Henry Nee came up with a great idea. If we standardize on a spreed sheet
format for
the mixture map we can share (even across programs). Yours and mine.
This is the megasquirt format.
It is broken down into 8 RPM's and 8 manifold pressures.
Usually EFI programmers interpolate between these values.
Keven, Please do this. It will help other people greatly.
The idea is to be able to dump the table to a PC through the USB and edit
it in the
PC as necessary. Then reload it back into the chip.
This is how it is done in Megasquirt.
These are median values so they can go down to zero and up to 255 as
necessary.
They are also a function of the injector used. If you find that the values
are all on
the high side you could go up on the injection pressure or use larger
injectors.
Same vice versa.
Tracy uses two staged injectors per rotor so there could be one table for
each
injector. The tables only require 65 bytes of flash memory each.
I am using one computer per rotor.
Paul Lamar
Paul,
You said earlier that the rotary typically uses a fixed 22 deg BTC firing
arrangement with both plugs firing simultaneously- are the turbo guys using
this setting as well?
Normally when using higher boost levels, the timing is retarded several
degrees as boost pressure increases. I was thinking that my timing table
would have a few more lines than standard to allow for this. As pressures
go above standard i.e. 31 inches, the timing would progressively be
retarded. I have read in more than one place that using as little as 8 psi
of boost in racing engines requires the timing to be retarded to as little
as 5 degrees BTC. At 8000 RPM this doesn't give much time to burn the
fuel/air charge, but this setting is selected to prevent pre-ignition.
Any thoughts?
Kevin Alderman
As far as I know they do. They may retard. Are you doing a turbo? It has it's
advantages if one plug goes out.
Well what ever you do keep the ign and inj tables the same so others can use them.
I am going to keep it simple and let the CAS fire the 2nd gen ignition directly.
If the computer fails the engine will still run using a small tube into the intake
with a needle valve from a header tank. Worked for the wright brothers :)
"The Wright Brothers 1903 aircraft piston engine fuel flowed through a small metal
fuel line from the high mounted tank to the engine. The fuel dripped into a flat,
enclosed pan that sits on the top of the engine. The floor of the pan was hot because
it sat over the hot engine cylinders. Air was drawn into the pan through the air
intake, because of the action of the pistons. The combination of air being drawn over
the fuel and the heat of the floor of the pan caused the gasoline to evaporate."
"The fuel flow to the engine was adjusted while the aircraft was waiting on the
launch rail. When the engine was running as fast and smooth as possible the aircraft
was ready for launch. The pilot had a control lever which was connected to a cut-off
valve to stop the engine at the end of the flight. The brothers had no throttle or
engine control during the 1903 flights. The Wright "carburetor" and intake system had
no moving parts. Without the moving parts, the brothers engine ran at just one speed
throughout the flights of 1903."
http://www.rotaryeng.net/simple-cheap-555.html
Klaus set that up recently and he found it works much to his surprise. No carb no
nothing, nada :)
Paul Lamar
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