| A few things to note: 1. Flow is not controlled solely by cross-section area. Crush-bends are detrimental to flow because they limit the cross-section and act as a bottleneck. Bends in general are detrimental to flow, so the statement: "mandrel bends is all that is important who cars if it has 90's the exhaust will flow the same" is incorrect. Bends create resistance in fluid systems. If you take a water pipe and blast water through it at full pressure, you would find that a pipe that has a 90 degree bend in it, even if that bend has the same cross-section area, will not flow as well as the straight pipe. The same is true for exhaust systems, although the effect is less noticeable since gases can compress while water does not. 2. Smooth pipes reduce turbulence and flow better. Pipes with many joints in them are going to see more turbulence than a pipe that does not have many joints. All those welded seams are likely to cause turbulence, unless you honed them. Rough pipes have more resistance than polished pipes. Jagged joints have more resistance and turbulence than smooth joints. Assuming that you did a good job of welding them, then the joints are relatively smooth rather than jagged, but even so they remain a source of turbulence. 3. Your x-pipe has the potential to be a bottleneck in the system. From what I understand, the idea behind an x-pipe is to create a scavenging effect that uses each alternating cylinder pulse to "pull" the next one along. If your pipes are not equal length and equal flow characteristics, then the pipe cannot function ideally. You may end up with pulses reaching the pipe at the same time and "fighting" each other to squeeze through. If this is the case then you are creating turbulence as well as restricting flow. I don't believe that this is always taken into consideration when companies design exhaust systems though, so perhaps I have misunderstood the way it works, or maybe they just don't care when it comes to non-race-based applications. However, all theory aside and on a more practical note... given that all of the above information is based on ideals and theory, I personally don't believe that your exhaust flows particularly better or worse than a mandrel-bent 3" exhaust or a crush-bent 3" exhaust, assuming that there are only mild bends in any of them. The mandrel-bent would likely be slightly better than yours, and yours (depending on the quality of the welds) may probably be a bit better than a crush-bent system. But honestly, the real-world difference would probably be similar to the margin-of-error for many dynos. The lack of symmetry seems a little strange to me and I'm not a big fan of side-exit pipes on a Z32, but honestly, I think it is a fine exhaust (despite what some of the "haters" on this board will tell you). It serves a purpose and it probably does a fine job of it, and it seems very obvious that it suits your needs. ::shrug:: It doesn't give me an automotive hard-on, but I don't see anything particularly wrong with it, and it looks pretty decent for a DIY affair. Congrats to you, ignore the haters, enjoy the ride. And that's my excessively wordy "two cents."
"The two seater is being joined in a few weeks by a larger two-plus-two model with a rear seat for munchkins." ~Jim Mateja, Chicago Tribune, in regards to the Z32.
Andrew Janeshek // jnshk@aol.com // 1992 NA 2+2 [Stage 2-ish]
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