YACT - What is the purpose of dual exhaust?

[spidey07]

Just curious...

Is it because the size of a pipe to carry the exhaust/manifold would be too large and it is easier space wise to use two paths?

Is it to separate both sides of the motor and maximize air out for performance/fuel reasons?

Or is it cosmetic?

My guess is a combination of points one and two.

 

[Brutuskend]

The easier things go in and OUT of a engine the more power you get.

(in a nut shell)

 

[notfred]

More air flows through two pipes than one pipe, plus it looks cool.

 

[SampSon]

one two AND three.

 

[Nebor]

Uh, a V configuration engine has two exhaust manifolds, so the only way to deal with that is by having two exhaust pipes. Some cars choose to combine them into one pipe before they get to the car, and usually that impacts flow and lowers overall power.

 

[spidey07]

Originally posted by: Brutuskend
The easier things go in and OUT of a engine the more power you get.

(in a nut shell)

absolutely true.

But a single 4" pipe is much larger than two 2" pipes.

i guess what I'm asking is what is the reasoning behind it?

I understand that a V or any other design has the exhaust manifolds on opposing sides...so what is the reason behind keeping them seperate?

Is it a fluid dynamics thing? Or is it to give the best performance (in/out) for both sides of the motor.

So in other words - is it a space thing or a performance thing?

 

[FallenHero]

Originally posted by: spidey07

Originally posted by: Brutuskend
The easier things go in and OUT of a engine the more power you get.

(in a nut shell)

absolutely true.

But a single 4" pipe is much larger than two 2" pipes.

i guess what I'm asking is what is the reasoning behind it?

I understand that a V or any other design has the exhaust manifolds on opposing sides...so what is the reason behind keeping them seperate?

Is it a fluid dynamics thing? Or is it to give the best performance (in/out) for both sides of the motor.

So in other words - is it a space thing or a performance thing?

Little bit of both...fitting a 4 inch pipe is harder than fitting 2 2 inch pipes.

 

[Zenmervolt]

Originally posted by: spidey07
absolutely true.

But a single 4" pipe is much larger than two 2" pipes.

i guess what I'm asking is what is the reasoning behind it?

I understand that a V or any other design has the exhaust manifolds on opposing sides...so what is the reason behind keeping them seperate?

Is it a fluid dynamics thing? Or is it to give the best performance (in/out) for both sides of the motor.

So in other words - is it a space thing or a performance thing?

Because, from a practical engineering standpoint, it is MUCH easier to package two 2" pipes than a 3" pipe. Less clearance needed around suspension and other things. Also, the tubing necessary to efficiently funnel a vee engine's two manifolds into one pipe is hard to package if it is as efficient as a dual exhaust. Basically, a single pipe that's large enough to flow everything will have problems with packaging.

ZV

 

[Evadman]

Originally posted by: Zenmervolt
Because, from a practical engineering standpoint, it is MUCH easier to package two 2" pipes than a 3" pipe. Less clearance needed around suspension and other things. Also, the tubing necessary to efficiently funnel a vee engine's two manifolds into one pipe is hard to package if it is as efficient as a dual exhaust. Basically, a single pipe that's large enough to flow everything will have problems with packaging.

ZV

Which is exactly why on larger vehicles with huge amounts of gas flow and more routing room (AKA turbo diesel trucks) you will see a gigantic single 4 or 5" exaust pipe when moving up to a larger turbo setup such as a system from Banks.

The cross sectional area of a 4" pipe (12.5 sq in) is 4 times the size of a 2 inch pipe (3.14 sq in) which means it can flow 4 times the gas and (theoreticly) support 4 times the power while having a diameter that is only twice as large.

There is a limit to more is better though. A scavenging effect is needed, and to get that a maximum header/exaust size can not be exceeded. When the exaust gas exits the engine and enters the header (be it cast or tubular) the exaust gas will pull a vacuum behind it, thus assisting the engine with expelling the last of the spent gasses from the combustion chamber. (kinda the same way a toilet flushes) If the header or exaust was too large, then that vacuum would not be created, and thus more spent gasses would be left in the combustion chamber, which is just 'wasted space' that could be filled with oxygen and fuel.

 

[Iron Woode]

Originally posted by: spidey07

Originally posted by: Brutuskend
The easier things go in and OUT of a engine the more power you get.

(in a nut shell)

absolutely true.

But a single 4" pipe is much larger than two 2" pipes.

i guess what I'm asking is what is the reasoning behind it?

I understand that a V or any other design has the exhaust manifolds on opposing sides...so what is the reason behind keeping them seperate?

Is it a fluid dynamics thing? Or is it to give the best performance (in/out) for both sides of the motor.

So in other words - is it a space thing or a performance thing?

its called back pressure.

and the sound is awesome when there are 2 mufflers.

 

[Sluggo]

I think the real question is why do we see dual exhausts on 4 cylinder Hondas?

Text

 

[Evadman]

Originally posted by: Sluggo
I think the real question is why do we see dual exhausts on 4 cylinder Hondas?

Text

There are performace reasons, and there are cosmetic reasons...

 

[Shawn]

Originally posted by: Sluggo
I think the real question is why do we see dual exhausts on 4 cylinder Hondas?

