> Wish I had time to discuss this at length but alas, I don't.
Working
> on other stuff like stand-alone auto-tune, knock sensor
handling
and have to actually build this stuff : )
>
> The EC2 was designed with a plenum manifold design but FWIW,
it
would work in this scenario just fine if the sample were taken
at the peak pressure point. Just need to know exactly what time it
occurs.
Will be
> interested in the results of your tests if it happens.
Knowing
the absolute value of peak would help to set the initial flow
rate in
Mode 3
> but not a 'must have' item.
> Tracy (replacing a failed LS1 coil on my plane today)
>
>
> --------------------------------------------------------------
>
> Thanks for your input on this Tracy. The problem with two
P-port
pressure taps "Teed" together like we are using now is the
runner pressure pulse data is 180 out of phase from runner one
to runner two thereby canceling some of the pressure.
>
> I was just thinking about using two pressure sensors one on
each
runner and an auxiliary PIC to process the info and send you
corrected
> pressure data when you need it.
>
> So far I have not figured out how to do the second part.
>
> ..... Wait a minute.... I just got it!!! Use the first
> RX7 gen vac solenoid valves to switch the hoses in time with
the
RPM. That might work. I could condition and amplify your
ignition pulse to switch hose connections. Forget the aux PIC.
> I'll have to check the speed of those valves. I have plenty
lying around.
>
> The ultimate p-port solution is two separate pressure sensors.
One for
> runner one and one for runner two. Mount the sensors on
> the manifold and run wires instead of hose for quicker
response.
>
> Paul Lamar
Except as a diagnostic tool, is it critical to get separate MAP
data for each rotor? Why not take the peak reading from one of
them and assume the
other one is going to have the same value?
I am starting to get it. I had an epiphany (well, maybe not,
but..
) last
night as I was going to sleep, and Tracy's comment confirmed it.
I
was considering the case of having the throttle on the cold side of
the plenum. In the case of having the throttle close to the port the
measurement of MAP is different. There is very little volume in the
system between the throttle and the combustion chamber.
Regards,
Matt-
Sampling only one might work. We need to try that. We can watch
the
EGT'S and see if they are nearly the same.
Problem is Tracy samples (for this rotor's injector pulse width)
right about the time the exhaust port opens. (20 degrees before TDC
on the other rotor.) Not optimum when the pipe is on song. (Is
resonant)
I need to talk him into moving the sample in software. That
should be easy and not affect the plenum systems.
Paul Lamar
That's more or less what I had in mind. It's easy to change &
use
one sample for both rotors and would not cause any problems in
aircraft applications.
Bill Dube' sent me the Renesis injector flow rates and I was a
little surprised to see that the yellows were rated less than the
Blues. 4 Blue injectors would work fine but 4 yellows are running
close to the limit at 8000 rpm. Above that, I'd use the 6 injector
solution I outlined before.
Tracy
Paul,
Thinking about this more.. If you used an integrator, you need to set
it up so that the integration window is only during the port-open time.
Otherwise, you might as well use the thing I was talking about
(essentially a mechanical integrator).
Okay, so maybe you need a peak-detect-hold circuit.. The way it would
work is the output from the MAP sensor would be fed to the input of the
peak-detect-hold circuit, and then to the MAP input on the EI computer.
An output from the EI computer would reset the peak-detect-hold circuit
- preferably when the port is closed on each cycle of operation. This
way, you get to see the full value of the supercharging effect, and the
timing of the MAP sample becomes a moot issue.. The hold portion of the
peak-detect-hold circuit retains the sampled peak voltage until it gets
reset. How's that?
Here's an IC that looks like it might be the right idea. I haven't
priced it..
http://www.amptek.com/ph300.html
Or maybe something like this, though you'd have to rig a switching power
supply to make it work..
http://www.chipcatalog.com/Analog/PKD01EP.htm
Matt-
I hate to reply to my own messages, but after re-reading this, I realize
that I didn't include something kind of critical... Even with the added
circuit that I suggested, the sample of the output of the peak-hold
circuit has to be taken when you are sure that the peak has already
happened.. During the exhaust period should be safe... And then
immediately reset the circuit so that it's ready for the next cycle..
Another idea - another software-only idea that is.. Start taking samples
once the intake port opens, and keep taking samples until the port is
closed. Prior to taking the first sample, load a general register with a
very low value (to initialize). Then, keep comparing the new sample
agains the value stored in the register. If the new sample indicates a
higher value than what is stored in the register, replace the value in the
register with the new sample. Software peak-detect-hold.. No math
(beyond comparison).
Regards.
Matt-
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