For all you F-Body enthusiasts, there's a rather simple solution for dual exhaust that I found handy. Dynomax makes a dual exhaust kit for f-bodies that isn't widely known. The kit is a 2 1/4 inch kit w/out cats. The part number is 89009. There is a small catch. This kit requires dynomax headers number 89012. It won't work with the 85098 headers which are listed as the Camaro/Firebird headers. The kit shows the pipes going both out the driver's side. It doesn't include mufflers, but they recommend a turbo muffler from dynomax. All these parts are available off of www.jegs.com or www.summitracing.com. All part numbers listed here are the Dynomax numbers. If you have any questions or comments or want more info or pictures, email robbie@kconline.com. Thanks!

 

"If you have any questions or comments or want more info or pictures"

Do you have pictures of this exhaust system installed? Please post them here.

 

when they make it dual 2.5" give me a call. single 3" is good to over 400 HP and is a hell of a lot simpler.

 

that system exits before the rear wheels and it has ben aroud awhile.......imo a single 3 would flow better

 

That kit looks kind of worthless to me. It would be much easier to fab up your own design. I'd rather stick with single 3" than dual 2 1/4

 

Jack- Actually, it doesn't exit before the rear wheels. I ordered one myself because my father works at the local Napa store. I installed it with much ease and I'm only 17.

You can't tell me that it would be much easier to fabricate a dual exhuast than it would be to slap on a kit. I'm gunna take some pictures the next time I get it up on the rack which should be within the next week. Personally I think that 3" and 2 1/4" Duals are the same in performance. Tell me, is 1-5 horsepower really gunna matter that much? Really, if you're that worried about it, buy a different air filter or flip your air cleaner upside down and the problem's solved. Many people are looking for an easy way to do duals on their 3rd gens and this is the easiest way w/out having to fabricate ANYTHING. My buddy owns a muffler shop and he said it was alot easier putting the 2 1/4" up than trying to stuff the 3" up in there, but I guess that may be personal opinion. Shoot, isn't all this personal opinion though.

 

POST PICS PLEASE

 

 

 

Do what??? maybe the same on a stock 305 or 350...but there is no way id run 2 1/4 on a motor that is pushing 750 at the flywheel...

 

That was obvious to all.....well, I guess all but one.

 

Thanks for the sarcasm, @sshole

 

I tried that part# and I get a mustang spolier

 

Ha I'd like to try and see u flip the air cleaner upside down on a thirdgen. True though the 1-5 horsepower wont really kill you all that much.

 

hows the ground clearence

 

ouch!

 

I tried, but you weren't there to see it.

AJ

 

And pics or further results on this kit?

 

now here is a question i know 3" would flow better but u guys are sayin that a SINGLE 3" will flow better than 2 1/4" duals. hows that u have 2 pipes flowing less but if u add it up it is like 4 1/2" compared to 3" all 8 cylinders into 3" would seem more restrictive than 4 cylinders into 2 1/4". i am just askin so dont bash me but my logic seems correct. oh yeah post some pics and was there any clearance issues?

 

We've been over this before. You can't compare the area of duals to the area of singles by adding the two together.
Area=pi (3.14) X Radius(squared)
Area of the 2 1/4's: 7.95 inches.
Area of the 3 single: 7.07 inches.

The difference isn't all that noticable.

 

i just wanna point out, all the single exhaust enthusiasts who told me single was just as good as dual always used the get a big single pipe and it is just as good as two medium pipes theory. what i always wondered is, all you people who are saying single 3" is more desirable than dual 2 1/4", why? honestly from my standpoint, it may be nearly equivelant in size but the fact is on single, the exhaust merges which creates turbulence in the exhaust flow. not a big deal, but it has always seemed to me the only reason people hate dual exhaust in the thirdgen community is that they cant do it, so they make it sound evil. i have never understood this, dual is superior in almost every application. high horsepower cars can use single exhaust, i have heard of 450 horsepower cars running single exhaust, but they make more horsepower with true duals. setups like the mufflex 4" cost more than it is to have a dual exhaust setup run in the tranny tunnel to be fabbed up for you. these are just observations, but a dual exhaust kit finally comes a long for our cars and everyone complains that it isnt mandrel bent oh well.

 

Amen brother, Ive been round and round with a whole bunch of people on this. All I have to say is Ive seen the results of swapping to duals produce a lift of .4 in the 1/8. (single 3" to dual 2 and 1/2 in the stock routing location) and even more gains going to dual 3" straight back. you can post all these area figures and equations all day long, but results show a whole lot more! It can be done with no problems if a person is determined to get them. I did.