Text

it's kinda dumb but making the car symmetric tends to look better.

 

[Kadarin]

Originally posted by: Evadman

Originally posted by: Zenmervolt
Because, from a practical engineering standpoint, it is MUCH easier to package two 2" pipes than a 3" pipe. Less clearance needed around suspension and other things. Also, the tubing necessary to efficiently funnel a vee engine's two manifolds into one pipe is hard to package if it is as efficient as a dual exhaust. Basically, a single pipe that's large enough to flow everything will have problems with packaging.

ZV

Which is exactly why on larger vehicles with huge amounts of gas flow and more routing room (AKA turbo diesel trucks) you will see a gigantic single 4 or 5" exaust pipe when moving up to a larger turbo setup such as a system from Banks.

The cross sectional area of a 4" pipe (12.5 sq in) is 4 times the size of a 2 inch pipe (3.14 sq in) which means it can flow 4 times the gas and (theoreticly) support 4 times the power while having a diameter that is only twice as large.

There is a limit to more is better though. A scavenging effect is needed, and to get that a maximum header/exaust size can not be exceeded. When the exaust gas exits the engine and enters the header (be it cast or tubular) the exaust gas will pull a vacuum behind it, thus assisting the engine with expelling the last of the spent gasses from the combustion chamber. (kinda the same way a toilet flushes) If the header or exaust was too large, then that vacuum would not be created, and thus more spent gasses would be left in the combustion chamber, which is just 'wasted space' that could be filled with oxygen and fuel.

Correct. While a larger pipe will have a higher overall flow rating, a smaller pipe will maintain a higher exhaust gas velocity, which aids in the scavenging effect, and improves torque.

 

[Howard]

Originally posted by: Iron Woode

Originally posted by: spidey07

Originally posted by: Brutuskend
The easier things go in and OUT of a engine the more power you get.

(in a nut shell)

absolutely true.

But a single 4" pipe is much larger than two 2" pipes.

i guess what I'm asking is what is the reasoning behind it?

I understand that a V or any other design has the exhaust manifolds on opposing sides...so what is the reason behind keeping them seperate?

Is it a fluid dynamics thing? Or is it to give the best performance (in/out) for both sides of the motor.

So in other words - is it a space thing or a performance thing?

its called back pressure.

and the sound is awesome when there are 2 mufflers.

Oy... please don't bring up backpressure or we are going to have a real mess on our hands.

 

[b0mbrman]

Originally posted by: Sluggo
I think the real question is why do we see dual exhausts on 4 cylinder Hondas?

Text

You don't even have to look at the aftermarket - Text

 

[pray4mojo]

I've always wondered why my 4cyl Mazda6 has 2 exhaust tips...

 

[OrganizedChaos]

so car companies have more places to shove 02 sensors they know will fail after 100,000 miles.

 

[CraigRT]

Originally posted by: pray4mojo
I've always wondered why my 4cyl Mazda6 has 2 exhaust tips...

so many 4 cyl cars have dual exhaust stock.. my old neon R/T had dual exhaust stock...

 

[Wags1974]

when you have one pipe feeding a miffler and two little pipes coming out of the muffler, it isnt technically dual exhaust. (common to see this on four bangers)

 

[makaze]

I put duals on mine because my bumper has 2 cut outs haha I drive a riced out car tho

 

[Vic]

Originally posted by: Nebor
Uh, a V configuration engine has two exhaust manifolds, so the only way to deal with that is by having two exhaust pipes. Some cars choose to combine them into one pipe before they get to the car, and usually that impacts flow and lowers overall power.

It has nothing to do with twin-bank configuration or pipe size (as noted, a single large pipe has more volume than 2 small pipes), and everything to do with exhaust pulses. Everyone knows that exhaust comes out in pulses. A 6-cylinder motor fires (and expels its exhaust) every 120 degrees of rotation. An 8-cylinder every 90 degrees. Yet the exhaust stroke lasts 180 degrees. Dual exhaust minimizes exhaust pulse interferences and reduces back pressure.
This is why putting a dual exhaust on a straight-6 would be a good idea but a bad idea on a flat-4, even though the straight-6 could have only 1 exhaust manifold and the flat-4 must have 2.

 

[imported_goku]

Originally posted by: OrganizedChaos
so car companies have more places to shove 02 sensors they know will fail after 100,000 miles.

Buahahaha, lol... Hey, would O2 sensors fail simply because of age?



Yea the tail pipe thing reminds me of honda civics with two of those tiny little pipes, it's like WTF? Just put one large pipe and the car will have more HP....

 

[Vic]

Originally posted by: goku
Yea the tail pipe thing reminds me of honda civics with two of those tiny little pipes, it's like WTF? Just put one large pipe and the car will have more HP....

Even a large pipe is pointless on an otherwise stock Civic. They run pretty to close to 100% VE from the factory as it is. All those CAI's and fart-can cat-backs do is make noise and ruin the already non-existent bottom-end torque.

 

[Zee]

Originally posted by: Shawn

Originally posted by: Sluggo
I think the real question is why do we see dual exhausts on 4 cylinder Hondas?

Text

it's kinda dumb but making the car symmetric tends to look better.

how do you know it's not boosted? or spraying?