Ok im not genius when it comes to engines but i know the basics. Now it seems to be that everyone is concerned that running your engine lean is bad for it. Im kinda confused as to why. I think you guys are trying to prevent knock/detonation for the most part.

Im guessing what happens is if you have too much air vs fuel then the fuel has a pentiful supply of oxygen to burn quick or too quick which causes the problem could someone correct me if im wrong.

 

When you run lean you build more heat which leads to excessive heat and pressure in the combustion chamber. That causes the fuel/air mixture to pre-ignite causing multiple flame fronts in the chamber instead of a single flame. All this puts very high loads on head gaskets, pistons, rings, plugs and rod bearings.

Hopefully that helps.

 

ahhh ok, lean = more heat. whys that tho? Youll be burning all the fuel you inject entirely (theoritically) but in a rich scenario your burning all the fuel until you run out of air so that doenst seem to make sense.

actually on a somewhat seperate topic whats the major heat source in engines? Is it more burning fuel as opposed to friction?

 

It has to be burnt at the correct time. With a lean condition it can be burned early casing undue stress on the above mentioned parts.
Good ? I would say friction, but I have no diffinitive proof. Any engineers out there that DO know?

 

is a bad word to use when talking about engines. Extra fuel tends to act as a coolant, keeping the cylinder a more cinsitant, cooler temperature.

Lean also results in an uneven burn front due to lack of fuel. (think of it as lack of fuel instead of extra air and you understand the bad part)

Coldie

 

A Google search found this:

http://www.misterfixit.com/deton.htm

See no. 9.

Dan

 

Google rules!

 

When I was in HS, my physics teacher and I had a big discussion as to what causes more heat. I thought it would be friction for sure, but she said it was from the burning fuel. I was working at a Ford dealer at the time, so I asked one of the techs what he thought. He said he agreed w/ my teacher. He said the oil does such a good job of lubricating that there really isn't much friction. I guess I don't KNOW, but two people who are very knowledgeable about the subject say it's the fuel burning, not the friction.