Exhaust questions for the engineer - TCCoA Forums
 
LinkBack Thread Tools
post #1 of 19 (permalink) Old 11-30-2011, 11:00 AM Thread Starter
4th Gear Poster
 
tbirdsps's Avatar
 
Join Date: Jan 2003
Location: Ridgecrest, Ca
Age: 66
Posts: 267
Exhaust questions for the engineer

Just what is the difficulty in making a six sound good? Engineers please explain.

1. The inline six with a split exhaust manifold and dual exhaust sound awsome. Chevy, Ford and Chrysler.

2. European V6 engines (Dino, Alpha, etc.) sound awsome with dual exhaust.

3. The 2011 Ford Mustang V6 with duals sounds.....decent but not awsome.

4. Chevy, Ford, Chrysler V6s with dual sound like crap!

What is the theory behind making a V6 sound good and us Americans can't seem to do it? Why do inlines sound great but not V6 American engines?

Is it something like even fire vs odd fire? Certainly it's something related to the pulse rate. Why does 4 cylinders per bank make so much difference? 25% less per bank?
tbirdsps is offline  
Sponsored Links
Advertisement
 
post #2 of 19 (permalink) Old 11-30-2011, 11:12 AM
Seasoned PostWhore
 
NetKeym's Avatar
 
Join Date: Aug 2009
Location: Florida
Posts: 5,862
Quote:
Originally Posted by tbirdsps View Post
Just what is the difficulty in making a six sound good? Engineers please explain.

1. The inline six with a split exhaust manifold and dual exhaust sound awsome. Chevy, Ford and Chrysler.

2. European V6 engines (Dino, Alpha, etc.) sound awsome with dual exhaust.

3. The 2011 Ford Mustang V6 with duals sounds.....decent but not awsome.

4. Chevy, Ford, Chrysler V6s with dual sound like crap!

What is the theory behind making a V6 sound good and us Americans can't seem to do it? Why do inlines sound great but not V6 American engines?

Is it something like even fire vs odd fire? Certainly it's something related to the pulse rate. Why does 4 cylinders per bank make so much difference? 25% less per bank?
We had a built Chevy 4.3L in a Toyota with headers and SS dual 2.5" exhaust we used to enter in 4/6 cylinder class of the mud runs (took 1st and 2nd place EVERY time). Point being that truck sounded EXACTLY like a GT Mustang V8 when running. We ALWAYS had to prove that is was a 6 cylinder because nobody believed it until we lifted the hood.

TRUE STORY. So 6 cylinders don't always sound like sh*t.

~Rick

TCCoA Sig
NetKeym is offline  
post #3 of 19 (permalink) Old 11-30-2011, 02:41 PM
Kind of slapped together
 
Join Date: Jan 2010
Location: Bossier City, LA
Age: 63
Posts: 4,838
Quote:
Originally Posted by tbirdsps View Post
Just what is the difficulty in making a six sound good? Engineers please explain.

....


Is it something like even fire vs odd fire? Certainly it's something related to the pulse rate. Why does 4 cylinders per bank make so much difference? 25% less per bank?
That's a chunk of it. It's also the fact that to run smoothly, a V6 usually isn't firing 120 degrees apart, but 90/150 degrees (due to the timing of the ignition pulses).

A V8 is firing every 90 degrees.

Add to that - well, let's see if it's up online somewhere, an article I read recently:

Sorry, can't find it. But there was an explaination of why most V8s have the "burbly" sound (has to do with the fact that the cylinders don't purely alternate one bank to the other in the firing order normally), because of a V8 that DOES that - it's a twin turbo V8, in a BMW IIRC. A new one.

Some mag like Motor Trend, Automobile, or Car and Driver. Forget which one, don't have it still.

Anyway - it can be done, but it may take a bit.

Then again, it could be you're expecting that V8 sound - which the V6 won't have.

(I'll say that the best sounding V8 I ever heard was a Studebaker V8 .. the Stude 289.)

RwP
RalphP is offline  
Sponsored Links
Advertisement
 
post #4 of 19 (permalink) Old 11-30-2011, 02:51 PM
Humble MN12 Genius
Super Moderator
 
XR7-4.6's Avatar
 
Join Date: Apr 2006
Location: Roselle IL
Posts: 16,580
Garage
Send a message via Yahoo to XR7-4.6
I've said it before and I'll say it again, V6s only sound bad if V8s are all that sound good to you. There's plenty of nice sounding 3.8s with true duals and a good pair of mufflers.

Inline sixes do have an inherently different sound for many reasons, one of the big ones being they're usually OHC or DOHCs vs. pushrods like most American V6s up until the last decade.

