"Robert M. Gary" wrote in message
oups.com...
Cars also use port fuel injection. I"m not aware of any airplane engine
that has port fuel injection. I'm sure that must add to the efficiency
of cars a lot. In the 80's some car manufactors used the intake
injection system airplanes use today (as well as throttle body
injection). Apparently they were very difficult to smog, that may tell
you something.

-Robert


The big advantage to port injection (v.s. throttle body injection) is that
you don't have the whole surface of the intake manifold covered with fuel.
With port injection the puddles are limited to the port area (including the
back of the intake valve). With less liquid fuel mass (and surface area) in
the intake, it is WAY easier to compensate for transient conditions when the
puddle mass is changing. The other advantage, is that it is difficult to get
good cylinder to cylinder fuel distribution with throttle body injection (or
carburetors for that matter).

Aircraft engines don't have the problem with transient conditions since they
pretty much run steady state. The cylinder to cylinder distribution
advantage still stands.

--
Geoff
The Sea Hawk at Wow Way d0t Com
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