[Super83Z]

Originally Posted by syr74

I've seen that, and all that accomplishes is to further cloud the issue of whether DI is beneficial enough on a pushrod V8 to even be bothered with. GM knows, but we don't and the info provided does nothing to help us. Why do I say that? Simple, DI by itself provides nowhere near that percentage of power improvement on any engine with the exception of forced induction pieces. That means that vast the majority of the power gain cited in that article is from a change other than DI, which in turn means that we have no idea how much of the power gain cited...if any of it....is actually from DI.

As I said before, if the DI versions of the LS series V8 engines were as magical as was claimed, it would already be here shoring up sales of full size trucks and improving fuel economy averages in the process. You aren't hearing much about them now for a reason, and my guess is that reason is disappointing performance in producable trim. Ford already figureD this out and they were thinking of implementing the system on a DOHC platform with three stage VVT on the intake and achaust sides of the valvetrain, meaning they should have been able to realize far more benefit than GM can plausibly hope for given the more limited valvetrain articulation the cam in block, pushrod V8 design is saddled with.

In naturally aspirated applications DI is a very, very expensive way to get a ten percent improvement in power on a very good day, and an even lesser improvement in economy (if any meaningful improvement in fuel economy is realized at all) at the expense of increased nox emissions. It isn't worth it.