Guys, let me fill you in on some practical experience which you may find
of interest. My car isn't a Tiger but have a look if you like:
http://www.mgbconversions.com/photoalbum/variousv8s/JimBlackwood.htm
I adapted the Ford EEC-IV/EDIS (SN95- '94 Mustang GT processor) with
TwEECer tuning aid to this car, and I have retrofitted my I-H 392
Travelall with a Megasquirt system and tuned both vehicles so I am
familiar with both. In theory what you are proposing sounds really good.
So good that I did it in fact. But reality often brings it's own
challenges, and tuning is one of those challenges. The Ford system has
an astonishing array of tuning parameters. Never in my wildest dreams
would I have imagined it could be so complex. For instance, in only one
of 3 or 4 tuning areas there are over 20 parameters for ignition timing,
and each one of those parameters is a 2D map. Say if it was an average
size of 8 x 8, you have 64 entries, times 20 (1280) or so and that's
only in one area, scalers I believe. Injector tuning is even more
complex, and all that might be acceptable with proper knowledge as to
what they all do but we don't have that because Ford doesn't believe in
open source. And that much touted learning capability will not correct
large tuning errors, takes time to learn, loses it's brains every time
the battery is disconnected or runs down, and has to be told what it is
you want it to do in the first place. Still, with the tweecer and the
support of their forum I was making progress with the EEC-IV system up
until the time that I got the truck running.
Now a little note on costs. With about the same investment in hardware
on both systems, the Megasquirt (MS) system came in roughly $700 less
than the EEC/ Tweecer combo, perhaps more. The "good" processor isn't
the $50 junkyard special and is hard to find for less than $175. Not
every processor is supported, just primarily the performance
applications, so with the $50 processor you are entirely on your own.
The Tweecer runs about $650. So in order to be able to tune the car the
investment is significant.
The MS on the other hand is very user friendly. It makes use of 3D maps
and has a handfull of enrichment settings, it is tunable in real time
and it is quite easy to take a ride down the road and tune the engine.
(By the copilot hopefully) There is in fact enough difference to
convince me to build another MS unit and put it on the car, which I hope
to do in the next couple of months. At the same time I'm building a
system for my brother's TR4-A.
The MS is batch fire and speed density, whereas the EEC is hotwire and
sequential, so there could be a very slight performance edge
theoretically with the EEC but that is more than cancelled out by the
difficulty of tuning. And, the MS is open source. Not only can you learn
every little detail of what the controller is doing if you want to, but
you are actually encouraged to modify the code to suit your own
application. Or not, if like me you aren't comfortable with that.
Bottom line, my recommendation is to forget the EEC stuff and go with
the MS. It's cheaper, it's easier, and it works just as well if not
better for performance applications.
Jim
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