YACT - What is the purpose of dual exhaust?

[DaTT]

Most V6's with "dual exhaust", in fact, are not a true dual setup......hell, even some V8's aren't a true setup either. Also, with the setup on 4 banger motors one of the exhaust pipes is typically a fake anyway (ie. one side isn't even open to the exhaust system, just there for looks). You can tell this by looking at the tips and noticing that one is black, and the other is not.

 

[AdamSnow]

To be honest, a lot of it is mostly cosmetic...

 

[Vic]

Originally posted by: DougK62
The car was a heavily modified Integra that was used just for autox. We did like you said and ran two cylinders together and then out each side of the car. The owner wanted something unique. It did not sound like crap, and everyone that sees it wants to know more and thinks it's neat. That is a true dual exhaust in every possible way. Your opinion doesn't count.

The issue is that (provided the headers are equal-length) dual exhaust is pointless on a 4-cyl. For the reasons I described above. The exhaust pulses on a 4-cyl do not interfere with each other. A 4-cyl fires every 180 degrees, and the exhaust stroke last 180 degrees. And a single large diameter pipe flows more than 2 small diameter pipes. That owner wasted his money to look cool.

 

[NutBucket]

Originally posted by: DaTT
Most V6's with "dual exhaust", in fact, are not a true dual setup......hell, even some V8's aren't a true setup either. Also, with the setup on 4 banger motors one of the exhaust pipes is typically a fake anyway (ie. one side isn't even open to the exhaust system, just there for looks). You can tell this by looking at the tips and noticing that one is black, and the other is not.

That's more of a ricer thing. Every factory dual-exhuast I've seen at least has a Y-pipe if it isn't a true dual setup.

 

[DaTT]

Originally posted by: NutBucket

Originally posted by: DaTT
Most V6's with "dual exhaust", in fact, are not a true dual setup......hell, even some V8's aren't a true setup either. Also, with the setup on 4 banger motors one of the exhaust pipes is typically a fake anyway (ie. one side isn't even open to the exhaust system, just there for looks). You can tell this by looking at the tips and noticing that one is black, and the other is not.

That's more of a ricer thing. Every factory dual-exhuast I've seen at least has a Y-pipe if it isn't a true dual setup.

I know this. However, some early to mid 90's GM's had the blanked out second tip.

 

[InlineFour]

the new civic si, which is a 4 cylinder, has dual exhaust pipes.

 

[spidey07]

Originally posted by: InlineFour
the new civic si, which is a 4 cylinder, has dual exhaust pipes.

now that is just funny.

I'll file that under the cosmetic option.

 

[DougK62]

Originally posted by: DaTT

Originally posted by: NutBucket

Originally posted by: DaTT
Most V6's with "dual exhaust", in fact, are not a true dual setup......hell, even some V8's aren't a true setup either. Also, with the setup on 4 banger motors one of the exhaust pipes is typically a fake anyway (ie. one side isn't even open to the exhaust system, just there for looks). You can tell this by looking at the tips and noticing that one is black, and the other is not.

That's more of a ricer thing. Every factory dual-exhuast I've seen at least has a Y-pipe if it isn't a true dual setup.

I know this. However, some early to mid 90's GM's had the blanked out second tip.

Can you give examples? I can't think of any that did this.

 

[spidey07]

I do remember a few cars that had dual tips and only one was actually used. can't remember the models though.

I remember them because I found it so comical. I think possibly a grand prix?

 

[DaTT]

Originally posted by: spidey07
I do remember a few cars that had dual tips and only one was actually used. can't remember the models though.

I remember them because I found it so comical. I think possibly a grand prix?

I think that was the one.

 

[Trikat]

Fvck! I wish I knew what you guys are talking about! LOL

 

[DougK62]

Originally posted by: DaTT

Originally posted by: spidey07
I do remember a few cars that had dual tips and only one was actually used. can't remember the models though.

I remember them because I found it so comical. I think possibly a grand prix?

I think that was the one.

Are we talking about the same thing? I'm thinking of cars that just had an exhaust tip hanging there with no pipe attached to it. The Grand Prix didn't do this.

 

[funboy6942]

Originally posted by: DougK62

Originally posted by: DaTT

Originally posted by: NutBucket

Originally posted by: DaTT
Most V6's with "dual exhaust", in fact, are not a true dual setup......hell, even some V8's aren't a true setup either. Also, with the setup on 4 banger motors one of the exhaust pipes is typically a fake anyway (ie. one side isn't even open to the exhaust system, just there for looks). You can tell this by looking at the tips and noticing that one is black, and the other is not.

That's more of a ricer thing. Every factory dual-exhuast I've seen at least has a Y-pipe if it isn't a true dual setup.

I know this. However, some early to mid 90's GM's had the blanked out second tip.