Only V6 I ever heard that had any semblance to V8 sound after idle was a 3.1 60* 6 from a beaten Chevy Celebrity with no exhaust... Still boggles my mind

-Matt
XR7-4.6 is offline  
post #5 of 19 (permalink) Old 11-30-2011, 02:58 PM
PostSlut
 
_95badbird's Avatar
 
Join Date: Jul 2004
Location: Spring Texas
Age: 39
Posts: 13,597
kinda how a viper sounds like poo in my opinion....sounds like two civics getting on it!

Nick......................I'm back!!!
May you fly low and fast
rest in peace JL
_95badbird is offline  
post #6 of 19 (permalink) Old 11-30-2011, 05:59 PM Thread Starter
4th Gear Poster
 
tbirdsps's Avatar
 
Join Date: Jan 2003
Location: Ridgecrest, Ca
Age: 66
Posts: 267
Quote:
Originally Posted by _95badbird View Post
kinda how a viper sounds like poo in my opinion....sounds like two civics getting on it!
Good one. What I'm talking about is the Ferrari Dino sounds great but it is a mid engine car. V6.

I think RalfP said it best. But I'm not expecting a V8 sound but something not "ricey" or too much "blat" as a good word.

Right now my 3.8 sounds nice and someone commented on it wondering which V8it had. Mainly because there's a dime sized hole and a crack in the inlet side of the muffler. It sure would be nice to keep that sound when I replace the muffler. Well muted most of the time but off idle it sounds great.
tbirdsps is offline  
post #7 of 19 (permalink) Old 11-30-2011, 07:18 PM
Seasoned PostWhore

Super Moderator
 
Join Date: May 2003
Location: Tinton Falls, NJ
Age: 36
Posts: 7,428
Garage
Send a message via AIM to MadMikeyL
There are a lot of factors in the exhaust sound of an engine, including pipe diameter and length, the muffler used, catalytic converters, valve size and orientation, cylinder bore diameter, etc., but the main thing that gives any engine its signature sound is the spacing of the exhaust pulses, which is determined by the location of the cylinders and the firing order. The reason for V8s having that signature sound is because of the cross plane design of the crankshaft, which means that if you look at each bank of the engine separately, the power stroke of each piston will not be evenly spaced out. As a result of this, the exhaust pulses are also uneven, so it creates a fluttering of pressure in the exhaust, that you hear as the signature V8 rumble. A typical 4-cylinder engine has what is called a flat plane crank, which means when 2 cylinders are at the top of their stroke (one on compression and the other on exhaust), the other 2 are at the bottom (one finishing the intake stroke and the other the power stroke), so there is an evenly spaced out sequence of exhaust pulses every 90 degrees, which produces a higher pitch humming type sound, which is characteristic of inline 4-cylinder engines. That is what produces the different sounds of typical 4-cylinders and typical V8s. It should be mentioned though that there have been some flat plane V8s made, which actually sound like 4-cylinders, as well as some cross plane 4 cylinders, which actually sound like V8s, but both a flat plane V8 and a cross plane I4 create unwanted vibrations, especially in larger displacements, so to my knowlege nobody is still manufacturing a flat plane V8, and I believe cross plane 4 cylinders have only been made for motorcycles, not cars. Also, some race cars and supercars have V8 engines with 180 degree headers, which connect each exhaust port with the piston that is 180 crankshaft degrees away from it. The reason for this is to improve exhaust scavenging, and it works quite well, but it has 2 downsides. First, it is a PITA to package because you need multiple header tubes to cross from one bank over to join with the other, and secondly, it will make the V8 sound like a large 4 cylinder.

When it comes to 6-cylinders, straight sixes give you some room to work with the sound where V6s don't. Most straight sixes use a tri-y type setup where you have 2 headers, each with 3 cylinders manifolded together, and then those to headers y together further down the exhaust. When all the cylinders are in a line, it is pretty easy to mix and match which cylinders are paired together, and that makes a huge difference in the sound. All straight sixes have a firing order of 153624. The simplest manifolding would be pairing 123, and then 456, however if you do this, as far as the exhaust goes, you have effectively created 2 separate 3 cylinder engines running simultaneously (because each of the front 3 cylinders fires 120 degrees apart just like a 3-cylinder, and each or the rear three fire 120 degrees apart), and as a result, it will sound like a 3 cylinder engine, and will buzz and whine worse than the a 4" exhaust on a honda civic. The solution is to move one of the primary tubes, which creates an uneven exhaust pulse, which is similar to what causes the V8 rumble. That is why if you look at the manifold of a straight six in a BMW, Mercedes, Jaguar, Supra, or pretty much any performance oriented straight six, they run the pipe from cylinder 4 in with 1&2, and the pipe from cylinder 3 in with 5&6. This will not make it sound like a V8 because with 2 fewer cylinders, no matter what you do, the exhaust pulses are going to be space apart differently, but it does eliminate that can of bees sound. In a V6, you have to work with the way the firing order is, and what cylinders are on what bank. The GM 60 degree V6 is actually known for having a good sounding exhaust due to the firing order of 123456, and thanks to GMs cylinder numbering, cylinders 123 are paired together, as are 456, so you have a very uneven exhaust pulse, which translates to horrible exhaust scavenging, but a nice rumbling sound.

