What Causes the Burbble Sound on Decel?
03-20-2013, 07:47 PM
#22
Team Owner
Member Since: Apr 2008
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There is a real technical explanation for this deceleration burble. It is not harmful at all.
The majority of factory exhaust systems are designed to prevent this burble, as the civilians would worry about it. Aftermarket exhausts are larger diameter and less back pressure, so they promote this noise. Turbochargers tend to mute this effect due to the spin down of the turbo.
Here's what happens: You let off the gas and the throttle butterfly valve shuts, causing the end of the "air pump" action that is an internal combustion engine, which causes the exhaust flow to come to a near complete stop. At the same time, engine vacuum drops to the lowest it can go, while the intake and exhaust valves are still opening. Since the intake valve is essentially 'shut' due to the throttle being shut, the engine vacuum is high.
Now, with a free-flow large diameter exhaust system, combined with low exhaust back pressure and no flow, and the engine drawing a vacuum, sucks in cold air from the outside due to the barometric pressure difference between the intake manifold and the outside air.
When the cold air (doesn't mean cold as in wintertime, but any normal atmospheric temp) rushes into the tailpipe, it 'hits' hot piping and residual hot exhaust air. That 'collision' is a mini-thunder clap, and that's what you hear. BTW, that thunderclap is slightly supersonic.
No harm done.
The majority of factory exhaust systems are designed to prevent this burble, as the civilians would worry about it. Aftermarket exhausts are larger diameter and less back pressure, so they promote this noise. Turbochargers tend to mute this effect due to the spin down of the turbo.
Here's what happens: You let off the gas and the throttle butterfly valve shuts, causing the end of the "air pump" action that is an internal combustion engine, which causes the exhaust flow to come to a near complete stop. At the same time, engine vacuum drops to the lowest it can go, while the intake and exhaust valves are still opening. Since the intake valve is essentially 'shut' due to the throttle being shut, the engine vacuum is high.
Now, with a free-flow large diameter exhaust system, combined with low exhaust back pressure and no flow, and the engine drawing a vacuum, sucks in cold air from the outside due to the barometric pressure difference between the intake manifold and the outside air.
When the cold air (doesn't mean cold as in wintertime, but any normal atmospheric temp) rushes into the tailpipe, it 'hits' hot piping and residual hot exhaust air. That 'collision' is a mini-thunder clap, and that's what you hear. BTW, that thunderclap is slightly supersonic.
No harm done.
03-20-2013, 07:51 PM
#24
Race Director
The popping and gurgling are music to the ears. People that want to eliminate this should buy Priuses. 
03-20-2013, 07:53 PM
#25
Le Mans Master
^my humble understanding is something similar to what the gentleman EasyRhino above posted. I have heard the same may be accentuated by varying pressures between each side of the exhaust especially with headers in place. I was told that this is not a function of unspent petrol being combusted in the headers or manifold. Please advise as I am unsure. Thanks fellas.
03-20-2013, 07:54 PM
#27
Melting Slicks
http://www.dsmtuners.com/forums/freq...kpressure.html
There is a common misconception that engines need backpressure in order to run properly, generate low end torque, etc. That is simply untrue. Backpressure is a bad thing. Always. Take a look at a top fuel dragster...how much backpressure do you think those zoomie headers make? Very little, and those engines produce 6500 hp.
So, what is backpressure? Any fluid flowing through a pipe experiences drag on the walls of the pipe. This depends on a number of factors, including the diameter of the pipe, the smoothness of the inside of the pipe, the viscosity of the fluid, and the velocity of the fluid. This drag results in a pressure drop through the pipe. In order for the fluid to flow at all, the pressure on one end of the pipe must be higher than at the other. In an exhaust system, that pressure drop is what we refer to as backpressure. It's pretty obvious that the engine has to produce this pressure differential, so the less power it has to spend making pressure to push the exhaust out, the more power it can send to the wheels.