 

The kit is cheesy, my brother bought it and he ended up having to buy different headers, and cut this to fit and cut that to fit...and it slowed him down...if ya want pictures of it I can get em cuz it's sitting on the ground where it belongs, stick with the single 3" your better off
sorry if I pi**ed anyone off but hey seen it first hand

Brian

ps. you can do dual exhaust on 3rd gen. and not have to resort to this kit, I dont have pictures but if anyone has heard of preston smith's camaro around here, he has/had dual exhaust all the way to the muffler in the rear so it can be done.

 

True dual 2 1/4" will flow better than a single 3" any way you look at it. Numbers are fine and dandy on paper but in the real world it doesn't mean a thing. Just my .02

 

On the summitracing site do a manufacturer's part # search and on the jegs site i get both the spoiler and the Dynomax header and manifold dual kits. Dynomax #89009

 

For someone just buying a 3rd gen w/out headers, this isn't a bad way to go eh? The 89009 headers match up with the 89012 headers and not the actual camaro headers, it's all a matter of preference. For the average joe who doesn't have a very deep pocket or access to a pipe bender, this is great. But you do have a point that it won't match up with much anything but the 89012's. BTW, how many race cars run a single pipe for exhaust... not to make anyone mad, but I'm just curious.

 

what was cheesy about it? it says all over the site not for use on long tube headers, shorties only, was your bro using long or short tubes?

 

bttt

still waiting for an answer blueiroc...

 

Actually on paper dual 2.25" will flow better because of the higher combined surface area, however the 3" probably flows just as much, if not more, because it doesn't have all the extra bends in the exhaust pipes. If i was going through the trouble of fabbing up true dual exhaust, i'd definately opt for something bigger than 2.25" pipes.

 

He used the shorty's that were required....really didnt line up that great....nothing lined up that great in fact, hangers were junk and the whole setup rattled enough to annoy anyone...and yes we do know about camaro's I have an 87 iroc stripped to the bone for new paint and a drag motor, he's got an 84 camaro, beautiful camaro and an 85 I think...but hey matter of opinion I guess but I've run low 12's on a single 3" pipe and drove the car home after and his camaro runs low 11's on a 3" single and mufflers but hey whatever If ya like it, buy it, you will doubtfully get any gains from it but if anyone just wants to be able to say "I have dual exhaust" go for it but I'd rather have quality parts that perform, and hey if ya want one I'm sure he'd sell it cuz it's just collecting rust at the moment....so flame away but hey, just my .02 worth

Brian

 

i didnt mean to flame if i did, i am actually very happy you replied with an intelligent response, its really helpful to me. thanks. i want the kit, but i am not sure if my headers will even work. it would be so much easier for me to just get the single 3", but i do want to be able to say i have duals

And RedFirebird, which do you think is worse, dumping two exhaust pipes into 1 or a pipe making bends?

 

You have to get the headers they require or you'll have alot of cutting and welding to make em work and if ya do get them do your self a favor and buy some GOOD hangers and throw theirs away, it'll save on rattles, i mean i'm sure theyre ok for most paople but neither me nor my brother were thrilled with them...anywho just my opinion...Have fun

-Brian

 

the reason behind a single outflowing a set of duals involves the resistance encountered by the walls of the pipes. The air (liquid also) does not flow at the same speed near the tube wall as it does in the center. I think the formula originates from fuild flow in pipes.

It more or less works out to be that 2.25" duals flow slightly less than 3" single. And the same thing for 2.5" duals versus 4".

U think 3" is tough to fit..
Just try 4" with 3" head pipes and still have ground clearance.

 

One point you guys seem to be missing is that when comparing 3" to 2 1/4, all your math equations are pointless. on a single your running 8 cylinders through ONE pipe. On a dual your only running 4 per side. I'd rather have a 2 1/4 pipe barking out 4 cylinders instead of having 8 stuffed into a pipe that is slightly larger.

 

Robbie8302: Have you got any pics? I'd like to at least see the cause of this debate.

To the rest: To each his own. True dual or single pipe don't matter. The right size pipe for your application-priceless. Since most of the members on this board have a 305 the "smaller" dual 2 1/4 would be better because it will help boost and maintain low and mid range tq. Bigger is not always better. In the end get what you want and can afford.

just my 2cents.

 

Here are some pics of mine. Just read the sig.
BTW. clearance is not a problem. I have NEVER scraped. Gotta love air shocks.

 

Ok, we're having fun now, eh?

The concept of the walls of the tubing causing resistance is valid, but negligible in the real world, because unlike a fluid, gas is compressible. It really depends on the finish of the inside of the tubes and the radius of the bends, which we will assume is the same for both systems, so this becomes a very small factor.

What is not a small factor is area. This is the amount of "space" that the gas can exit through.

area= Pi x Radius squared (you guys remember this one, right?

