BACKPRESSURE MYTH DESTROYED. I believe this is TRUTH.
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From: Orlando
BACKPRESSURE MYTH DESTROYED. I believe this is TRUTH.
http://www.team-integra.net/forum/bl...st-basics.html
A great read and it was basically a deciding factor for me to have a muffler delete done rather than have a flowmaster installed. F**k the muffler!
What do you think of this? I believe it is true, everything is logical and ties together rationally with the physics of sound waves and high-low pressure attraction. I don't have the time to delve further at the moment.
Sorry for the caps, was excited haha.
A great read and it was basically a deciding factor for me to have a muffler delete done rather than have a flowmaster installed. F**k the muffler!
What do you think of this? I believe it is true, everything is logical and ties together rationally with the physics of sound waves and high-low pressure attraction. I don't have the time to delve further at the moment.
Sorry for the caps, was excited haha.
Last edited by Tigre; Oct 31, 2012 at 09:21 PM.
Terry ( correct name? its late, im tired) at Motordyne is an ex rocket scientist... apparently locations for the bends of the pipe and its components even make a difference in the Z.
Dunno..
every car/engine/set up truly is different. I will attest to the fact by personal experience as well as countless testimony from others ..that large diameter pipes or too much flow on NA 350z certainly does not equate to useable power as torque, which is what you can equate to power that you can feel.
Just a thought, didnt even read the link provided.
Dunno..
every car/engine/set up truly is different. I will attest to the fact by personal experience as well as countless testimony from others ..that large diameter pipes or too much flow on NA 350z certainly does not equate to useable power as torque, which is what you can equate to power that you can feel.
Just a thought, didnt even read the link provided.
Last edited by bmccann101; Oct 31, 2012 at 10:10 PM.
Interesting read. But i suggest you read it again as i think you missed the main point of the 2nd last paragraph.
"This would be another one for the Magazine Mechanics. "This muffler will reduce backpressure and you'll see at least 15-20HP with this ultimate free flowing design!" By now I hope we can see what a big fat load of crap that is. In the stock exhaust system, the pulses have already been jammed together, and the backpressure has already affected the engine. So you change your muffler to a better flowing one, so what? The amount of backpressure in the exhaust system remains unchanged. You're just putting a fire hose at the end of a garden hose, the flow remains unchanged. So unless your exhaust has reduced backpressure enough so that the muffler becomes a restriction, then changing the muffler to a "free flowing" design will have no effect on real-world performance."
So a muffler delete is pointless. Is what its saying.
"This would be another one for the Magazine Mechanics. "This muffler will reduce backpressure and you'll see at least 15-20HP with this ultimate free flowing design!" By now I hope we can see what a big fat load of crap that is. In the stock exhaust system, the pulses have already been jammed together, and the backpressure has already affected the engine. So you change your muffler to a better flowing one, so what? The amount of backpressure in the exhaust system remains unchanged. You're just putting a fire hose at the end of a garden hose, the flow remains unchanged. So unless your exhaust has reduced backpressure enough so that the muffler becomes a restriction, then changing the muffler to a "free flowing" design will have no effect on real-world performance."
So a muffler delete is pointless. Is what its saying.
Yep. The mtdyn. Xyz pipe is titz... and that's why their test pipes are also worth four times the regular cost..I TRULY wish it were not the case.. but the theory behind waves etc makes a difference in vq Turbo cams...intake runners and most certainly our exhaust too
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From: Orlando
Interesting read. But i suggest you read it again as i think you missed the main point of the 2nd last paragraph.
"This would be another one for the Magazine Mechanics. "This muffler will reduce backpressure and you'll see at least 15-20HP with this ultimate free flowing design!" By now I hope we can see what a big fat load of crap that is. In the stock exhaust system, the pulses have already been jammed together, and the backpressure has already affected the engine. So you change your muffler to a better flowing one, so what? The amount of backpressure in the exhaust system remains unchanged. You're just putting a fire hose at the end of a garden hose, the flow remains unchanged. So unless your exhaust has reduced backpressure enough so that the muffler becomes a restriction, then changing the muffler to a "free flowing" design will have no effect on real-world performance."
