John Kahoon wrote:
> What I've wondered is if.. you remove the fuel bowl, attach the fuel
> lines to the jets, then fabricate a needle that would go from, full
> shutoff to the appropriate "wide open" amount of fuel for the maximum
> air. Would you not have a throttle body fuel injector, with its own
> engine sensor ( slide/ vacum ) compensator ? Anyone game ?
Might be an interesting plaything. I can think of two problems,
but interestingly, they cancel out a bit.
One is that the fuel pump is really low pressure. The first
EFI systems used a fuel pressure of about 15psi, late models
typically run around 40psi. Our fuel pumps run less than 4psi.
The other problem is that the fuel opening in an EFI car is
only opened very quickly, just pulsed. Mechanical fuel injection
cars run like you suggest, however, but the injection ports
are very tiny.
So you have an opening that's much too large, and fuel pressure
that is much too low.
> My guess is that this set up would ( properly setup and adjusted )
> would out perform any standard throttle body injector available.
> Any thoughts?
Have a look at the Lucas or Bosch mechanical fuel injection
of the 70-era. Like LUCAS PI or Bosch K-jetronic. They kind of
do what you are suggesting, but they don't work with that
method.
Essentially, there is a very tiny piston in a tube that
has "just the right" holes in it. The piston is connected to
a lever, the other end of which is a rather large plate
that has one side at atmospheric pressure and the other
side at manifold (ie, like a carb jet).
The effect is that as more air flows over the plate the
pressure decreases, and the plate is sucked more and
more one way. This levers the piston up and down in the
tube and uncovers just the right about of holes to get
the correct fuel flow.
It works well when it works, but it's notoriously finicky
and requires a lot of fiddling.
--
Trevor Boicey
Ottawa, Canada
tboicey@brit.ca
http://www.brit.ca/~tboicey/
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