Now we get to our beloved ford 3.8. The firing order of the 3.8 is 142536. Ford numbers their cylinders in straight lines so that on one bank you have cylinders 123, and the other bank is cylinders 456. First cylinder 1 fires on the passenger side bank, then 60 degrees later, cylinder 4 on the driver's side. Next cylinder 2 fires 60 degrees after that, which is 120 degrees away from cylinder 1. Next comes 5, which is 120 degrees away from 4, then 3 which is 120 from 2, then 6, which is 120 away from 5. So on each bank of cylinders that are paired together on a 3.8, you have one cylinder firing every 120 degrees, so on a Ford 3.8 V6, if you look at each bank separately, it is effectively its own 3 cylinder engine, so when you hear the exhaust on a Ford 3.8, you are hearing 2 inline 3-cylinders running simultaneously, and that is why they have a tendency to buzz and hum and whine and generally sound like a Honda with a fart can. My advice if you want a 3.8 to sound decent is to try to keep it quiet. It will never rumble like a V8, and if you run too large a pipe, or too loud a muffler, or delete the resonator or the cats, it is all too easy to make it sound horrible.

-91 Cougar LS, coming soon, complete overhaul with a 427" Windsor.
-90 XR7 5-speed black on black w/sunroof, MP2, coated rotors, double intercooler, 15%OD, ported heads, comp stage 1 cam, 85mm TB, 90MM LMAF, 80# injectors, and ported big valve heads
-98 Mark VIII LSC, Procharger P600b, TR3650 swap and 3.73s.
-90 SC Automatic rustbucket winter beater
-97 Tbird Sport 4.6 Nice weather daily driver
-"Your buddy Mike is INSANE!" -ClintD's dad
MadMikeyL is offline  
post #8 of 19 (permalink) Old 11-30-2011, 07:39 PM
Seasoned PostWhore
 
NetKeym's Avatar
 
Join Date: Aug 2009
Location: Florida
Posts: 5,862
Judge for yourself.....

What do you think this v6 car would sound like with bigger pipes?
http://www.youtube.com/watch?v=kS6iCa859JM

Cam up a v6 and see what YOU think?
http://www.youtube.com/watch?v=nwRq4LCEqCc
http://www.youtube.com/watch?v=ztG3_NyHSUo
http://www.youtube.com/watch?v=0khk2hkQw2Y
http://www.youtube.com/watch?v=YOm07KqAsrw


Here is a stock v8 vs stock v6 exhaust comparison where the v6 sounds better! lol
http://www.youtube.com/watch?v=o7VIBi-2wg4

~Rick

TCCoA Sig
NetKeym is offline  
post #9 of 19 (permalink) Old 12-01-2011, 08:03 AM Thread Starter
4th Gear Poster
 
tbirdsps's Avatar
 
Join Date: Jan 2003
Location: Ridgecrest, Ca
Age: 66
Posts: 267
Wow, thanks MadMikeyL. Fantastic explanation. My immediate solution is to keep the hole in the muffler and the crack! Ha Ha.
tbirdsps is offline  
post #10 of 19 (permalink) Old 12-01-2011, 09:47 AM
6th Gear Poster
 
Join Date: Jun 2003
Location: NOVA
Age: 42
Posts: 616
Needabirdinva just got his redone and it sounds good. We have to get a good driveby clip of it tho.

I don't think it has any of that Hum at WOT like that chevy truck in the last video. Pretty close to a v8 sound.

But it won't be legal for you in CA.
BLOWN38 is offline  
post #11 of 19 (permalink) Old 12-01-2011, 02:45 PM
Humble MN12 Genius
Super Moderator
 
XR7-4.6's Avatar
 
Join Date: Apr 2006
Location: Roselle IL
Posts: 16,580
Garage
Send a message via Yahoo to XR7-4.6
Quote:
Originally Posted by NetKeym View Post
Judge for yourself.....

What do you think this v6 car would sound like with bigger pipes?
http://www.youtube.com/watch?v=kS6iCa859JM

Cam up a v6 and see what YOU think?
http://www.youtube.com/watch?v=nwRq4LCEqCc
http://www.youtube.com/watch?v=ztG3_NyHSUo
http://www.youtube.com/watch?v=0khk2hkQw2Y
http://www.youtube.com/watch?v=YOm07KqAsrw


Here is a stock v8 vs stock v6 exhaust comparison where the v6 sounds better! lol
http://www.youtube.com/watch?v=o7VIBi-2wg4
The Silverado sounds the best out of all of them. None of them sound even remotely like a V8 to my ears though. I don't count idle sound.