So a muffler delete is pointless. Is what its saying.
"This would be another one for the Magazine Mechanics. "This muffler will reduce backpressure and you'll see at least 15-20HP with this ultimate free flowing design!" By now I hope we can see what a big fat load of crap that is. In the stock exhaust system, the pulses have already been jammed together, and the backpressure has already affected the engine. So you change your muffler to a better flowing one, so what? The amount of backpressure in the exhaust system remains unchanged. You're just putting a fire hose at the end of a garden hose, the flow remains unchanged. So unless your exhaust has reduced backpressure enough so that the muffler becomes a restriction, then changing the muffler to a "free flowing" design will have no effect on real-world performance."
So a muffler delete is pointless. Is what its saying.
I am deleting my muffler, not changing it. I'm taking out all that bouncing of exhaust pulses onto one another and allowing them to flow out nicely.
Terry ( correct name? its late, im tired) at Motordyne is an ex rocket scientist... apparently locations for the bends of the pipe and its components even make a difference in the Z.
Dunno..
every car/engine/set up truly is different. I will attest to the fact by personal experience as well as countless testimony from others ..that large diameter pipes or too much flow on NA 350z certainly does not equate to useable power as torque, which is what you can equate to power that you can feel.
Just a thought, didnt even read the link provided.
Dunno..
every car/engine/set up truly is different. I will attest to the fact by personal experience as well as countless testimony from others ..that large diameter pipes or too much flow on NA 350z certainly does not equate to useable power as torque, which is what you can equate to power that you can feel.
Just a thought, didnt even read the link provided.
What you said is in the right mindset about exhaust flow, you should really skim over the article it goes into exactly how the diameter of the piping affects both N/A and F/I applications including at low and high RPM's. I am sticking with the stock pipe diameter (70mm outside diameter I've heard? So probably about 2 and a half inch inside) as I am assuming it is or is close to the most efficient diameter for providing the most efficient exhaust flow and therefore gains throughout the RPM range on N/A 350z's.
Last edited by Tigre; Oct 31, 2012 at 10:52 PM.
I think you misunderstood what the author was implying, that calling a muffler "free flowing" is a complete contradiction as the whole point of mufflers is to do the exact opposite of that in order to create destructive interference of the sound waves thereby reducing noise drastically.
I am deleting my muffler, not changing it. I'm taking out all that bouncing of exhaust pulses onto one another and allowing them to flow out nicely.
I am deleting my muffler, not changing it. I'm taking out all that bouncing of exhaust pulses onto one another and allowing them to flow out nicely.
And there are other manufacturers out there that feature straight through designs if that is your primary concern.
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The writer of that article isn't giving you a definitive answer of "delete your muffler for winz!". He's merely explaining the process of exhaust gas flow and giving you an understanding of how too many people screw it up.
Basically, if your backpressure has already been optimized at a point before the muffler then you aren't gaining by deleting the muffler. You'll get noise, but not performance. It's not just about eliminating restrictions, it's about maximizing the "push-pull" effect of exhaust pulses.
Basically, if your backpressure has already been optimized at a point before the muffler then you aren't gaining by deleting the muffler. You'll get noise, but not performance. It's not just about eliminating restrictions, it's about maximizing the "push-pull" effect of exhaust pulses.
OP, if you are OK with your car sounding like complete garbage, then don't stop at removing the muffler. Remove the exhaust after the headers, this will get rid of choke points - the cats and the resonator. Otherwise you are wasting your time. The cats and resonator are probably screwing up the flow anyways, so your muffler is not the weak point.
OP you don't think that all the companies with engineers, flow testing, and practical experience know more about exhaust than you do? Go ahead and cut the muffler off. It will still be slow and then sound like shyt.
