I want the Audi RS4 exhaust sound from my BMW E46 328i

[hough]

I hope this is the right place to ask this question but i heard an Audi RS4 V8, and the exhaust note was just mental, with a proper roar to it, but here is the silly question, I know the audi is a V8 and my BMW is a straight 6 but can i get a similar sounding exhaust note (roar) from my exhaust, i know on my model the E46 the there are 2 headers which are 3 into 1, then a pair of cats then a pair of resonators then the system merges into 1 pipe then splits again at the rear box into twin tail pipes, but if my exhaust was a proper twin pipe with all separate boxes as in after each header a cat then 2 silencers would this give me the same sort of sound????

 

[stamford]

Best option would be to get a Powerflow exhaust made up to suit, they can tailor the sound that you wish by changing the box types and pipework. Decat will also give a great noise, as long as you can still pass the emissions and don't annoy the local law enforcers.

 

[kain35m]

BMW I6 sounds a lot more high pitched and racy. You can make it louder, and change the note a bit, but just the way that BMW head design is and the fact that it is an I6 will mean it won't have a big v8 growl.

Even BMW v8s don't really sound like audi v8s It's a lot like comparing Ford vs Chevy. They both have the nice v8 sound, but it's not the same. Audi sounds a lot more mellow, and smooth, while BMW is a lot more harsh and unshaven.

Think of it this way, It won't bellow, It will scream.
I'm a chunky monkey from funky town
Now, if you get a nice aggressive cam in there, you can make it idle nice and deep. I've even heard the odd I4 sounding very deep and grumbling like a v8 at Idle.

Your engine will sound great. But it will sound sixy. Learn to love it, it's a good sound.
HIt up youtube. You'll hear what different exhaust systems sound like.

 

[obi_waynne]

I guess you need to isolate exactly what you like about the RS4 engine sound. In terms of pitch you can probably get quite close but the distinctive V8 burble will never happen on a straight 6.

 

[hough]

its the growling noise of the audi i like as the pipe i have seems to be more of a deep dronning noise, but would my bmw engine sound any better if it had a proper twin pipe system from the headers back or a like a lot of companys do join the twin pipe exhaust after the resonators in to 1 pipe to the back box with twin tail pipes?

 

[obi_waynne]

I think you should focus on the air intake for more of a growling noise. It is the induction roar rather than the exhaust for this noise.

 

[hough]

what sort of filter would help to produce that growling sound and not that horrible dronning noise that i have at the moment

 

[obi_waynne]

Probably a cone filter, like the K&N.

To test it out remove the air filter box (leaving an open duct pipe into the engine bay) and see what it's like when you rev it. As long as you don't drive too far or through too much dust you shouldn't have a problem with doing this to test the sound you get.

If you like the sound then a cone filter is the way to go, if you don't then this is not what you are looking for.

(I've known some people pull a sock tightly over the open pipe and wrap a tight tie around it to stop large particles entering the engine, but I think this is overkill for a short test.)

 

[hough]

ok will try that in a bit as i have a closed cone filter on at the moment, but do you or who on this forum is the best person to ask question about exhaust systems?

 

[pgarner]

probaly say old git, his exhaust was custom built for his car/engine to his requirements.

if you have a good custom exhaust place, make sure the mandrel bend rather than crush bend the pipes, have a chat with them

 

[obi_waynne]

Quite a few of the guys have experience in exhausts but I'll warn you now, one mans cool is another mans annoying! Exhausts are incredibly subjective. Personally i'd only consider a fully resonated exhaust from Miltek but I know lots on here will strongly disagree with me on that one!

 

[kain35m]

I think you should focus on the air intake for more of a growling noise. It is the induction roar rather than the exhaust for this noise.

Very much agree with this one. For a deeper growl, It's all about the air going in.

That's why I mentioned a cam earlier. If you get a nice agressive cam, It will keep your intake valves open more/longer. Not only does this provide you with a bit deeper purr, but more power and maybe even a bit better fuel economy as well, with the right tune.

You may even change out your intake manifold for a bigger, more free-flowing one.

I'm not talking price here. I'm talking max Hp gains and max sound. You gotta be able to back up that noise with some performance. Hahaha

 

[Sid447]

A straight-six engine,

cannot have the same sound as a V8.

IMO there's sure not much wrong with the sound of this I6, see what you think...: http://www.youtube.com/watch?v=ZL7T9BD_Q3k (M3 CSL-SC)

...or this http://www.youtube.com/watch?v=pvTzKwnDy04&playnext=1&list=PLA450309886965B0D (Osella-BMW M-power)

or even this!.......http://www.youtube.com/watch?v=MzgvKBt9wkk (Norma M20 with BMW M3 power)

 

[obi_waynne]

Welcome back Sid, how have you been?

Thanks for the links, there is a lot of inspiration there.

 

[hough]

@kain35m what do you call a nice agressive cam?

and what sort of intake would you go for to give that growl and performance?

 

[Prince]

A straight 6 will never sound like a V8. To get more growl out of it get yourself a Dave F induction kit an an Eisenmann race exhaust. If you're not happy with that then you never will be!

