I always hear its bad and will break things in an engine, but why? From what I understand it means that I have less than desirable gas than air in my engine. So why will that break things?

 

If your running lean in a combustion chamber it will cause your EGT to raise to a higher temp. You also lose a lot of power when running lean plus it can cause detonation.

I would rather run rich then lean any day

 

Think of it this way. a piston being a tent steak. the best way to drive it into the ground is to hit it with a big hammer thats what happens with a good mixture. when u run lean the mixture dosent burn it explodes and indsted of hitting it with a hammer its like shoting it with a gun. u can blow holes in your pistons or cylinder walls.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cstay &raquo;</TD></TR><TR><TD CLASS="quote">Think of it this way. a piston being a tent steak. the best way to drive it into the ground is to hit it with a big hammer thats what happens with a good mixture. when u run lean the mixture dosent burn it explodes and indsted of hitting it with a hammer its like shoting it with a gun. u can blow holes in your pistons or cylinder walls.</TD></TR></TABLE>

yup detonation is bad... been there done that... rich is a lot better than lean.. holes in pistons arent cool... for your motor or your wallet

 

The internal combustion engine is a "controlled" process.

Having a lean running engine takes away from that "controlled" process and the engine can pre-ignite on it's own. If you run a lean air/fuel mixture, you run the risk of overheating the combustion chamber. Heat is good, but too much heat and you run the risk of damaging some internal parts.

 

Detonation & Pre-Ignition Article

 

I always thought that you wanted to run the leanest mixture you could safely get without detonation. without detonation being the key to that statement. somebody correct me if i'm wrong, and tell me why not.

 

No you are correct. People seem to think there is a majic A/F ratio when in fact there isn't. Tune your motor for the best particular A/F that makes the most power with out burning to much fuel for burning to little.

 

Lean isn't always bad. It's all relative. AFR's of up to 15.0:1 are often used at idle and even higher at cruising conditions to reduce fuel consumption and hydrocarbon emissions. It gets even higher than that when you let off the throttle at rpm's greater 1100 and the injectors shut off.

From what I have read, you can safely and efficiently run cruising (light load) AFR's up to 16.0:1 -17.0:1 with a long duration, multi-spark ignition, which is usually lean misfire territory.

Under heavy load (at any rpm), lean conditions increase combustion temperatures, which can cause pre-ignition and detonation.

 

cool, thanks guys. that explains it great!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cstay &raquo;</TD></TR><TR><TD CLASS="quote">Think of it this way. a piston being a tent steak. the best way to drive it into the ground is to hit it with a big hammer thats what happens with a good mixture. when u run lean the mixture dosent burn it explodes and indsted of hitting it with a hammer its like shoting it with a gun. u can blow holes in your pistons or cylinder walls.</TD></TR></TABLE>


This is the worst analogy EVAR!

This tent "steak," is it rare, or well done?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kpt4321 &raquo;</TD></TR><TR><TD CLASS="quote">


This is the worst analogy EVAR!

This tent "steak," is it rare, or well done?

</TD></TR></TABLE>

hahahhaha

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allmotorEG-SI &raquo;</TD></TR><TR><TD CLASS="quote">I always hear its bad and will break things in an engine, but why? From what I understand it means that I have less than desirable gas than air in my engine. So why will that break things?</TD></TR></TABLE>

unless you have a diesel compression ignition engine, you don't want to run too lean, remember the magic 10 dollar number-14.7