new exhaust giving me headaches!

[_turtle_]

is it possible same exhust on NA car will be louder then on Turbo?

definetly is in my opinion. the exhaust on the NA car is louder and drones. iv'e never heard the droning noise in the turbo, it mite be loud but doesn't drone. its the drone noise which is killing me atm. weird, from say 2000-3000rpm it will drone at constant speeds, if i hold it at 4000+rpm there is no drone and sounds quite nice.

thanks MegaGTS4, i will be going to exhaust place on friday and asking for a chambered resonator, now hopefully i'll sound like i know what i'm talking about and don't get ripped off!

thanks for the help everyone.

[Warpspeed]

Turbos quieten the exhaust a lot. The passageway in the snail of the exhaust housing tapers down to a small slot. The exhaust gas speeds up to very high speed to drive the turbine.

The restriction in the exhaust housing tends to smooth the exhaust flow, and this will greatly reduce the noise level.

Droning is caused by a resonance in the full length of the exhaust pipe. Pressure waves move back and forth along the pipe, and at certain speeds can build up to a deafening level. Large diameter pipes are far worse because the sound travels more easily down the centre of the pipe.

Small bore pipes offer a pressue drop, and this, along with pipe friction dissipates the sound down the pipe. It dies away going in both directions and cannot build up in amplitude to create the deafening drone.

There are several ways to overcome this problem, but chief among them are absorbtion, and decoupling sections of pipe to create sound traps.

Absorbtion is the primary function of the muffler. Fibreglass or steel wool within the muffler absorb the sound by converting the pressure waves to frictional heat. This does not work too well with straight through mufflers and large diameter pipes, because the sound goes straight down the middle without much absorbtion effect.

Decoupling sections of pipe is achieved by placing one or more chambers along the pipe. These chambers are usually within, and part of the mufflers construction.

What happens is a pressure wave travels along the pipe, and when it reaches a chamber the wave tends to spread out to fill the large volume. Some of the wave is reflected back, some is dissipated in filling the chamber, and some carries on down the pipe, but reduced in strength.

If the chamber volume is large enough compared to pipe volume, and if the chamber is perhaps half way down the pipe, then the two sections of pipe will behave independantly. They are decoupled, and will tend to drone at their own resonant period.

If you are really clever, or fortunate, the two separate pipe resonances can fight each other and further reduce the sound.

Mega GTS4 is spot on with his advice, but this type of muffler does not work properly if placed right at the back. It must be mounted somewhere near the middle, or towards the front.

[Steve]

Turtle, this may sound a little weird, but I had the same problem and fixed it by going down to spotlight and buying some 2" thick quilting material and some spray glue. I then cut several pieces to size and stuck them everywhere I could in the boot that was out of sight. This actually helped immensley and was quite cheep - about $15 all up. The end result was no more headaches. The exhaust is still loud but not deafening. Just hope the EPA don't find me

Steve

[GTR-80Y]

I'm having the exact opposite with my car......i want it louder!:lol:

[_turtle_]

I'm having the exact opposite with my car......i want it louder!

hehe, believe me GTR-80Y, quiet is all good!

Steve, that sounds like a cheap option but i want to reduce the noise outside as well. friends tell me they can hear me leaving and know exactly where i am till the next block.

[doxximus]

want my exhaust :devil2:

[Warpspeed]

A loud car may be cool, but it is also a cop magnet. Trust me.

[_turtle_]

warpspeed, thats another reason why i want to quiet her down. i can't afford to cop a fine and then have to pay more money to change it.

hey doxximus, how big is ur exhaust? does it drone at all?

[Warpspeed]

I know the feeling. The trouble is, that once they hear you coming, and focus their beady little eyes on you, you are stuffed.

When they have you pulled over on the side of the road, you are going to get the full works. Licence check, rego check, tyres, ground clearance, blow into this driver, - they are going to find something, even if its total BS.

Best just to glide past them in complete silence, and let the guy behind in the rice mobile, get done instead. Hehe.

[Pva_Glue]

well I got done once on Freeway due to loud exhust... I told cop this is BS...

but he gave me yellow...

so I went to pits all got claeared and got me self modification Permit.

so next time cop say anything about the modofication? then I shove me permits to their ass

:lol:

cheers

Joe

[Warpspeed]

I have a full three inch system that is quieter than stock (true) under light load, or when you rev it up in neutral. On the freeway all I can hear is wind and tyre roar at 100Kmh.

Flat out it is fairly loud, but probably still legal though. I have been sitting on zero points now for three and a half years.

A month ago there was a police car going in the other direction, In the rear view mirror I saw him do a U turn and come up fast behind me, I eased off (using the handbrake) and was just below the speed limit.

He put on the flashing lights and pulled me over. Walked right around the car, it looks completely stock, and told me my front numberplate was illegible. He was right. Cost me $24 for a pair of nice shiny new plates, which make the car look better anyhow.

Now if he had looked under the car, or under the bonnet, he would have put me off the road instantly for illegal modifications. My car is fairly radical, but because it is quiet and looks stock I can get away with it.

[A31_Cefiro]

My mate had a RX4 with a 13B NA engine. This car had the maddest exhaust I've ever seen. Twin 3.5" dumps from the engine right the way through, There were two hot dogs per outlet so 4 in total, this went back into a truck muffler with twin outlets. I've never heard anything louder. Outside it was loud, inside wasn't too bad btu what do you expect from that setup...

That car was fast. 12K RPM redline from a professionally built setup...

[_turtle_]

ok, just came back from exhaust place. they weren't very helpful kept telling me to take this exhaust off and they'll make a custom one for me. man, i can't afford that, then i just wasted all my money on this exhaust. sheesh.

gonna wait till monday now, and goto Dandy exhaust, heard they were pretty decent.

btw, if anyone wants to swap their current muffler for a bigger size one then let me know. so any turbo guys out there with a 2.5" oval shaped or something muffler and want the apexi n1 style chrome with 5" tip let me know.

cheers

[Warpspeed]

From your last post I gather you plan to replace the rear muffler.

I would leave it right where it is for the moment, and add a second chambered muffler halfway down the pipe.

Putting an offset chambered muffler right at the back is not going to give you the sound reduction you need. It will work far better closer to the engine.

You can try it right at the back, but I dont think you are going to be happy with it.

[_turtle_]

yep, i'm thinking about getting rid of the muffler, thats what the guy kept telling me the problem is.

he said, we could change the resonator, but "its like chopping ur leg off wen u have a headace", its not going to fix the problem.

but really, i'd prefer not to change it and just put in a chambered resonator as suggested by ppl here. plus i don't have money to do that.

i think maybe he was trying to get more money outta me by making me change the full exhaust hehe.