Given that exhaust pipes are pretty smooth, and that we can't change the viscosity (thickness) of the waste gas being forced through the pipes, we are left with basically 2 parameters we can have any control over: The pipe diameter and the gas velocity.
Unfortunately, the pipe diameter controls the gas velocity since the volume of gas is prescribed by the engine. So, we really only have one thing we can change. So, bigger pipes allow less pressure drop for a given volume of gas because the velocity is lower. The pressure drop (backpressure increase) is proportional the gas velocity squared, so if I double the gas velocity (by reducing the cross sectional area of the exhaust pipe by half) then I quadruple the pressure drop.
Well, there's an easy solution for that: Just make the exhaust pipe bigger. Bigger pipe, lower gas velocity, less pressure drop, so less backpressure. Wow, that was easy. After all, this is the way it's done for basically any type of commercial plumbing system. Need less pressure drop on a chilled water pipe or a natural gas line? Just make the pipe bigger.
But wait, there's a problem....Having a huge exhaust pipe has killed my low end torque!!! What's different? Oh, there's no backpressure!! Therefore backpressure makes torque!
Wrong.
An exhaust system is different than just about any other plumbing situation. How? Because the flow is pulsed, and this turns out to be a big deal. Every time a pulse of exhaust gas runs through the pipe, a strange thing happens: it as it passes, it has a little area of vacuum behind it. Just like a NASCAR stocker running around the track, the pulse generates a little bit of a vacuum behind it. In NASCAR, a driver can take advantage of another driver's vacuum by getting right behind him and driving in it. The wind resistance is drastically reduced. This is called drafting.
Well, how big the vacuum behind each pules is depends on the gas velocity. The higher the velocity, the bigger the vacuum the pulse has behind it.
Now, this means that I can "draft" the next pulse, just like in NASCAR. In NASCAR, it's called drafting, in an exhaust system, it's called scavenging. You've probably seen this term used when talking about headers, but the same concept applies in the pipe.
I get the maximum scavenging effect if the gas velocity is high, so the pipe needs to be small. By maximizing the scavenging effect, I help to pull pulses out of the combustion chamber, which means the engine doesn't have to work as hard to do that.
This has the most effect when there's a bunch of time between pulses...in other words, at low rpm. As the revs rise, the pulsed flow becomes more and more like constant flow, and the scavenging effect is diminished.
So, at low rpm I need a small pipe to maximize scavenging, and at high rpm I need a big pipe to minimize pressure drop. My exhaust pipe can only be one size, so it's a compromise. For a given engine, one pipe diameter will make the most overall power (i.e., have the largest area under the curve on a dyno chart).
So, the loss of torque has nothing to do with backpressure, and everything to do with gas velocity. So you need exhaust components that are not restricive (manifolds/headers, mufflers) and that are sized correctly for your application.
To further dispel the "backpressure is necessary" theory, try this if you want. If you have access to a vehicle with open headers, make a block off plate that will bolt to the collector. This plate should have only a 1" hole in it for the exhaust to flow through. That will give you PLENTY of backpressure, and zero scavenging. Then you can report back on how much low end power it has.
The one exception to sizing an exhaust is for turbo cars. Since the turbo is in the exaust stream, the gas flow spinning the impeller tends to come out of the turbo with the pulses greatly diminished. In this case, you can get away with running a larger pipe than on an equivalent HP N/A engine because you can't take as much advantage of the scavenging effect.
So, what is backpressure? Any fluid flowing through a pipe experiences drag on the walls of the pipe. This depends on a number of factors, including the diameter of the pipe, the smoothness of the inside of the pipe, the viscosity of the fluid, and the velocity of the fluid. This drag results in a pressure drop through the pipe. In order for the fluid to flow at all, the pressure on one end of the pipe must be higher than at the other. In an exhaust system, that pressure drop is what we refer to as backpressure. It's pretty obvious that the engine has to produce this pressure differential, so the less power it has to spend making pressure to push the exhaust out, the more power it can send to the wheels.
