Subject	Re: strictly speaking within a straight pipe, it is better
Posted by	kZtt (zedparts.com) on February 21, 2002 at 3:40 PM
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In Reply To	strictly speaking within a straight pipe, it is better posted by Jefe on February 21, 2002 at 03:28 PM
Message	uh I believe fluid prefers to flow along the surface rather than the center. By choosing a too large pipe diameter, you slow down the flow... not good. By having a good exhaust velocity, you reduce pressure in the exhaust pipes (Bernoulli eqn) and improve scavaging (and for turbos, increase the pressure differential across the turbos). But if exhaust velocities are too high, frictional losses from flow along the surface increases and so a certain amount of energy (back pressure) is needed to expel the exhaust gases. So too small a pipe diameter is not good either. I think there is an optimal pipe size for a given hp...
Follow Ups	Need new exhaust, recommendations 4 TT conversion, not 2 $'y (n/m) - CowBoy 14:23:44 02/21/02 Brullen, under $800, Stainless, X-pipe, 3" - not-hrz 14:43:57 02/21/02 3" is not as good for performance in TTZ's as 2.5" (n/m) - F8IZHIS 14:50:02 02/21/02 Oh pray tell why? (n/m) - wildestyet 15:06:15 02/21/02 Way too big...exhaust gases will have more turbulence>> - Seb 15:09:08 02/21/02 Turbulence has more to do w/ the bends than pipe diameter... - presto 15:19:59 02/21/02 strictly speaking within a straight pipe, it is better - Jefe 15:28:50 02/21/02 So fluid dynamics would suggest that 3" is better, right? (n/m) - presto 15:40:19 02/21/02 Re: strictly speaking within a straight pipe, it is better - kZtt (zedparts.com) 15:40:50 02/21/02 fluid has max velocity at center and ZERO velocity on edges> - my91z 15:47:16 02/21/02 Re: fluid has max velocity at center and ZERO velocity on ed - kZtt (zedparts.com) 16:08:46 02/21/02 it's been too long since I had the classes in school>> - my91z 16:20:24 02/21/02 yes i am currently in fluid dynamics , and that is what i - Jefe 16:34:42 02/21/02 Re: yes i am currently in fluid dynamics , and that is what - kZtt (zedparts.com) 16:55:04 02/21/02 So now that we know who our fluid dynamics guys are: - wildestyet 17:10:11 02/21/02 I don't remember why the fluid doesn't move at the wall>> - my91z 17:44:06 02/21/02 yea my book doesnt explain it at all. here is what it says: - Jefe 22:51:04 02/21/02 also, about Bernouli's equation and lower pressure>> - my91z 15:51:11 02/21/02 not that I'm a turbo expert, but it seems 3" would be better - my91z 15:33:26 02/21/02 Please provide evidence. Also, some have 2.5" Brullen. - presto 15:07:34 02/21/02 When it comes to exhaust on a turbocharged car... - wildestyet 15:43:25 02/21/02 "as easily and as quickly as possible" - F8IZHIS 17:26:57 02/21/02 From the Borla website: Bigger is not always better... - Gordo 93TT NYC 16:24:52 02/21/02 Turbocharged car is a different animal. - wildestyet 16:55:00 02/21/02 3" DP -> 3" to 2.5" TP -> 2.5" exhaust works 4my power level (n/m) - Arnel(Z32racing.com) 16:46:33 02/21/02 You know we never really made too many suggestions so... - wildestyet 17:02:50 02/21/02
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