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Another exhaust thread.

P

PurpleCherokee

NAXJA Forum User
Location
MO
Due to the recent "which muffler sounds best" threads, I started thinking more specifically about the 4.0 and exhaust sound.

My question is, what makes the 6 banger supercars sound so damn good, and how can you make the 4.0 sound similar?

Mainly for street guys I guess cause I doubt the trail rigs really wanna sound like Porsches.

So what is it? Valve configuration? Valves per cylinder? Tuning/timing? Compression ratio? Genereal head design (size/shape of ports, valves/springs, combustion chamber)? Stroke ratio? Header design? Exhaust design? Or is it all of the above?

I was very please with the way my jeep ended up sounding after my exhaust job. I honestly can hear a hint of "supercar" in the tone. Maybe I'm crazy but nevertheless I think it does.

It always thought that a two valve, pushrod motor could never sound very good unless you added two more cylinders but I have a little bit of hope now. So can anybody offer any insight?
 
Eh, I guess we could use the GT3 as an example, it has a pretty close CID.

I'm mainly curious as to what gives those cars that sound regardless of whether or not it's remotely achievable with the 4.0. Then maybe the same principles could be extrapolated to the 4.0.
 
well the Porsche 911 GT3 is a flat 6 your not gonna get a 4.0 to sound like that. The closest 6-cylinder supercar is gonna be a 2jz supra!
 
PurpleCherokee said:
Eh, I guess we could use the GT3 as an example, it has a pretty close CID.

I'm mainly curious as to what gives those cars that sound regardless of whether or not it's remotely achievable with the 4.0. Then maybe the same principles could be extrapolated to the 4.0.
Click to expand...

A Porsche motor, GT3 included, is a flat 6. Meaning it's like a V-6 but completely flat and opposite of each other. Where as the 4.0 is an inline 6. Also, 219 CI vs. 242 on the Jeep. The lighter, shorter stroke allows it to rev QUICKLY and build better power for it's application. The 4.0 creates more torque with it's longer stroke. You'll never get the 4.0 to sound like any other "supercar" motor.
 
That's the question I'm askin, granted, the GT3 is a boxer, but several other supercars aren't and sound the same. I don't think it's the cylinder configuration that does it. It does however, give it that distinct sound, but I don't think it is what makes that "supercar" sound. I'm thinkin it might just that they're grossly oversquare but I dunno. Someone tell me.
 
PurpleCherokee said:
That's the question I'm askin, granted, the GT3 is a boxer, but several other supercars aren't and sound the same.
Click to expand...

No... they don't. The flat 6 boxer motor and the flat 4 boxer motor both have a distinct sound, unlike any other cylinder configuration.

PurpleCherokee said:
I don't think it's the cylinder configuration that does it.
Click to expand...

Then you'd be wrong.

PurpleCherokee said:
It does however, give it that distinct sound, but I don't think it is what makes that "supercar" sound.
Click to expand...

If by supercar sound you mean 8,000+ RPM, then yes... You'll never get your Jeep to hit 8k rpm, quit smoking.[/quote]

PurpleCherokee said:
I'm thinkin it might just that they're grossly oversquare but I dunno. Someone tell me.
Click to expand...

What did I JUST say about bore/stroke? Did you learn a new word and just wanted to use it so you created a new thread?

If you already "knew" this why did you start a thread about it.
 
I agree, you'll never get the 4.0 to sound like a "supercar". The engine that comes to mind when I think of stright six performance motor would be the BMW M3...not much of a supercar at all if you ask me, but nonetheless, a high revving, performance oriented straight six. That motor has 4 valves per cylinder and is generally tuned to rev high. The 4.0 is tuned for low end torque and has 2 valves per cylinder.

If you ask me, they sound different because of the exhaust ports, valve configuration, valve lift and duration, exhaust layout etc...

The jeep motor sounds like a tractor, you'll never get it to sound like an M3
 
I had a nice long reply and then it asked me to log in again and then it was lost--bs.
Inline 6s do have a unique sound and I do hear similarities in mine w/ the bmw i-6 w/ aftermarket exhaust(ss, b&b, borla). Port size and shape play a role as does the exhaust system. I didn't get a chance to hear the difference of my head by itself after the p&p(it was installed same time as stroker), but I'm sure it's contributed. Those boxers(porsche and subi) have a unique sound of their own and of course the porsche with its rear engine has short pipes, so that'd be difficult to reproduce. Anyhow, I'm sure there are exhaust gurus out there that can make your vehicle sound a variety of ways(louder, quieter, mellow, raspy, deeper, etc). While on the topic, I'll be shopping for a 95 avus blue m3 come springtime.
 