Can you give examples? I can't think of any that did this.

He is saying he took a 4cyl engine and ran 2 pipes off the one side then calling it true dual. 2 cyl into one pipe and the other 2 into another and run to the back of the car. IMO that does not constitue a ture dual exhaust when you split the cyl in hal on the same side of the engine and the pistons are the same size my lawnmower uses. It in no way could have a low dual exhaust tone like you get from a true dual american V8 but instead what I like to call a pop corn popper exhaust.

 

[Vic]

For the last time, the number of engine banks has NOTHING to do with dual exhaust.

Your "true dual american V8" (or cross-plane crank V8 as it is properly called) still has problems with pulse interference even with dual exhaust because pistons on the same bank fire in sequence twice every full 720 degree firing order. Because the pulses are only 90 degrees apart and 180 degrees long, that's what causes the low "rumble bumble" sound. That louder lower-pitched pulse you hear every couple of pulses at idle is actually 2 pulses interfering with each other.

edit: for example, Chevy small-block firing order: 1-8-4-3-6-5-7-2

 

[DougK62]

Originally posted by: funboy42

Originally posted by: DougK62

Originally posted by: DaTT

Originally posted by: NutBucket

Originally posted by: DaTT
Most V6's with "dual exhaust", in fact, are not a true dual setup......hell, even some V8's aren't a true setup either. Also, with the setup on 4 banger motors one of the exhaust pipes is typically a fake anyway (ie. one side isn't even open to the exhaust system, just there for looks). You can tell this by looking at the tips and noticing that one is black, and the other is not.

That's more of a ricer thing. Every factory dual-exhuast I've seen at least has a Y-pipe if it isn't a true dual setup.

I know this. However, some early to mid 90's GM's had the blanked out second tip.

Can you give examples? I can't think of any that did this.

He is saying he took a 4cyl engine and ran 2 pipes off the one side then calling it true dual. 2 cyl into one pipe and the other 2 into another and run to the back of the car. IMO that does not constitue a ture dual exhaust when you split the cyl in hal on the same side of the engine and the pistons are the same size my lawnmower uses. It in no way could have a low dual exhaust tone like you get from a true dual american V8 but instead what I like to call a pop corn popper exhaust.

You need to learn how to read a thread properly.

And the situation I described earlier IS true dual exhaust, whether you like it or not. Sorry.

 

[murphy55d]

My Hyundai Tucson has 2 exhaust pipes - no idea why.

 

[Engineer]

Two exhaust pipes just look better than one (especially a big one)!

FTW!

Hey, I'm an EE...not a mechanical or combustion engineer!

 

[Zenmervolt]

Originally posted by: JulesMaximus

Originally posted by: Vic

Originally posted by: funboy42
How will going larger hurt unless your engine is a 2 stroke engine which is maily found in off road dirt bikes where back pressure is needed to have it run better?

The same reason. The reduction in scavenging effect can reduce low-end torque. The trade-off is supposed to be more torque at higher revs and thus more hp, but that can be more difficult to tune for in today's computer-controlled cars than it was back in the muscle car days.

QFT

Also, the closest to true dual exhaust I've seen is the Mustang GT (the only place the two sides join is at the H pipe). I haven't been under many newer cars though so I don't know if that's still true. Still, I'd say at least 95% of production cars today do not have true dual exhaust.

Almost every true dual exhaust will have either an H-Pipe or an X-Pipe to balance pulses. Very few cars run straight pipes (duals without a crossover).

ZV

 

[Iron Woode]

Originally posted by: 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.

I am sorry.

 

[spidey07]

Originally posted by: Zenmervolt
Almost every true dual exhaust will have either an H-Pipe or an X-Pipe to balance pulses. Very few cars run straight pipes (duals without a crossover).

ZV

Interesting...do tell oh wise one.

So the pulses pull from each other??

Just trying to visualize it.

 

[DivideBYZero]

Originally posted by: Vic

Originally posted by: DivideBYZero
You know up until the 06 model(and certain JDM's) the Impreza WRX has very bad pulse interference. That's what gives it character, but the eaqual length headers are more effecient. Ergo, I conter that a twin pipe setup on a boosted scooby would in fact be an OK solution.

But as we have ELH's it doesn't matter.

Meh. I love my unequal-length headers. I'll sacrifice a couple hp so my Scooby doesn't sound like a Honda.

Agreed. That's why I looked at an '06 the other day and walked away.

My MY00 GF sounds awesome with the prodrive centre and a 3" bore rear section, expading to a ricey 4" tip. Nice bassy flat four throb, and over 4K it is very loud.

I love tunnels.

