[Advice Please] Argh! Exhaust Droooooone...

[Lozza150]

All mufflers quieten the sound, you will find most exhausts have a centre muffler and whats called a "Hot Dog" which is another muffler shaped like the pipework. The cannon is the last point that deadens the sound... The cannon has the control of the overall sound of the note.

The super dragger has a Centre muffler - hot dog - and BIG barrell cannon to really soak up the noise

[drunkenmaster]

Thanks guys - sounds no middle muffler and a good quality rear muffler will flow better then a cannon with a middle muffler yeah?

If so I'll look at a HKS super dragger because I've heard their quiet yet they still have the cannon look (which will fit my car's rear skirt.. I'm worried a normal muffler won't sit out far enough.)

The other alternative is a really good centre muffler and a straight through from there.

My question is (newb question) why do cars have a centre muffler and a rear muffler? If one can do the job wouldn't it be cheaper to produce one that would do the job? - I don't understand why people have 2 when I assume it would cause more restriction (or is it negligible?)

Finally if cannons don't flow better why the hell do people use them? (to be loud?)

Well, no. No mufflers at all would flow better, which is almost like using a cannon anyways as a 3" straight through cannon on a 3" exhaust isnt really much of a restriction, nor is it much of a muffler.

I dont really know about sounds of different brands and what looks best.

A high flowing muffler doesnt absorb much noise. A muffler designed to absorb a lot of noise doesnt flow very well as usually they U-Turn inside the casing to make sure all the gas and noise hit the packing. It makes sense then that to have a good compromise would be to have 2 high flowing mufflers, each not being much of a restriction and each reducing some noise.

Cannons do flow well, but the dont absorb much noise at all so therefor are 80% there to look nice.

Like I said earlier, the best compromise is a straight through centre-offset muffler. They flow almost as well and are twice as quiet as a cannon, i.e. no drone. If you didnt understand what I mean by centre-offset, they are muffler which inlet pipe is in the centre of the casing, and the outlet is offset to one side of the casing. The flow therefore is diagonal but still straight through. The result is more surface area inside the muffler and therefore more noise reduction. If you must have the "look" of a cannon, I would highly recommend using one of these in the middle instead of a hotdog. In my car I will use two of these, probably genie tornado's as they have been shown to flow very well.

[Sydneykid]

Hi guys, there seems to be some general belief here that you have to decrease the horsepower in order to decrease the noise. This has NOT been my experience, I have decreased the noise on a number of cars and actually increased the horsepower. You have to choose the components and sizes appropriately.

[Lozza150]

Exactly... That's why the Super Dragger is 3.5" and has a 5 inch tip.

Make sure you get a 3" cat or bigger if you can.

[someonestolecc]

Any tips for my situation or general theory advice S-Kid?

I have a sr20 with standard exi-mani, tomei style dump pipe, 3" to a crappy looking cat then 3" all the way to a xforce 3" with (guessing) 5" tip.

Currently too loud, probably flows crap, looking to change the cat and get some sort of quieter muffler. Still haven't experimented taking my flatmate's kakimoto from his r32 to put on to see if it's quieter but I'm expecting it would be.

[Sydneykid]

Any tips for my situation or general theory advice S-Kid?

I have a sr20 with standard exi-mani, tomei style dump pipe, 3" to a crappy looking cat then 3" all the way to a xforce 3" with (guessing) 5" tip.

Currently too loud, probably flows crap, looking to change the cat and get some sort of quieter muffler. Still haven't experimented taking my flatmate's kakimoto from his r32 to put on to see if it's quieter but I'm expecting it would be.

For drone prevention I have found that a "larger" muffler in the middle with a "smaller" muffler at the rear is more effective than a "smaller" muffler in the middle with a "larger" muffler at the rear. For a road only or combo car, a 3 1/4" (80 mm) seems to work well on RB's. Once you get to 3 1/2" and larger they get tricky to shut up at all rpm ranges.

[DEVL25]

make sure your exhaust system is nice and loose too (but not too loose). Does your exhaust tip move much if you give it a kick side to side? I say this because the stiffer your exhaust is the more vibrations will travel to inside the cabin via the '8' shaped exhaust rubbers.

When it is looser the exhaust rubbers absorb more of the vibration and reduce the droning in the cabin.

Hope that makes sense.

[Elithrar]

I've found that heaps of the jap-brand mufflers don't drone; or, at least from what I've heard. Expensive, for sure; but you can normally pick up the muffler separately and get custom piping. Cheaper.

[someonestolecc]

Sorry guys my trouble isn't so much normal in cabin drone.. it's more-so the drone because it's too loud

Thanks guys - I'll try fitting a kaki muffler only first then if that doesn't work I'll put in a larger well flow middle muffler and leave the cannon on the end.

Bugger - was hoping to get away with quietining it for around $200...

[drunkenmaster]

Replace the "smallish resonator" in the middle with a mid muffler, $200. Done.

I am not sure what the talk of 5" tips are about, doesnt have anything to do with anything.

[someonestolecc]

Replace the "smallish resonator" in the middle with a mid muffler, $200. Done.

I am not sure what the talk of 5" tips are about, doesnt have anything to do with anything.

Thanks but I don't have a smallish resonator. I have no resonator/middle muffler.

