I have been following this thread and have found it very informative. There is one thing I do not understand and was wondering if someone would explain.
How is the a/f ratio determined?
The Dyno Run Stats and Questions
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BULLCBX
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The Dyno run and Questions
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Atlanta, GA
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E Lee
Dyno
The air fuel ratio is done by a "sniffer" stuck into the exhaust. Same as when you have your car smogged; or is it only California such things are done. It's a gadget that feeds back to a computer and can determine the content of exhaust gas. This is compaired to a scale perfect mixture being "around" 13 (around). The lower the number the richer the mixture; above that magic number to lean. So the objective is to get the best mixture with out going to lean. Since the carbs work different mixtures from different circuits it's important to know what each one is doing and make adjustments accordingly. Example, you could have a great mixture full throttle from 7.5 to 10K rpm but below that it could be way to rich, a different circuit, same for idle to 2.5K. The dyno can determine all this, then you adjust from there and do it again, and again.... then when you go to far you do it again back to that last setting.
Well how'd I do guys.
Later,
Ed
Well how'd I do guys.
Later,
Ed
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EMS
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- Location: North East OH, ICOA 3904
Air Fuel Ratio
Air fuel ratio or Lambda (you heard fo lambda-sensors? - I don't have Greek characters on my keyboard, sorry) is the ratio between actual air available to minimum air required for complete combustion of the fuel induced. The amount of air is put in relation to the amount of fuel:
L=Available amount of air in grams per grams of fuel induced, L(min)=Minimum amount of air in grams per grams of fuel induced.
Lambda= L/L(min).
Theoretically, for Gasoline engines Lambda is around 1 and for Diesel engines about 1.2, both at full throttle. Ideally, best use of fuel occurs when it burns completely and Lambda is close to 1 , in order to prevent the energy loss through heating of unnessecary air. However, as the fuel/air mixture is not quite homogeneous, in the real world a Lambda of slightly larger than 1 is required. Engine designers shoot for 1.3 for optimum performance. The EPA, of course, in their infinite wisdom, may cause everybody to want something different.
L=Available amount of air in grams per grams of fuel induced, L(min)=Minimum amount of air in grams per grams of fuel induced.
Lambda= L/L(min).
Theoretically, for Gasoline engines Lambda is around 1 and for Diesel engines about 1.2, both at full throttle. Ideally, best use of fuel occurs when it burns completely and Lambda is close to 1 , in order to prevent the energy loss through heating of unnessecary air. However, as the fuel/air mixture is not quite homogeneous, in the real world a Lambda of slightly larger than 1 is required. Engine designers shoot for 1.3 for optimum performance. The EPA, of course, in their infinite wisdom, may cause everybody to want something different.