Why round exhaust pipe?

[BigBlockMopar]

Here's another one...
With the same wall diameter, a round tube has the same strength and bend resistance in all directions. A square tube only in 4.

[TC]

Well Nascar doesn't have a problem using square exhaust.......

[DanStokes]

My guess is that it really won't hurt performance in any significant way and often Hot Rodding is the Art of the Possible. As I understand gas flow in a pipe, there would be individual vortecees (sp?) in each corner, leading to significant boundary layers. But "a difference isn't a difference unless it makes a difference" (C. Don Paulsell) and I suspect that this wouldn't matter in any practical way.

Dan

[anotheridiot]

around here, houses are all built on concrete slabs.

But yeah...making a big square duct is easier to branch off of. This has nothing to do with exhaust tubing.

square duct also fits between the structure of the building walls to allow the big pipe, otherwise you would have to use 2x10's to get round pipe upstairs.
If you can make a transition I think it would look good. You did mention 1 1/4 x 5 which is well bigger than 2 1/2" round, its closer to 3". There is the back pressure discussion that usually ends up being brought into the discussion that may be a bigger downside of square pipe. I am not about low riding cars, but might steal your idea.

[SuperBuickGuy]

Here's another one...
With the same wall diameter, a round tube has the same strength and bend resistance in all directions. A square tube only in 4.

tell that to my exhaust pipe that got crushed on a driveway entrance

square duct also fits between the structure of the building walls to allow the big pipe, otherwise you would have to use 2x10's to get round pipe upstairs.
If you can make a transition I think it would look good. You did mention 1 1/4 x 5 which is well bigger than 2 1/2" round, its closer to 3". There is the back pressure discussion that usually ends up being brought into the discussion that may be a bigger downside of square pipe. I am not about low riding cars, but might steal your idea.

dumb questions generally turn into the next great idea use away, I'm thinking of using a flowmaster type muffler I built years ago, cutting the back off it, then transitioning to an elbow then the outlet

[skullbucket]

Round pipes have less wall resistance just like a sewer pipe so there is nothing to hang up on.

[SuperBuickGuy]

Round pipes have less wall resistance just like a sewer pipe so there is nothing to hang up on.

as opposed to skid plates?

[Matt Cramer]

Round bends can be welded together at any arbitrary angle. Square or oval pipe, you've got to match how it's clocked.

[Beagle]

get it shaped like this?



oh wait - that was just a dumb response, not a great idea.

[MR P-BODY]

At the factory we can make any shape of tubing but round works and its easy to make
on a series of rollers... mandrel bend tube has a mandrel pass through the tube during
the bend and that works much easier... you can oval a tube to a point and still maintain
the area of the round tube... the only reason the nascar boys do it that way is to get the
ground clearance at the sill(most use round sides with the flat top and bottom so that by
rights is a oval tube) also round is stronger than having a flat area

[anotheridiot]

pretty soon you are gonna have guys using their frames for exhaust like some top fuel dragsters use their tubing as vent are and not even bother with tubing anymore lol.

[MR P-BODY]

I have seen the frame tubing used for a fuel tank

[SuperBuickGuy]

With how low my Corvette is, square will be the cat's pajamas. Especially since I'm not hearing anyone who's convinced me that there'd be any kind of performance loss.

I may even make a new muffler into the last 2 or so feet of the rectangular tube. Although, I do care a bit about apparances, so it'll go from 1x5 at the frame to 2 1/4 x 4 or 5 at the side of the car

[MR P-BODY]

If you make it with round side walls specially in curves you wont
have any issues... just make sure it has great enough surface area
to match or be greater than the other tubing

[SuperBuickGuy]

If you make it with round side walls specially in curves you wont
have any issues... just make sure it has great enough surface area
to match or be greater than the other tubing

round through the cross member, angle towards the exit point just after with round, transition to square and combine a muffler in the square, then under the frame and out. I'm going to make it out of fairly heavy guage material so if it does hit a speed bump it won't crush. the other bit, where it goes under the frame, that's also the lift point for my hoist - so it'll be strong enough to handle that kind of weight at that point.... if it doesn't work, no big deal. Heck, I'll probably make most of it out of 304 stainless