Direct fuel injection: What it is, how it works
Direct fuel injection isn't exactly a new technology, but it is new to most automotive consumers. Isuzu introduced the first gasoline direct injection vehicle to the US market in 2004 (anyone remember what it was called? Click the "comments" link below -- no fair looking it up online, that's cheating!). Today, Audi and Volkswagen are probably the most prolific purveyors of direct-injection gasoline engines; they call it FSI (for Fuel Stratified Injection, although I'm sure it stands for something much more impressive in German).
I've got direct injection on the brain because I'm just putting the finishing touches on my review of the 2008 Cadillac CTS, which offers an optional direct injection engine. Cadillac recently introduced a direct-injection V6 as the base engine in the 2008 STS. With 35 MPG CAFE on the way, you can expect to see more and more vehicles with direct injection under the hood -- so I've put together an artcle that explains what direct fuel injection is and how it works. -- Aaron Gold
Photo © General Motors
Comments
I’m pretty sure it was the V6 in the Rodeo. Not sure if any of their other models shared it, and have no clue what they called it, maybe DFI? Nah, now that I think about it, the ‘DFI’ moniker had been so soiled by the horrible 4100 V8 Caddy motor of the 80’s I doubt anyone would use it. Now I’ll google it and see…
Interesting article. It is surprising that what appears to be a very minor change in the fuel/air intake process should bring such huge benefits in power and mileage.
All of the automakers seem very interested in this technology. Ford says they are well along in the process of bringing direct injection into that most mainstream of vehicles, the F150. Apparently, there will be a turbo-charged, direct injection V-6 available in the 2009 F150, and Ford claims that this engine will have V-8 power with V-6 MPG.
It seems that the standard CTS V-6 engine, while producing less horsepower, produces more torque at lower rpms than the optional direct injection engine.
This should mean more power available when pulling away from stop lights and in lower speed maneuvers that most people make most often in real-life. It sort of makes me question the value of the additional horsepower available in the direct injection engine.
Hey Johnster — Torque of the DI engine is higher, but it does come at a higher peak — the non-DI engine is 253 @ 3100, the DI is 273 @ 5200. Not sure what the DI’s engine is putting out at 3100 RPM; I can try to find out. But I can tell you that it has no trouble pulling away from stoplights.
Great explanation of what is sure to become a common fuel delivery system soon. I wonder if this will ever lead to using direct injection gasoline with combustion like a diesel? If technology gets to where that type of ignition could be controlled it could yield even better gas mileage.
great post aaron!
Steve - you are spot on. Ford is one company that is very interested in this technology for the flex, explorer, f150 (as you said) and the 2010 mustang.
*As a disclaimer I’d like to point out that I Ford is a client of the company I work for. I trust I am being transparent enough
Aaron, I always thought that Cars already had this. The Old VW Rabbit I drove had 5 injectors. One on each cylinder and one in the main intake for acceleration. Were these before the intake valves?
Frank — Multi-point fuel injection (the system used on most cars) does have individual injectors for each cylinder, but the injectors spray fuel into the intake manifold (above the intake valve), albeit close enough to the intake valve so that the fuel should all make it into the correct cylinder. But, anyway, this is different than direct fuel injection.
Ouch! My head hurts reading this stuff!!!