Given that exhaust pipes are pretty smooth, and that we can't change the viscosity (thickness) of the waste gas being forced through the pipes, we are left with basically 2 parameters we can have any control over: The pipe diameter and the gas velocity.
Unfortunately, the pipe diameter controls the gas velocity since the volume of gas is prescribed by the engine. So, we really only have one thing we can change. So, bigger pipes allow less pressure drop for a given volume of gas because the velocity is lower. The pressure drop (backpressure increase) is proportional the gas velocity squared, so if I double the gas velocity (by reducing the cross sectional area of the exhaust pipe by half) then I quadruple the pressure drop.
Well, there's an easy solution for that: Just make the exhaust pipe bigger. Bigger pipe, lower gas velocity, less pressure drop, so less backpressure. Wow, that was easy. After all, this is the way it's done for basically any type of commercial plumbing system. Need less pressure drop on a chilled water pipe or a natural gas line? Just make the pipe bigger.
But wait, there's a problem....Having a huge exhaust pipe has killed my low end torque!!! What's different? Oh, there's no backpressure!! Therefore backpressure makes torque!
Wrong.
An exhaust system is different than just about any other plumbing situation. How? Because the flow is pulsed, and this turns out to be a big deal. Every time a pulse of exhaust gas runs through the pipe, a strange thing happens: it as it passes, it has a little area of vacuum behind it. Just like a NASCAR stocker running around the track, the pulse generates a little bit of a vacuum behind it. In NASCAR, a driver can take advantage of another driver's vacuum by getting right behind him and driving in it. The wind resistance is drastically reduced. This is called drafting.
Well, how big the vacuum behind each pules is depends on the gas velocity. The higher the velocity, the bigger the vacuum the pulse has behind it.
Now, this means that I can "draft" the next pulse, just like in NASCAR. In NASCAR, it's called drafting, in an exhaust system, it's called scavenging. You've probably seen this term used when talking about headers, but the same concept applies in the pipe.
I get the maximum scavenging effect if the gas velocity is high, so the pipe needs to be small. By maximizing the scavenging effect, I help to pull pulses out of the combustion chamber, which means the engine doesn't have to work as hard to do that.
This has the most effect when there's a bunch of time between pulses...in other words, at low rpm. As the revs rise, the pulsed flow becomes more and more like constant flow, and the scavenging effect is diminished.
So, at low rpm I need a small pipe to maximize scavenging, and at high rpm I need a big pipe to minimize pressure drop. My exhaust pipe can only be one size, so it's a compromise. For a given engine, one pipe diameter will make the most overall power (i.e., have the largest area under the curve on a dyno chart).
So, the loss of torque has nothing to do with backpressure, and everything to do with gas velocity. So you need exhaust components that are not restricive (manifolds/headers, mufflers) and that are sized correctly for your application.
To further dispel the "backpressure is necessary" theory, try this if you want. If you have access to a vehicle with open headers, make a block off plate that will bolt to the collector. This plate should have only a 1" hole in it for the exhaust to flow through. That will give you PLENTY of backpressure, and zero scavenging. Then you can report back on how much low end power it has.
The one exception to sizing an exhaust is for turbo cars. Since the turbo is in the exaust stream, the gas flow spinning the impeller tends to come out of the turbo with the pulses greatly diminished. In this case, you can get away with running a larger pipe than on an equivalent HP N/A engine because you can't take as much advantage of the scavenging effect.
03-20-2013, 09:14 PM
#31
Burning Brakes
Popping yes, gurgling sounds like an inboard, which rarely sound like anything at all. The LS series tend to gurgle long before they pop and it sounds like utter crap. Put a nice cam and some headers in and pretty much any cat back will sound good. Stock cam and manifolds, not so much.
