MSA exhaust questions

[Pomorza]

I'm going to have to partly agree with Zedyone kenobi here on this one. Here is why. A 35+ year old car will have something wrong with it no matter how well it runs. My 280z (1976) runs great, hell it gets 30+ mpg on the freeway but there are plenty of things on it that are not functioning exactly the way they should. Even if the car was your daily driver before this incident it is possible that there were things in need of replacement before the headers were installed and they fell apart during assembly.

Here is my advise, I have three mechanics that I use on my Z and I've done this a number of times when it needed to be fixed. First call up the mechanic(s) that worked on your car. Ask them specifically if they know (or have ever worked on) Z's. These cars aren't exactly the hardest things to work on but there are some tricks and things that a normal mechanic would not know.

Secondly, talk to the manager or the owner or someone that is higher up. Explain exactly what happened. If the car came there with no huge problems and left with them something had to happen in between. See what exactly they can do.

Thirdly, if you don't believe they can fix it and you don't believe you can take it to a Z expert. I've done that before when my mechanic had no idea how to fix something. He literally said "I've never dealt with that problem," and he didn't feel confident that he could fix it. I'm sure that there are places in your area that work on Zs or people in your area that can help you. It is a matter of figuring out what is wrong and fixing it incrementally.

Hope that helps

Jan

[OhDearAudrey]

Thanks for the advice, Really appreciate it.

[bpilati]

Twice pipes have been discussion ad nauseum since at least the 1990's. From what I remember about all those discussions, the general sentiment was that they didn't make your car perform any better than a good single pipe exhaust. This even goes back to the Internet Z Car Club mailing-list days. Remember, it's a 2.4-2.8 liter six, not a 7 liter V-8. In fact I might even argue that a twice pipe has less effective flow than a single pipe system. Your going to have turbulence along the boundary, and a twice pipe probably has more surface area. I know there were some people back then that actually ran flow tests on different configurations....we definitely had some exhaust fanatics in the group. There was even a discussion about inserting a stainless braided section after the downpipe to reduce vibration in the system (less noise). Those discussions use to be on the Z-31.com. You can search at this site if you like.

http://www.z31.com/izccarchives/

Edited November 1, 2011 by bpilati

[LeonV]

Flow losses do have something to do with surface area, but not with some sort of boundary turbulence. Flow actually tends to be stationary at the boundary layer, if there is one. Exhaust flow is turbulent, thus there is no boundary layer and turbulence exists everywhere inside the pipe, not just the surface. But this is a tangent to this topic...

Frictional losses go up with surface area, so twice pipes with an equivalent total cross-sectional area to a single pipe will suffer more losses. How much more? I have not quantified this with calculations or testing yet, so I don't know how strong the effect will be. Be aware that the inherent differences in design between a single and dual system also have an effect on engine performance.

[bpilati]

I don't think I said there was a boundary layer.

[240ZGL]

Maybe I'm not seeing it, is the oxy sensor in the system ? I have a 73, so I don't have to deal with all that FI stuff but that header looks like a non smog item.

[LeonV]

I don't think I said there was a boundary layer.

My reply was poorly phrased, but looks like it's already locked from editing...

In a nutshell, exhaust flow is not only turbulent at the boundary, but is so everywhere else. If you would have said "friction" instead of "turbulence" in your post, then that would make sense. Otherwise, mentioning "turbulence along the boundary" doesn't make any sense.