Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Wed, 04 Jun 2003 19:50:11 -0400
Message-ID: <redirect-2402572@logan.com>
Reply-To: "Dan Schaefer" <dfs155@earthlink.net>
From: "Dan Schaefer" <dfs155@earthlink.net>
Subject: Re: TSIO 550 Rich or Lean of Peak?
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Shannon Knoepflein wrote:

"I just can't see how properly running LOP would ever burn a valve,...."

FWIW, at an engine management forum I attended many years ago, a factory
guru (don't remember if it was L or C) made the point that if running on the
lean side, by definition there is in general more air (oxygen supply)
ingested into the cylinders than required for the combustion process. This
means that when the fuel is completely burned, there is some small amount of
excess oxygen left over in the hot gasses that must flow out past the
exhaust valve. Since, as a rule, the exhaust valve is one of the hottest
parts in the cylinder and being subjected, blow-torch like, to the flow of
high velocity, high temperature gasses exiting the cylinder, any excess
oxygen in those gasses is likely to have some deleterious effects (like
burning) on said valve over time.

On the rich side, the oxygen is consumed leaving (unburned) excess fuel in
the ehaust gas. The excess fuel flowing past the valve can carry away some
heat and being oxygen starved, is less likely to promote burning.

Food for thought.

Dan Schaefer