There is bewildering amount of info and options in Megasquirt.
The relative low cost ($250) and very simple early board known as the MS I V2.2 is
still available and will work on a rotary. It does not have injector dampers but you
don't need injector dampers with Mazda high impedance injectors. Also it cannot stage
the injectors.
Both sets of two injectors fire at the same time on each rotor. No staging of the two
injectors on any one rotor. That means you will get the engine to run well at medium
and high RPM with a prop load but it may idle very poorly as the dynamic range of
most injectors is limited. For example the RX8 engine has 3 staged injectors on each
rotor and Tracy uses 2 staged injectors on each rotor. The injection is not timed
simply because a rotary rotates too fast to time the injectors.
Also the software does not support timed injection. It is referred to as "batch fire"
and that is probably what Tracy is doing as well. Timed injection does not make much
sense in a p-port rotary because the intake port never closes. That is unique to an
intermittent class combustion engine. Yes the rotary is an intermittent class
internal combustion engine. Only turbo jet engines work that way and they are called
continuous combustion engines.
The ignition is not there so you must provide that. In fact it won't even work unless
you provide a tach signal of some sort. You must use it with one of several stand
alone ignition systems that will work and that put out a tach signal. These are GM
HEI, GM DIS, Ford EDIS, Ford TFI, Bosch 0 227 100 124 and MSD 6A. IMHO the MSD6 is
the best of the bunch but expensive. All of these are documented.
No direct coil control (dwell) is available on MS 1 Version 2.2 and that includes
late LS1 and RX8 coils with built in high current switches. Of course there is no
electronic way of leaning the engine from the cockpit. You could rig a mechanical way
of changing the pressure setting on the fuel pressure regulator to affect leaning.
The documentation frankly is a mess with megasquirt. Basically what has happened
over the years is one kludge is piled on top of the last one as they have added
features. There is a lot of redundancy in the html docs (many web sites) so the whole
mess of dozens of html files has becomes extremely confusing.
The the top of the line hardware is also a mess with daughter cards and adapters
piled on the original MS II using the MC9S12 on daughter card instead of the
MC68HC908. The whole mess is in dire need of separate USB mother boards tailored to
the needs of the customer. Say 4, 6 and eight cylinders.
A documentation trick I use is set up Word doc files on various subjects such a USB
and dwell among others and cut and paste the pertinent info from the many redundant
html files.
I aim to fix all this with a simple board specifically designed for the rotary with
just the features we need. USB and RX8 or LS1 coil support (dwell) and cockpit leaning.
Paul Lamar
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