03-20-2013, 09:24 PM
#32
Safety Car
Member Since: Apr 2006
Location: Anaheim Hills, Ca
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It is in fact caused by fuel being combusted in the exhaust system rather than in the combustion chamber on decel; "unspent fuel" as has been referred to. You'll notice that it will stop burbling after a short time if you don't touch the gas. That's because the fuel is actually shut off to the cylinders after that brief period.
03-21-2013, 06:06 AM
#35
Race Director
Exhaust Burble on Deceleration
An exhaust burble, or throaty popping noise which could be likened to a babbling brook, is has a different cause if it only occurs when suddenly backing off on a vehicle's throttle. Essentially, the sudden easing off the throttle causes an immediate decrease in exhaust emissions to the degree that atmospheric pressure surrounding the exhaust pipe pushes cool air up into the exhaust system. This air collides with the warm exhaust gasses and creates a rumbling not unlike thunder. Normally this will only happen if the tailpipe has too wide a diameter to maintain equalized air pressure, or there is a seam in the exhaust pipes which is not air tight.
http://www.ehow.com/how-does_5545351...le-causes.html
An exhaust burble, or throaty popping noise which could be likened to a babbling brook, is has a different cause if it only occurs when suddenly backing off on a vehicle's throttle. Essentially, the sudden easing off the throttle causes an immediate decrease in exhaust emissions to the degree that atmospheric pressure surrounding the exhaust pipe pushes cool air up into the exhaust system. This air collides with the warm exhaust gasses and creates a rumbling not unlike thunder. Normally this will only happen if the tailpipe has too wide a diameter to maintain equalized air pressure, or there is a seam in the exhaust pipes which is not air tight.
http://www.ehow.com/how-does_5545351...le-causes.html
03-21-2013, 06:20 AM
#36
Safety Car
OP, it is unburned fuel "popping" in the exhaust system, and a good tuner can practically eliminate it if desired. My 2011 vette will vary from a burble, to a rumble, to what people think is back firing, depending on the temperature of the engine, outside air conditions, and the way that I'm decelerating. My 2008 did not sound nearly as aggressive, both were LS3s, but with with slightly different factory NPP exhausts, and probably a slightly different tune from GM.
I can personally eliminate it by putting my NPP exhaust in "normal" mode by pressing my floor petal switch, but I generally like it too.
And OP, there is sooooo much misinformation in this thread, it's scary.
Last edited by Seadawg; 03-21-2013 at 06:33 AM.
03-21-2013, 06:35 AM
#37
So it sounds like there are 2 different explanations being offered here. Pressure reversal when you let off the accelerator pedal (closing the throttle body, increasing engine vacuum, and actually sucking some air back in through the exhaust tips), and combusting fuel in the exhaust instead of the engine.
So which is it? I lean towards the pressure reversal because it makes more sense to me, but don't know enough about either scenario to know for sure (what causes fuel to make it's way through the engine without burning when you let off the accelerator pedal?). Does gas igniting in the exhaust system sound the same as the sound that's made during an exhaust pressure reversal? Or would those two scenarios lead to different sounds? In that case, which one are we actually talking about?
So which is it? I lean towards the pressure reversal because it makes more sense to me, but don't know enough about either scenario to know for sure (what causes fuel to make it's way through the engine without burning when you let off the accelerator pedal?). Does gas igniting in the exhaust system sound the same as the sound that's made during an exhaust pressure reversal? Or would those two scenarios lead to different sounds? In that case, which one are we actually talking about?
There is a real technical explanation for this deceleration burble. It is not harmful at all.
The majority of factory exhaust systems are designed to prevent this burble, as the civilians would worry about it. Aftermarket exhausts are larger diameter and less back pressure, so they promote this noise. Turbochargers tend to mute this effect due to the spin down of the turbo.
Here's what happens: You let off the gas and the throttle butterfly valve shuts, causing the end of the "air pump" action that is an internal combustion engine, which causes the exhaust flow to come to a near complete stop. At the same time, engine vacuum drops to the lowest it can go, while the intake and exhaust valves are still opening. Since the intake valve is essentially 'shut' due to the throttle being shut, the engine vacuum is high.
