[rppngears]

I understand what being to lean or rich is, and that it causes severe damage to your engine; metling pistons, detonation, etc. What I don't understand is why?

It seems to me if you have a lean condition where you have say 17:1, then it seems to me you would have complete combustion of the fuel that is present and just have some left over oxygen at the end. Now this seems that this explosion would be less intense then say a mixture of 13:1 where there is the same amount of oxygen in the cylinder, we just increased the amount of fuel. Since there is more fuel, that would seem to tell me there would be a greater explosion.

I know of course if you keep decreasing the fuel air ratio, this will not stay true of course because you will eventually have insufficient oxygen, but assuming these ratios, why is the lean condition worse for your engine?