Why leaning an engine out is bad?

[Lord_Karango17]

I never got why not supplying the engine with enough fuel is detrimental in the long term... Wont the engine just cut out?

 

Having more air than fuel in the combustion chamber seems safer than having more fuel than air...

[stealth80]

I never got why not supplying the engine with enough fuel is detrimental in the long term... Wont the engine just cut out?

 

Having more air than fuel in the combustion chamber seems safer than having more fuel than air...

 

The mixture burns lean which increases the heat and therefore the wear

[Lord_Karango17]

The mixture burns lean which increases the heat and therefore the wear

Ahh. The only thing I guessed was that the fuel lubricated the pistons a bit, so not having enough of it would warp the cylinders or something...

[stealth80]

Ahh. The only thing I guessed was that the fuel lubricated the pistons a bit, so not having enough of it would warp the cylinders or something...

 

Its a little more complex than that, involves timing and hot spots etc

[Liltrekkie]

Quite simply, an engine likes to have a certain ratio of air per part of fuel. If you take out too much fuel, the mixture wont properly combust. It creates more heat and can lead to things like a misfire (detonation is the proper term for it) and when a misfire happens, there is a potential for catastrophic failure. Like a piston exploding and taking out an entire engine block leaving holes in the oil pan.  

[FireFox]

Ahh. The only thing I guessed was that the fuel lubricated the pistons a bit, so not having enough of it would warp the cylinders or something...

 

In diesel engines this is true and also providing lubrication for the fuel system but petrol engines don't get any additional lubrication from the fuel.