Hey guys, I was wondering how much power will be lost if I ran a single 3" exhaust VS. and dual 2.5" system.

I ask because my new toy is a 280z. Details:
http://www.chevelles.com/forum/ultimatebb.php?ubb=get_topic;f=4;t=020031

Of course because the car originally cam with single exhaust the car has 'notches' in the tranny crossmember, rear axle crossmember, and rear sheet metal for single exhaust.

Option #1:

Because I am going for the 'sleeper' look I'd prefer to continue running single exhaust system. However I don't want to lose a boat load of power in the process either.

Option #2:

I can run dual 2.5" exhaust without too much trouble, but I'll lose the ghost in keeping the 'stock' look.


So, the question is: will I lose alot of HP/TQ with a single 3" system over a dual 2.5" setup?

Thanks guys.

3rd generation (maybe 4th) camaros/firebirds usually use a single 3" exhaust because of the torque arm suspension. I have heard that a single 3" flows between a dual 2 1/4" and 2 1/2".

you might check some of the 3rd gen camaro sites to see how much power they are giving up and maybe some workarounds they use. Probably more experience there than here on the subject.

That's true, I didn't think of that.

i think the power loss- if any- would be minimal. but it would be a bit quieter and the overall tone would be more mellow and stealthy. if you are worried about it, how about a 3.5" or even a 4" setup?

The link is to an article written by Jim Hand a noted Poncho guy. The article has some interesting points about exhaust systems. Could be helpful. http://www.pontiacstreetperformance.com/psp/exhaust.html

What about trying to fit up a muffler from a late model truck (dual inlet/ 4" outlet) for that ricer fart pipe look, or maybe just run 3" duals all the way out but exit with side by side chrome tips? X pipe and Borla's to keep that ricer rattle.

Area of a 2.5" circle= 4.906 sq. inches. 4.906 X 2 =9.81 sq. inches of flow area for a 2.5" dual exhaust.

Area of a 3" circle=7.065 sq. inches of flow area for a single 3" exhaust.

A single 3" pipe gives up nearly 3 sq. inches of flow area over dual 2.5 pipes. Counteracting the reduced area, however, is that the single 3" exhaust has far less pipe surface area, for less friction on the exhaust gasses. The single 3" pipe should warm up faster, and run hotter, than the dual 2.5 pipes. In my area of the country, this would be quite welcome in terms of reducing exhaust system rust-out.

I think the performance difference could go either way, depending on the severity of bends needed to fit the chassis. Either one will be restrictive with crush-bent pipes. Even with mandrel-bent pipes, tight bends to my way of thinking would favor the dual 2.5", whereas gentle bends would favor the single 3". In part, because to clear a given obstacle, the 3" pipe has to be bent tighter than a 2.5" pipe. But other opinions are welcome.

First guess: You won't notice a performance difference on the street whichever way you go. Sound quality may vary, though. I'm quite curious to see what actual testing shows for dual 2.5 vs single 3".

Cable,

As a former 280Z owner this is a project that I would have loved to do, have researched, and even picked out my license plate for: "2V8EZ".

A small block/TH350 combo doesn't weigh a heck of a lot more than the I6/4 or 5 speed set up - maybe 100 pounds. It'll be a fun toy.

1) Unless you are going to rework the trans tunnel, a TH400 presents a bigger packaging problem than either a TH350 or a PG. Moreover, with the stock rear sheet metal and suspension bits in place there's just not a lot of room for tires - it'll be tough to get even close to enough traction. A PG is a very good choice here.

2) You are going to tip some people off with the tires and 10 point cage so appearing to be stock - in the best sleeper tradition, is going to be somewhat compromised. BUT, back when these cars were popular, an awful lot of people ran a muffler with dual, chrome tipped, outlets but the outlets were arranged vertically. A talented exhaust person could probably arrange the dual 2.5's in the same manner.

3) You are going to break the rear end. A lot, especially with a BB. At the least you're going to need to find a donor rear from a later model Z, preferably one from a 280ZX/300ZX turbo. I think the earlier turbos had 4 lugs, the later ones had 5. You'll have to address that.

Go here http://hybridz.org/nuke/index.php for some interesting reading.

Dan

Another vote for, One OVER the other at the rear.

Originally posted by ss3964spd:
Cable,

As a former 280Z owner this is a project that I would have loved to do, have researched, and even picked out my license plate for: "2V8EZ".

A small block/TH350 combo doesn't weigh a heck of a lot more than the I6/4 or 5 speed set up - maybe 100 pounds. It'll be a fun toy.

1) Unless you are going to rework the trans tunnel, a TH400 presents a bigger packaging problem than either a TH350 or a PG. Moreover, with the stock rear sheet metal and suspension bits in place there's just not a lot of room for tires - it'll be tough to get even close to enough traction. A PG is a very good choice here.

2) You are going to tip some people off with the tires and 10 point cage so appearing to be stock - in the best sleeper tradition, is going to be somewhat compromised. BUT, back when these cars were popular, an awful lot of people ran a muffler with dual, chrome tipped, outlets but the outlets were arranged vertically. A talented exhaust person could probably arrange the dual 2.5's in the same manner.

3) You are going to break the rear end. A lot, especially with a BB. At the least you're going to need to find a donor rear from a later model Z, preferably one from a 280ZX/300ZX turbo. I think the earlier turbos had 4 lugs, the later ones had 5. You'll have to address that.

Go here http://hybridz.org/nuke/index.php for some interesting reading.

Dan Thanks Dan, no worries on the rear end. I already have the R200 rear end and I am ditching the U-joint axles in favor of the later 300ZX (Z31) CV axles. I've seen those rears go into the nines with welded spider gears, in fact I have never heard of someone breaking one with the CV's.

Oh and my plates already read, "MEAN CAR".

LOL cable - I should have guessed that you already knew the ins and outs of this deal.

I've driven a few of these and I can tell you that they are nothing less than an impressively large bag of fun, but they high winding small block cars, 2 autos and one 4 speed. Owners didn't have the rears set up so it was "easy on" but, I tell ya, roll into these and let 'em wrap up = big a$$ grins.

Good luck. Send Pictures.

Dan

A buddy of mine runs 400 c.i. in his 240Z's. He normally runs dual exhaust on his (2.5) I've never really paid attention to the difference in sound, performance etc, but he seems to like the dual exhaust. He runs the car with flowmasters, unfortunately he is overseas (okinawa japan) and it's really hard to get in touch with him or I would get him to send me all his information. :(

The Chevy Cyclone or whatever that Supercharged S10 from a few years ago was, it had single 3" exhaust on it because of the performance gain. Someone will correct me if I'm wrong. But this is what an owner told me once at the track.

This is what I ended up doing:

http://memimage.cardomain.net/member_images/1/web/685000-685999/685533_18_full.jpg