-Matt
XR7-4.6 is offline  
post #12 of 19 (permalink) Old 12-01-2011, 04:33 PM
Seasoned PostWhore
 
NetKeym's Avatar
 
Join Date: Aug 2009
Location: Florida
Posts: 5,862
Quote:
Originally Posted by XR7-4.6 View Post
The Silverado sounds the best out of all of them. None of them sound even remotely like a V8 to my ears though. I don't count idle sound.
Which Silverado? The 6 or the 8?

~Rick

TCCoA Sig
NetKeym is offline  
post #13 of 19 (permalink) Old 12-01-2011, 04:38 PM Thread Starter
4th Gear Poster
 
tbirdsps's Avatar
 
Join Date: Jan 2003
Location: Ridgecrest, Ca
Age: 66
Posts: 267
Quote:
Originally Posted by XR7-4.6 View Post
The Silverado sounds the best out of all of them. None of them sound even remotely like a V8 to my ears though. I don't count idle sound.

I agree but they all sounded decent at idle but when rpm increased none that did that sounded good to me.

Stock muffler with a hole is the way to go.
tbirdsps is offline  
post #14 of 19 (permalink) Old 12-01-2011, 07:45 PM
6th Gear Poster
 
Join Date: Jun 2003
Location: NOVA
Age: 42
Posts: 616
Here's how mine sounds at idle. Good.
[IMG][/IMG]

And then going down the track. Not so good.


But hey atleast we can say the vipers sound like us or vice versa.
BLOWN38 is offline  
post #15 of 19 (permalink) Old 12-02-2011, 07:51 AM Thread Starter
4th Gear Poster
 
tbirdsps's Avatar
 
Join Date: Jan 2003
Location: Ridgecrest, Ca
Age: 66
Posts: 267
Quote:
Originally Posted by BLOWN38 View Post
Here's how mine sounds at idle. Good.
[IMG][/IMG]

And then going down the track. Not so good.


But hey atleast we can say the vipers sound like us or vice versa.
Race cars don't count. However your left rear brakelight is dim....
tbirdsps is offline  
post #16 of 19 (permalink) Old 12-02-2011, 11:42 AM
Seasoned PostWhore
 
Tbird1997's Avatar
 
Join Date: Feb 2009
Location: Murfreesboro, TN
Age: 27
Posts: 2,134
lots of power make them sound good IMHO

-Patrick
[email protected] on used street tires
See profile for full list of mods

Pics here.. http://forums.tccoa.com/showthread.php?t=129479
Tbird1997 is offline  
post #17 of 19 (permalink) Old 12-04-2011, 09:50 AM
50 years of Mercury Cougar 1967/2017
 
r429460's Avatar
 
Join Date: Jun 2007
Location: Davie, Fla.
Posts: 1,246
A I6 or a V6 will never sound like an eight.
Don't try. Embrace the sound of the six shooter.
r429460 is offline  
post #18 of 19 (permalink) Old 12-07-2011, 06:55 AM
PostWhore
 
Join Date: Apr 2005
Location: Walton, KY
Posts: 1,606
A 6 can sound good at idle, but it's when you step on the cas that the 6 will fail in the sound department.

But "what sounds good" is soooo subjective. Typical car enthusiaists immediatly lean toward that deep V8 rumble. Hell some exotic V12's sound like crap to me so it's not the "the more cylinders the better the sound."

Engine, exhaust pipe diameter/length routing all play a role.

Case in point...alot of Tbird owners want their 4.6 to sound like a Mustang GT, the different length and routing and pipe dia make the mustang a mustang. Not to mention when you think of a Ford 4.6 you may think mustang and flowmasters... (which sound like sh!t to me IMO) but A LOT of people see that as THE mustang sound.

You could put the same midpipe/cats/muffler setup on a tbird and a mustang with the same motor and they will sound diff.

most people talk, but few are up for the moment
-where there's money and imagination, there's cool cars
ohhh the Junkyard , one man's trash is another man's treasure

1993 3.8L Tbird----sold
1994 4.6L Tbird----sold
1995 Mark VIII----sold
2004 Mustang GT----sold
2003 Mach 1----current
smitty2919 is offline  
post #19 of 19 (permalink) Old 12-07-2011, 07:06 AM
PostWhore
 
Join Date: Apr 2005
Location: Walton, KY
Posts: 1,606
double post....

most people talk, but few are up for the moment
-where there's money and imagination, there's cool cars
ohhh the Junkyard , one man's trash is another man's treasure

1993 3.8L Tbird----sold
1994 4.6L Tbird----sold
1995 Mark VIII----sold
2004 Mustang GT----sold
2003 Mach 1----current
smitty2919 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the TCCoA Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome