Thread: why lean is bad
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Old 08-29-2002, 05:18 AM   #15
jimberg
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Join Date: Oct 1998
Location: Rogers, MN
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RoadWarrior, the fanning a flame analogy is really not a good one for describing this particular problem. A camp fire is an open system that is burning slowly. Since it's burning in the atmosphere, you have an unlimited amount of oxygen for a limited amount of fuel.

The chemical reaction that occurs in your combustion chamber is a closed system that has a limited amount of fuel and oxygen. It is also compressed so it explodes.

As far as air/fuel ratio goes, let's say that our engines run with hydrogen as the fuel in a pure oxygen atmosphere. If you have 100 hydrogen atoms and 50 oxygen atoms, the combustion should produce 50 water ( H2O )molecules with nothing remaining. This would be a stoichiometric reaction since no fuel or oxidant remains. If you have 100 hydrogen atoms and 100 oxygen atoms, you'd still only get 50 water molecules and 50 left over oxygen atoms. This would be a lean mixture, but since only 100 hydrogen atoms and 50 oxygen atoms were combined, the same amount of energy (heat) would be released from the chemical reaction. The same would be true if you had 200 hydrogen atoms and 50 oxygen atoms. Only 50 water molecules would be created but you would have 100 left over hydrogen atoms with it being a rich mixture.

There are other factors that generate heat such as the rapid compression of gas and other chemical reactions such as nitrogen combining with oxygen to form NOx, but I hope the above examples will be pretty clear as to what is happening as far as air/fuel ratio.

Jared, I hope the above example helps with your question. The amount of heat generated is based on the amount of fuel that can react completely with oxygen, but yes, I think you have the gist of what I'm saying. There's also the added heat that is generated by rapidly compressing the left over oxygen.

I'm pretty sure that my lightning block came with a roller cam from the factory. The block is definitely roller cam ready. As far as the headers go, that's an interesting question. I would think that the 351W swap headers for a fox would fit the same way. You should call Mac or Holcomb Motorsports to see what the difference would be. I'm really glad that I went with a 351.

I really like the color scheme, too, but after 13 years, it's time for a change. I'm thinking of going with all silver.
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