Exhaust Poll

Sh0velMan · 10-16-2013, 10:11 PM

I think.... I think you guys don't really "get it" when it comes to my car.

Maybe if you saw and heard it in person? I think you have this impression that the car sounds like a small displacement Honda 4 cylinder with a straight pipe on it...

It doesn't.

Is there rasp? Yes, I can detect the sound of the rasp amid the other exhaust noises, but it definitely doesn't sound like yard equipment.

I mean, I've posted a video in my build thread of revving the damned thing, if all you hear in that sound clip is rasp, then I can't help you. My car is loud and in your face, and if people are laughing at the way it sounds, well, good for them. I'm glad I could give them something to laugh about.

And what's this about power? I'm losing power because I don't have extra pipes hanging off of my exhaust? Do you just make this stuff up as you go along? lmao. Do you even understand what causes the rasp? The mere act of acoustically cancelling out the pulses that generate the rasp can cause back pressure in the exhaust system. You're far more likely to see a power dip at specific RPMs WITH extra resonating chambers attached than you are with a straight pipe as 'canceling out the rasp' is breaking up an acoustic wavefront that helps with scavenging. I assume you know what that is, at least, and why you would not want to do so? This is exactly why you have to be careful with resonance alterations that close to the engine and why I will do no such thing.

THAT is fact, THAT is science. I don't want to make this an acoustics and fluid dynamics debate thread, it's already ridiculous enough.

Chuck33079 · 10-16-2013, 10:18 PM

Quote:

Originally Posted by chii370

Ive seen plenty of cars ive had buddies build that fell into the DERP BIGGER MEANS BETTER retard mindset and went from 2.5 to 3 or even bigger. And then gained absolutely nothing on the dyno. There IS a point when its too much. and FI 370's arent exactly a popular choice as we all know, so metric a55tons of options are not available, nor have they been around for 10+ years for tuner experience. So its hard to say what that limit really is. But yeah, im sure at 8000 RPM with a tt setup pushing tons of HP WOULD benifit, but at any other time, it doesnt, especially NA cars. its not just about flow restriction, i wish people would get that **** out of their heads. its about FLOW VELOCITY. you can have MORE, LESS RESTRICTED exhaust through a 2.5 on a motor than a 3!!! OMG HOW you ask. well, allow me to give you a physics lesson. Exhaust comes out in pulses, not a constant stream of air. ahead of the pulse is a high pressure zone, behind is a low pressure zone. each pulse "pulls" the pulse behind it through the pipe. Now if you have pipes that are too big, the pulse will esentially use too much "energy" and start to slow down and instead curl in an outward motion toward the pipe walls. this does 2 things. causes turbulence, and causes a possitive pressure against pressure still exiting the engine, which can raise the pressure directly outside the exhaust valves. If this happens you can be robbed of power by less exhaust exiting the cylinders so less new air and fuel can enter or maf will be incorrect, and more effort to "push" the exhaust out the pipe. this also causes the infamous "rasp" everyone talks about. its NOT a noise the engine makes. Its caused by a drop in exhaust velocity somewhere along the pipe, which creates turbulence. this breaks up the nice individual exhaust tone "puffs" you hear and exits the back in a nasty sounding wheezing noise. havent you made the corrolation between setups that rasp, and the fact that MOST of them are the LEAST restrictive? or have LTH? or HFC or cat deletes? its not simply a "sound the engine makes" EVERY CAR can make that sound. start watching vids for aftermarket exhausts on other cars on youtube. like a tiberon or something. one setup will sound great, and the next will rasp like hell.

I was simply addressing the statement you made about FI cars in your previous post. You're correct in your point on NA and supercharged motors. Once you stuff a turbo in the exhaust path, the pulses no longer work like you described. With a turbo, you want the largest pressure differential pre/post turbo possible to keep velocity up. The turbo itself is plenty of restriction, even if appropriately sized. That's why you see drag cars just running a dump tube out the side of the car. That's also beyond the scope of this thread since the vast majority of people looking for a Z34 exhaust are keeping it NA.

Sh0velMan · 10-16-2013, 10:18 PM

And if EITHER of you think for half a ******* second that you have any ground to lecture me on tuning principles as they relate to this car, you need to go think about what you're saying.

