엔진오일 교환 수리 사례

2026. 6. 30. 작업

난이도 & 준비물

증상

What's the meaning of a "lean" vs "rich" air fuel mixture

처리 내용

I do not know the etymology of these words or the history of their use in the context of air-fuel ratios, although their dictionary definitions ( lean [adj.], rich , too bad I don't have an OED subscription) and usage in other contexts does parallel their usage here. I did some cursory research but gave up, the folks on the English site may be able to help there. However, answering your basic question: The terms are relative in the same sense that "dim" and "bright" are relative: "Lean" means a lower fuel-to-air ratio; that is, less fuel in the mix; compared to something context-dependent. "Rich" means a higher fuel-to-air ratio; that is, more fuel in the mix; compared to something context-dependent. If you say, "the air-fuel mixture is rich" (or "too rich", same thing), it is implied to mean that there is more fuel in the mix than there should be in whatever situation you are talking about. Now, there's a commonly quoted stoichiometrically ideal ratio of 14.7 air:gasoline. "Stoichiome