why lean is bad
 

before you get all sad for me thinking that I have blown my engine by running it leaning, I am actually just asking a general tech question. Why exactly is it so bad for our engines to run lean when under boost? I would think this would just make them inefficient, or not run at all, because nothing would burn. but how is it that this condition can be so destructive? I guess i am showing how green I am, but I don't care -- I wanna learn.

Re:why lean is bad
 

lean=hot

Re:why lean is bad
 

but why?? can anyone give me a deeper answer?

Re:why lean is bad
 

Why? Heat is very bad for your motor. Unwanted heat is caused by running lean and creates hot spots all over the place which will eventually eat a hole in your piston or fry your rings. It's like cooking french fries too long. You can cook them for the correct amount of time and they come out great. You can crank the temperature up in the pot and burn the ---- out of them and nobody wants to eat them, not even the dog. You can leave them in the deep fryer for too long and get the same results.

EDIT: wow that was a horrible analogy. ::)
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Re:why lean is bad
 

Well the fuel actually acts as a cooler. So when you lack fuel (known as running lean) your combustion chamber gets a lot hotter than it should. You will yield more power running lean to a certain extent but its bad. Like Dr. Boost said you can do many things like burning a hole in your piston, fry your rings, melt your head gasket etc etc...

Also if memory serves me correctly the hotter you run the more prone you are to pre-detonation. Meaning that the fuel in the combustion chamber ignites before spark is applied by your coils; due to such a high heat. Pre-detonation can damage tons of things. It can bend or break rods, break the piston lands and I think I've heard crushing spark plugs before but I'm not positive.

Anyways running lean is bad, as is running too rich. I'd much rather be too rich than too lean though.

Re:why lean is bad
 

Ahhh....To knock or to ping that is the question.....

Ive seen a little worse then melted head gaskets...try explosions, shooting holes through hoods, rods blowing clear of the car and picking them up in the bushes a few dozen feet away...Just search Engine Blow on google he he

Re:why lean is bad
 

Its pretty much that... when you add more air and not enough fuel.... it gets really really hot...

Try this... next time you have a BBQ... bust out the blow dryer.... and once the charcoal has been lite... turn it on full blast high heat... and watch the charcoal wither away in a glowing red blaze.... thats what your doing to your pistons when you run lean with no intercooler... now put it on full blast cold... and notice it doesnt burn that fast anymore....

damn.. i feel like bill nye...

Re:why lean is bad
 

Gasoline has an ability to absorb heat out of your combustion chamber. The ability of gasoline to do this is called its specific heat (correct me if that is wrong) and less gasoline, as mentioned above, takes less heat out of the chamber. It can only take out a certain amount of heat because eventually, it reaches its point of maximum volatility (when it is the easiest to ignite) and cylinder pressure will be enough to create the extra heat to make it combust without the spark ignition (detonation!) and ---- everything up. Lean a/f is bad for those two reasons- more heat left in the cylinder and easier detonation. These are directly related. Water injection is such a beautiful thing because water has a high specific heat, it takes a lot more energy to heat water than gasoline so it can remove a ton of heat to quench detonation tendencies.

Re:why lean is bad
 

diesel engine anyone?

Re:why lean is bad
 

detonation claimed the life of my first engine....damn ghettodyne