Hello, I just joined the site and am loving it so far. I am nearly ready to begin my first project and I have a couple questions about the use of an auto engine conversion if anyone can help. I know they are used some but not often what are the big drawbacks people find when trying to use a modern auto engine in an airplane? It seems to me parts would be much cheaper and more available but I don't understand why they aren't used more. Also, wouldn't the O2 sensor on an auto engine be able to control the mixure automatically? The onboard computer in a car uses this sensor to set the mixture more lean or rich for the most economical setting, shouldn't it work just as well in an aircraft? I am interested in learning as much as I can about this aspect of powering a homebuilt, thanks for the help.