I have over a hundred dyno pulls across a dozen iterations of build on my car with tons and tons and tons of data collected. I'm not some ******* idiot buying random parts based upon brochure stats.

I would hazard a guess that I am probably in the top 20 or 30 people in the ******* world when it comes to knowledge on what makes THIS CAR'S engine tick and where to get power N/A. Just wait, here before too long I'll post some **** that will really blow your mind.

chii370 · 10-16-2013, 10:19 PM

rasp isnt that weed whacker buzz noise. thats just ..... shitty sounding exhaust. you only hear rasp when you let off the gas JUST as the rpms are about to the 1k-500 level.

heres a raspy **** example. Nismo 370z with ARK high flow cats and ARK DTS exhaust with techno tips - YouTube

heres a non raspy **** example of the same exhaust

ARK Performance Nissan 370z DT-S Exhaust - YouTube

listen for when the engine RPM's drop from rev, to almost idle. its that noise thats like someone sticking there toung out and blowing.

and good for you, you get a bro high five. im not lecturing you about THIS car. Im lecturing you about ALL cars. physics just so happen to apply to all of them. just sayin. so stop acting like a know it all and do the research for yourself. Im sure for your super ultra 1337 "in your mind" build only useful on a track that about 2% of the community would ever care to do will be awesome. but im talking about the real world, where dyno numbers arent the only thing that matters about owning a vehicle that most of us drive daily. derp

Chuck33079 · 10-16-2013, 10:22 PM

Quote:

Originally Posted by chii370

rasp isnt that weed whacker buzz noise. thats just ..... shitty sounding exhaust. you only hear rasp when you let off the gas JUST as the rpms are about to the 1k-500 level.

heres a raspy **** example. Nismo 370z with ARK high flow cats and ARK DTS exhaust with techno tips - YouTube

heres a non raspy **** example of the same exhaust

ARK Performance Nissan 370z DT-S Exhaust - YouTube

listen for when the engine RPM's drop from rev, to almost idle. its that noise thats like someone sticking there toung out and blowing.

Are we discussing rasp, or the "VQ hiss"?

Sh0velMan · 10-16-2013, 10:23 PM

Quote:

Originally Posted by chii370

rasp isnt that weed whacker buzz noise. thats just ..... shitty sounding exhaust. you only hear rasp when you let off the gas JUST as the rpms are about to the 1k-500 level.

heres a raspy **** example. Nismo 370z with ARK high flow cats and ARK DTS exhaust with techno tips - YouTube

heres a non raspy **** example of the same exhaust

ARK Performance Nissan 370z DT-S Exhaust - YouTube

.. are... are you serious?

This entire time, you think we're talking about the HR/VHR 'hiss'????

That's a phenomena that's been around since the HR and is caused by the VVT system on the exhaust side.... You can get rid of that by running a simple resonator (glass pack) in the exhaust stream.

The grown ups are talking about exhaust rasp during WOT use caused by supersonic wave fronts within the exhaust stream as the exhaust valves open.

At least, this grown up is. I respect Synolimit's grounding in the subject, so I am assuming he is referring to the same thing.

Not the stupid hiss. Who cares about that ****.

Sh0velMan · 10-16-2013, 10:23 PM

Quote:

Originally Posted by Chuck33079

Are we discussing rasp, or the "VQ hiss"?

rofl

chii370 · 10-16-2013, 10:29 PM

wow theres an aweful lot of other cars besides Z's and G's that must use the VQ then. I should go inform them that we have solved it. its gotta be the "VQ hiss" since its obviously the only engine ever made that does it. trademark that ****. I get whats being refered too as rasp here now, the annoying buzz fart can sound? never really put a word to it. just **** exhaust. my bad there.

and just sayin, I care about that. as well as any other annoying/bad noise an exhaust makes. regardless of your reasoning, point is gaining a little HP and making your car sound like **** is a giant fail imo.

synolimit · 10-16-2013, 10:36 PM

Quote:

Originally Posted by chii370

Ive seen plenty of cars ive had buddies build that fell into the DERP BIGGER MEANS BETTER retard mindset and went from 2.5 to 3 or even bigger. And then gained absolutely nothing on the dyno. There IS a point when its too much. and FI 370's arent exactly a popular choice as we all know, so metric a55tons of options are not available, nor have they been around for 10+ years for tuner experience. So its hard to say what that limit really is. But yeah, im sure at 8000 RPM with a tt setup pushing tons of HP WOULD benifit, but at any other time, it doesnt, especially NA cars. its not just about flow restriction, i wish people would get that **** out of their heads. its about FLOW VELOCITY. you can have MORE, LESS RESTRICTED exhaust through a 2.5 on a motor than a 3!!! OMG HOW you ask. well, allow me to give you a physics lesson. Exhaust comes out in pulses, not a constant stream of air. ahead of the pulse is a high pressure zone, behind is a low pressure zone. each pulse "pulls" the pulse behind it through the pipe. Now if you have pipes that are too big, the pulse will esentially use too much "energy" and start to slow down and instead curl in an outward motion toward the pipe walls. this does 2 things. causes turbulence, and causes a possitive pressure against pressure still exiting the engine, which can raise the pressure directly outside the exhaust valves. If this happens you can be robbed of power by less exhaust exiting the cylinders so less new air and fuel can enter or maf will be incorrect, and more effort to "push" the exhaust out the pipe. this also causes the infamous "rasp" everyone talks about. its NOT a noise the engine makes. Its caused by a drop in exhaust velocity somewhere along the pipe, which creates turbulence. this breaks up the nice individual exhaust tone "puffs" you hear and exits the back in a nasty sounding wheezing noise. havent you made the corrolation between setups that rasp, and the fact that MOST of them are the LEAST restrictive? or have LTH? or HFC or cat deletes? its not simply a "sound the engine makes" EVERY CAR can make that sound. start watching vids for aftermarket exhausts on other cars on youtube. like a tiberon or something. one setup will sound great, and the next will rasp like hell.

You read Tonys post too.

chii370 · 10-16-2013, 10:41 PM

lol I dont know people here by name, and dont know a tony.... but maybe? :P No, I just like reading and watching things on the physics behind mechanical equipment. sometimes I get terminology mixed a bit sometimes, but sometimes its nice to know WHY or WHATS causing a specific quote "phenomena" as its been said which usually has a pretty simple explanation. just get sick of people talkin about putting giant exhausts on with HCF, and headers and all this other **** and they dont even know WHY, they just do it because its the general consensus that it makes car go vroom vroom faster. Im happy with my 6 million ton ARK DTS with zero drone, zero rasp, zero hiss, real exhaust tone. and PROBABLY zero gains on a dyno and couldnt care less. goal was to make the car not sound like a toyota prius, goal accomplished. and all of the physics knowledge played a part in proper choice. diameter of pipe, mid pipe style, how restrictive is it, what shape, how long are the pipes, what are they made of, how is it welded, how is it bent, hows the muffler packed and sectioned. ALL THAT **** MATTERS in its exhaust scavenging, flow velocity, sound, everything. leave the engineering to us ENGINEERS.

synolimit · 10-16-2013, 10:48 PM

Quote:

Originally Posted by Sh0velMan

I think.... I think you guys don't really "get it" when it comes to my car.

Maybe if you saw and heard it in person? I think you have this impression that the car sounds like a small displacement Honda 4 cylinder with a straight pipe on it...

It doesn't.

Is there rasp? Yes, I can detect the sound of the rasp amid the other exhaust noises, but it definitely doesn't sound like yard equipment.

I mean, I've posted a video in my build thread of revving the damned thing, if all you hear in that sound clip is rasp, then I can't help you. My car is loud and in your face, and if people are laughing at the way it sounds, well, good for them. I'm glad I could give them something to laugh about.

And what's this about power? I'm losing power because I don't have extra pipes hanging off of my exhaust? Do you just make this stuff up as you go along? lmao. Do you even understand what causes the rasp? The mere act of acoustically cancelling out the pulses that generate the rasp can cause back pressure in the exhaust system. You're far more likely to see a power dip at specific RPMs WITH extra resonating chambers attached than you are with a straight pipe as 'canceling out the rasp' is breaking up an acoustic wavefront that helps with scavenging. I assume you know what that is, at least, and why you would not want to do so? This is exactly why you have to be careful with resonance alterations that close to the engine and why I will do no such thing.

THAT is fact, THAT is science. I don't want to make this an acoustics and fluid dynamics debate thread, it's already ridiculous enough.

Well I have LTH also so I know what It sounds like. It was nothing but rasp as I'm sure yours is also. Reving a car doesn't count. I heard yours under load and my statement stands.

If you have rasp you're losing power, period. Read Chii post again. All that is from Tony at motordyne. Do you think tony makes more power with his ART pipes and CBE over straight pipes and other CBE because he lucky? No he's not lucky. He's smart and combated the rasp and drone with a proper setup using Helmholtz resonators which you don't have and I do. Guess what? I don't rasp or drone ever, and to boot because of the way a Helmholtz works with storing air pressure and acting as a vacuum when the flow has a gap in it, I bet I make more power than you too. The fact that you're talking about back pressure automatically makes you unqualified for this conversation. You need to read more and learn.

PS your science is wrong because your source you got it from don't have an understanding and years after years people are just passing BS along and down the line.

chii370 · 10-16-2013, 10:59 PM

well your right about one thing shov. a resonator too close is bad, but a resonator further down stream is not, where it helps create a negative pressure zone. You would also want it as far away from the originating source anyway to help dissipate the sound waves before they even GET to the resonators for frequency cancel. So I see no reason at all why it would rob power unless its improperly designed with too little flow, too little velocity, or improperly shaped entry and exit to the resonating chamber that causes turbulence. I would like to see something to back that claim up, as in my personal experience thats just not true. cats sure, resonators, no.

synolimit · 10-16-2013, 11:07 PM

Something just came to me I think will explain better.

Imagine a vein in your arm with a syringe of blood stuck in. Your rasp is a gap of blood flow. When there is a gap the syringe (Helmholtz resonators with stored air pressure) will automatically inject blood to fill the gap and in a car will take away the rasp as it injects air back in. This helps with scavenging because the flow is kept up with no gaps. In fact the air doesn't inject in because it acts as vacuum and the air is sucked into the gap of flow. That's why art pipes make more than just straight test pipes.

This also would work with a garden hose as an example which we all can see everyday. When you first turn it on the water spits and sputter out the end because in between the water (in a car it would be exhaust gas) is air gaps. These gaps of air slow the flow and the water pressure sucks. Now if you had syringes of water stuck in the hose to inject water every time a air gap was seen, the flow would be 100% out the end of the nozzle from then second you turned on the faucet. If you have rasp, you have power loss.

synolimit · 10-16-2013, 11:12 PM

Quote:

Originally Posted by chii370

well your right about one thing shov. a resonator too close is bad, but a resonator further down stream is not, where it helps create a negative pressure zone. You would also want it as far away from the originating source anyway to help dissipate the sound waves before they even GET to the resonators for frequency cancel. So I see no reason at all why it would rob power unless its improperly designed with too little flow, too little velocity, or improperly shaped entry and exit to the resonating chamber that causes turbulence. I would like to see something to back that claim up, as in my personal experience thats just not true. cats sure, resonators, no.

But you do realize a Helmholtz isn't an inline resonator right? Two different things.

chii370 · 10-16-2013, 11:22 PM

no idea what Helmholtz is, was just speaking from a general standpoint. wasnt arguing with you, was arguing with shovelman. but it must be said that both parties are right on various points. Im saying this through a mostly lifetime of experience of being involved with building cars since i was old enough for my dad to force his mechanical way of life on me. not just from 100 dyno runs with a Z. these principles apply to every car, its science/physics as we have both stated. If you wanna make a useless million HP noisebox go right ahead, by all means its your right to do so. But passing on your dumbfuck logic to people who DONT understand the science behind it will cause people to follow in your tracks unknowingly and be disappointing in the results for their daily driving car. theres a difference between doing things the right way, and doing things the 1% way that also just so happens to work. dont know about you, but im humble enough to say i learned something today.

