The octane thread got me thinking (very dangerous).

With all this talk of DFI intake valves gunking up, I saw this Porsche graphic a while ago which shows fuel being sprayed directly over an opened intake valve. If this is accurate, it appears Porsche figured this problem out.

Opinions?

Peace
Bruce in Philly

http://mywebpages.comcast.net/bruced...2009911DFI.jpg
I can't get the pic to just appear.... any help here? Too big?

 

I am not sure the graphic is an accurate description. Why would one need DFI if you are going to inject while the valve is open? Would the intake valve be wide open at the bottom of he piston stroke? Maybe, I do not know. Perhaps someone else can comment.

You get better mixing and lower emissions with port injection. DFI enables a higher compression ratio for more power. The upcoming engines from VW/Audi ( 290 hp 2.0L 4 cyl turbo) have both DFI and port injection. DFI is only used for idling and for full power. Port injection is used most of the time to keep emissions lower, produce less soot and keep the intake and valves clean. I had a 2008 DFI BMW 535 ( big problems). That is why I am happy that I have a Porsche with port injection.