More tubing = more weight = slower autoX times.

That's my reasoning.

You don't need to have double pipes the whole way back. My idea was to split a single exhaust just after the rear axle, and have dual glasspacks & single tips each, or split the tailpipe to have dual tips.

A side effect would be that with enough separation between the two exhaust tips, you could get the wave pulses out of sync, and should be hear what sounds like a dual exhaust, and probably even double RPM, so your 6 cylinder evgine would sound more like a 12 cylinder.

TomoHawk, you used the diameter instead of the radius. Here are the correct values:

2" muffler outlet = 3.14 sq. in.

2 1/4" muffler outlet = 3.97 sq. in.

2 1/2" mufler outlet = 4.91sq. in.

dual 1" tips = 1.57sq. in.

dual 1 1/4" tips = 2.45 sq. in.

dual 1 1/2" tips = 3.53 sq. in.

Also, along the lines of what someone else said, 2 smaller pipes with a total cross section the same as one larger pipe will still provide more resistance to the flow of the gases since there is more surface area of the pipe for the gas to pass by. Keep in mind that the speed of the gas right at the surface of the pipe will be zero. So all else being equal, a single pipe will flow more than 2 smaller pipes of equivalent cross section.

Yes, exhaust gases are fluids, but not as dense as liquids, like water. Water is 600 times as dense as air.

I'm still tlooking ofor some 1 1/2 tips tho. Most auto parts & muffler stores have 2 or 3 inch stiff.

TomoHawk, you used the diameter instead of the radius. Here are the correct values:

2" muffler outlet = 3.14 sq. in.

2 1/4" muffler outlet = 3.97 sq. in.

2 1/2" mufler outlet = 4.91sq. in.

dual 1" tips = 1.57sq. in.

dual 1 1/4" tips = 2.45 sq. in.

dual 1 1/2" tips = 3.53 sq. in.

Also, along the lines of what someone else said, 2 smaller pipes with a total cross section the same as one larger pipe will still provide more resistance to the flow of the gases since there is more surface area of the pipe for the gas to pass by. Keep in mind that the speed of the gas right at the surface of the pipe will be zero. So all else being equal, a single pipe will flow more than 2 smaller pipes of equivalent cross section.

But as stated, 2 pipes may sound better, in theory. Not too sure about that, though. I'm not an acoustical engineer.

A side effect would be that with enough separation between the two exhaust tips, you could get the wave pulses out of sync, and should be hear what sounds like a dual exhaust, and probably even double RPM, so your 6 cylinder evgine would sound more like a 12 cylinder.

I highly doubt the 6 would sound like a 12.:stupid:

It can and has been done, under controlled conditions, and in the lab. Wave machanics.

When I put four pipes at the back of th GTO replica, I used 1 7/8" pipe because that was the smallest Borla made stainless extractor tips for.

I ceramic coated (silver) the tubes and they look pretty good-even without the tips!

Will

I've seen some cars on the vintage races that look like they have four pieces of exhaust tubing sticking out..

What do you guys think about using the DTM-style tips on a Z, ricey? I think dual straight tips are more nostalgic.

lots of interesting thoughts here. Keep in mind that some back pressure will yield better torque numbers for a street car. If you like the nostalgic look of dual exhaust it comes with a price, added weight, and not as good scavenging capability vs a single exhaust.

My dual racing exhaust is exceedingly loud, it sounds like two open header, three cylinder cars at low RPM. At high RPM it sounds like nothing else I can compare it too.

But as stated, 2 pipes may sound better, in theory. Not too sure about that, though. I'm not an acoustical engineer.

2 pipes on a tip does sound a little different. I went from one large pipe to a dual tip and it made the exhaust sound a little louder and maybe a little higher pitched. I was going for look rather than sound though, and it wasn't enough differnece to make it noticeable.