 

[kain35m]

First off, I don't know what kind of budget you're working with. For the best reliability, I'd say go Dinan all the way. They're pricey, but they have been making BMW performance parts forever.

If you're feeling lucky, and you know some machinists around town, you could go all custom. A blank cam isn't usually that expensive, and finding specs is easy with a bit of research. An agressive cam is one with much longer duration and lots more lift than factory. You have to find out how big you can go without striking a piston. Look around. Someone has some specs for a cam that would probably be perfect for you. If you don't understand all the numbers, post them up here and someone will explain them to you.

A custom intake manifold would be fairly easy if you know someone who is good at welding/machining piping. They can make a bigger pipe and match it to the ports on your head. Then it's a matter of whether you want to tune for high end HP or low end tq. You're playing with small numbers here, so don't be afraid to go big in one direction or the other. Length=higher velocity=more tq. Width=more volume=more hp.

Then get a header made or ordered. and a nice cat-back. It'll sound great and have a little more power.

A machinist/welder may cost less than a manufacturer, but they may be more too. It's a crap-shoot. but you may get lucky. If you go through a manufacturer like dinan, it's easy. order parts. wait. recieve. install. drive. smile.

 

[hough]

thanks kain the inlet manifold and cam sound a good idea, i was looking at a manifold convertion but cant get a straight answer on the bmw forums as to which manifold i need to replace the one on my e46 328, i can do the welding myself as thats what i do for a living, and i did have ago at making my own exhaust but its got a horrilbe mono tone drone and need to sort it out.....

 

[kain35m]

What did you make? A header or a muffler? Mufflers are tricky and can take some real fenagling to get just right. If it's a header, I'd say find someone who has one that sounds the way you want it to sound and get a mental image of it before you try to throw it together.

If it's a whole exhaust system, first off, kudos to you and can you make one for me? Haha J/K but for real, I would say check your bends and all. Do you do any machining? If you do, you can work the head porting a bit too. Plenty of specs around if you don't mind banging your head against a wall for about an hour (research can get a bit frustrating)

I think you'll have it though.

 

[hough]

Well here is the mufler/back box that i made out of 316 s/steel sorry its a bit grumby should give it a good clean and a polish really

 

[kain35m]

That's a straight through design, isn't it? I can tell you right now, That's your problem.


Try a design like this:

>>>>________________
>>>>l::: /:::::::::::\::::l
_____l::/:::/:::::\:::\:::l____
_____ <:::<::<>::>::>:____
>>>>l:::\:::\::::::/::/:::l
>>>>l___\________/___l


Ignore the dots.

Make sure there is space between the plates and the outside wall, you want the gas to hit the < and travel to the outside wall, bounce back in, bounce around a bit, and eventually find it's way out the other side.

Should give it a "tunnel effect" if done right.


Sorry about my crappy drawing.

 

[hough]

i take it this design still need some sort of exhaust wadding? and i think i follow the drawing, iv been trying to lookup exhaust designs and i think the perforations in the inner tube are a bit big at 6mm each i was thinking of having a centre chamber but thought straight through was best at the time

 

[kain35m]

Better work than I could ever do anyways. I couldn't weld to save my life.

Yes, you can use fiberglass or something in the walls and in the center if you want, but the design itself should have a fair muffling effect. I guess it just depends how strict the laws are governing noise ordinances. Shouldn't be too loud though. It's made to cause exhaust gasses slamming into each other canceling out some of the sound.

 

[hough]

Thanks kain, will look at making another muffler when i got time in the workshop, i was thinking of replacing the resonators with two 4"dia x 10" mufflers, then into the centre mufflers and onto the back box, want to try a few different ideas and see how things sound, i was thinking about making a box with a butterfly valve so at lower revs the gases flow into a different chamber and at high revs the gases just go straight through!!!

also trying to find out if the lenght and dia of the tail pipe affect the sound of the exhaust?

 

[HDi fun]

What about removing the resonator?

 

[hough]

i was thinking about removing the resonators might have to give that a try

 

[kain35m]

It will make the car more vibrate....y. A little louder and more harsh. You may like it, you may not.

 

[HDi fun]

It won't vibrate at all unless you bolt the rear box rigidly to the body.

I'm not a fan of noise at all, I like the abolishment of the stuff, but each to their own.

 

[Prince]

Why not just fit an exhaust to enhance performance instead of just make noise?

 

[HDi fun]

Why not just fit an exhaust to enhance performance instead of just make noise?

exactly
straight six BMW engines are very pleasant. Inherently smooth by the laws of physics. A V8 is only two fours strapped together sideways on. They still need balancer shafts. straight six engines don't. There are no free moments of inertia

 

[Sid447]

exactly
straight six BMW engines are very pleasant. Inherently smooth by the laws of physics. A V8 is only two fours strapped together sideways on. They still need balancer shafts. straight six engines don't. There are no free moments of inertia

Not quite correct,

Only flat-plane crank V8's require balancer shafts.