Differences between automotive & airplane engines

Ignoring paperwork issues for the moment: Is this an ignition system that
could be easily(?) retrofitted to a standard Cessna 172 / Piper Warrior?

Here's something to ease the paperwork issues:

http://www.unisonindustries.com/prod...ains_menu.html

This system varies the timing on certified aircraft engines,
but does not advance timing beyond the setting specified by the engine
manufacturere. I don't know if this is because there are no gains to be
had (25 degrees BTDC on an O-320, for example, should be plenty for
2700 RPM), or if the engine's TC would prohibit it. They do claim
better performance at any power setting below max, though, and smoother
operation.

Dan

Yea...all of them.

The OBD-2 standard, which all cars sold in the US have had to meet since
1996, demands that if the O2 sensor goes bad, the "limp home" or "open loop"
mode (in other words just what you want) must be good enough to not only run
fine, but it's gotta still pass the smog check (750 PPM In my state).

If your computer has a "closed loop" mode, great, but there is no advantage
to insisting on a computer that CAN'T use an O2 sensor if one's available.

Just put some black electrical tape over the "check engine" light and you're
as good as if you'd spent $2K on an aftermarket ECU!


Is there any really easy way to tell what engines are available with non
O2
sensing ECMs?

wrote in message
...
On Wed, 15 Feb 2006 02:14:33 GMT, Ernest Christley
wrote:

Adjusting the injectors such that they produce aproximately equal
fuel/air distribution within the combustion chambers allows the pilot
to lean to the point where the engine quits, without any roughness to
that point.

Corky Scott

You will get roughness due to the slow burns and ocassional misfires before
it quits no matter how well you match cylinder to cylinder air fuel.
There is considerable cycle to cycle variation in the burn rates and
effective power for a single cylinder when you get too lean.
BSFC also goes up around that point as well.

--
Geoff
The Sea Hawk at Wow Way d0t Com
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"Peter Dohm" wrote in message
...

My reasoning is that the higher average power levels in aircraft use may
keep the oxigen sensors in the exhaust system hot enough for the
inevitable
lead deposits to sublimate off as fast as they would otherwise build.

Sorry, no. If you want to run lean - then you want a wide range sensor - I
don't recall the operating temperature on those, I'm embaressed to admit,
but if you look in the holes in the protection tube, you can see the sensor
element glowing (At least the NTK brand has a hole right on the end that
lets you see the element directly - I never tried to look into a Bosch or
Denso sensor). And, if you get the sensor much hotter than the normal heated
temperature, they will be damaged and give inaccurate readings (guess how I
know.) The element temperature is actually controlled via a closed loop
controller that reacts to the measured impedance of the sensor.

The more common swicthing sensors are not as sensitive to variations in
temperature and generally don't run as hot.

If you want to put in Oxygen sensors, you are pretty much stuck with
unleaded fuel.

My
best guess is that average power levels in automotive use run around 10%
of
maximum, due to a lot of time spent idling. Even allowing for very
substantial derating, aircraft use would involve much higher power. For
example, I just drove a Plymouth Neon on a 450 mile road trip and, judging
by fuel burn, the 130 HP engine produces less than 25% power at 70 MPH (or
about 70-75% rpm).

Sounds close.

--
Geoff
The Sea Hawk at Wow Way d0t Com
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"Peter Dohm" wrote in message
...


Is there any really easy way to tell what engines are available with non
O2
sensing ECMs?

Yes, just visit a dealer in Saudi Arabia and see what they sell.

:-)

--
Geoff
The Sea Hawk at Wow Way d0t Com
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"Ron Webb" wrote in message
...

Yea...all of them.

The OBD-2 standard, which all cars sold in the US have had to meet since
1996, demands that if the O2 sensor goes bad, the "limp home" or "open
loop" mode (in other words just what you want) must be good enough to not
only run fine, but it's gotta still pass the smog check (750 PPM In my
state).

OBD-II requires you to set a code and turn on a light. It does not require
any kind of performance once the failure has been detected. On the other
hand, I don't know about EVERY brand, but the ones I work on will run just
fine with the O2 sensor disconnected. We try very hard to make sure you can
make it home in the event of just about any sensor failure.


If your computer has a "closed loop" mode, great, but there is no
advantage to insisting on a computer that CAN'T use an O2 sensor if one's
available.

Just put some black electrical tape over the "check engine" light and
you're as good as if you'd spent $2K on an aftermarket ECU!

Yea, the bulb takes a LONG time to burn out on it's own.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
Spell checking is left as an excercise for the reader.