Paul -

 Something I noticed earlier that no one has brought up regarding your
 555 EFI design:

 The airflow sensor you use measures airflow by the cooling of a hot
 wire.  The problem is that it measures airflow in ANY direction.  Into
 the manifold or reflecting back out - they both cool the wire.

 As your Renesis engine video demonstrates, air pulses do travel BOTH
 ways in the manifold, and at some RPMs will resonate.  In the video
 this caused mist demons above the carburetors, actually spitting air
 and fuel back out of the carb.

 This will likely give erroneous airflow readings when transitioning
 those resonant RPMs, since the sensor will be measuring the airflow
 both ways.  Quick transitions may be alright, but hovering near a
 resonant RPM range will probably get interesting, especially if you're
 in the air.

 This problem isn't insurmountable.  You could use the "mist demon box"
 you described earlier to contain resonant pulses, and place the
 airflow sensor at the intake to that box.

 I just thought I'd throw that out there ...

 -Vince Orton

 That is what we intend to do. Note the RX8 uses a mass airflow sensor
 and it is a highly tuned system. In fact by switching certain intake
 valves
 on and off it is tuned almost over the entire RPM range.
 I should also point out the pulsing is 180 degrees out of phase
 for each pipe. When one sucks the other blows.

 We had the same vapor standoff problems back in the mid 1960's
 on the Chaparral 2D race car using carbs. That is when I designed my first
 ram air box plenum on a car that won the Nurenbergring.

 For the new guys here is a video on the RX8 p-port engine on the
 Mazdatrix dyno showing the phenomena.

 http://www.youtube.com/watch?v=KQL45DYgIFw

 Here are some 3D's showing a 2nd gen mechanical mass airflow
 sensor.

 Also Mark Suspinski just built one for his Mustang 2 with
 a p-port 13B engine and it is running OK. Tracy is working
 on tuning it as we speak but with only a single few micro second
 sample of the intake manifold pressure he has his work
 cut out for him :)  For 10 microseconds the instantaneous pressure
 could be anything inside an intake manifold.

 IMHO that is one possible reason why people have so much trouble tuning
 their
 systems. I have discussed this with Tracy and suggested a bunch
 of samples over a time period and then averaged in software. I don't know
 whether he implemented that or not. He does not pass out the program
 source
 code.

 The mass air flow hot wire sensor averages the flow.

 Paul Lamar


Paul,
my favorite part of the Chaparral picture is not the air box.... it's the
spare tire!
Larry :)

Required for racing in that class. We lost the Targo Florio while leading
because the spare was flat :)

Paul Lamar