Fuel Injection and Variable Timing

"Robert M. Gary" wrote in message
ups.com...
I would say that the advantage of direct port injection is that the
computer puts exactly the right amount of fuel in that cylinder at the
exact right time. The injectors on my Mooney are running all the time,
the injectors on my Saturn only run (actually pulse) when on the intake
stroke. I've never seen aircraft injectors that had computer wires
going to them.

-Robert

I also own a couple of 96 S1 series Saturns and am very happy with their
economy and utility, however I think you are mistaken regarding the fuel
injection.

AFAIK the 91-94 SOHC engines used a single electric injector mounted in the
throttle body. The 95 and all DOHC engines use one injector per cylinder
located in the port close to the valve, however while this is called
sequential port injection the injectors pulse once per revolution (@60
degrees BTDC) or twice per cycle so are actually pulsing on both the intake
and exhaust cycle. It seems counter-intuitive to me, but it works well so
the Saturn engineers must know something we don't. The ignition is also a
waste spark type that simultaneously fires two cylinders, one near the top
of the compression stroke and one near the top of the exhaust stroke.