| I believe the most important characteristics of exhaust components are: (1) Radius: Affects exhaust flow velocity. The larger the radius, the higher the volume it can handle at a certain exhaust gas velocity. Larger is not always better however, too large and the exhaust gases will expand rapidly, thus cooling and losing velocity in the exhaust piping. If the piping is too small, exhaust gas velocity will be much greater, but the flow volume will restrict performance. There is a critical exhaust velocity that is "just right" for your Z - I believe around 2.5" is the recommended piping diameter. (2) Coatings applied: Affects exhaust flow velocity by proxy. The heat stored in the coatings help the exhaust to stay hotter, and thus move exhaust gas more rapidly. Also a good coating can help extend exhaust life, and insulate the body from exhaust heat radiation. (3) Junction type: Where the opposing cylinder bank exhaust gasses meet (X or H, is there another?). The junction geometry affects the scavenging mechanics of the exhaust. You see, as an exhaust gas pulse from one cylinder bank travels down the exhaust, once it hits the junction it has a higher velocity than the opposing exhaust pipe, thus creating a vacuum that scavenges exhaust gas from an opposing cylinder as it expels it's own gases. The junction type also affects the flow dynamics of the exhaust gases when they meet, suffice to say the X type is preferred. (4) Bend geometry: The bending of the exhaust pipes directly affects the flow rate of exhaust gases through each pipe. The smoother the better. The tips are typically of a larger diameter than the exhaust tubing, and it's the generally held belief that it has little to no effect on performance, unless they have some strange geometry such as a large bend at the end, or they are actually smaller than the exhaust pipes. I imagine a single tip would have a slight better flow than multiple tips, but again the difference is so marginal that it is of no consequence.
Recursively Yours,
Kenny...
PETZ Member #5
SteamyZ. Never had did me wrong. - SL103 07/06/04 11:58:15
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