful (T-)FSI. Why I wax lyrical about SG-DI here is because the BMW system has up to three separate injection events per stroke, with the last one coming very close to TDC and spark plug firing. Contrary to intuition, this last, very late injection drastically lowers soot emissions (yes, read up people, gasoline engines DO produce soot, DI engines especially more than PFI ones!).