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Old 01-13-2014, 06:15 PM   #14
H. L. Chauvin
Senior Member
 
Join Date: May 2010
Posts: 4,179
Default Re: Boring A intake for B carb....

Mr. Brent is correct in that this B vs. A intake is a deeper subject than one can imagine.

In his reply no. 11 above mentioning a B vs. an A intake diameter, without thinking, if one is quickly asked what is the difference in cross sectional area between a 1" pipe & a 2" pipe, many slightly uninformed would say the 2" pipe has double the area of a 1" pipe; however, a 2" pipe has (4) times the area of a 1" pipe.

So when Mr. Brent is mentioning using a 1.30" diameter intake in lieu of a 1" diameter intake, the cross sectional area of the 1" intake is increasing from about 3.14 square inches to a whopping 5.30 square inches, (about a 70% increase in cross sectional area), which also directly influences the velocity of the air/fuel mix where the velocity of the fuel/air mix with the 1.30" intake decreases theoretically approximately 70%.

Bottom line may be thought of as a larger diameter length of pipe upstream & a smaller diameter length of pipe downstream has greater forced flow at the end than that of a smaller diameter pipe upstream with a larger diameter pipe down stream; however, keep in mind that the lengths of each of the pipes are a major concern as well as the interior surface friction inside each of the pipes in which both length & surface friction can affect the volume of flow at the end of the pipe.
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