1.125 (radius not diameter!) x 3.1415, squared, times 2 pipes =24.98 Sq in.

1.5 x 3.1415 Squared
= 22.20 Sq in.

The dual 2.25's have a small edge, but most of the single large diameter systems are dominant in our market because many states require that you run the same number of Cat converters, in the same locations as stock, which pretty well locks the single exhaust into the car if it came with it. And it came with a single cat from the factory because cats are big, heavy and expensive.

my .02 c

 

Don't know how you came up with that result, but your math needs work.

To wit:

the formula,...

pi x r²
<p>or to avoid confusion:
<p>pi x radius x radius

so for a 3" pipe, the area would be determined by

pi x rad x rad = 3.1416 x 1.5 x 1.5 = 7.07 sq in.

All fine and good, but we're the forgetting something here. We want the inside area, so we need to subtract the wall thickness from the radius. As an example let's use 14 ga pipe(.064") and try again.

1.5 - 0.064 = 1.436

3.1416 x 1.436 x 1.436 = 6.478 sq in.

And for dual 2 1/4's:

1.125 - 0.064 = 1.061

(3.1416 x 1.061 x 1.061)2 =(3.537)2 = 7.073 sq in.


So Round 1 goes to the 2 1/4 duals, which have 9.2% more inside area than the single 3" pipe- ((7.073-6.478)/6.478)100

 

Round Two(ding, ding)

The concept of the walls of the tubing causing resistance is valid, but negligible in the real world, because unlike a fluid, gas is compressible.

Not sure how the gas's compressibilty is relevant(don't take that as a flame), but I see the wall surface as more than negligible.

First, let's take a look at the difference in wall surface between a single 3" pipe and two 2.25" pipes(yay, more math):

Circumference = pi x diameter

In the case of the 3" pipe, with 14 ga walls(0.064"), the inside diameter will be 3 - (0.064 + 0.064) = 2.872" so the inside circumference will be = pi x 2.872 = 9.022"

For a 2.25" pipe, the inside diameter = 2.122" and the inside circumference will be 6.666". But remember there's two of those smaller pipes, so the combined surface of the duals presents 13.333" of pipe to the exhaust gases, which represents a 48% increase over the single larger pipe.

However, negligible the resistance, increase it by 48% and it gains in significance.

Score Round Two as a win for the 3" pipe.

 

How about showing us a comparison in power between duals and single 3 using your "resistance method" 88. Thats what I thought.....YOU CAN'T. So until I see scientific proof I'll stick with what I got.

 

Round Three:

Finally, let's take a look at the gas's velocity. Regardless of how the resistance of the walls will affect the velocity, two other factors will have an effect on the velocity
1. Lost heat = lost velocity
2. Restrictions and bends

Since the dual setup presents 48% more inside pipe surface, it will have a more significant effect of removing heat from the gas. I'm not sure how you'd formulate the heat loss by given distance, but I'm sure you'll agree that dual setup will relinquish more exhaust heat. As portions of the gas cool, their velocity slows down, which conversely will slow down adjacent and following portions. And as those gases slow down, they will cool and condense and present more restriction to the following gases.

If your dual setup goes over the axle(the under-axle example posted above would't allow me into my driveway), then it should be assummable that the dual setup will have a more significant restriction. When flowing gases around a bend, the gases nearest to the inside of the bend slow significantly. Since the dual setup has quite a bit more inside surface, that effect should be magnified.

I've also noticed that almost every muffler sold has some degree of necking-down restriction at the inlet(including my favourite Borla's). Again, if you have two inlets, this restriction will be multiplied.

Barring an appeal, I'll award the split(2 -1) decision to the single 3" system. I can see where at the very high-end of the engine's range a dual setup may improve flow, but for most street setups I'd still favour the single pipe.

 

And you can? If not, what was your point?

So until I see scientific proof I'll stick with what I got.

I'd heartily agree. If you've made an invetment either way, I'd doubt you'd see enough of an improvement to justify switching. There's a lot of wild claims on both sides of this argument, but no real apples-to-apples comparisons.

 

I don't know where the hell you live but my driveways a bitch and I have no problem getting into it. I have never scraped driving my car with the exhuast the way it is. Just so you know The mufflers do not go under the axle but are hung from the rear seat floorpans.

Your arguments have absolutely no credibility or proof!!!! You are making an argument up that is based only on BS info from your head. Again where the hell are you getting this information. There is no scientific proof or otherwise showing that the resistance is greater in duals and velocity is slower.

I asked you a question....not the other way around. I'm not up with these "well you can't prove it either" games bulls**T!! Either answer the question or don't post. I don't need to prove you wrong because I have results. You are the one who made a claim and a warrant and now you need to back it up!!

I'll be waiting

 

No4njunk:

Calm down. Nobody's trying to kill your hamster :-) Don't take bench racing as an insult to your preference, we're just "moving hot air" looking for better ideas :-)

88 Iroc:
Oops, yes I did get things in the wrong order, but bear with me, i had the flu at the time (a bad excuse is better than no excuse!) The compressibility of gas is very significant. It is because the molecules are much further apart, and therefore do not create a lot of friction against each other, are able to slide by each other without much fuss. In other words, a boundary layer slowed by the walls of the tube would be much smaller for a gas than a liquid, because the liquid molecules are in much closer proximity, and therefore "drag against each other' to a much much higher degree. 48% does get my attention, but not for the reason you mention. What about weight?

In my personal opinion, which everyone values very highly (sigh) even though the dual system would offer a margnal if any decrease in back pressure (there will be a boundary layer, just not like a liquid!) The edge in ground clearance is very significant to me. But nobody has touched on weight here, and a 48% difference in wall area (give or take) will make for a very significant difference in weight of the systems. On a dual system, you not only have the additional weight of two smaller pipes instead of one big one, but 2 mufflers (maybe, maybe not?) and possibly 2 cat converters. This could more than double the weight of a single tube system.

There is a company that makes oval crossection tubing in large sizes, and flat wide mufflers to go with them (Spin Tech) I have seem these systems used on NASCAR stockers, but not on a street car. Does anyone out there have any experience with them? large oval tubing seems like the best of both worlds. It makes the math a lot harder, though :-)

 

I forget who it was, but someone not to long ago said that they gained like 3 or 4 tenths going from single 3" to dual I think 2.5s. If anyone know who that was or if this person reads this, let me know who you are because I would like to talk to you. Oh, and I hope someone knows who it was because that would add some validity to some of the arguments.

Ben

 

Momar:

We were comparing figures for 2.25 vs 3'. If you go up to 2.5, we have to do all this math all over again!! :-)

 

I realize that. I am just saying that there was someone who actually went from 3" to duals and did get quite a gain.

 

To those that think my single 3" single would flow better than a dual 2 1/2 on my application, you may be inhaling a little bit too much exhaust fumes. I will gladly dyno my car now, switch to a TRUE dual set-up with dumps, then dyno again if someone would cough up the coin to do it. My motor would breathe better with a dual set-up, anybody that tries to tell me differently is smoking something funny.

 

Area of a 3" single
Pi x (Radius Squared)
= 7.069 Sq In

Area of a dual 2.5"
Pi x (radius Squared) x 2
=9.818

Boys, these are not even close. 3" single vs 2.5 dual, the dual wins in a big way. No question.

 

Well, I'll give you this one. From the picture, it looks like your setup dumps underneath the panhard bar. If you say it doesn't, I'll take you at your word. At the entrance to my driveway, there is a slight(2") dip, 2 feet after the curb. That, combined with the fact that the rear tires are still on the street(3" below the curb), means the underside of my IROCs come very close to scraping.

Your arguments have absolutely no credibility or proof!!!! You are making an argument up that is based only on BS info from your head. Again where the hell are you getting this information. There is no scientific proof or otherwise showing that the resistance is greater in duals and velocity is slower.
Wonderful! The fact that you have taken a personal affront to my argument has got you frothing at the mouth. I don't know if I should even try to respond, but I'll try to keep a cooler head about it. If you consider my equations to be BS and lacking in credibility, please show me where I have erred. If you say that science doesn't back-up my arguments, show me that it refutes it. At the very least, I tried to show why I believe that which I stated, and how I came to my conclusions. You on the other hand have done nothing more than argue for the sake of arguing(which I believe is referred to as 'being a troll').

I asked you a question....not the other way around. I'm not up with these "well you can't prove it either" games bulls**T!! Either answer the question or don't post. I don't need to prove you wrong because I have results. You are the one who made a claim and a warrant and now you need to back it up!!
Apparently, you expect others to meet a higher standard than the one you assign yourself. If you wish to challenge my assertions and lay my argument to waste, then you'll have to do better than: "because I say so". If you have actual verifiable proof(something you allude to), please share it with us. I don't have a problem with being wrong, or admitting I've erred, but you haven't shown us anything that backs what you're claiming. At least I've tried to use some logic and reasoning for what I've said and again, I've tried to show why I believe what I do.

Either answer the question or don't post.
Did someone just make you a moderator, or are you just insulted when someone has views that differ from your own and you feel the need to shout them down? Sorry, I'm not down with that type of BS game. If you ask a valid question to which I have a reply, I'll answer. But if I sense the question is posed only to try and make me look bad, I'll throw it right back in like kind. Turnabout is fairplay Bubba. Deal with it.

I'll be waiting,...NOT!