Quote:
Originally Posted by aerohead
One context with respect to 'lean burn' is that you're hard-pressed to initiate combustion.
HONDA's CVCC engine,with 3-valve head pre-combustion chambers allowed the spark plugs to light off a relative rich,but small local mixture,with the flame front propagating outward into the leaner,non-stoiciometric mixture.
With the V-TEC engines,HONDA is pulling off the same trick without the expensive castings and mechanicals.I believe that air-fuel ratios as lean as 21-1 can be achieved.Heat is an issue,so the otherwise 'inert' Nitrogen is reacting in to NOX,but the catalysts keep these emissions in check.
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I run an AFR of 18-22 to 1 at cruise and never have an exhaust temp over 500*C measured 2" from the exhaust port. Under boost at that ratio I am never over 650*C. The only ratio under load I have to be concerned about is in the neighborhood of 15.6 to 1. Above 16 and under 15-1 I have no problems.