Morgans wrote:
"Lou" wrote

A question I've never asked nor have I seen asked.
Can you use Avgas in an auto conversion engine? I'm not
against using avgas so if this can be done I would be interested
in the results.

Yes, generally. If you are going to use an oxygen sensor for fuel (mixture)
control, then there is the problem of the lead fouling the sensor, and
making it nearly useless in a relatively short period of time. Some people
have put a deflector ahead of the sensor to keep from fouling them as fast,
but then they are not doing a very good job at measuring the mixture.


Ed Anderson runs avgas in his rotary powered RV. The lead killing the
oxygen sensor is somewhat of a misnomer, he says. What happens is that
the sensors response rate drops dramatically as it becomes contaminated.
This does make it useless in a car, where the onboard computer uses
the sensor output to maintain a proper mixture; however, if you're just
using the sensor to tune the engine or manually lean at altitude, it's
not much of an issue. It still responds much faster than a human will.

There are always the same problems of lead deposits, but as usual, keeping
things hot help. The largest problems with that are valve deposits, and
since auto engines are generally more tolerant of higher operating
temperatures, it is important to aggressively lean all the time, and also to
not run as rich at full power like you would an air cooled engine, but
appropriately leaned.