Hey all, here's a question I'd like to throw out there. :D
Now, first off, I'm normally a pretty conventional guy. :o But, in light off the trend in our cars being built lower to the ground these days and the fact that we're using larger diameter exhaust systems such as the 3" pipe and all...do the exhaust systems have to be made out of "round" material? Is there some reason that we could not have a free breathing exhaust system that was built oval or flatter shaped (or even rectangal shaped)?

Yeah, I know, making the tubing would cost more money, yada, yada, yada... :boring:

But just for discussion sake, what would be the pitfalls of an exhaust system that was oval shaped, rectangular shaped, etc, as a way to help with ground clearance problems? Would it affect exhaust perfromance i,e, breathing, "sound", etc?

I know there are some exhaust that are already manufactured in an oval shape, but my bringing this up is really just to provoke "thought and discussion" about unconventionalism as a way to approach the ground clearance issue.

I have had trouble with my '69 Nova for years with ground clearance problems because I choose to use a dual muffler system rather than the usual crossflow type as per factory design for the Nova. Also, I remember dragging off my brand new Turbo mufflers on a Chevelle I had while trying to carefully drive down my Father-in-laws "dirt" road so my wife could pay them a visit. :mad:

Don't the roundy-round boys use a flatter shaped exhaust system (of course, no mufflers)?

Is there something wrong with using an exhaust pipe shape other than round? Would it affect breathing characteristics, etc?

It could be flatter (oval/rectangular) under the body of the car and then convert back to round for conventional tailpipe tips if preferred.

How difficult could it be in this 21st century to manufacture an exhaust sytem that is oval or rectangular,square,etc?

Like I said, this subject is just to promote discussion. What do you all think? Couldn't exhaust be just as effective in some other shape than round? Or, are we really bound by traditionalism and round exhaust? What about some new thinking towards the shape of more "ground clearance freindly" exhaust/muffler shape...something more flatter shaped that would promote more ground clearance...

Just thought I'd provoke some discussion on the subject on this great forum. Anybody care to expound? :)

Just food for thought... Have a great day :thumbsup:
Dave

do butterflys fart when they fly?

Already been done, here ya go.......

http://www.drgas.com/store/home.php?cat=8

Here is what i'm going to use on my Pro Street car.

http://www.drgas.com/store/home.php?cat=8

http://drgas.com/store/files/master/product_images/thumbnails/straight_oval_pipe_thumb.gif

Dr. Gas offers a wide line of oval parts:

http://www.drgas.com/store/home.php?cat=8

I guess we have Dr. Gas covered....

Round is the most efficent. With oval you'd need to have a larger cross sectional area than round. I learned all about air flow building a dust collection system in my workshop.

just like the butterfly.....if he holds it ...at some point, there is a build up of back pressure, reduces thrust......and flys right into an 18 wheeler on the highway.:D

how about some 3 in square stock??:thumbsup: :D

GM used to offer oval exhaust kits through GM performance about 8-9 years ago or around there. I believe they were sourced from Dynomax (could be wrong). They touted the fact that with a oval exhaust, you gained more flow due to the additional space on the sides, though I would think you could actually go with a smaller height (2" instead of 2-1/2" for instance) and still flow like a 2-1/2".

Nope!

http://www.chevelles.com/showroom/data/500/medium/1152ten.jpg

just like others said, doesnt have to be round, but if its not round, it needs to be bigger as the flow is less efficient... now thats a good picture!

a

flow in a tube is mostly based on the cross-sectional area. area of a 2.5" tube is about 5 sq. in. area of a 3" tube is about 7 sq. in. so, to replace either with rectangular tubing you just need a size where width x height = either 5 or 7 sq. in. Oval tubing cuts off the corners so the w x h measurement will have to be a little bigger. AFAIK, like on 3" tubing being replaced by rectangular tubing it wouldn't matter much if it was 1 x 7 or 2 x 3.5, as long as it comes out to 7.

Nope!

http://www.chevelles.com/showroom/data/500/medium/1152ten.jpg

What else do you notice about that exhaust system?

It looks like all round tubing until after the X-pipe where it connects to what looks like either a very flat "oval" or rectangular tubing. Just by eye-balling it, it looks like the rectangular area might have more cross-sectional area, I'm guessing that would be to end the exhaust "tuned length" just after the X and the rest of the tubing is just to get the gasses out from under the car.

