exhaust ? duel vs. single 21/2 "

[beandip]

I have a question , years ago I owned another car with a inline 6 , and I modified the exhaust manifold to in stall dual exhaust . I used two 20" glass packs , and it sounded real nice , both inside and outside the car. I experienced zzero resonence , and I have heard time and again that it is a problem with the large piping. I am redoing alot of things on my '73 240 , and one is the installation of a modified 280 engine. Nothing drastic , just a street cam and milled head and 12--80 dist, and headers. I have a 21/2" plumbing systime I can stick on . My old exhaust was only the stock 240 , and was shot. So here is my question . What is the reason vary few of us Z drivers run dual exhaust ? Is it because of emissions and having to run duel converters ? Is it because of the tight space under the car ? I am just wondering because I am really contimplating a dual exhaust with 2" or smaller pipe off the headers. I am running SUs on this flat top engine , and have no emission concerns . this Z is for street use. I am asking this because most of my experience is with large V-8s and making them run , and this Z is a different bread of cat. Thank you for your input. :classic:

[Ed]

Gary, besides the obvious cost factor I think there might be a performance issue. I'm not sure here so pipe in someone.

Opening the exhaust with duels would cause you to loose bottom end torque but will give you more power at the upper rpm range. And vice versa, moderate restriction would gain low end torque but you would loose power at the upper rpm range.

I think......

[beandip]

Ed , this is why I am asking . Running a duel exhaust would mean that each pipe would be like 11/2" and use only a glass pack of 20" or longer . The two pipes would be inter connected just before the mufflers to ballance and help stop the resonance and backrap on decelleration. I wouldent need any C. converters and no big rear muffler, just run the two pipes parellel and out the rear like stock , one over the other. I have done this in the past but a long time ago before over head cams and electronic ignitions and such . and it worked fine. I never tested the sixs on a dyno but on the big v-8 it was the only way to go. This systime sounded really good ,but I was young at the time and it was 48 yrs ago. These engines wire not putting out the performance that the Z is , this is a whole different breed of cat. Again this is why I am posing the question. GAry:classic:

[Bruce Woolmore]

I quite like the look of twin pipes, and they are used on quite a few sixes (Triumph, BMW)

Ed , I dont think you'd need to worry about loss of torque, because you'd use smaller pipes (around 1.75" sound right?) which would actually have less cross-sectional area than one large one (and less noise?) - if anything, it would be an all-out racer where this setup might not work. My experience with Triumphs supports Beandips theories, with balance pipes to chop back the resonance.

I have a single 2.5 " pipe and I'm finding it a bit raucous even with two mufflers, so I figure it won't be any worse! wish it could sound liek my Skyline turbo, which has a wonderful throaty burble at idle which goes quiet as I come off idle - wonderful!!!

but Like Ed, I'm open to other opinions on this!

[beandip]

thanks Bruce, I think the same thing, My brother had a Triumph 3000 and it had a dual exhaust and sounded great . I think I am going to go this route and will post what is what . Gary