Re: Direct injection gas engine with 18:1 CR - Saab General Bulletin Board - Saabnet.com
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Re: Direct injection gas engine with 18:1 CR
Posted by Craig [Email] (more from Craig) on Wed, 12 Sep 2012 07:36:56
In Reply to: Direct injection gas engine with 18:1 CR, ryan [Profile/Gallery]
, Tue, 11 Sep 2012 20:11:34
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Wouldn't say it is timed by injection exactly; it's really just timed by compression. This is why diesels can't rev very high - a combustion process happens at a fixed rate on any engine, and with compression ignition there's no way to 'advance' the start of the combustion process like you would by advancing the ignition timing(firing the spark plug earlier) in an gasoline engine. The injection process is really just introducing the right amount of fuel for the requested amount of power. Diesels do this with injectors rather than a throttle because diesel combusts over a broad range of air/fuel ratios and therefor doesn't need a throttle to manage air intake (and corresponding fuel intake) like gasoline engines.
I'm sure direct injection gas engines do inject at the optimal time, but the gas is still going to ignite after at a certain compression ratio.
I'm not too up on the fancy stuff, but there is some cool stuff going on with gasoline engines that use compression ignition under certain light load/cruising conditions where a very lean ratio is feasible.
Craig
posted by 66.44.127...
Posts in this Thread:
- Direct injection gas engine with 18:1 CR, ryan , Tue, 11 Sep 2012 20:11:34
- Re: Direct injection gas engine with 18:1 CR, Justin VanAbrahams , Wed, 12 Sep 2012 09:29:25
- Re: Direct injection gas engine with 18:1 CR, Simon S, Wed, 12 Sep 2012 08:12:47
- Re: Direct injection gas engine with 18:1 CR, Craig, Wed, 12 Sep 2012 07:36:56 <-- Viewing This Message
- Re: Direct injection gas engine with 18:1 CR, BobS, Tue, 11 Sep 2012 21:15:34
- Re: Direct injection gas engine with 18:1 CR, Cmyles , Tue, 11 Sep 2012 20:44:16
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