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From: Huntington Beach
After reading this, I have become a tad concern with my setup. I have an HKS Rep from eBay (I know, I know) But it sounds great. Its 2.5 true duel. I decided to delete the front resonators off the and install a x-pipe, which sounds so fki'n sexy. However, I'm not sure if I have too much flow... Any insight on this?
They lose torque.
I have one..
But...id not lose a moment of sleep.. very few 350z exhausts make ANY power..unless you have 1500 avail for motordyne, enjoy what u have.
Cams make power..extra fuel n a tube makes power..fi makes power..bolts r for fun..so have fun w them..especially if u like the sound..powerful vq exhaust doesn't actually sound so hot..function over form.
I have one..
But...id not lose a moment of sleep.. very few 350z exhausts make ANY power..unless you have 1500 avail for motordyne, enjoy what u have.
Cams make power..extra fuel n a tube makes power..fi makes power..bolts r for fun..so have fun w them..especially if u like the sound..powerful vq exhaust doesn't actually sound so hot..function over form.
Registered User
Joined: Jun 2012
Posts: 199
Likes: 1
From: Huntington Beach
They lose torque.
I have one..
But...id not lose a moment of sleep.. very few 350z exhausts make ANY power..unless you have 1500 avail for motordyne, enjoy what u have.
Cams make power..extra fuel n a tube makes power..fi makes power..bolts r for fun..so have fun w them..especially if u like the sound..powerful vq exhaust doesn't actually sound so hot..function over form.
I have one..
But...id not lose a moment of sleep.. very few 350z exhausts make ANY power..unless you have 1500 avail for motordyne, enjoy what u have.
Cams make power..extra fuel n a tube makes power..fi makes power..bolts r for fun..so have fun w them..especially if u like the sound..powerful vq exhaust doesn't actually sound so hot..function over form.
Last edited by TheWoods; Nov 1, 2012 at 11:35 AM.
That article is mostly right, but the reasoning leading to the conclusions is wrong. For example, the pressure pulses won't "wander" around like that. They will still have the same shape in the big pipe but they will be wider, decreasing the magnitude of the pressure wave. What causes overly large exhausts to lose pressure is the reduction in exhaust gas velocity which decreases the "sucking" (scavenging) effect of the exhaust out of the cylinder.
It's also not correct that you must have optimized the system upstream of the muffler to see any benefit from a high flow muffler. The flow rate through a pipe is dictated by the overall pressure drop which is a function of a lot of things. If you reduce ANY pressure loss anywhere in the system while all other things are held constant, the flow rate will increase. So removing the muffler will increase the flow rate and therefore the power created by the engine. That said, removing the muffler will not produce enough of a decrease in pressure drop to produce significant gains. The catalytic converters are a much greater source of pressure loss/backpressure and when removed will produce noticeable gains. Also, the catalytic converters will not disrupt the pressure pulses in the system, just decrease their magnitude (pressure loss due to restriction). They are essentially a laminar flow element (this isn't laminar flow but still) so the flow distribution entering will be maintained.
It's also not correct that you must have optimized the system upstream of the muffler to see any benefit from a high flow muffler. The flow rate through a pipe is dictated by the overall pressure drop which is a function of a lot of things. If you reduce ANY pressure loss anywhere in the system while all other things are held constant, the flow rate will increase. So removing the muffler will increase the flow rate and therefore the power created by the engine. That said, removing the muffler will not produce enough of a decrease in pressure drop to produce significant gains. The catalytic converters are a much greater source of pressure loss/backpressure and when removed will produce noticeable gains. Also, the catalytic converters will not disrupt the pressure pulses in the system, just decrease their magnitude (pressure loss due to restriction). They are essentially a laminar flow element (this isn't laminar flow but still) so the flow distribution entering will be maintained.