 

[Vic]

Originally posted by: DivideBYZero

Originally posted by: Vic

Originally posted by: DivideBYZero
You know up until the 06 model(and certain JDM's) the Impreza WRX has very bad pulse interference. That's what gives it character, but the eaqual length headers are more effecient. Ergo, I conter that a twin pipe setup on a boosted scooby would in fact be an OK solution.

But as we have ELH's it doesn't matter.

Meh. I love my unequal-length headers. I'll sacrifice a couple hp so my Scooby doesn't sound like a Honda.

Agreed. That's why I looked at an '06 the other day and walked away.

My MY00 GF sounds awesome with the prodrive centre and a 3" bore rear section, expading to a ricey 4" tip. Nice bassy flat four throb, and over 4K it is very loud.

I love tunnels.

I run an Invidia downpipe and mid with the Prodrive oval-tip axle-back on my 03 WRX. It's a beautiful thing.

 

[DivideBYZero]

Originally posted by: Vic

Originally posted by: DivideBYZero

Originally posted by: Vic

Originally posted by: DivideBYZero
You know up until the 06 model(and certain JDM's) the Impreza WRX has very bad pulse interference. That's what gives it character, but the eaqual length headers are more effecient. Ergo, I conter that a twin pipe setup on a boosted scooby would in fact be an OK solution.

But as we have ELH's it doesn't matter.

Meh. I love my unequal-length headers. I'll sacrifice a couple hp so my Scooby doesn't sound like a Honda.

Agreed. That's why I looked at an '06 the other day and walked away.

My MY00 GF sounds awesome with the prodrive centre and a 3" bore rear section, expading to a ricey 4" tip. Nice bassy flat four throb, and over 4K it is very loud.

I love tunnels.

I run an Invidia downpipe and mid with the Prodrive oval-tip axle-back on my 03 WRX. It's a beautiful thing.

Full decat? I only have the downpipe cat for emissions purposes and it still cracks out ~250hp (215hp is the MFG quoted figure for these models).

 

[Vic]

Originally posted by: DivideBYZero

Originally posted by: Vic

Originally posted by: DivideBYZero

Originally posted by: Vic

Originally posted by: DivideBYZero
You know up until the 06 model(and certain JDM's) the Impreza WRX has very bad pulse interference. That's what gives it character, but the eaqual length headers are more effecient. Ergo, I conter that a twin pipe setup on a boosted scooby would in fact be an OK solution.

But as we have ELH's it doesn't matter.

Meh. I love my unequal-length headers. I'll sacrifice a couple hp so my Scooby doesn't sound like a Honda.

Agreed. That's why I looked at an '06 the other day and walked away.

My MY00 GF sounds awesome with the prodrive centre and a 3" bore rear section, expading to a ricey 4" tip. Nice bassy flat four throb, and over 4K it is very loud.

I love tunnels.

I run an Invidia downpipe and mid with the Prodrive oval-tip axle-back on my 03 WRX. It's a beautiful thing.

Full decat? I only have the downpipe cat for emissions purposes and it still cracks out ~250hp (215hp is the MFG quoted figure for these models).

Yep. Plus VF39, STi TMIC, stage 4 ECU reflash and some other goodies. I haven't had a dyno tune (although my ECU map was done by a highly reputable tuning shop and based off many comparable builds), but I'm told it should be in the 350 bhp range (270 whp). It screams.

 

[DivideBYZero]

Originally posted by: Vic

Originally posted by: DivideBYZero

Originally posted by: Vic

Originally posted by: DivideBYZero

Originally posted by: Vic

Originally posted by: DivideBYZero
You know up until the 06 model(and certain JDM's) the Impreza WRX has very bad pulse interference. That's what gives it character, but the eaqual length headers are more effecient. Ergo, I conter that a twin pipe setup on a boosted scooby would in fact be an OK solution.

But as we have ELH's it doesn't matter.

Meh. I love my unequal-length headers. I'll sacrifice a couple hp so my Scooby doesn't sound like a Honda.

Agreed. That's why I looked at an '06 the other day and walked away.

My MY00 GF sounds awesome with the prodrive centre and a 3" bore rear section, expading to a ricey 4" tip. Nice bassy flat four throb, and over 4K it is very loud.

I love tunnels.

I run an Invidia downpipe and mid with the Prodrive oval-tip axle-back on my 03 WRX. It's a beautiful thing.

Full decat? I only have the downpipe cat for emissions purposes and it still cracks out ~250hp (215hp is the MFG quoted figure for these models).

Yep. Plus VF39, STi TMIC, stage 4 ECU reflash and some other goodies. I haven't had a dyno tune (although my ECU map was done by a highly reputable tuning shop and based off many comparable builds), but I'm told it should be in the 350 bhp range (270 whp). It screams.

I would not be surprised if you are running those numbers. I'm just on the humble TD04, but it's only puffing the stock 12lb right now. I keep toying with the idea of a remap for an easy 270+...