Pretty much exactly what I have been thinking about.
2 injectors (approx 22lb) one in each intake runner.
A TBI somewhere around 1.75"
Wasted spark EDIS 4 fired from Megasquirt 2
The existing dist would be used as a cam position sensor
Ford 36-1 Crank Sensor mounted on the 1275 Crank pulley
The injector pulse width is not the problem. The VE table and the sensors
handle that.From what I have read so far on MS the injectors are fired based
upon ignition events rather than crank degrees. For the A series we need to
fire the injectors at set crank degrees due to valve overlap and one
cylinder robbing the other. So each bank would fire twice as in 2-1 then 4-3
If the MS can do that without code changes then great but not what I have
seen so far. I am going through the source code for MS2 (written in C)
figuring out exactly how they did it.
Duncan
-----Original Message-----
From: derf [mailto:derf247@gmail.com]
Sent: Tuesday, May 15, 2007 8:49 PM
To: Duncan Sinclair
Cc: Brad Fornal; spridgets
Subject: Re: webers and webers
I'm learning a little about Megasquirt as I assemle one for
installation on the Miata. You don't have to "alter the code". You
just tell it how long to pulse the injector at given RPM, throttle
position, temp, etc., with a sort of laptop GUI and fuel ratio "maps".
MS also allows only two "banks" of injectors. True sequential
injection isn't really what one might think. You gain little by
firing each injector individually. The MS for 4 cylinders fires two
pairs of injectors at the same time, for 8 cylinders it fires two sets
of four at a time, etc. There is a technical writeup on the MS site
about how little the gains, if any, with true sequential injection.
People who want IRTBs (individual runner throttle bodies) on their
Miatas seem to migrate toward using motorcycle TBs and injectors. It
seems you can get sets of stock motorcycle TBs on ebay for very
little.
Also, it is popular with the MS crowd to use Ford EDIS ignitions
systems. They are easy to find, cheap and use a 36-1 crank trigger
wheel. You can find them on ebay for around $75 or at the UPullIt
cheaper than that. The MS can also work with the distributor. But,
if you get the EDIS or similar system, you can use the MS to control
spark and timing, too.
If I wanted to do a Spridget with fuel injection I would get the MS,
some kind of UPullIt TB off a similar sized motor with TPS(throttle
position sensor), a single HIF intake manifold, coolant temp
sensor(again UPullIt), and intake air temp sensor(UPullIt again),
either one big injector in a tube between the TB and intake or two in
the intake runners, and probably do the EDIS. The MS has a MAP sensor
built in. To tune properly you'd want a WBO2 setup. It would be
cool. But, then it would be like putting a jet turbine in a biplane.
Cool, but, why?
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