cmattson

Direct Injection and pushrods

10 posts in this topic

Ok, think of the top of a cylinder on a GM pushrod. Ideally, you'll have 3 valves, put possibly only 2. You have a rocker assmebly sitting over the top of the valve that actuates the valve itself -- and that takes room. You don't want to limit placement of the spark plug -- ideal location is dead center of the cylinder -- to provide with a complete, uniform spark -- which will give you the cleanest, most efficient fuel burn. How do you squeeze a fuel injector into that all that? If direct injection provides the substantial power boost and fuel economy gains it's rumored to deliver, does this deliver a death-blow to GM's pushrods? I'm not saying they'd immediately go away -- I'm saying that if/when direct injection becomes common-place, if GM cannot adapt the technology to it's pushrods, GM may have to make the decision to not create the next-generation pushrod engine. Your thoughts? Has anybody heard of GM attempting direct injection on a pushrod?
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Sure, why not? If you can make a 3 valve pushrod, you can easily make a 2 valve direct injection.
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Mercedes houses its spark plugs and fuel injectors in the same unit on their DI units. Why would it be different with Pushrod engines vs OHC?
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GM will do it, they have done nearly everything else with the pushrod, VVT, 3 valves, high revving. You gotta have faith!
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Ok, think of the top of a cylinder on a GM pushrod.  Ideally, you'll have 3 valves, put possibly only 2.  You have a rocker assmebly sitting over the top of the valve that actuates the valve itself -- and that takes room.  You don't want to limit placement of the spark plug -- ideal location is dead center of the cylinder -- to provide with a complete, uniform spark -- which will give you the cleanest, most efficient fuel burn.  How do you squeeze a fuel injector into that all that?  If direct injection provides the substantial power boost and fuel economy gains it's rumored to deliver, does this deliver a death-blow to GM's pushrods?  I'm not saying they'd immediately go away -- I'm saying that if/when direct injection becomes common-place, if GM cannot adapt the technology to it's pushrods, GM may have to make the decision to not create the next-generation pushrod engine.  Your thoughts?  Has anybody heard of GM attempting direct injection on a pushrod?

[post="41352"]<{POST_SNAPBACK}>[/post]


Direct injection does seem to be in the plan.

http://www.bayern-innovativ.de/media/stati...trag_FIndra.pdf Edited by Ghost Dog
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You don't want to limit placement of the spark plug -- ideal location is dead center of the cylinder -- to provide with a complete, uniform spark -- which will give you the cleanest, most efficient fuel burn.

Spark plug placement has everything to do with the shape of the combustion chamber. A hemispherical (or in the case of the Hemi: a shrouded hemisphere), central location is paramount. But wedge chambers have the plug offset to one side. Modern multiple-discharge, high energy sparks reduce the importance of plug location to a degree, also.
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My 64 Fordson Dagenham Diesel 330 cu in I6. Is a pushrod 2 valve engine and has direct injection. Im trying to vision this and I cant see how theres more room in a DOHC & multi valve engine. In fact I believe the inblock cam could offer less conjestion.
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It does seem though, that much of what was talked about for the ohv engines is M.I.A. The Three valve heads. D.O.D for the 3.9 litre v6 I wonder if the technology failed.
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It does  seem though, that  much of what was talked about for the ohv engines is M.I.A. 

The Three valve heads.
D.O.D for the 3.9  litre v6

I wonder if the technology  failed.

[post="63251"]<{POST_SNAPBACK}>[/post]


the 3.9L DOES have DoD currently, but its deactivated... i suppose you could turn it on yourself if you dont mind a "noise" of some sort
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