And I thought p'raps the 5" tip would make it louder. *shrug*

[CerealKiller]

My drone's pretty bad, it's nice going through tunnels though - it's louder than most trucks

I have 3" dump/front pipe --> high flow cat --> 3" cat back w/ 5" muffler. No centre muffler which is why it's so noisy. But I'll be going to get one put on as I'm finding it too loud, OR if I can get a 2.5" stand cat back I'll put that on if it's cheaper.

[drunkenmaster]

Thanks but I don't have a smallish resonator. I have no resonator/middle muffler.

Well that still won't stop you from fitting one for $200 or less will it?

I dont understand that problem, is it that you dont want to fit anything in the middle?

EDIT: Oh i see now, I didnt see the person with the drone problem swapped half way through the thread

[someonestolecc]

drunkenmaster - the name says it all O_o

Well if I can get away with getting a good high flowing rear muffler then that'd be cheaper for me.. I'd just get a second hand muffler and either get it welded where my one is now is see if the pipe that connects to it can just connect to my middle pipe and be the right length/shape.

Otherwise I have to pay some dudes to cut and weld a middle muffler in... then when that starts to die I'll have to get a whole new length of pipe (unless I pay them to put flanges on). I guess this has it's advantages too as then I don't have to get a new rear muffler and I get to keep my cannon. (the cannon itself isn't a high priority howeveR).

I'm not sure I could get that for $200? I mean if you and S-Kid reckon just pay the man the money and get the pipe cut and get em to weld on flanges then stick a fatty muffler will do the trick and be the most economical and still give me good flow then I'll be happy to give it a go.

One side of me really really wants to keep my car as it sounds... then the fact ceffo got done for $600 just for his exhaust being loud makes me think.. maybe I should be totally totally legal.

The only thing to sway me at the moment is performance. If I can't get legal without degrading performance (much) then I might just tip the other way and try another muffler to make it a bit quieter but not quite legal.

Know what i mean?

[drunkenmaster]

Well, this is my story and my opinion, others may vary:

I had a loud car, I liked it.

I began to notice after a while I would drive my girlfriends car instead.

I got done by the EPA.

I bought a generic stainless steel centre-offset muffler from wholesaler for $110 (pretty cheap, but you could get it cheaper if you use mild steel), paid the exhaust dude $90 to cut out ~2feet of exhuast pipe where there was room to fit the muffler under the floorpan (actually was closer to the rear then middle) and then had him weld the new muffler in place.

Cleared the EPA notice at the local exhaust tester joint with ease.

Couldnt beleive how much nicer it was driving a car that didnt give you a headache after driving for more than an hour and make you have to yell at your passengers to communicate.

Love the sound of the motor rather than the drone of the exhaust.

Will do all I can to never have an obnoxiously loud exhaust again.

**disclaimer: was not a turbo or an RB motor, if anything turbo motors should be quieter**

Dig up the old autospeed article on the muffler shoot out, its dated but gives you and idea on flow vs styles etc.

[someonestolecc]

Good stuff drunken. Thanks for that I know what you mean.

See theres two halves of me... when v8s or rotors pull up I think ha ha my little 2L sounds as nice.

On the other half I gave my mum a lift the other day (first time shes been in the car) and as soon as she got in and I said hello I said "this car is rather loud isn't it?" I noticed she was raising her voice to say Yes. haha It's ok with the lads but yes I think I'll do what you did.

Thanks for the prices - that helps to know what it's worth.

Should I be getting flanges welded on so I can replace the centre muffler or just get it welded in?

Also any recommendations re: where to obtain the muffler from?

[drunkenmaster]

The flanges shouldnt add much cost at all, its really up to you. Its almost as easy on a street car that doesnt change exhaust setup too often to cut and weld as it is to bolt and unbolt so it's personal preference i guess.

Cant help you with shops unless you are in Melbourne, I would just rock up to several exhaust exhaust places (not the type you see in HOT4s) and ask for a price on what you want, much like everything else it will vary from store to store. What I did was find out where the wholesaler was that supplies all the exhaust shops and went direct, sometimes they will sell to you, sometimes they wont. Just dont tell the exhaust fitter where you got it from or he might crack the shits like mine did

They do it for a living so chances are they may even have a better idea of how to fix your problem than me. I have found though, that if your exhuast is really too loud, all the resonators and hotdogs in the world isnt going to fix it so dont beleive that if you are told. I learnt the expensive way. I have used hotdogs, large cased resonators, baffled resonators and it was all a waste of time and not to mention money.

[someonestolecc]

Hmm thanks mate food for thought there.

I've read that autospeed article too so I will have to specify a straight through middle muffler. I guess my idea is with flanges atleast I can replace it when it starts to flow badly... but as you say I guess a bit of pipe ain't worth that much to keep eh.

Hopefully with that in place it won't be as loud and will still sound ok - if it doesn't ill go the kakimoto for a bit more of that nice purry sound or try to find myself a cannon styled muffler that does the job.

Thanks for your help! As soon as I fix my exhaust manifold I'll be hunting around for this

[drunkenmaster]

I dont think there is such a type as "middle muffler", it will just be the same as an "rear muffler".

Probably your biggest choice here is centre straight through or centre-offset straight through. I'd use the latter, but the autospeed article shows you the flow differences which i think is negligable but others might think is too much?

[Oosh]

Cant help you with shops unless you are in Melbourne

But by the sounds of it you CAN help me!

So who's good in Melb, south-east preferably...

Cheers.