We ran it and flew it Matt. Mustang II. No fuel cloud with
 fuel injection. The cloud is caused by the reverse flow through
 a carb. The venturi cannot  tell the difference so fuel comes out
 regardless of the flow direction.

       Mark Steitle is flying one as FI p-port 3 rotor.

       Paul Lamar

  Paul,
   Do p-port engines have much of a tendency for fuel stand-off? It
 is a bit of a problem in piston engines especially with IR type
  intakes  because of the pressure pulse reversal when the intake
  valve closes.  A p-port does not really close the intake flow and
  stop it  momentarily. It gets redirected to the next side of the
 rotor as the  apex seal passes the port. Your charts of intake
  pressure show like  a sine wave. Intake tuning does affect this but
  the amount of  pressure difference should not cause a stand off problem.
   Dale Davies

   There is no stand off with Tracy's efi. IMHO it is a carburetor phenomena.
  The venturi in the carb cannot tell whether the air is flowing in
   or  out so to feeds fuel into the air stream regardless.
   Paul Lamar

 I don't think a carburetor p-port will have an issue with fuel
 stand  off for the reasons I stated. Automotive V8s will have it
 even with  a single carburetor. Even note the brown stain on the air
 filter  lid? If there is a tendency to have stand off with a carb,
 it will  do it with EFI also due to the pressure pulse. Throttle
 body EFI  more prone to show this phenomena. Port EFI masks it as
 the runner  length does not allow the fuel cloud to escape before
 being injested  again. A port EFI with the injectors at the open
 inlet end could  display the fuel stand off. A side port engine
 should have a  slightly greater chance of it, due to the longer port
 closing  between intake events.
 Dale Davies

 The carb p-port standoff is spectacular. This is a Weber carb.
   http://www.youtube.com/watch?v=NKJ00JsnS8A

 Paul Lamar

 Ok. So if you removed the Weber and installed a throttle body EFI
 from say a 454 Chev, the fuel stand off should be the same. If you
 extend the runners to the same length as the Weber carb tops and
 then put injectors just above the pipes, the stand off should also
 be similar. On the long intake of 24 to 28 inches, the stand off
 should be changed. At least the RPM that it becomes prevalent, will
 change due to the tuning effect. How was the Le Mans 26B engine for
 stand off? Yes the youtube video is spectacular and revealing.

 Dale Davies

 Here is about what your are describing and there was no stand off.
 We ran it with the top off the air box. I was surprised.

 Paul Lamar


So Paul,

If you moved the injectors to spray in the open tubes, do you think you would
get fuel stand off? With the Weber carb, if you mounted ram stacks like on the
Can Am Chev engines on the throats, do you think you would see the stand off
then. Possibly the length upstream of the fuel introduction keeps it inside.
May increase bsfc or help it. I know if you shine a bright light down a carb,
you can see a fog in the intake manifold.

Dale Davies

We saw a lot of stand off on the CanAm Chevy engines with and without stacks.

I designed a ram air scoop for the roof with boundary layer bypass on the
the Nürburgring winning 2D.. We got much better MPG.

I have not tried spraying fuel into the opening yet.

Paul Lamar