View Poll Results: Which exhaust do you have or recommend I get???
Stillen	34	14.29%
FI	108	45.38%
ARK	31	13.03%
Berk	30	12.61%
Invidia	35	14.71%
Voters: 238. You may not vote on this poll

10-16-2013, 10:11 PM	#106 (permalink)
Sh0velMan A True Z Fanatic Join Date: Jan 2012 Location: Dallas/Ft.Worth Posts: 3,349 Drives: Noisily. Rep Power: 20	I think.... I think you guys don't really "get it" when it comes to my car. Maybe if you saw and heard it in person? I think you have this impression that the car sounds like a small displacement Honda 4 cylinder with a straight pipe on it... It doesn't. Is there rasp? Yes, I can detect the sound of the rasp amid the other exhaust noises, but it definitely doesn't sound like yard equipment. I mean, I've posted a video in my build thread of revving the damned thing, if all you hear in that sound clip is rasp, then I can't help you. My car is loud and in your face, and if people are laughing at the way it sounds, well, good for them. I'm glad I could give them something to laugh about. And what's this about power? I'm losing power because I don't have extra pipes hanging off of my exhaust? Do you just make this stuff up as you go along? lmao. Do you even understand what causes the rasp? The mere act of acoustically cancelling out the pulses that generate the rasp can cause back pressure in the exhaust system. You're far more likely to see a power dip at specific RPMs WITH extra resonating chambers attached than you are with a straight pipe as 'canceling out the rasp' is breaking up an acoustic wavefront that helps with scavenging. I assume you know what that is, at least, and why you would not want to do so? This is exactly why you have to be careful with resonance alterations that close to the engine and why I will do no such thing. THAT is fact, THAT is science. I don't want to make this an acoustics and fluid dynamics debate thread, it's already ridiculous enough. __________________ Buy My Car! \| Build Thread

10-16-2013, 10:18 PM	#108 (permalink)
Sh0velMan A True Z Fanatic Join Date: Jan 2012 Location: Dallas/Ft.Worth Posts: 3,349 Drives: Noisily. Rep Power: 20	And if EITHER of you think for half a ***** second that you have any ground to lecture me on tuning principles as they relate to this car, you need to go think about what you're saying. I have over a hundred dyno pulls across a dozen iterations of build on my car with tons and tons and tons of data collected. I'm not some *** idiot buying random parts based upon brochure stats. I would hazard a guess that I am probably in the top 20 or 30 people in the *** world when it comes to knowledge on what makes THIS CAR'S engine tick and where to get power N/A. Just wait, here before too long I'll post some that will really blow your mind. NickTurnon likes this. __________________ Buy My Car!** \| Build Thread

10-16-2013, 10:19 PM	#109 (permalink)
chii370 Track Member Join Date: Jul 2010 Location: . Posts: 642 Drives: . Rep Power: 15	rasp isnt that weed whacker buzz noise. thats just ..... shitty sounding exhaust. you only hear rasp when you let off the gas JUST as the rpms are about to the 1k-500 level. heres a raspy ** example. Nismo 370z with ARK high flow cats and ARK DTS exhaust with techno tips - YouTube heres a non raspy ** example of the same exhaust ARK Performance Nissan 370z DT-S Exhaust - YouTube listen for when the engine RPM's drop from rev, to almost idle. its that noise thats like someone sticking there toung out and blowing. and good for you, you get a bro high five. im not lecturing you about THIS car. Im lecturing you about ALL cars. physics just so happen to apply to all of them. just sayin. so stop acting like a know it all and do the research for yourself. Im sure for your super ultra 1337 "in your mind" build only useful on a track that about 2% of the community would ever care to do will be awesome. but im talking about the real world, where dyno numbers arent the only thing that matters about owning a vehicle that most of us drive daily. derp Last edited by chii370; 10-16-2013 at 10:24 PM.

10-16-2013, 10:29 PM	#113 (permalink)
chii370 Track Member Join Date: Jul 2010 Location: . Posts: 642 Drives: . Rep Power: 15	wow theres an aweful lot of other cars besides Z's and G's that must use the VQ then. I should go inform them that we have solved it. its gotta be the "VQ hiss" since its obviously the only engine ever made that does it. trademark that **. I get whats being refered too as rasp here now, the annoying buzz fart can sound? never really put a word to it. just exhaust. my bad there. and just sayin, I care about that. as well as any other annoying/bad noise an exhaust makes. regardless of your reasoning, point is gaining a little HP and making your car sound like ** is a giant fail imo. Last edited by chii370; 10-16-2013 at 10:33 PM.