Now, with a free-flow large diameter exhaust system, combined with low exhaust back pressure and no flow, and the engine drawing a vacuum, sucks in cold air from the outside due to the barometric pressure difference between the intake manifold and the outside air.
When the cold air (doesn't mean cold as in wintertime, but any normal atmospheric temp) rushes into the tailpipe, it 'hits' hot piping and residual hot exhaust air. That 'collision' is a mini-thunder clap, and that's what you hear. BTW, that thunderclap is slightly supersonic.
No harm done.
The majority of factory exhaust systems are designed to prevent this burble, as the civilians would worry about it. Aftermarket exhausts are larger diameter and less back pressure, so they promote this noise. Turbochargers tend to mute this effect due to the spin down of the turbo.
Here's what happens: You let off the gas and the throttle butterfly valve shuts, causing the end of the "air pump" action that is an internal combustion engine, which causes the exhaust flow to come to a near complete stop. At the same time, engine vacuum drops to the lowest it can go, while the intake and exhaust valves are still opening. Since the intake valve is essentially 'shut' due to the throttle being shut, the engine vacuum is high.
Now, with a free-flow large diameter exhaust system, combined with low exhaust back pressure and no flow, and the engine drawing a vacuum, sucks in cold air from the outside due to the barometric pressure difference between the intake manifold and the outside air.
When the cold air (doesn't mean cold as in wintertime, but any normal atmospheric temp) rushes into the tailpipe, it 'hits' hot piping and residual hot exhaust air. That 'collision' is a mini-thunder clap, and that's what you hear. BTW, that thunderclap is slightly supersonic.
No harm done.
http://www.dsmtuners.com/forums/freq...kpressure.html
There is a common misconception that engines need backpressure in order to run properly, generate low end torque, etc. That is simply untrue. Backpressure is a bad thing. Always. Take a look at a top fuel dragster...how much backpressure do you think those zoomie headers make? Very little, and those engines produce 6500 hp.
So, what is backpressure? Any fluid flowing through a pipe experiences drag on the walls of the pipe. This depends on a number of factors, including the diameter of the pipe, the smoothness of the inside of the pipe, the viscosity of the fluid, and the velocity of the fluid. This drag results in a pressure drop through the pipe. In order for the fluid to flow at all, the pressure on one end of the pipe must be higher than at the other. In an exhaust system, that pressure drop is what we refer to as backpressure. It's pretty obvious that the engine has to produce this pressure differential, so the less power it has to spend making pressure to push the exhaust out, the more power it can send to the wheels.
Given that exhaust pipes are pretty smooth, and that we can't change the viscosity (thickness) of the waste gas being forced through the pipes, we are left with basically 2 parameters we can have any control over: The pipe diameter and the gas velocity.
Unfortunately, the pipe diameter controls the gas velocity since the volume of gas is prescribed by the engine. So, we really only have one thing we can change. So, bigger pipes allow less pressure drop for a given volume of gas because the velocity is lower. The pressure drop (backpressure increase) is proportional the gas velocity squared, so if I double the gas velocity (by reducing the cross sectional area of the exhaust pipe by half) then I quadruple the pressure drop.
Well, there's an easy solution for that: Just make the exhaust pipe bigger. Bigger pipe, lower gas velocity, less pressure drop, so less backpressure. Wow, that was easy. After all, this is the way it's done for basically any type of commercial plumbing system. Need less pressure drop on a chilled water pipe or a natural gas line? Just make the pipe bigger.
But wait, there's a problem....Having a huge exhaust pipe has killed my low end torque!!! What's different? Oh, there's no backpressure!! Therefore backpressure makes torque!
Wrong.
