Very very simple compared to EFI.
           --
           Paul Lamar ...No rotor no motor.



      Does sliding the throttle provide a valving effect on fuel flow?  You
      sent out a slightly more detailed depiction of the interface between
      the
      fuel line and the slide throttle, but it wasn't quite clear enough
      for me..

      Roughly what fuel pressure will be required to make this system work?
      If you assumed a 0.5" fuel line, roughly how much pressure is required
      to make 300hp, assuming the mixture valve is open (full rich)?  If that
      pressure is applied to this system, what keeps fuel from spurting out
      the top when the throttle is closed?


      Matt-

      Yes.

      The Teflon is a close fit inside the spacer. Any fuel
      getting past the sliding seal will flow to the bottom of the slide
      and out the slide drain back to the fuel tank unless it is
      a high wing airplane. Then, ironically, you will need another
      pump or let it drain over board. However if you close the
      throttle you will probably pull the lean knob which will cut
      off the fuel supply.

      2 to 3 psi has been quoted but it will probably work
      with gravity feed from a header tank according to Aerocarb.
      12 inches of fuel is .34 psi.

      Here is an Aerocarb plumbing diagram.

      Here is the equation.

      Q = AV

           Q = The flow in cubic feet per second (ft3/sec).

           A = The area of the orifice in square feet (ft2).

           V = The velocity of the liquid in feet per second (ft/sec).

            V = 8.02 times the square root of the head for water.

         .387 hole A = .1179 square inches or .0008189.
                   V = 1 for a 12 inch head (water)

      Therefor Q = .0008189 cubic feet per second. 1728 cubic inch
      per cubic foot. 1.415 cubic inch per second. Fuel is 49 pounds per
      cubic foot or flow is equal to .04 pounds per second or 2.4
      pounds per minute or 144 pounds per hour or 24 gallons
      per hour or more than enough :) Whew!

      At .5 BSFC 144 pounds per hour is 288 HP so you might need
      a larger line than 3/8th for 300 HP or a low pressure pump.

      Check my arithmetic.

      The C182 has 3/8 fuel lines but the head is more like 3
      or four feet.

      Paul Lamar ...No rotor no motor.



Okay thanks Paul..  Have you read either of the following?

http://www.ellison-fluid-systems.com/manual/section1.htm#4

http://www.ellison-fluid-systems.com/article/notaposa/notaposa.htm

I find it interesting that Ben Ellison talks about a demand regulator,
"Fuel is admitted to this metering tube by a demand regulator designed
to maintain a slightly negative fuel pressure. "

Your system sounds much simpler...  More like the Aerocarb than the
Ellison..

I found this comment about the aerocarb, which I thought was
interesting:

"Mine was also easy to set, and works well. 25 hrs of run time
on it. The only interesting thing it does is run faster at idle
when the tank is full, versus when the tank is empty. which makes
sense since it would have different pressure at the carb. I just
set it at a happy medium. I also added a spring to pull the
throttle open if the cable should come loose. this also took
away the last little bit of stickiness that was left."

http://mylist.net/archives/corvaircraft/2003/002499.html

Paul, do you think the mixture in your system will be dependent
on fuel system pressure?  If not, why?


Matt-

No it will be but with a low pressure regulator that should take
care of it.

----------------------------

I was making some flow calculations based on 2 psi (4 foot head)
and I was amazed about the amount of fuel you can get through
a .016 orifice at 2 psi. Hard to find a 2 psi regulator these days
as everything is either a 800 HP carb for NASCAR or EFI.

Here is another company making low pressure mechanical fuel
injection.

http://www.kinsler.com/constantflow.htm

Here too are some of their tables.

Looks like I need to do a bit of experimenting with
some holes with a one foot head.... header tank.
I think a simple header tank with stand pipe and recirculating
fuel back to the fuel tank may be the way to go.

It is also becoming  obvious the 1/4 pipe valve from
Home Depot is too large for the leaning valve. McMaster
Carr has some smaller 1/8th pipe valves  that will probably work
better. Cost is about $11 :)

Here is some data from a 2 psi system.

Somebody PLEASE check my flow numbers.

-------------------------------------------------
OK the results of the program look more reasonable
when I add gallons per hour and HP.
HP is based on a .6 BSFC which is more like what you
will get running full power. You lean from there to
get down to .47 at cruise.

BTW McMaster Carr to the rescue. They have a little 1/8
pipe brass regulator with a tiny pressure gage on it
for $27 :) Put it on the floor after the low pressure
electric pump.

----------------------------------------------

Here is the ball valve I bought for the leaning
valve. The lever can be extended to get the full
three inch travel of the vernier control cable.