12 c
My objection to all EFI's on the market is; I am not sure what they
will do in some unforeseen scenario. In an aircraft it is a life or
death environment. What goes up MUST come down.
The flooding of all new RX8's is a good example.
Ford was involved with Mazda then and Ford extensively tests all
new vehicles. They missed it. They also missed it on the apex seal oil
injection.
I don't begin to know what some bodies EFI is going to do under all
circumstances. Even if I had total access to the source code.
If it was written in C it would be Greek to me anyway as it takes
years to learn C. With most EFI's the source code is secret anyway.
I suspect this is the reason the FAA refuses to certify EFI and
they do have the source code.
I have written my share of complex software in assembly language
and it is near impossible to predict all possible situations or scenarios.
At least In assembly you know exactly what every instruction is
going to do.
In any high level language you do not. BASIC however is much much
easier to learn than C.
That is why I suggest one Maximite per injector. It is as simple
as possible and highly redundant. Same goes for the throttle pot and a 555.
If you want engine parameter recording and or instrument panel
display use a separate Maximite and software. If there is a bug in that
no big deal.
If there is a bug in your EFI software that is a big deal.
Megasquirt is not widely used in aircraft. That is true for all after
market EFI's with the exception of Tracy's. Tracy had his share of
unforeseen problems as well. They called it glider time :-) He wrote it
in assembly language so he knew far more about it than anybody using it.
He did not release the source code until recently and believe me it was
very complicated. About half just to control the ignition.
I used to be a fan of Megasquirt back when they published the
source code in Motorola 6800 assembly language. The 6800 was simpler
than the
6502 I used so I could at least understand what they were trying to do.
They now use C.
That is fundamentally why we fly the Motec TTC at Oxnard airport.
If the engine quits we are always near enough to the air port to
dead stick it in.
Paul Lamar
Hi Paul,
I cannot understand why anyone would want to go through all this
B.S. for EFI when a simple mechanical throttle body is just as good
with
MANUAL control of leaning (Ellison or Rotec) I had an Ellison in my
previous Long EZ for EIGHTEEN YEARS ! It NEVER gave me any trouble and
was the most economical device ever. When I took off the original
antiquated carb (M.S.) the improvement was amazing, more power, better
economy etc. It appeared to be extremely resistant to carb icing as I
tried to get it to ice up on known icing days, it wouldn't ice up!
Cheers Chris Hoskins.
I think you will need two if your looking for 250 HP.
Paul Lamar
Hi Paul,
I have a rotec TBI 48-4/5. The guys at the factory tell me it
is good for 300HP easily.
Chris Hoskins
A rotec or a bendix rsa-10 or airflow performance or any of
those would be great up to 300hp naturally aspirated and turbocharged
much higher, but then you still have the electronic ignition system. I
know little about rotarys and don't know what's the most reliable but
the mid 80s ignition seems ok from what I can see, so maybe a rs-10 and
mid 80s distributor and back up battery.
Although my thought is if you don't have a magneto and need
electronics for spark, then you might as well go all the way with efi,
you can run redundant systems 2 computers and 2 sensors for every
sensor, 2 fuel pumps, back up alternator preferably driven off
somewhere else maybe a stator in the psru, good back up batteries and
indicators.
EFII (ef double i) does that for lycoming and other applications
right now and instead of a mag check you switch between computer a and b
for your run up and take off on all computer and sensors and if there's
a sensor or computer failure it runs off the other automatically. From
what I hear they are very successful.
Like you basically said it can be very dangerous, if not done
properly. If you look at ntsb reports or read the forums auto engine
conversions have a much much higher failure rate than aircraft engines
in experimental aircraft, but if you read into it, it is almost never
the engine or the actual efi electronics itself it seems more often
than anything its the loss of electrical power, battery or alternator
and then subsequent loss of engine power. They don't catch the loss of
electrical power in time or don't have good enough warnings indicators
and back up power systems. So i think that's the first place to start
from a reliability standpoint, as Paul has experienced with the TTC a
lot of ignition systems are very sensitive to low voltage, injectors and
fuel pumps too.
It can be done though and be done safely, lycoming and continental are
both making single lever efi systems. I would feel pretty confident with
back up systems, mechanical is defiantly not immune to failure either I
had to put the rv6 down twice this year with a low time io-360 in it
once a new mag destroyed itself in the air and the other for a plugged
injector both times we got down fine but it was running extremely rough.
Thanks, Jacob Sturgis
As far as I know Lycoming does not sell and EFI equipped engine.
What airport are you located on Jacob?
Paul Lamar
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