10-16-2013, 10:41 PM	#115 (permalink)
chii370 Track Member Join Date: Jul 2010 Location: . Posts: 642 Drives: . Rep Power: 15	lol I dont know people here by name, and dont know a tony.... but maybe? :P No, I just like reading and watching things on the physics behind mechanical equipment. sometimes I get terminology mixed a bit sometimes, but sometimes its nice to know WHY or WHATS causing a specific quote "phenomena" as its been said which usually has a pretty simple explanation. just get sick of people talkin about putting giant exhausts on with HCF, and headers and all this other ** and they dont even know WHY, they just do it because its the general consensus that it makes car go vroom vroom faster. Im happy with my 6 million ton ARK DTS with zero drone, zero rasp, zero hiss, real exhaust tone. and PROBABLY zero gains on a dyno and couldnt care less. goal was to make the car not sound like a toyota prius, goal accomplished. and all of the physics knowledge played a part in proper choice. diameter of pipe, mid pipe style, how restrictive is it, what shape, how long are the pipes, what are they made of, how is it welded, how is it bent, hows the muffler packed and sectioned. ALL THAT ** MATTERS in its exhaust scavenging, flow velocity, sound, everything. leave the engineering to us ENGINEERS. Last edited by chii370; 10-16-2013 at 10:45 PM.

10-16-2013, 10:59 PM	#117 (permalink)
chii370 Track Member Join Date: Jul 2010 Location: . Posts: 642 Drives: . Rep Power: 15	well your right about one thing shov. a resonator too close is bad, but a resonator further down stream is not, where it helps create a negative pressure zone. You would also want it as far away from the originating source anyway to help dissipate the sound waves before they even GET to the resonators for frequency cancel. So I see no reason at all why it would rob power unless its improperly designed with too little flow, too little velocity, or improperly shaped entry and exit to the resonating chamber that causes turbulence. I would like to see something to back that claim up, as in my personal experience thats just not true. cats sure, resonators, no.

10-16-2013, 11:07 PM	#118 (permalink)
synolimit A True Z Fanatic Join Date: May 2013 Location: Columbus, OH Posts: 5,051 Drives: 2013 Silver 370z Rep Power: 3389	Something just came to me I think will explain better. Imagine a vein in your arm with a syringe of blood stuck in. Your rasp is a gap of blood flow. When there is a gap the syringe (Helmholtz resonators with stored air pressure) will automatically inject blood to fill the gap and in a car will take away the rasp as it injects air back in. This helps with scavenging because the flow is kept up with no gaps. In fact the air doesn't inject in because it acts as vacuum and the air is sucked into the gap of flow. That's why art pipes make more than just straight test pipes. This also would work with a garden hose as an example which we all can see everyday. When you first turn it on the water spits and sputter out the end because in between the water (in a car it would be exhaust gas) is air gaps. These gaps of air slow the flow and the water pressure sucks. Now if you had syringes of water stuck in the hose to inject water every time a air gap was seen, the flow would be 100% out the end of the nozzle from then second you turned on the faucet. If you have rasp, you have power loss. __________________ 13 370z- Last edited by synolimit; 10-16-2013 at 11:10 PM.

10-16-2013, 11:22 PM	#120 (permalink)
chii370 Track Member Join Date: Jul 2010 Location: . Posts: 642 Drives: . Rep Power: 15	no idea what Helmholtz is, was just speaking from a general standpoint. wasnt arguing with you, was arguing with shovelman. but it must be said that both parties are right on various points. Im saying this through a mostly lifetime of experience of being involved with building cars since i was old enough for my dad to force his mechanical way of life on me. not just from 100 dyno runs with a Z. these principles apply to every car, its science/physics as we have both stated. If you wanna make a useless million HP noisebox go right ahead, by all means its your right to do so. But passing on your dumbfuck logic to people who DONT understand the science behind it will cause people to follow in your tracks unknowingly and be disappointing in the results for their daily driving car. theres a difference between doing things the right way, and doing things the 1% way that also just so happens to work. dont know about you, but im humble enough to say i learned something today.

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