axle back vs catback exhaust

[kozzmo49]

Can someone please explain to me the advantages and disadvantages of both of these. Is our stock piping good enough and wide enough where getting an axle back wouldlnt make that much of a difference?

[franknbeans]

Big Bird Style -

The larger your exhaust pipe the easier it is to get the air out of your motor, thus the more air you can put in, thus making more power.

I am unsure what the size is on the stock exhaust though.

[SemperFi]

Originally Posted by franknbeans

Big Bird Style -

The larger your exhaust pipe the easier it is to get the air out of your motor, thus the more air you can put in, thus making more power.

I am unsure what the size is on the stock exhaust though.

Yes, but keep in mind that the engine is only going to suck in so much. Also if you are getting much bigger pipes, you are going to have to get new headers as well.

Then when you realize you made more space than you need, get it supercharged.

[THE EVIL TW1N]

Originally Posted by franknbeans

Big Bird Style -

The larger your exhaust pipe the easier it is to get the air out of your motor, thus the more air you can put in, thus making more power.

I am unsure what the size is on the stock exhaust though.

bigger isn't always better.


the stock 2.5 exhaust is pretty big, should support up to about 550 rwhp no problem without being a hinderance. They have nice bends to them too, the real restrictions are probably at the mufflers and maybe the cats.

[THE EVIL TW1N]

also, with bigger piping you will lose back pressure, which will result in the possible loss of low end tq without necessarily gaining anything up top. the dyno might not reflect it at WOT, but can be felt at part throttle.

[pruettfan]

I am pretty happy that there will be several AXLE back options. This allows for a pretty cheap way to improve the sound of the car and perhaps get some increase of performance. The Cat back systems theoretically offer a larger diameter or straighter bend which could increase performance. Since most of us won't be going with a full exhaust and header setup for ultimate performance we are more likely doing exhaust for a more robust sound rather than all out performance. I anticipate that I will go with an Axle back solution to get a little more performance sound rather than the ultimate exhaust system.

The additional benefit will be to not have to see those huge mufflers hanging under the car.

[Kyle2k]

Originally Posted by THE EVIL TW1N

also, with bigger piping you will lose back pressure, which will result in the possible loss of low end tq without necessarily gaining anything up top. the dyno might not reflect it at WOT, but can be felt at part throttle.

http://www.uucmotorwerks.com/html_pr...torquemyth.htm

[Epitaph]

Thank you ^

Remember, you can get different HP/Tq ratings with different mufflers. Just because you go with Borla rather than Magnaflow, it doesn't mean you're going to get more Tq. It depends on the size of your pipe, initial HP/Tq, etc... It would be cool if someone did a comparison on stock Camaro's similar to these:

http://allfordmustangs.com/forums/5-...-shootout.html
http://www.v8s10.org/forum/viewtopic.php?f=43&p=155840

As you can see, that was 7 years ago, and there wasn't THAT much of a difference. Of course, if you ran the test again, the numbers would change. Also, I have no idea if this was an average or what... It would be cool to see some new tests.

I searched around for axel back vs cat back, and found several different answers, basically:

If you're wanting more HP/Tq gains, just replace the entire exhaust system (including Long tube headers IF AND ONLY IF you don't need to pass inspection! If you do, get a high-flow cat put on there).

If you're looking to change the notes your exhaust plays, get the muffler changed out.

[GMtothecore]

Good info, thanks guys

[FNKNSTN]

good posts, dudes

[rayhawk]

Originally Posted by Kyle2k

http://www.uucmotorwerks.com/html_pr...torquemyth.htm

There is more involved here than this article discusses. This article seems to say that the biggest exhaust you can bolt on your car results in the most power. This is far from reality, especially at lower-midrange rpm. An appropriate size exhaust produces the best all around power, too big of an exhaust will always result in less low end power. This has nothing to do with A/F ratio. The exiting exhaust gases of any engine and the velocity of those gases create a scavenging effect to help remove burnt gases and draw in a new intake charge (where the intake and exhaust valves are both open-the overlap). This is what makes long tube headers so effective. Put a set of 2 1/4" race headers on a bone stock LS1 and I guarantee you will lose a ton of low end power. The same thing applies, maybe less so for the rest of the exhaust being too big. The further downstream, the lower the effect on scavenging is.

[lakersftbl69]

ok question say if i were to change stock pipes from 2 1/2 -3 would that be that big of a difference

[franknbeans]

It's not a "big" difference but I was running a 3" exhaust on my Srt-4.

Also, does anyone know the manufacturer of the mufflers on the GM exhaust?

[hp for life]

Going from 2.5 to 3 on a stock motor will net you a lose of bottom end TQ. You will see it on a dyno and feel it alittle but i don't think 1/4 mile times would suffer. As said before dual 2.5 pipes can support 550rwhp. A plus side or down ( dending on ears) is you will gain more bass in your exhaust note. On my 93 I run long tubes to a off road y-pipe into a 4in i-pipe to a stock muffler with the square tips. I've yet to hear a car sound like mine.

[franknbeans]

Also, does anyone know the manufacturer of the mufflers on the GM exhaust?

[THE EVIL TW1N]

Originally Posted by franknbeans

It's not a "big" difference but I was running a 3" exhaust on my Srt-4.

Also, does anyone know the manufacturer of the mufflers on the GM exhaust?

3" dual exhaust??

I know pretty much ALL the 03/04 Cobra guys run 2.5 Catback (stock was 2.25) and midpipe unless they are running a KB or Whipple (600 rwhp) and even then, they don't always jump onto the 3".

