Tuning exhaust sound.
 

I wanted to start a thread to discuss exhaust sound. What makes a car sound the way it does? Is it all in the muffler/piping/header? or is it because of the head design? What makes some civics sound like buzzing rice burners, and some have a deep tone to them? What makes the 350z sound the way it sounds?

How would one tune the sound of a car?

Re: Tuning exhaust sound. (danielm3)
 

It's generally a product of the cat/testpipe/resonator/muffler.

350z's exhaust sound is more controlled by the muffler and resonator than anything. Notice it can change radically with a dual exhaust vs. single to the large rear muffler into 2 outlets.

As for some imports sounding deep vs. high, that's all on where the car is running in the RPM.

an import 4 banger, non-turbo, that sounds deep does so because it's running stock header and a cat converter. Anyone who tells you they're running a header, testpipe, and straight exhaust to a muffler on a n/a 4banger that their exhaust sounds low and deep like a rumble is full of crap LOL. .....maybe at idle, but under any load at speed, no way.

Re: Tuning exhaust sound. (chimmike)
 

Guess I am a liar then...

It all depends on muffler design, how many resonators you have (if any) and if you have things such as cams or a race header. You can have a completely straight through exhaust that sounds low and deep, all you need is a GOOD oval muffler and lots of resonators.

i know the WRX lose the cool WRX bubbly sound if you put an equal length manifold on it

but lengths and whatnot controls your powerband and watnot...sorta

Re: Tuning exhaust sound. (danielm3)
 

the only way to get a N/A 4 cylinder to sound good is to have some backpressure.. like through a turbo muffler.. with a header and a nice intake... Just an opinion though..

Re: Tuning exhaust sound. (punkinbeck)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by punkinbeck &raquo;</TD></TR><TR><TD CLASS="quote">the only way to get a N/A 4 cylinder to sound good is to have some backpressure.. like through a turbo muffler.. with a header and a nice intake... Just an opinion though.. </TD></TR></TABLE>

uh, what?

There is a lot that goes into designing the way an exhaust sounds...Logically it starts in the exhaust port and continues all the way out the tailpipe. It all acts as a system and every little change can affect the outcome.

Re: Tuning exhaust sound. (k24em2)
 

Interesting stuff. Lets keep this going. I am not directly talking about civics or 4 bangers, just using that as an example.

I can see how firing order can change the way a car sounds.

Re: Tuning exhaust sound. (danielm3)
 

firing order can make a big difference...listen to a standard small block chevy...then listen to one that has a 4-7 swap cam in it

Re: Tuning exhaust sound. (mensalmanac)
 

Exhaust tuning/science is basically the study of sound. Sound waves are influenced by many factors. What the ear sounds is a factor of speed, temperature, and the volume of exhaust gas. Sound wave frequency and sound wave amplitude are the core of what you hear.

Definite ways to influence sound is through muffling devices, devices that restrict flow, and pipe diameter. The materials used have some influence, probably for some resonant reasons, but I doubt it's that profound. You can look into wave cancellation chambers as well. Chambered mufflers use this approach, but clearly that leads to backpressure, as well as power losses.

Re: Tuning exhaust sound. (RC000E)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RC000E &raquo;</TD></TR><TR><TD CLASS="quote">Exhaust tuning/science is basically the study of sound. Sound waves are influenced by many factors. What the ear sounds is a factor of speed, temperature, and the volume of exhaust gas. Sound wave frequency and sound wave amplitude are the core of what you hear.

Definite ways to influence sound is through muffling devices, devices that restrict flow, and pipe diameter. The materials used have some influence, probably for some resonant reasons, but I doubt it's that profound. You can look into wave cancellation chambers as well. Chambered mufflers use this approach, but clearly that leads to backpressure, as well as power losses.</TD></TR></TABLE>

Good stuff!

Re: Tuning exhaust sound. (danielm3)
 

you can try welding a pipe to the side of the exahaust pipes to cancel out certain frequencies.

just like the stock s2k exhaust.

Re: Tuning exhaust sound. (hayabusa160)
 

Along with crank shaft styles
Flat plane vs. Cross plane
And engine stroke, bore

Re: Tuning exhaust sound. (Coal_forge)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Coal_forge &raquo;</TD></TR><TR><TD CLASS="quote">Along with crank shaft styles
Flat plane vs. Cross plane
And engine stroke, bore </TD></TR></TABLE>

bingo. listen to a ferrari flat plane v8 and a chevy small block. similar displacement. totally different sound. displacement is not everything.

Re: Tuning exhaust sound. (Mr.E.G.)
 

the 360z has a real nice sound and so does the infiniti sports coupe, don't know the number.

so basically, it is impossible to get our d15b7 motor to sound like a 360z, or anywhere close.

Re: Tuning exhaust sound. (Mr.E.G.)
 

