How to make a quiet exhaust ?

[kim0663]

I've got a full 3" s/s system that the previous owner had made up for my jzz30 soarer. Failed wof today, 101dB
But it gave me a good excuse to quieten it down quite some bit. I'd like the car to be like.... silent, no exhaust noise when normal city driving.

The setup is a 3" downpipe off the turbo Y pipe, no resonators then splits into 2x 2.5 " pipes into small ish but twin tip mufflers.

Thought about putting in resonators but woolf mufflers told me that it'd only bring it down to about 95dB. Thats with two 18" resonators. Which isn't good enough!!

I found a soarer uzfe exhaust system on trademe tho, and was wondering if i replaced the my mufflers to these ones, would it be close to silent? Im guessing it wouldn't be as quiet as factory as factory ones have more mid mufflers....?

Would it be a good road to take? or are the factory rear mufflers not enough to quieten down my car? Im not really fussed about losing some flow/power (well..it's not the fastest car in the house in the first place ! )

[strx7]

part of the problem is its stainless steel. If you replaced the mufflers at the back with larger more "muffling" mufflers you'd probably be sweet.

If you put mufflers instead of resonators part way along it would probably also achieve the same thing

[edwagon]

I've made exhaust systems for my jzz30 and jzs147 and both were nice and quiet. I used mild steel, which is half the battle won (as strx7 says), but what really makes the difference is the mufflers.

I ran a single 3" from the dump back through an 18" reso in the centre of the car, and then split into twin 2.5" pipes, with straight thru, big, oval mufflers at the back. The big, oval mufflers are ugly, but have heaps of packing around them and are quiet, yet still flow well as they are straight through.

You could ask woolf if they'd put an oval muffler in the middle of the car (instead of reso) - should be able to fit a nice long one there and that'd take alot of noise out of it - otherwise replace the rear mufflers with something thats gonna muffle!! Those stainless cans don;t do alot except look good

[Stealer Of Souls]

Could try adding the two resonators and changing the end mufflers to something a little smaller and as strx7 said, something more muffling. I hear stainless "pings" and mild (??) steel is better for quietness.

I also hear that some factory exhausts (maybe not a soarer but some manufacturers) have a valve type thing that blocks off one exhaust path until you the exhaust volume goes beyond a certain point. This would turn you two pipe into a one pipe exhaust. I think that would quieten it up some what (at least until you boot it).

If you really don't care much for power, the more extreme end of the deal might be the reso's, then reducing the pipe from them to the mufflers another 1/4 or 1/2 inch AND the new rear mufflers....
I've seen an article on Autospeed which suggests the rear muffler usually impacts the least on performance for a certain amount of muffling.

[Bazda]

Easy fix, Get a silencer for the muffler, they make them in all sizes there days to fit anything.

I run a 3" system the whole way through to a cannon type muffler, pretty loud! as soon as I put in the silencer its fine, as quiet as a road car (nearly).

[strx7]

I've generally found what effect the tone of the exhuast is the length of pipe after the muffler.

Does it drone at the moment???

[kim0663]

yes ... ALOT of drone which is the reason i want a silent muffler.

I'm going out right now to have a look at the uzz30 mufflers, so might retro fit that to my rear pipes as i believe they have the same 2.5" pipeing and then i can flange it so it's interchangeable just incase for future

[strx7]

do you NEED to keep it twin system at the back? if no, ditch the stainless twin system and just go with a single 3inch with a couple of descent mufflers and use mild steel not stainless, and possibly wrap the mid section of pipe (under seating area) with fibreglass tape.