There's so many variables, valve size/layout, displacement, compression ratio, layout, engine block material (yes it makes a difference), cylinder head port sizes. That doesn't even take into account header design, pipe diameter and length.

GM Spent millions trying to get the new GTO's to sound like the 65'/66' GTO's when they were first coming into production. That should tell you there is much involved.
 
I wish mine sounded more like my old 4.2 SJ Cherokee, now that sounded like a tractor! Yay exhaust leaks.
 
crazyjim said:
No... they don't. The flat 6 boxer motor and the flat 4 boxer motor both have a distinct sound, unlike any other cylinder configuration.



Then you'd be wrong.



If by supercar sound you mean 8,000+ RPM, then yes... You'll never get your Jeep to hit 8k rpm, quit smoking.



What did I JUST say about bore/stroke? Did you learn a new word and just wanted to use it so you created a new thread?

If you already "knew" this why did you start a thread about it.
Click to expand...

Wow... If you don't know much about the subject and you post up on a thread just to act like a dick then just do us all a favor and save it.

:D Thanks!
 
gradon said:
I had a nice long reply and then it asked me to log in again and then it was lost--bs.
Inline 6s do have a unique sound and I do hear similarities in mine w/ the bmw i-6 w/ aftermarket exhaust(ss, b&b, borla). Port size and shape play a role as does the exhaust system. I didn't get a chance to hear the difference of my head by itself after the p&p(it was installed same time as stroker), but I'm sure it's contributed. Those boxers(porsche and subi) have a unique sound of their own and of course the porsche with its rear engine has short pipes, so that'd be difficult to reproduce. Anyhow, I'm sure there are exhaust gurus out there that can make your vehicle sound a variety of ways(louder, quieter, mellow, raspy, deeper, etc). While on the topic, I'll be shopping for a 95 avus blue m3 come springtime.
Click to expand...

That'd be a nice ride for sure. I dunno bout you but I'm kinda disappointed that they ditched the six for the eight... that was an awesome motor. Not that the E90 v-8 isn't impressive too.
 
don't forget that even minute changes in your camshaft/shafts (depending on what engine we are referring to) can change the sound as well, something as small as a 2* change in the LSA can tweak the sound, not to mention adding lift, duration and all that.

There are so many different things involved in the sound an engine makes that you will never be able to match two different engines, even if they are the same size but made by different people. ex: my moms Chrysler Pacifica sounds nothing like my dads 350z even though they are both 3.5 V6s.

The easiest way for you to achieve sound on your car is muffler, header, and head work. other then that your just getting into a money pit worth of work, all just to sound like a Porsche.

good luck
 
Stroke it and supercharge it if that doesn't sound badass enough throw yourself off a cliff.
 
lancey3 said:
Stroke it and supercharge it if that doesn't sound badass enough throw yourself off a cliff.
Click to expand...

ROFL.

Purple you named all your answers in the first post.

x2 on companies tuning exhausts for sound too. The Ferrari sound is almost a trademark, so they do darn well to keep it.

The difference between the 4.0 and the Bimmer I6 is the same kind of difference between a 302 and a Ferrari v8. Simple design vs. a better, technological based design.
 
Stallacrew said:
Purple, your blinkers needs some work.
Click to expand...

Lol yea it's been fixed since the vid.

Elias said:
That's what people are saying about you... Go figure.

E
Click to expand...

Go ahead and show me when I was acting like a dick.

seanyb505 said:
ROFL.

Purple you named all your answers in the first post.

x2 on companies tuning exhausts for sound too. The Ferrari sound is almost a trademark, so they do darn well to keep it.

The difference between the 4.0 and the Bimmer I6 is the same kind of difference between a 302 and a Ferrari v8. Simple design vs. a better, technological based design.
Click to expand...

I realize I identified a lot of the reasons they sound different, but nobody's answered MY question. Which, if any of those variables most affect the sound of the motor?
 
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