antman89iroc

Ok to keep it simple(er) we're discussing the pros and cons of single vs dual exhaust on a 3rd gen Camaro without a cat (for off road applications, of course) and with shorty headers. I suppose it would in theory apply to other vehicles and long tube headers as well.

I have seen a lot of 3rd genners go to great lengths to install "true" dual exhaust on these cars. While there may be great mystique in dual exhaust I wonder if it is indeed worth the effort or even best. Here's what I see as being the goal of a well executed exhaust.

It should route exhaust gasses from the engine to the rear (or other suitable location) of the car.
It should provide an acceptable level of noise in dbs and hopefully sound cool.
It should provide the least backpressure possible.

Now, the chassis of these cars pose a bit of a challenge with the "snake around the passengers side" routing of the stock pipes, the torque arm on the drivers side, the panhard bar, the stock transverse muffler and the lack of alternative space for mufflers. We're basically left with a near stock routing unless you want to give up some ground clearance. I don't.

With the assumption we're gonna use shorty headers and use the typical 2.5" head pipes routed over to where the cat used to reside, the issue is now what to do from here. Let's take a look at options.

Dual 2.5" intermediate pipes have a combined area of 9.8in2. (4.9 x 2) and a total circumference of 15.7".
Single 3.5" int pipe has an area of 9.62in2 and circumference of 10.99".

It seems the single 3.5" pipe would be the best choice since the area is about the same but the total pipe wall is less. Beside we're gonna install an X or H crossover anyway so keeping the pipes separate isn't a requirement= right? "Line drop" or resistance should be less but the question here is will the velocity be less due to the larger pipe or about the same since 2 are combined. Other than the area are there other considerations?

Now we've made it to the axel. There is barely enough room to get a 3.5" pipe or 2x2.5" through.

Option one is to stay with the 3.5" pipe and get the largest, highest flowing muffler, mount it in the stock location and route a 3.5" tailpipe to the drivers side. This will work but the problem is flow. It's gonna be difficult to find a single muffler which will flow enough for hot V8, let alone a stroker of 400+CI. Another problem is few manufacturers actually publish CFM ratings.

Option two is to diverge back into 2x2.5" pipes, either before or after the axel, and route them to two mufflers just behind the tires. Here we've solved the flow problem but now we have to deal with mufflers hanging down which could be seen from the rear. The other issue is that short tail pipes generally do a poor job at dampening resonation. They tend to growl more. (remember the second half of goal 2?)

Who really cares if there are 1, 2,3 or even 8 pipes going to the rear as long as the goals are met-right? In the end it's personal preference but from a performance standpoint the single exhaust should provide equal performance to duals, providing we can find a suitable muffler. Otherwise a dual to single to dual setup should be preferable.

Any thought's or comments?

MrBrooks

You have valid points.......
However.........i think your math is off......
the key factor here is not just area........but flow capabilities.
just because a larger pipe is say 25% larger does not mean it will only flow 25% more.
it will actually flow well beyond that.........

What one needs to keep in mind is 2.2...............you need a total of 2.2scfm per hp.
I used to have a chart of pipe size and flow rates........I will see if i can dig it up

A single 3" pipe is good for ~400hp while 3.5" is good for 650(i think) and a 4" will support ~800hp.

MoJoe

iTrader: (5)

A single 3.5" may tuck next to the driveshaft better than 2x 2.5"s.
When crossing an obstacle, such as the panhard brace, 2.5s are 1" thinner the the 3.5". But, a panhard relocation or here can give you more clearance...

ETA: If you have the space, 2x 2.5" mufflers should make the car quieter, and you will find more options than a 3.5" muffler.

antman89iroc

In regard to the total area that is basically what I was speculating. One large pipe with the same area of two smaller pipes should flow more due to the reduced wall friction. There are other factors such as gas velocity and tuning pulses that are above my pay grade lol. But the end results are still valid. And Mo you're right, there are more muffler choices with 2.5" pipe, it's more popular. And MrB it is flow that counts. If you can obtain the flow values for various pipe sized that would be helpfull. Now if the muffler mfgs would publish CFM ratings it would be greatly helpfull. We can still surmize that two 2.5 mufflers would flow better than one 3.5 of simular construction. Sound level and quality is also very important.

MrBrooks

You are correct.
the only mfg i have seen put out any good flow specs is DynoMax. If their claims are true then a pair of 2.5" super turbos is good for 630hp. And the sound fdom a super turbo is a good mellow tone that wont draw any attention fron the noise ***** out there. The ultra flows they claim wil flow "up to" 2000scfm...............i assue that is the largest inlet/outlet they offer doing that..............tbe ultra flow has a nice sound @ idle and cruise, then lets you know full well when the throttle is opened up.......... much like the Hooker MaxFlow..........the max flow is what i plan on running, if i ever get the 427 built........3" y into a 4" i-pipe over the axle......muff in stock location with hidden exit on drivers side.

Badass355ciz28

iTrader: (17)

I just finished a 4" exhaust from the front , over the axle and out the back. Came out well and plenty of room

antman89iroc

Very interesting. Please share more details. Muffler type and location etc. If you could post some pictures that would be helpfull.

Did you purchase mandrel bent elbows & pipe and fit and weld it or was it done at a shop?

What is your power level and how does it sound at idle and under power?

When you say there is plenty of room how tight was it over the axle? Do you have a factory rear panhard bar bracket?

How much did it cost?

antman89iroc

Ok I found this chart muffler cfm comparison.

www.exhaustsoundclips.com/cfm.pdf

Check it out.

Badass355ciz28

iTrader: (17)

I have a build thread in the Exhaust section.

I did purchase mendrel bends and 2 bullet mufflers. One is at the converter location and the other is at the rear under the fuel tank.
I welded it myself and provided hangers as well.
Ive also added a 4" vband right before the first bullet muffler for quick disconnect.

As far as room over the axle there is about 1/2 inch clearance from the upper panhard bar support and 1/4-3/8" clearance elsewhere. It does not hit or vibrte anywhere. I am running 16 psi of boost so im guessing im shooting for 650-750 fwhp.

the cost was 260.00 in materials including the Dynomax bullet mufflers.

It is not quiet but i like the tone. Drone isnt too too bad either. Also has a nice crackle when i get on it.. Idle has a nice rumble as well

FJA1791

iTrader: (3)

From past expieriance I've used long tubes with 2 three inch pipes exiting before rear axle. Worked great but car used for track only. My current car is used for street & strip so my exhaust choice was to use factory lay out. My engine is a carbed 383 with AFR 195s and exhaust is as follows. Dyno Don 1 3/4 shorty into test pipe and Hooker cat back. I recently raced car and car performed pretty well. Went 11.41 @ 120.54 MPH race weight 3390. Works out to be 476 hp at crank wich is pretty accurate for engine combo. Exhaust looks great and not to loud. Stock configuration with the right set up is the way to go.

Kennerz

I'm at this crossroads right now. Run dual cats(2.5) to either a 3" or 3.5 catback to a 3.5 straight center in/out magnaflow race muffler. Or a modified 3.5 single cat setup. would there be any difference in power output with the dual cats at 9.8 area vs. a modified single 3" (modded to 3.5") 9.6 area cat with the same 3.5 catback/magnaflow muffler setup? has anyone tested this? gonna do one or the other soon.. want to know.. Very timely topic for me.

BrutalGTA

iTrader: (2)

I've become a big fan of the AeroTurbine brand mufflers. Basically a bullet design with a built in airfoil to help promote better velocity. You can buy them with or without built in resonators too. YouTube has some good sound clips, I've had a AT4040XL (4")on my 6.2L Sierra, and it was such a great distinct sound. I even have a AT2525XL (2.5")on my 1.4 Turbo dart the sound is so deep everyone compliments it.

I'll be running a pair of there 3" resonated version on my 89 GTA with 2nd gen tips.

Hooker Aero Chambers sound great but come apart internally.

Buy a 3" system and add muffler of choice or if you believe you need more, buy the sinister 4" or it's knockoff version with muffler of choice

Pocket

iTrader: (24)

Ive never understood the argument in dual vs single, esp under a Fbody where space is limited. 4" singles outflow ALL drivetrains on this forum barring a small handful and are off the shelf parts. There is no reason to go with the complexity of adding a second pipe for some silly notion of performance. Heck, 3" single is more than 90% of the cars on this forum will ever need and there are TONS of options available

Also, dumping before the axle does not constitute as duals

antman89iroc

Agreed! I'm probably going for the 3.5 setup.

Just got my motor this week. It has a fairly wide kick-out Moroso pan. The main problem is the pan is deeper right before the sump, at the point the driver's side crosses over. So now I'm left with a dilemma- change pans, modify my Edelbroc headers or change headers completely. Once this is figured out then I'll deal with the rest. Any suggestion???

zraffz

If you are running the exhaust out the back, anything but a single exhaust is pointless. Why add twice the weight for zero gain in performance?

My track car is longtube, 6" of 3" pipe, dynomax bullet, 45* bend and out under the rocker on each side. This should be a mid to high 10 second car on the bottle and was done for two reasons; it sounds better than a single exhaust and it saved weight to dump under the doors rather than run them to the back... my 3" magnaflow single exhaust wasn't any more restrictive but it weighed at least 40 lbs more. I would not attempt this setup on anything I planned on driving on the street further than from my shop to the local deli - it's ridiculously loud and would most certainly get you pulled over.