>> What else do you notice about that exhaust system?

it's upside down? :)

4 into 2 very long collectors.

jeez, you think they're running some kind of tri-y deal on those things?

nasty bend where it goes around the corner at the back of the tranny too.

flow in a tube is mostly based on the cross-sectional area. area of a 2.5" tube is about 5 sq. in. area of a 3" tube is about 7 sq. in. so, to replace either with rectangular tubing you just need a size where width x height = either 5 or 7 sq. in. Oval tubing cuts off the corners so the w x h measurement will have to be a little bigger. AFAIK, like on 3" tubing being replaced by rectangular tubing it wouldn't matter much if it was 1 x 7 or 2 x 3.5, as long as it comes out to 7.

It has to bigger than the cross sectional area of the round due turbulance and friction of the wall.. It makes quite a difference.

Apparently, something other than "round" doesn't seem to bother the NASCAR boys for the sake of ground clearance...which is the reason I started this discussion...ground clearance!

Are we more concerned with the conventional looks of round as opposed to oblong, rectangular, etc?

What about the oval chrome exhaust tips like my '69 Chevelle SS had...remember those? :hurray:I always thought they looked much "cooler looking" than the typical aftermarket round tips!

Dave :thumbsup:

Very long stepped primaries, small collectors, "expansion chamber" before the X, smooth transitions from round to oval, etc., X is very tight to the collectors.

What did I miss? :)

I dunno... seems to me that headers and mufflers are bigger ground clearance problem than pipes?

I don't believe appearance or flow has anything to do with it for 99.9% of the population. I believe you'll find that cost is the issue. Round tube is MUCH cheaper and readily available in many sizes. Dr. Gas and Spintech are the only oval tube suppliers I found for oval tube. Sizes are more limited, and you have at least one round to oval transition to contend with, as header outlets are typically round. You can either run Spintechs oval mufflers or transition back to round for your muffler. I happen to have a 4-1/2" round header collector. I installed a transition to 5" oval (actual dimensions are about 3-1/2 x 6-1/2) for additional ground and floor pan clearance, then back to 4-1/2" round through 4-1/2" Borla XR-1s. Then it all went out for ceramic coating. I estimate that a traditional round tube between the collector and muffler would have been maybe 1/3 the price I have in mine, possibly less. That's a lot of bucks for a little clearance. On the other hand, and 66Rat might agree, it looks bad to the bone!! and that is priceless.

R/ Dave

What about those really cool chebby bow-tie tips?!?!?! They're bad ass, think that they restrict flow? Wonder if they puff bow-ties when you have a motor that smokes...

I think the cost of puttin' together an exhaust system out of something other than the conventional round pipe would definitely be a cost factor...at least right now. But what if enough demand was there? Cars are getting lower as the fad is today. An exhaust system that hugs closer and tighter would really be an improvement.
As with anything new, the cost no doubt would be higher initially. On the other hand, how much do each of us put into our cars whether it is to make them more "original" or in modifications?

I think a stainless steel "oval' shaped 3" exhaust system going all the way out to the back bumper ending with Chevelle SS looking oval tips would really look great, would it not? :yes:

The oil pan and the headers are no doubt a factor. There's always a dry sump oil system approach to consider...now were talking "moneyyyyy!"

The price you pay for building our hot rods, eh? ;)

Dave :thumbsup:

a butterfly make look cool also with a squared of behind.......wonder if he could fly louder? ......thinking about evolution and all any butterflys develop square butts? .....:D

The exhaust on my Chevelle is low-tech and totally correct & stock (& inefficient at making power). It cost me $200. On my Passat it would easily cost in excess of $2000 to replace. Factory mufflers are $625.

Great post! I'm learning from all this, and the link to Dr. Gas is someplace I will spend some time.

The links to Dr Gas are definitely worth looking at. :thumbsup: I already had them in my favorites. It shows that they were already previously considering exactly what I am talking about in this topic and why I started this topic in the first place...the need for something other than the conventional exhaust systems we have been using in the past. My hat's off to Dr Gas! I will definitely be considering their products when I redo the exhaust on my Nova. :D

I too have learned much from this topic!
"Thanks" to those who responded to this topic with useful postings. :hurray:

Dave

The circle track guys around here are now paying huge money for headers that are built with rect. tubing. I have no idea why they think its an advantage but I will say they are the ugliest set of headers I have ever seen.

I would think oval tubing would be a nightmare to get over the axle and not run into weird angles to the piping.