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?

Sure, why not? If you can make a 3 valve pushrod, you can easily make a 2 valve direct injection.

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?

GM will do it, they have done nearly everything else with the pushrod, VVT, 3 valves, high revving. You gotta have faith!

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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Direct injection does seem to be in the plan.

http://www.bayern-innovativ.de/media/stati...trag_FIndra.pdf

Edited December 24, 200520 yr by Ghost Dog

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.

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.

The XV8 was a direct-injection dual-cam 3V pushrod engine.

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.

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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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