[blackedout010]

Originally Posted by THE EVIL TW1N

3" dual exhaust??

I know pretty much ALL the 03/04 Cobra guys run 2.5 Catback (stock was 2.25) and midpipe unless they are running a KB or Whipple (600 rwhp) and even then, they don't always jump onto the 3".

yea the cobra run stronger off the exhaust backpressure with the 2.5 up to around 600+rwhp!! however a lsx motor thats been modded (cam, heads, etc.) runs better with the 3 inch piping.

[LDGn63]

Originally Posted by franknbeans

Also, does anyone know the manufacturer of the mufflers on the GM exhaust?

Samsonite?

[davidj]

FYI going from 2.5 to 3 IS a big difference. 2.5 = 4.906 Sq/in 3 = 7.065 Sq/in. So you can see only a 1/2" diff flows a lot more than you would think.

[franknbeans]

Originally Posted by blackedout010

yea the cobra run stronger off the exhaust backpressure with the 2.5 up to around 600+rwhp!! however a lsx motor thats been modded (cam, heads, etc.) runs better with the 3 inch piping.

Not dual. .it was a srt-4. . 4cyl turbo.

But it was 3" from the turbo back

[franknbeans]

Originally Posted by LDGn63

Samsonite?

what?

don't they make TV's?

strike that.. luggage

[SilverBulletSS]

Originally Posted by franknbeans

Also, does anyone know the manufacturer of the mufflers on the GM exhaust?

I believe it was quoted on here as Borla....I think they said they made the GMPP catbacks, as well....

[radz28]

Originally Posted by THE EVIL TW1N

bigger isn't always better.


the stock 2.5 exhaust is pretty big, should support up to about 550 rwhp no problem without being a hinderance. They have nice bends to them too, the real restrictions are probably at the mufflers and maybe the cats.

Originally Posted by THE EVIL TW1N

also, with bigger piping you will lose back pressure, which will result in the possible loss of low end tq without necessarily gaining anything up top. the dyno might not reflect it at WOT, but can be felt at part throttle.

Originally Posted by rayhawk

There is more involved here than this article discusses. This article seems to say that the biggest exhaust you can bolt on your car results in the most power. This is far from reality, especially at lower-midrange rpm. An appropriate size exhaust produces the best all around power, too big of an exhaust will always result in less low end power. This has nothing to do with A/F ratio. The exiting exhaust gases of any engine and the velocity of those gases create a scavenging effect to help remove burnt gases and draw in a new intake charge (where the intake and exhaust valves are both open-the overlap). This is what makes long tube headers so effective. Put a set of 2 1/4" race headers on a bone stock LS1 and I guarantee you will lose a ton of low end power. The same thing applies, maybe less so for the rest of the exhaust being too big. The further downstream, the lower the effect on scavenging is.

Originally Posted by hp for life

Going from 2.5 to 3 on a stock motor will net you a lose of bottom end TQ. You will see it on a dyno and feel it alittle but i don't think 1/4 mile times would suffer. As said before dual 2.5 pipes can support 550rwhp. A plus side or down ( dending on ears) is you will gain more bass in your exhaust note. On my 93 I run long tubes to a off road y-pipe into a 4in i-pipe to a stock muffler with the square tips. I've yet to hear a car sound like mine.

Originally Posted by THE EVIL TW1N

3" dual exhaust??

I know pretty much ALL the 03/04 Cobra guys run 2.5 Catback (stock was 2.25) and midpipe unless they are running a KB or Whipple (600 rwhp) and even then, they don't always jump onto the 3".

to pretty much everything here. Just because the pipes will support the airflow, doesn't mean the engine is pumping that amount of air. As the exhaust gets further from the combustion chamber, it gets cooler and slows down. When it slows down efficiency is less. It's my understanding what the headers and exhaust should do is completely evacuate the chamber of all burned and unburned gasses on the exhaust stroke. In order to do that, the headers/manifold and the rest of the exhaust has to be tuned in order to facilitate a vacuum to extract the chamber. The bigger pipes will retain less heat because there's more surface area to radiate it, therefore the exhaust gasses will cool sooner. Unless you have an engine that pumps enough exhaust, you'll just have a loud exhaust and not make use of all the power the engine has the potential to generate.

Originally Posted by davidj

FYI going from 2.5 to 3 IS a big difference. 2.5 = 4.906 Sq/in 3 = 7.065 Sq/in. So you can see only a 1/2" diff flows a lot more than you would think.

But the engine has to support that additional flow, otherwise you're adding restriction within the exhaust and not vacuuming all the gasses out of the combustion chamber on the exhaust stroke.

Originally Posted by SilverBulletSS

I believe it was quoted on here as Borla....I think they said they made the GMPP catbacks, as well....

I believe Borla has specifically designed the GMPP exhaust and has two separate designs for their mufflers/CBs.

Personally, I'll be looking at finding an X-pipe system sans resonators with good flowing mufflers. If my engine can support dual 3-inch pipes I'll go that route, otherwise, I'll look into modifying the H-pipe and resonators. No LTs in Cali' mean shorties and OEM cats' :(

[davidj]

Originally Posted by radz282003

But the engine has to support that additional flow, otherwise you're adding restriction within the exhaust and not vacuuming all the gasses out of the combustion chamber on the exhaust stroke.

I was just comparing the two sizes nothing more.

[radz28]

Originally Posted by davidj

I was just comparing the two sizes nothing more.