Fact or myth? Lean fuel can kill an engine.

[Skunksmash]

Im sure we have all heard it at one point or another, that old myth. Or is it? Can anyone here say for sure if running an engine to lean for to long can "burn up a piston" or otherwise do damage to an engine? Some people seem to think that the gasoline "cools" the piston or something like that on every intake stroke. Some people will tell you that it's hogwash, and some will tell you that you can tear up a motor running it to lean. I always thought that you just got low power out of it or it would die often or not run at all, but that was it. Maybe someone here can clear it up for me? Maybe it's different on some engines?

[VileZambonie]

Lean a/f ratios = hot

Rich a/f ratios = cool

Yes too lean too long too bad.... I have plenty of engine parts saved that have suffered from too lean a/f ratio. Head gaskets, cylinder heads, exhaust valves, pistons, spark plugs all annihilated.... believe it.

[Skunksmash]

Ok. Well under what circumstances can it be running lean, but really not hurt anything? Is it just if it runs a little lean, or if it runs lean but not for very long? Or maybe something else. Cause there seems to be an awful lot of people who think it's fine (from another forum) so they might be thinking about a particular, common problem that doesn't really hurt anything.

[HAULIN IT]

A little off, but not really...Think about a cutting torch. You light in, a little soot comes off (straight Acetylene) It's "Rich", all fuel. How hot is it? Can you cut steel or even make it Red? Now add the Oxygen, now we have heat Big time, "Lean". At idle or low load, a leaner condition (in moderation) & not cause damage, can save fuel, less emissions, ect. However as Vile mentioned, heat is an effect, this is why you see "newer" vehicles running at a higher temperature than what is normal in a '76 truck.
 I'm guessing the "other forum" with the people thinking it's "hogwash" is not a nitrous tunning site? They might have a different outlook on lean. Lorne     

[VileZambonie]

A lean burn system uses a different combustion chamber design than these engines. Modern lean burn systems use displacement on demand and a precombustion chamber like a stratified charge engine does. Running an engine lean to try and save fuel might save you a few cents until you reach your threshold.

[Blue 82]

E85 requires more fuel per HP than gasoline
so running E85 through your non flex fuel, delivery system would lean out the mixture
so try this test:



Run your tank down to fumes
Put 15 gallons of E85 in it
Hook up to a 5000 LB trailer
Run it up to the highway, to the legal speed limit, for 1 hour
Report back to us if the engine lives....

[Blazin]

Leaner is meaner they say, but it will smoke a piston if run that way for an extended period.

[rmauto1]

detonation is a huge side effect of running one lean. bad times.