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

bingo. listen to a ferrari flat plane v8 and a chevy small block. similar displacement. totally different sound. displacement is not everything.
</TD></TR></TABLE>


Actually it's the head and valve train design not the plane of the cylinders. A flat 8 only sounds different because of the overhead cam design and more valves per cylinder compared to a pushrod V8.

Re: Tuning exhaust sound. (Sims)
 

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


Actually it's the head and valve train design not the plane of the cylinders. A flat 8 only sounds different because of the overhead cam design and more valves per cylinder compared to a pushrod V8.</TD></TR></TABLE>

so the dohc mustang engine will sound like a ferrari engine?


http://www.autozine.org/techni...4.htm

read down toward the bottom.

i'm not trying to be a dick or imply that I am definitely right (feel free to educate me if i am in fact incorrect) but based on what i've read over the years i think you are mistaken

the example about the mustang above obviously leaves out many other variables, but nevertheless if the head is really what makes the difference then why wouldnt that engine sound like a ferrari v8?


Modified by Mr.E.G. at 11:26 AM 6/20/2008

Re: Tuning exhaust sound. (Mr.E.G.)
 

I have NEVER heard any other DOHC multi-valve motor sound anything like a Ferrari flat 12.

Another random thought - every notice that flat, air-cooled motors have a distinctive sound whether in an old VW flat 4 or 911/930 turbo flat 6?

being that making a 4 cylinder sound like a ferrari 8 or 12 is out of the question, exhaust note tuning is very difficult. the factors that affect this as mentioned before are egt's tubing material, muffler desings, exhaust length and so on. different mufflers with different baffles and filters will change the note. take a "turbo" muffler with the million holes in the inner tube of the can. each little hole would count as a high pass filter giving you a higher exhaust note. the s2000's little pipe that sticks out is considered a band pass filter letting a limited range of frequencies through which can be tuned by pipe length/ volume kind of like when you blow in a bottle. a low pass filter would be somewhat like an "H-pipe" design exhaust. also the harmonics of the tube lengths will affect resonance at different rpm's and so on. this is such a huge topic its really hard to cover. i would also like to hear more.

Re: Tuning exhaust sound. (Sims)
 

I was refering to crank shaft shape and its relation to firing order.

Another note:
Ever note the the sound of a subaru boxer engine in relation to a (old) vw bug engine. Both flat engines but the firing orders are different and so is the sound.

VW engine the firing order is sequential to the banks and the subaru's is alternating banks.

So if you were to put true duel exhasts on both engines (no crossovers or h pipes)
The subarus would have single alternating puffs of exhaust coming out of each tail pipe and the vw would shoot 2 puffs from one side then alternate to the other side with 2 puffs.

Now for some super rice somebody make a header that makes an inline 4 sound like a subi.

Re: Tuning exhaust sound.
 

Came across this thread while researching via google for where I can actuall read about sound science. By far most informative thread out of all the very un-informative threads I've found.
Bascially from what I've found on exhaust I've built for various race cars (all using no mufflers) is to large a diameter pipe for the car tends to give it a really nasty untuned sound. Building too small a diameter even with no mufflers makes it a lot quieter but gives more of a rushing air noise. Usually sounds better, but limits power. What I'd like to find is if someone has done the math for reducing exhaust diameter as the air cools to keep the flow up but give the sound of a smaller pipe. I've got a stroaker Ford V-8 in a volvo and I'm getting ready to build headers and exhaust all the way out. I quite frankly dislike the sound of most V-8's and I know I'll never make it sound like a Ferrari V-8 I'd like to see how close I can get by manupulating it with Mufflers and varying tube diameter. If I can't make it sound better (non-mustang like) then I'll just make it silent.... Sleeper hehe.

Re: Tuning exhaust sound.
 

I know the the cheap cannon mufflers always have a bad raspy sound. This is because of the thin metal that they use. If it has a big 4" tip, it makes it worse. Just flick it with your finger next time you see one. It will ring like a bell. They remind me of a bumble bee.

Re: Tuning exhaust sound.
 

plus the majority of them are on stock single cams with 1.75 piping going to a 4 inch outlet.

Re: Tuning exhaust sound.
 

i haven't read the thread but here's a fun fact pertaining to mufflers:

If you could set your muffler to sound at 333Mhz, when a female hears it, it will raise her testosterone levels thus...u know... lol

manswers for the win!

Re: Tuning exhaust sound.
 

This is a good thread so let's keep this rolling. I will post some theories when I get to my laptop.

Re: Tuning exhaust sound.
 

I think its a combination of everything, muffler,resenator, manifold, displacment, cams, and air velocity as well. even rpms.
why the higher rpm's its a higher pitch sound. and thats why v8 guys do cam swaps to change the sound, and also why a small block sounds diffrent then a big block. so answer your question imo i think everthing about the engine and exhuast has something to do with the sound.