Kennerz

Just had the 3.5 single done. 3.5 merge from the SLP's to a modded 3.5 cat, to a magnaflow 3.5 race muffler to a turndown at the bumper. I'll get some pics or start a new post about it. Car runs really, really good. Very noticeable over a 2.3/4 intermediate pipe to a 3" cat and a 3" flowmaster 40 series. It is WAY quiter at idle (which is surprising, being a "Open" muffler) but under a load or opened up it sounds AWSOME. really good quality of sound, just sounds powerful and deeeeep! Could feel a big pick up in HP & TQ in the SOTP meter. SOunds absolutely bitchen when you floor it. Great mod, for a built car you can't go wrong..

antman89iroc

Here's the latest update. I ended up changing out the headers to Hooker 2064 shortys. I was not impressed with the ports at the head so I welded them from the outside and reported them to match my heads. Round to squar- a real PITA but it turned out great. I used VHT high temp paint and baked them in my oven (which my wife thought was insane but she was a sport) so we'll see how it holds up.
Next I used "header buddys" collectors which have a ball-type hook up. It gave me a little bit of adjustment. I custom fabricated the 2 1/2 head pipes which run straight by the trans into a Flowmaster 2 1/2 x 3 1/2 merge pipe. I used mandrel bent U pipes of different radius to get the right bends as well as a pair of 2 1/2 header extention, turned around backwards, and I welded header flanges on the merge pipe so both head pipes are removable and independent. I also modified my trans x-member to gain an additional 3/4 clearance. The header extensions had about 5" offset so it allowed me to jog the pipes over and up after the crossmember. I welded in a bung for my wide band in the merge pipe and ran a 3 1/2 pipe back to the axel with a 60' elbow going up to the existing pipe and muffler setup. Which, by the way is a mandrel bent Flowmaster kit. Unfortunatly its a 3" setup with the dual exit muffler so it is my bottleneck for now. At least I now have an exhaust system and hope to get it running this week or next. My plan is to finish it off in 3 1/2 pipe over the axel with an open style muffler mounted in the stock location with a single outlet on the drivers side. I an very happy with how it turned out and appreciate all the input.

articwhiteZ

iTrader: (56)

ALSO DONT let the tips be seen.. looks Tacky. GM did not let them hang down. or stick out from under the bumper...yuck

LB9GTA

iTrader: (1)

Long tube headers (1 7/8 primary) to 3" collectors to single 4" over the axle through a single flowmaster

Results below
Lots of clearance too!

Marc 85Z28

iTrader: (3)

I've had several different 3" single setups, a 4" single, and 3" duals. All the 3" single systems from a cheap Hooker to a very expensive Corsa were restrictive and sounded awful - like ALL single exhaust F-bodies. The 4" Mufflex had a great tone and didn't hurt power at all, but it still had some of that single exhaust note and some rasp, along with being VERY HEAVY. The y-pipe and 4" catback weighed MORE than my dual 3" system that is run over the axle and out the back. The dual setup sounds FAR better than any single system, period. Furthermore, the 3" dual setup has better ground clearance than the Mufflex did.

Performance-wise, a well setup 3" single system will support ~450hp with little restriction. No need for duals unless you hate the single exhaust sound as much as I do.

Orr89RocZ

iTrader: (20)

Thats interesting. My single 5" weighs less than dual 3" that had x pipe and four mufflers

Simple fact is dual exhaust allows for more mufflers. Bullets in I pipe region plus 2 more small box/oval or rounds under bumper. Thats as quiet a system as you are gonna make that still flows.

I now have the biggest exhaust one can likely build on a thirdgen without cutting car up and losing clearance. 3" flared to 3.5" y into 5" single exit all way back into a mbrp diesel muffler. Its fairly loud, very badasss and very mean. Theres a point where you just cant fit big enough duals and this is it. 5" outflows all and will handle 1200+ hp i plan to push thru it. Then again a turbo car doesnt care what the exhaust size is, bigger is better

IROCThe5.7L

I couldn't agree more. I switched to 3" duals and the sound is great. I've never had so many compliments on the sound when just cruising around town.

Orr89RocZ

iTrader: (20)

It may be a mufflex thing but my 4" and 5" singles clear just a good as my dual 3" did. If you have shorties instead of longtubes duals down stock location clear exceptionally well as does a big single. Longtubes you are gonna have issues around the trans crossmember in either configuration.
As for sound i was very impressed with my 4" single 383 car as it had a very unique tone at part throttle which i have never heard in any other car to date, and also very impressed at my buddys old 4" straight pipe sbc setup. It remains the best sounding domestic v8 motor i have ever heard.
Sound will really depend on the arrangement, design of the header primaries, muffler types and locations, x or h pipe design and location, etc.
i spent along time searching for a way to alter the sound of my ls1 car even doing custom 180 deg type header in a 4-2-1 arrangement with duals and never got it to sound better than the 3" single with gmmmg clone chambered tubes

Marc 85Z28

iTrader: (3)

I had both the Spintech dual in and the Flowmaster single in/out Mufflex systems. The Spintech with tailpipes was ridiculously heavy. The 4" Flowmaster muffler is lighter, and so is the single tailpipe. However, I'm comparing it to a dual system with 3" Flowmaster 10 series which are both small and light. You're right in that the Mufflex systems did sound very unique, and I loved them years ago. However once I had a properly setup dual system, I realized the err of my ways.

Orr89RocZ

iTrader: (20)

I've only run dynomax bullets and ultraflos and powerstick tubes in my dual systems. Never tried a flowmaster type chambered design.

My 5" muffler to I pipe section is 63 lbs. ypipe is likely 25. Not as bad as one would expect

Real trick is 4" aluminum exhaust! Now theres a badarse system