An exhaust system is different than just about any other plumbing situation. How? Because the flow is pulsed, and this turns out to be a big deal. Every time a pulse of exhaust gas runs through the pipe, a strange thing happens: it as it passes, it has a little area of vacuum behind it. Just like a NASCAR stocker running around the track, the pulse generates a little bit of a vacuum behind it. In NASCAR, a driver can take advantage of another driver's vacuum by getting right behind him and driving in it. The wind resistance is drastically reduced. This is called drafting.
Well, how big the vacuum behind each pules is depends on the gas velocity. The higher the velocity, the bigger the vacuum the pulse has behind it.
Now, this means that I can "draft" the next pulse, just like in NASCAR. In NASCAR, it's called drafting, in an exhaust system, it's called scavenging. You've probably seen this term used when talking about headers, but the same concept applies in the pipe.
I get the maximum scavenging effect if the gas velocity is high, so the pipe needs to be small. By maximizing the scavenging effect, I help to pull pulses out of the combustion chamber, which means the engine doesn't have to work as hard to do that.
This has the most effect when there's a bunch of time between pulses...in other words, at low rpm. As the revs rise, the pulsed flow becomes more and more like constant flow, and the scavenging effect is diminished.
So, at low rpm I need a small pipe to maximize scavenging, and at high rpm I need a big pipe to minimize pressure drop. My exhaust pipe can only be one size, so it's a compromise. For a given engine, one pipe diameter will make the most overall power (i.e., have the largest area under the curve on a dyno chart).
So, the loss of torque has nothing to do with backpressure, and everything to do with gas velocity. So you need exhaust components that are not restricive (manifolds/headers, mufflers) and that are sized correctly for your application.
To further dispel the "backpressure is necessary" theory, try this if you want. If you have access to a vehicle with open headers, make a block off plate that will bolt to the collector. This plate should have only a 1" hole in it for the exhaust to flow through. That will give you PLENTY of backpressure, and zero scavenging. Then you can report back on how much low end power it has.
The one exception to sizing an exhaust is for turbo cars. Since the turbo is in the exaust stream, the gas flow spinning the impeller tends to come out of the turbo with the pulses greatly diminished. In this case, you can get away with running a larger pipe than on an equivalent HP N/A engine because you can't take as much advantage of the scavenging effect.
There is a common misconception that engines need backpressure in order to run properly, generate low end torque, etc. That is simply untrue. Backpressure is a bad thing. Always. Take a look at a top fuel dragster...how much backpressure do you think those zoomie headers make? Very little, and those engines produce 6500 hp.
So, what is backpressure? Any fluid flowing through a pipe experiences drag on the walls of the pipe. This depends on a number of factors, including the diameter of the pipe, the smoothness of the inside of the pipe, the viscosity of the fluid, and the velocity of the fluid. This drag results in a pressure drop through the pipe. In order for the fluid to flow at all, the pressure on one end of the pipe must be higher than at the other. In an exhaust system, that pressure drop is what we refer to as backpressure. It's pretty obvious that the engine has to produce this pressure differential, so the less power it has to spend making pressure to push the exhaust out, the more power it can send to the wheels.
Given that exhaust pipes are pretty smooth, and that we can't change the viscosity (thickness) of the waste gas being forced through the pipes, we are left with basically 2 parameters we can have any control over: The pipe diameter and the gas velocity.
Unfortunately, the pipe diameter controls the gas velocity since the volume of gas is prescribed by the engine. So, we really only have one thing we can change. So, bigger pipes allow less pressure drop for a given volume of gas because the velocity is lower. The pressure drop (backpressure increase) is proportional the gas velocity squared, so if I double the gas velocity (by reducing the cross sectional area of the exhaust pipe by half) then I quadruple the pressure drop.
Well, there's an easy solution for that: Just make the exhaust pipe bigger. Bigger pipe, lower gas velocity, less pressure drop, so less backpressure. Wow, that was easy. After all, this is the way it's done for basically any type of commercial plumbing system. Need less pressure drop on a chilled water pipe or a natural gas line? Just make the pipe bigger.
