integra-modder

As seen in this discussion, https://honda-tech.com/zerothread?id=499436, we are trying to find a quiet exhuast but not loose power. We all know that basic physics states that the loudness is a side effect of more power, just as heat is.

Basically, on an exhuast system, are the muffler and resonators that control the exhuast loudness or does piping size play an important role?

A few quotes:

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StyleTEG &raquo;</TD></TR><TR><TD CLASS="quote">

I am 100% positive it is correct.

Common misconception.

The diameter of the pipe does not amplify, or dampen sound waves. If you run a straight pipe back from the engine its going to carry the same noise level under a 3" pipe as it would a 4" pipe, it won't get louder.

If you have any poster rolls laying around you can test it. Hold a small and a large one up to a speaker and listen to both one after another, you will notice the decible level is the same.

As far as resonation you mention in your above posts, a quality exhaust will have resonationer(s).

My friends turbo GSR with 3" piping is one of the queitest tegs I have ever herd with aftermarket exhaust.

Don't tell him not to go to a proper sized exhaust on a TURBO car!? Even if it does make exhaust louder (which it doesn't), it would be much MUCH more effective to just use a chambered muffler.

Not shrink your whole exhaust tubing on a turbo integra.
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<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by VoltageBlue01 &raquo;</TD></TR><TR><TD CLASS="quote">I thought exhaust waves and sound waves completely are different. exhaust waves are considered transverse waves, almost like a fluid displacement.

sound waves can travel longitudinally, although restricted by the diameter of the pipe. not to mention exhaust waves dont travel at the speed of sound.

I would think that the diameter of the pipe MAKES a difference in sound level. Destructive interference from the smaller piping would be greater as the waves have less of a diameter to travel to change directions and cancel out another wave not in its phase. Bigger pipes would let more of the waves escape without cancellation, producing a greater sound.

Someone with great physics knowledge see if this makes any sense. I'm just guessing. Not too sure what role the resonator plays in all this. </TD></TR></TABLE>

ClubSiRacer

If someone tells you that a 3" exhaust pipe isnt louder than a 2" pipe, smack them silly for me...

I'll use my old Integra LS for an example. I had a Borla muffler on it (this was back in 93 when Borla was the only company making good stainless exhaust for imports) but it had the stock B-pipe still. It wasnt much louder than stock but it did sound nice. Later I decided for more power I would have a full 2.5" pipe done from the cat to the muffler. Boy was that a mistake. Same muffler but 3x the noise! (This was WITH a resonator still.) It still sounded good but it was a lot louder and it lost some of its bottom end grunt (however it was quicker up to by a bit).

Chrome Pipes

I went from a resonated & muffled 2.5" Tanabe Racing Medallion to a custom 3 in exhaust w/ an Apex N1 muffler. The 3 in was louder but also made much more power. My 1/4 mile times between no exhaust & 3 in where the same. Although the exhaust is louder, it sounds sick as hell. 3 in exhaust + turbo =

integra-modder

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Instant Message Conversation &raquo;</TD></TR><TR><TD CLASS="quote">(9:53 AM 5/16/2003) integra-modder: https://honda-tech.com/zerothread?id=499436
check out the post by voltage blue


(12:14 PM 5/16/2003) StyleTEG: yeah, he said "i would think". But the fact is the muffler and the resonator determin sound level rather than the size of the piping. You have a straight through muffler its going to be really ******* loud regardless of size. I would know, mine was defening with only 2.25"
Saying "don't go 3" because its louder is beyond *** backwards". You can get a chambered muffler and 3" and it will be quite plus you won't **** up your exhaust system especially on something as important as a turboed engine. Not to mention the turbo quites down the exhaust to begin with.


(2:31 PM 5/16/2003) integra-modder: Im speaking out of experience. I know many people that have gone the three inch route, and they complain about loudness. Those running 2.5 inch systems dont. Its as simple as that.
Maybe Kteller8 would know, the guy selling exhuast piping in 2.5 and 3, because he could build identical systems with different piping.


(4:47 PM 5/16/2003) StyleTEG: You are speaking incorrectly. Those that complained didn't know enough about exhaust system to make such claims. If the 3" diameter does make a different, the determining factor for sound level should be the muffler and resonator not the size of the piping. If you go too small you are shooting yourself in the foot, **** sound level. If you care abuot sound level get a chambered muffler, don't go smaller because smaller can still be loud as all hell. I have a 2.25" straightthrough and its deffening with out a silencer.
Research your recommendations before you give shitty ones.

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SiRkid

who is this style teg???
3"= loud. period!(when you get on it)

Full-Race Javier

what is your definition of loud, db level? to me, open dp is loud
u could always use the e-cutout and have the best of both.

integra-modder

loud is loud. like an N1 catback on a NA car....

something that gives your head a pounding after being in it for half an hour

Smashback

Yep, I went from a 2.25" with a magnaflow to a 3" with the same magnaflow (but 3" instead of 2.25" of course) and it was MUCH louder.

