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Christ · 05-17-2010, 01:24 AM

Adding to the mandrel bent exhaust tip (which, apparently, many GM cars have as OE exhaust systems), any curves in the exhaust should be kept to a minimum. Even if you have a mandrel bent exhaust, the flow around a curve is not at a constant diameter. As speed increases, the flow attempts more and more to continue traveling in a straight line. Changing the flow's direction suddenly causes it to "stack up" against the outer radius of the curve, just past the apex (highest point, or center of the arc).

In order to keep exhaust velocity constant (mostly) you actually need more shallow bends (if any at all) and any bends you do have must be smoothly designed and of a larger diameter than the entry pipe, with no more than a 15-18* (I believe) transition step angle (the expansion of the pipe can't be any more than that).

Getting a little complicated, yet?

05-17-2010, 01:24 AM	#11 (permalink)
Christ Moderate your Moderation. Join Date: Nov 2008 Location: Troy, Pa. Posts: 8,919 Pasta - '96 Volkswagen Passat TDi 90 day: 45.22 mpg (US) Thanks: 1,369 Thanked 430 Times in 353 Posts	Adding to the mandrel bent exhaust tip (which, apparently, many GM cars have as OE exhaust systems), any curves in the exhaust should be kept to a minimum. Even if you have a mandrel bent exhaust, the flow around a curve is not at a constant diameter. As speed increases, the flow attempts more and more to continue traveling in a straight line. Changing the flow's direction suddenly causes it to "stack up" against the outer radius of the curve, just past the apex (highest point, or center of the arc). In order to keep exhaust velocity constant (mostly) you actually need more shallow bends (if any at all) and any bends you do have must be smoothly designed and of a larger diameter than the entry pipe, with no more than a 15-18* (I believe) transition step angle (the expansion of the pipe can't be any more than that). Getting a little complicated, yet? __________________ "¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"