That article is mostly right, but the reasoning leading to the conclusions is wrong. For example, the pressure pulses won't "wander" around like that. They will still have the same shape in the big pipe but they will be wider, decreasing the magnitude of the pressure wave. What causes overly large exhausts to lose pressure is the reduction in exhaust gas velocity which decreases the "sucking" (scavenging) effect of the exhaust out of the cylinder.
It's also not correct that you must have optimized the system upstream of the muffler to see any benefit from a high flow muffler. The flow rate through a pipe is dictated by the overall pressure drop which is a function of a lot of things. If you reduce ANY pressure loss anywhere in the system while all other things are held constant, the flow rate will increase. So removing the muffler will increase the flow rate and therefore the power created by the engine. That said, removing the muffler will not produce enough of a decrease in pressure drop to produce significant gains. The catalytic converters are a much greater source of pressure loss/backpressure and when removed will produce noticeable gains. Also, the catalytic converters will not disrupt the pressure pulses in the system, just decrease their magnitude (pressure loss due to restriction). They are essentially a laminar flow element (this isn't laminar flow but still) so the flow distribution entering will be maintained.
It's also not correct that you must have optimized the system upstream of the muffler to see any benefit from a high flow muffler. The flow rate through a pipe is dictated by the overall pressure drop which is a function of a lot of things. If you reduce ANY pressure loss anywhere in the system while all other things are held constant, the flow rate will increase. So removing the muffler will increase the flow rate and therefore the power created by the engine. That said, removing the muffler will not produce enough of a decrease in pressure drop to produce significant gains. The catalytic converters are a much greater source of pressure loss/backpressure and when removed will produce noticeable gains. Also, the catalytic converters will not disrupt the pressure pulses in the system, just decrease their magnitude (pressure loss due to restriction). They are essentially a laminar flow element (this isn't laminar flow but still) so the flow distribution entering will be maintained.
But back to the original article. What he is saying (as idrm350 mentioned) if you dont optimize the flow upstream from the muffler it wont make a difference if you change the muffler (including a delete). Fire hose at the end of a garden hose reference. So if youre basing your decision on what he said. Muffler delete is pointless.
Last edited by Arvin89; Nov 1, 2012 at 02:56 PM.
Interesting article.From my experiece,owning many cars,it all depends on the car.
However,from what I've experience,proper design of an exhaust system depends
on some back pressure in the system to force the exhaust gasses from the car
n the most efficient manner.I agree with bmccann101's comments on Motordyne.
However,is the increase in power that you can actually feel worth the price?
Yeah,lets be truthful,most guys want the sound and the primary reason for
an exhaust mod.To illustrate my earlier point,I like many others owned a VW bug.
These are great cars to learn the basics of how a car works.Anyone that has heard
a bug knows that flat mettalic exhaust sound coming out of the pea shooter exhaust
tips.I added some over size tips with resonators to get a deeper sound.Hopefully to get a few more ponies over the measly 40.The results?Less power!Backpressure was designed in the system to give the engine more torque.
Got to laugh on how many posts are from owners "opening up" their exhausts
only to lose power.If the other components are there,mods in intakes,cam etc
together with a tune it makes sense.
However,from what I've experience,proper design of an exhaust system depends
on some back pressure in the system to force the exhaust gasses from the car
n the most efficient manner.I agree with bmccann101's comments on Motordyne.
However,is the increase in power that you can actually feel worth the price?
Yeah,lets be truthful,most guys want the sound and the primary reason for
an exhaust mod.To illustrate my earlier point,I like many others owned a VW bug.
These are great cars to learn the basics of how a car works.Anyone that has heard
a bug knows that flat mettalic exhaust sound coming out of the pea shooter exhaust
tips.I added some over size tips with resonators to get a deeper sound.Hopefully to get a few more ponies over the measly 40.The results?Less power!Backpressure was designed in the system to give the engine more torque.
Got to laugh on how many posts are from owners "opening up" their exhausts
only to lose power.If the other components are there,mods in intakes,cam etc
together with a tune it makes sense.