You_Get_Vapors

I believe that the larger the diameter of the piping will only change the tone of the exhaust and not the amplitude of it.

bigger = deeper or bassier
smaller = higher or trebley

integra-modder

any more educated opinions?

Tofurky

clearly the muffler('s design) plays a role in determining how loud it will be...

but to say that size doesn't matter, it a straight out lie.
a 3" will be louder, than a 2.5" with the same muffler/set up.

sorry boys, but like in life, sometimes size matters...

integra-modder

can anyone show or explain with physics how the size is a major part of determinning the loudness of the exhuast?

pub

The physics of it would show that size isn't part of loudness.

I am only talking about straight piping in this - no mufflers.
Say you have
Test A: Motor w/ 2" piping
Test B: Same motor w/ 3" piping

Same energy being put into each test. The sound waves would be closer together in Test A due to a closer sidewall of the piping. With the sidewalls spread out, the sound waves can be farther apart. Thus Test A's exhaust sound would be higher pitched than Test B's. The energy should be the same (exhaust decibel's should be the same as well, only a change in pitch)

Now when you put mufflers and what not in there. You'll probably have more gases running through the muffler easier on a bigger diameter setup. Less energy spent on the gases hitting the muffler material = more energy in sound.

b16ahybrid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pub &raquo;</TD></TR><TR><TD CLASS="quote">The physics of it would show that size isn't part of loudness.

I am only talking about straight piping in this - no mufflers.
Say you have
Test A: Motor w/ 2" piping
Test B: Same motor w/ 3" piping

Same energy being put into each test. The sound waves would be closer together in Test A due to a closer sidewall of the piping. With the sidewalls spread out, the sound waves can be farther apart. Thus Test A's exhaust sound would be higher pitched than Test B's. The energy should be the same (exhaust decibel's should be the same as well, only a change in pitch)

Now when you put mufflers and what not in there. You'll probably have more gases running through the muffler easier on a bigger diameter setup. Less energy spent on the gases hitting the muffler material = more energy in sound.</TD></TR></TABLE>


I agree to a point, with the wave lengths spread out it will have an impact on the amplitude of the sound waves. Reflections will occur, some cancelation and amplification will happen.
Take for example a sub woofer. Stand directly in front of the woofer you will hear bass. now turn the speaker around and face it into a corner or even just towards the wall, you will hear louder bass. the volume has stayed the same so the speaker is producing the same volume at that frequency, but since the sound waves have bonced off the walls it has amplified before reaching your ears.

So yes it will be louder and of a different tone. How much? depends on your muffler and resinator.

soundman

I've been in the sound industry for 5 years. I run professional sound for concerts and ****. When we're talking sound you have frequencies. The exhaust frequencies probably run between 40 herts to 500 hertz. These sound waves are longer in length. Some low end sound waves (around 20 hertz) could be up to 8-10 feet in length just to get the full wave to form. So what does that mean on an exhaust? Well why do you put subwoofers in a box? So it gives the bass more time to create the wave. Well when you increase your exhaust size you are allowing more room for the bass wave to create itself, otherwise the wave would bounce around causing cancellation. Cancellation is when 2 frequencies smack each other and just like hot and cold make each other turn neutral. That's why there are chambers in resonator mufflers. So larger diameter allows your sound waves to form better and also the sound will not bounce as quick as in a smaller diameter because it's not as restricted. So larger diameter just like a larger subwoofer box = more sound. That's why Honda put the little 1 3/4" exhaust on their economic car. it helped keep them quiet.

integra-modder

thanks guys, any more input is greatly appreciated.

StyleTEG

Fine, size makes a difference, its still the absolutely wrong thing to focus on when looking at an exhaust system.

On an exhaust system you are focusing on the wrong thing when you pick a smaller pipe for sound *PERIOD* , its rediculess to pick an exhaust system that is smaller because 3" is too loud when you can simply get a longer resonator and a chambered muffler.

Your exhaust system absolutely positively has to be sized CORRECTLY for your engine package otherwise you are going to get crappy gains and be bottlenecking your potential power.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">2-1/4" up to 210HP @ the flywheel (about 180-185 whp)

2-3/8" (60mm) up to 235HP @ the flywheel (about 200-207 whp)

2-1/2" up to 265HP @ the flywheel (about 225-235 whp)

2-3/4" up to 325HP @ the flywheel (about 275-285 whp)

3" big for big HP (Forced Induction: &gt; 275 whp)
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For every 60 hp you have to the flywheel, you need at least 1 square inch of exhaust (cross section) in order to obtain adequate exhaust flow to gain scavenging out of the cylinder. This is even MORE important when you go FI.

