I suggest if you are interested in this system you make
 a folder and drag over all the many future messages on this
 subject otherwise delete it.

 I just add another idea.

 Since we have 16 channels of A to D it would be real cheap
 to add a compression checker.
 All it takes is another FreeScale $10 pressure sensor.

 That means you turn the engine over with the starter,
 connect a hose to the pressure sensor and a phony
 spark plug pressure tap. The computer samples the pressure
 1000 times a second so you get a plot of the compression
 pressure.

 A very low cost option.

 http://www.zbasic.net/

 So simple a caveman like me can do it.

 Paul Lamar


----------------------------------------------------
Paul,

 This may be a good time to incorporate a knock sensor into the system.

Which board are you recommending interested parties order.  I didn't see
the
1284p development board that you mentioned in an earlier post listed.

Mark S.

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

The easy way to do a knock sensor system is connect the knock
sensor to a simple amplifier and use an ear bud. The brain is great
at detecting different sounds. It is much tougher designing
an audio filter that only passes the unique sound of detonation.

Knock is unheard of (pardon the pun) on normally aspirated rotaries
however the higher compression ratio RX8 engine might be different.

Turbo engines are a different matter. Real possibilities there.

Here are some ideas. I tested one or two of these circuits
by hitting a rotor housing with a ball peen hammer to simulate knock.

This is the $90 computer board I choose. ZX-1280n

IMHO you want the knock circuit to hardware interrupt the processor
so the knock can be detected immediately and dealt with by
retarding the ignition and or richening the mixture. This board
has seven hardware interrupts to work with. This can happen in
microseconds after the interrupt pin is taken low by
the knock amplifier/filter. Still might be too late.

BTW Mistral determined it is nearly impossible to crack
an Ianettie ceramic apex seal by detonating the turbo engine
and they were running on kerosene.

Paul Lamar


Paul

Thanks for the clarification on the development board p/n.  I may order one
and play around with it.  Who knows, I may accidentally develop something
useful!

Funny you would mention running a rotary on kerosene.  Bob Darrah and I were
discussing this just the other day, more specifically, running on pump
diesel.  The attraction is that it is $1 - $1.50/gallon cheaper than 100LL.
That equates to a savings of $100 - $150 per fill-up on my Lancair.  Also,
it doesn't contain ethanol like most mogas does.  I understand that you must
start the rotary on gasoline, then switch over once it is warmed up.  Do you
know of any serious studies on doing this?

Mark S.


I am just getting mine talking to my XP computer.

If you plan to use the USB rather than the RS232 port for communicating
you must do this.

You’ll need to download USB drivers from the FTDI site and install
them manually.  The FT232R drivers are available directly from FTDI at
http://www.ftdichip.com/Drivers/VCP.htm.  Note that the CDM driver (whatever
that is) is not  available for all operating systems.  Be sure to download
the drivers for the FT232R device that match your OS.

No instructions on running on kerosene and a lot of people that were at
Mistral are now gone. They may have had direct injection. Wankel AG
uses direct injection to run on kerosene.

Perhaps Francois remembers how to do it.
I'll forward this to him. You will be down on power and as I recall
there are no BSFC benifits.

Paul Lamar