So Al how well does this work? Does it keep the mixture constant
    as you change altitude? As you change prop pitch?

    Paul Lamar

    Paul, I am wondering here why you are concerned about mixture
    change
    vs. pitch? Any carb system will change mixture slightly until you return
    to a steady state. In the Holley carbs they use a secondary system to
    maintain the mixture in a WOT low RPM state. (power valves) I'm sure
    you know this. A vacuum slide carb works better, but isn't instant.
    The Alpha-N FI systems will usually still outperform carbs in this
    situation.
    There may be some variance but it will be slight. If you run a O2
    sensor
    it will be better than carbs by far. Just curious what the buzz is
    about?
    Bill Jepson

A carb has a mass airflow sensor and throttle position sensor built in
so to speak. It also senses the rate of change of throttle opening.
That is done by the acceleration pump.

Tracy is using manifold air pressure, RPM  and air temperature
sensors only.

It does not appear to work on a dyno where the load changes
widely at any RPM. I attempted to tune the system and gave up
after a day or too. It was getting too expensive at $650 a day.
We stuck the Weber on there and had it tuned in five minutes.

A fixed pitch prop has only one load for each RPM.
A variable pitch prop and engine dyno has many loads for the same RPM.
What ever is going on I could not get it to run well
on the dyno for what ever reason.

The O2 sensor will work for awhile to set up the  look up
table in the computer but will deteriorate with the use of 100LL.

BTW this is another  interesting EFI system  I just discovered.

http://www.dtafast.co.uk/
http://www.zetecinside.com/xr2/injection.htm
http://dtaforum.psycode.com/index.php


Paul Lamar ...No rotor no motor.

Paul,
I think it was mentioned that you didn't have plenum to get a good manifold
pressure. I think Tracy put his in the Plenum.
I don't know enough about these sorts of things, so if I'm wrong ignore my
message.
George ( down under)

That is correct. We had a T in the system connecting the two intake
runners down stream from the throttles. Perhaps a large vacuum chamber
is necessary to damp out the variations. Tracy also takes a snap shot
of the intake manifold pressure while several samples over time and
averaged would perhaps work better.

Paul Lamar

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