If you don't want a loud exhaust, use a chambered muffler, its going to be a hell of a lot quiter than a smaller exhaust with a straight through muffler. And you won't be trying to shove 250whp worth of exhaust down a pipe only able to flow 180whp.

Its simply iresponsible to recommend a member get a smaller exhaust pipe for his turbo kit for sound levels, which is where this coversation stemmed from.

Focus on the resonator and the muffler if you are concerned about exhaust decible, not on the size of the piping.

Notice I said...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
If the 3" diameter does make a different, the determining factor for sound level should be the muffler and resonator not the size of the piping. If you go too small you are shooting yourself in the foot, **** sound level. If you care abuot sound level get a chambered muffler, don't go smaller because smaller can still be loud as all hell. I have a 2.25" straightthrough and its deffening with out a silencer.
Research your recommendations before you give shitty ones.
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This quesiton is a moot point because regardless of it does or not, you shouldn't go smaller because of noise level.

b16ahybrid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StyleTEG &raquo;</TD></TR><TR><TD CLASS="quote">Fine, size makes a difference, its still the absolutely wrong thing to focus on when looking at an exhaust system.

On an exhaust system you are focusing on the wrong thing when you pick a smaller pipe for sound *PERIOD* , its rediculess to pick an exhaust system that is smaller because 3" is too loud when you can simply get a longer resonator and a chambered muffler.

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Thats good and all, but i believe the question was "Does pipe diameter have a direct correlation to exhaust loudness" not "does pipe diameter have a direct correlation to power production"?.......
And then there is the fact that not everybody wants a loud car. Some would rather sacrifice a little power for a little more sanity, then again most street cars are not making 300+hp and if they are, noise is probably lower on the scale of importance.

Also while i'm here i also want to point out some thing about your comment

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StyleTEG &raquo;</TD></TR><TR><TD CLASS="quote"> its rediculess to pick an exhaust system that is smaller because 3" is too loud when you can simply get a longer resonator and a chambered muffler..</TD></TR></TABLE>

Doing that also effects airflow. Thats why it's quieter. So say you have a 2.5'' non-resinated exhaust system with a strait through muffler, its going to flow about as much as a 3'' exhaust system with a 12'' resinator and a chambered muffler. Inorder to reduce noise you have to slow down the flow of the exhaust, slowing the flow of exhaust creates back pressure, back pressure effects power.....etc etc etc..........I'm not trying to bust your ***** but not everybodys idea of a perfect car is the same.
I for one don't like loud exhaust systems (i have 2.5''), wings, body kits, colored lights,chrome, extravagent colors,etc.....My car looks stock except the fact it's lowered and has rims..(oh and some notice the intercooler in the stock front bumper)....I'm all about looking clean, others llike wings,and all that other crap....different strokes for different folks

lazerus

remember with exhaust, HEAT plays a big part of exhaust velocity, the hotter the exhaust stays all the way back, the louder it will theoretically be, because the gas will be trying to make it's way out of the exhaust system faster due to the pressure differential, and the greater volume of the exhaust gases. (remember, hotter gas means larger volume.)

So, this would lead me to belive that larger exhaust piping will lead to a quieter sounding exhaust because of the more surface area of pipe to absorb sound energy, and heat, thus lowering exhaust velocity.

This would lead me to belive that to find the ultimate power, larger is NOT better, but the right size is best, a good size low restriction exhaust that retains as much heat as far back as possible.

My 3" Exhaust on my turbo car sounds very quiet at idle, in fact not that much louder than stock, just a lot deeper.

Brad

to add i more or less agree with style TEG, too small exhaust can become restrictive, but too large can become detremental because of the low velocity/low heat. Properly sized is always best.

Straight through mufflers are in my mind the best muffler for a turbocharged vehicle. N/a is a different story, really.

(of course there are tricks to get more power out of an exhaust system but i'm not going into that..)

tony1

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StyleTEG &raquo;</TD></TR><TR><TD CLASS="quote">
For every 60 hp you have to the flywheel, you need at least 1 square inch of exhaust (cross section) in order to obtain adequate exhaust flow to gain scavenging out of the cylinder. This is even MORE important when you go FI.</TD></TR></TABLE>

So a bigger exhaust will help scavenging of the cylinder in a turbo car?

StyleTEG

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b16ahybrid &raquo;</TD></TR><TR><TD CLASS="quote">

Thats good and all, but i believe the question was "Does pipe diameter have a direct correlation to exhaust loudness" not "does pipe diameter have a direct correlation to power production"?.......
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The original debate was about integra-modder recommending a small exhaust to someone who has a turbo because he wanted it quieter. Thats where it came into play. I stated several times even if larger exhaust was louder, it shouldn't be a factor.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">and then there is the fact that not everybody wants a loud car. </TD></TR></TABLE>

I agree completely, but there is the right and the wrong way to go about making your car quieter.... which leads me too...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
Doing that also effects airflow. Thats why it's quieter. So say you have a 2.5'' non-resinated exhaust system with a strait through muffler, its going to flow about as much as a 3'' exhaust system with a 12'' resinator and a chambered muffler. Inorder to reduce noise you have to slow down the flow of the exhaust, slowing the flow of exhaust creates back pressure, back pressure effects power</TD></TR></TABLE>

What calculations did you use to figure 2.5 straight through = same as 3" chambered? My guess is you were just making an infrence?

While no doubt a chambered muffler will slow things down, that is not disputed. But a whole exhaust system that is too small for the exhaust flow, compaired to a short section of muffler that doesn't flow as well at the very end of exhaust system are EXTREMELY different.

Which is why you should pick a more restrictive muffler (either straight through + silencer, or chambered) way before you pick a restrictive exhaust size.

b16ahybrid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lazerus &raquo;</TD></TR><TR><TD CLASS="quote">So, this would lead me to belive that larger exhaust piping will lead to a quieter sounding exhaust because of the more surface area of pipe to absorb sound energy, and heat, thus lowering exhaust velocity.
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The piping isn't going to asorb the sound waves, it's actually going to reflect them. metal generally doesn't asorb sound very well.Thats why resinators and mufflers are filled with fiber glass to asorb the sound

b16ahybrid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StyleTEG &raquo;</TD></TR><TR><TD CLASS="quote">
The original debate was about integra-modder recommending a small exhaust to someone who has a turbo because he wanted it quieter. Thats where it came into play. I stated several times even if larger exhaust was louder, it shouldn't be a factor.
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I never read that post, i was just refering to this post.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StyleTEG &raquo;</TD></TR><TR><TD CLASS="quote">

What calculations did you use to figure 2.5 straight through = same as 3" chambered? My guess is you were just making an infrence?
.</TD></TR></TABLE>

none it wa just a reference,

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StyleTEG &raquo;</TD></TR><TR><TD CLASS="quote">

While no doubt a chambered muffler will slow things down, that is not disputed. But a whole exhaust system that is too small for the exhaust flow, compaired to a short section of muffler that doesn't flow as well at the very end of exhaust system are EXTREMELY different.

Which is why you should pick a more restrictive muffler (either straight through + silencer, or chambered) way before you pick a restrictive exhaust size.</TD></TR></TABLE>

True, but your taking that to the extreem. thats like comparing 3'' exhaust to 1'' exhaust. I have 2.5'' exhaust on my car, it's a lot quieter then most 3'' exhaust systems i've heard. now for me to switch to 3'' is not worth it sure i may pick up a few hp but i'm happy with the sound/noise level of my exaust now.
doing your little calculation how much hp difference is there going to be on an engine that is making 250whp. 3'' vs 2.5''?
I know the noise difference, so how much power are we really talking about? Not much huh? It's not like going from stock to 3'' exhaust where you can easily pick up 20hp...

StyleTEG

I think you completely missed my point

Let me put it into terms of your car
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
226whp 160ft lbs of tq
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You have 226whp of NA torque, if you factor 60 flywheel hp = 1 square inch of cross section in your exhaust you come up with 2.5" being the proper sized exhaust for adequate scavanging. (225 - 235hp)

Now lets say you are REALLY concerned about noise level, should you drop your exhaust down to 2.25" which is only adequate for 180-185whp, or simply get a chambered muffler?

Chambered muffler of cource, because diameter is king. A small section of restrictive muffler is NOTHING compaired to a whole exhaust piping that is too small. Not to mention the area that you will get the most choke off/backpressure is the closest parts to the engine. And guess what, a 3" with a chambered muffler is going to be QUIETER than a 2.5" with a straight through.

You don't think its that big a difference in performance? Going from 2.25 to 2.36 (barely more than a tenth of an inch) is the ability to adequately flow 22whp.

Thats huge, and its even more important for forced induction(which was originally part of the question).. look at these diagrams of cylinder pressure in a NA engine vs FI.





Why do you think that is?

soundman

If you're making that much power then you shouldn't be driving it as an everyday driver, but if you are then there are sacrifices that you have to make, and one of that is the loudness of your car. You have to retain low back pressure too.

If you haven't also noticed, turbo engines don't make as much noise as NA engines. A buddy of mine has an integra turbo, which at this moment is running straight down pipe, and no exhaust, it is actually quieter than my D series engine with a straight through muffler. If you want HP, and a longer life on your turbo, just go with the bigger exhaust, and if you want your car to be as quiet as a mouse, then sell your Honda, and get a ford Taurus or something because you don't deserve to be driving a turbo car.