Degrees of Dual Exhaust

[Carbon]

There is a continuum of "dual exhaust" systems. Here is my list:

1. Separate manifolds to different catalytic converters which feed with dual pipes and everything to the back
2. Single exhaust pipe with a Y at about the back axle that feeds two mufflers with separate tail pipes.
3. Single through the muffler with a Y to two separate exhaust pipes.
4. A single muffler with dual outputs
5. A hybrid of #3 and #4

6. A single system to a dual exhaust tip

7. An extra exhaust tip not connected to anything.

I was considering a vehicle a while back, and I felt #2 was hokey in contrast to a plain single exhaust with slightly larger diameter pipes. I am thinking that maybe I missed giving some functionality points. What do you think?

 

[Kruse]

Wait till the owner of the car with the #2 photo gets an estimate to repair his exhaust. He will then wish that he had a single exhaust.

 

[Colt45ws]

Everything below #1 is hokey, IMO. My Mom's Fusion is setup like #2 or #3. Does absolutely nothing. If anything, you want less flow as it goes back to keep the velocity up as the gas cools and condenses.

Originally Posted By: Kruse
Wait till the owner of the car with the #2 photo gets an estimate to repair his exhaust. He will then wish that he had a single exhaust.

That one is super redundant. Whats the point? There is no backpressure at that point to push gasses through that curve to the second exit. Might as well just have a dummy pipe and save the stainless.

 

[NMBurb02]

I'm guessing the #2 system has a larger diameter pipe up to the Y (let's say 3"), then drops down a few sizes (let's say 2") after the Y, which feed into the mufflers. That's what I have on my GP (don't know the pipe sizes, but doubt they're that big). Plus, my GP has a resonator before the Y. Maybe that is the reason: allows the use of a single resonator to get the sound you want, then muffles at the back end?

 

[aquariuscsm]

What kind've car is it going on? I'd keep the stock look.

 

[jdawg89]

You forgot one, straight pipes off each manifold with no cats or mufflers. Sounds great.

 

[Donald]

Originally Posted By: Carbon
There is a continuum of "dual exhaust" systems. Here is my list:

1. Separate manifolds to different catalytic converters which feed with dual pipes and everything to the back
2. Single exhaust pipe with a Y at about the back axle that feeds two mufflers with separate tail pipes.
3. Single through the muffler with a Y to two separate exhaust pipes.
4. A single muffler with dual outputs
5. A hybrid of #3 and #4

6. A single system to a dual exhaust tip

7. An extra exhaust tip not connected to anything.

I was considering a vehicle a while back, and I felt #2 was hokey in contrast to a plain single exhaust with slightly larger diameter pipes. I am thinking that maybe I missed giving some functionality points. What do you think?


A single large pipe is better in almost all cases.

A 4" pipe has 12.56 sq. inches of surface area
Two 2" pipes have 6.28

 

[RamFan]

Originally Posted By: jdawg89
You forgot one, straight pipes off each manifold with no cats or mufflers. Sounds great.


Umm no...

At the end of the day the only true exhaust would be two pipes off the manifold, through two cats, through two mufflers.

However for simple cost vs. benefits analysis I'm curious what the difference would be between two pipes, two cats, Y pipe, single muffler, two outlets.

 

[OVERKILL]

We must not forget the H and X pipes.

Ford loved using the H-pipes.

 

[NMBurb02]

Originally Posted By: RamFan
Originally Posted By: jdawg89
You forgot one, straight pipes off each manifold with no cats or mufflers. Sounds great.


Umm no...

At the end of the day the only true exhaust would be two pipes off the manifold, through two cats, through two mufflers.

However for simple cost vs. benefits analysis I'm curious what the difference would be between two pipes, two cats, Y pipe, single muffler, two outlets.

The Burb comes stock with two pipes, two cats, Y pipe, single muffler, and single outlet. Per Gibson Performance Exhaust, on a truck or SUV with such a setup, you get the best performance sticking with a single outlet; going to a dual outlet simply adds noise. Even on auto applications with dual cats and mufflers, there is usually an X pipe to connect the two engine banks, which I think is meant to improve exhaust scavenging, reducing pulses in the exhaust system and actually helping pull exhaust from the opposite engine bank.

Edit: Or H pipe, as OVERKILL pointed out.

 

[440Magnum]

Originally Posted By: Carbon
There is a continuum of "dual exhaust" systems. Here is my list:

1. Separate manifolds to different catalytic converters which feed with dual pipes and everything to the back
2. Single exhaust pipe with a Y at about the back axle that feeds two mufflers with separate tail pipes.
3. Single through the muffler with a Y to two separate exhaust pipes.
4. A single muffler with dual outputs
5. A hybrid of #3 and #4



Only #1 is a TRUE dual exhaust, although you left out the best performing system- #1 but with a "balance tube", crossover, or "X" pipe joining the two separate exhaust systems- very important on a 90-degree crankshaft v8. Not so important on a 180-degree crank v8 or on any v6.


That said, #s 2, 3, and 4 can perform just as well as true dual exhausts, provided the catalyst(s), the single section and muffler are BIG. Heck, SINGLE exhaust performs as well as true dual if everything is sized properly.

#5-7 are just stupid (especially 7)- 100% for show.

 

[jdawg89]

I hate cats and mufflers. They get In the way and restrict flow

 

[mechtech2]

Also there is the good twin pipes going back with a balance pipe between them.
Is this just a kid's bench racing thread?

 

[NMBurb02]

No matter the style, the system needs to be tuned to the specific vehicle. Pipes that are too big, improper lengths on either leg of the Y pipe coming off the manifolds/cats, increasing or decreasing pipe sizes too abruptly, non-mandrel bends, and a number of other things can kill certain performance aspects (low end torque, low end HP) real quick.

 

[Jarlaxle]

Originally Posted By: Colt45ws
Everything below #1 is hokey, IMO. My Mom's Fusion is setup like #2 or #3. Does absolutely nothing. If anything, you want less flow as it goes back to keep the velocity up as the gas cools and condenses.


My Magnum had a variation on that and it was functional: it had dual headpipes & cats, which went to a large single muffler (nicknamed the "suitcase" for good reason), then dual tailpipes. Many dual setups are fake, but not that one.

First fake duals I can think of was probably the 1982 F-body...no room for the second pipe!

 

[Jarlaxle]

Originally Posted By: jdawg89
I hate cats and mufflers. They get In the way and restrict flow


My wife is making 900HP through a catalyst. Yer full of it!

 

[OVERKILL]

Originally Posted By: Jarlaxle
Originally Posted By: jdawg89
I hate cats and mufflers. They get In the way and restrict flow


My wife is making 900HP through a catalyst. Yer full of it!


What in the flying *bleep* is SHE rockin?

 

[OVERKILL]

The M5 has an interesting exhaust setup:

The factory tubular headers come off the heads in sets of two that merge at their own (larger) "Y's" so you essential have four pipes after the headers. However, slightly further downstream, these merge into a larger single pipe on each side, giving you duals.

These hit an "H" when they hit the crossmember, then go another few feet and "X" in the factory resonator, where they break off again into four mufflers and quad tails.

Interesting setup.........

 

[Cujet]

I have always favored large single exhausts.

 

[ls1mike]

LS1 F-bodies had dual out with dual cats, to one large single pipe than back out to dual. Worked fine for those cars, some guys went true dual and didn't pick up enough power to matter.