But wait, there's a problem....Having a huge exhaust pipe has killed my low end torque!!! What's different? Oh, there's no backpressure!! Therefore backpressure makes torque!
Wrong.
An exhaust system is different than just about any other plumbing situation. How? Because the flow is pulsed, and this turns out to be a big deal. Every time a pulse of exhaust gas runs through the pipe, a strange thing happens: it as it passes, it has a little area of vacuum behind it. Just like a NASCAR stocker running around the track, the pulse generates a little bit of a vacuum behind it. In NASCAR, a driver can take advantage of another driver's vacuum by getting right behind him and driving in it. The wind resistance is drastically reduced. This is called drafting.
Well, how big the vacuum behind each pules is depends on the gas velocity. The higher the velocity, the bigger the vacuum the pulse has behind it.
Now, this means that I can "draft" the next pulse, just like in NASCAR. In NASCAR, it's called drafting, in an exhaust system, it's called scavenging. You've probably seen this term used when talking about headers, but the same concept applies in the pipe.
I get the maximum scavenging effect if the gas velocity is high, so the pipe needs to be small. By maximizing the scavenging effect, I help to pull pulses out of the combustion chamber, which means the engine doesn't have to work as hard to do that.
This has the most effect when there's a bunch of time between pulses...in other words, at low rpm. As the revs rise, the pulsed flow becomes more and more like constant flow, and the scavenging effect is diminished.
So, at low rpm I need a small pipe to maximize scavenging, and at high rpm I need a big pipe to minimize pressure drop. My exhaust pipe can only be one size, so it's a compromise. For a given engine, one pipe diameter will make the most overall power (i.e., have the largest area under the curve on a dyno chart).
So, the loss of torque has nothing to do with backpressure, and everything to do with gas velocity. So you need exhaust components that are not restricive (manifolds/headers, mufflers) and that are sized correctly for your application.
To further dispel the "backpressure is necessary" theory, try this if you want. If you have access to a vehicle with open headers, make a block off plate that will bolt to the collector. This plate should have only a 1" hole in it for the exhaust to flow through. That will give you PLENTY of backpressure, and zero scavenging. Then you can report back on how much low end power it has.
The one exception to sizing an exhaust is for turbo cars. Since the turbo is in the exaust stream, the gas flow spinning the impeller tends to come out of the turbo with the pulses greatly diminished. In this case, you can get away with running a larger pipe than on an equivalent HP N/A engine because you can't take as much advantage of the scavenging effect.
03-21-2013, 12:58 PM
#38
Pro
I have Corsa Sport on my 2009 and I have the factory X pipe that they changed too. I still get significant burble, popping, cracking with my exhaust. I love it! It's one of the best part about it. I'll purposely downshift just to hear that noise. Enjoy it!
03-21-2013, 01:05 PM
#39
Simplify
Member Since: Aug 2012
Location: forging ahead...making up for lost time and embracing each day thankful to be alive.... nj
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St. Jude Donor '13-'14-'15
~~~ CFOT Book Folder ~~~
NCM Sinkhole Donor
I just recently installed the Corsa Sport Mufflers on my car and all I can say is Wow! For anyone on the fence, go for it! The sound is really nice but it is not too much. Been driving all around town enjoying the exhaust "music". The rest of my exhaust system is stock. I have a 2006, with the H-Pipe and a 6-speed manual.
As I am cruising around and the car is decelerating or upon pushing in the clutch I get that burbling sound. I personnally love it. But I am trying to understand what is exactly happening in the system to make that happen. Is it air getting sucked back into the mufflers? If anyone can explain the physics behind it, I would like to know. Just curious.
Thank you!
As I am cruising around and the car is decelerating or upon pushing in the clutch I get that burbling sound. I personnally love it. But I am trying to understand what is exactly happening in the system to make that happen. Is it air getting sucked back into the mufflers? If anyone can explain the physics behind it, I would like to know. Just curious.
Thank you!
