How to get a car under 90db (damn epa)

[richzx]

Everybody is telling you the same thing really tour mufflers are shit! Just get decent mufflers I doubt very much that you lose much if any power through a good quality muffler. Ask Linden for a price on his because everyone says how nice and quiet they are, do it properly as there's nothing worse than getting hassled by the fuzz because of the noise.

[CrUZida]

Magnaflow mufflers are usually of a very high quality.

[Toy77]

hey Guys,

I had a simmilar issue with my exhaust... i wrote up a thread with testing a few different ideas

http://www.toymods.net/forums/showth...ht=engineering

that doesnt look like it has linked - if you search for "engineering the toy" with me as the author it will come up.

I actually noise tested a few different plates in the exhaust system - benefits of having noise monitoring gear at work i spose....

cheers
Stew

[andrew_mx83]

na the mufflers arent shit at all, the car sounds horn, i get complimented on it at least once a week.

i just need to get it past the test and then it will go back to how it was. i certainly wont be adding any more mufflers for normal driving. just need something temporarily.
looks as though i may be best to borrow a standard system & fit for the test...will just be a bitch to wrestle those extractors out of the engine bay. they took forever to get in.

ill try and get up there after work this afternoon michael, i live not far from there now.

thanks for the help guys.
epa have told me to write in for an extension so ill do that today and see how it goes.

[beasht]

Easy fix, get yourself a big nasty round truck muffler. Similar shape to a cannon, straight through design but they have a hell of alot more baffling inside them. Wont look pretty but nothing a god tip wont fix and does the job if you want to get past EPA.
I had your basic 3A Racing 3" cannon and a resonator and i put out around the 100db mark then with the truck muffler and NO resonator or extra muffler I didnt go over 74db through the whole rev range and didnt lose any performance because it is still a straight through design and i was able to get rid of the resonator.
Oh and if you want the cannon on for a bit more of a gruntier sound during shows or whatever just get it flanged so you can swap back and forth

[Stefan]

I think oldcorollas has hit on a good point - do you have a resonator fitted?

This could make a big difference.

[Cressid@]

Get a restrictor flange, put after/before the cat.
My old 2.5" tested 92dB, after I put a flange with 2" diameter, got it down to 84dB and passed engineering.
Quick and simple, 2 bolts on and off under 5 mins.

[thechuckster]

a hot-dog style resonator after the CAT will take a lot of the bark out of the system plus will have little restriction (e.g. can leave in place).

A straight-thru or kinked turbo muffler (or any ebay cannon-style muffler) won't be long enough nor have the right outer-shell shape to reduce resonance and the internal ID of cannon-style mufflers make them not work the same way.

[oldcorollas]

Get a restrictor flange, put after/before the cat.
My old 2.5" tested 92dB, after I put a flange with 2" diameter, got it down to 84dB and passed engineering.
Quick and simple, 2 bolts on and off under 5 mins.

until he gets pulld up by the same cops week after week...

you can have it sound good and flow well AND be under the noise limit... and then you don't get defected and have to waste time going and getting it tested each time to clear the defect.

Cruz, i wasn't trying to say "magnaflow" are a bad muffler.. just that in this case, poster chose the wrong "kind" of muffler for the job

[andrew_mx83]

get scourers from safeway
stuff in exhaust, pass, wait for them to fly out

this seemed to work quite well.

i was going to have mrshin fit his old stock exhaust and get it tested like that but i was bored on sunday and figured i may as well give this a shot for lack of anything better to do. the car was as quiet as a stocker til around 3500 then got a bit louder but still quite muted.

tested at 87db @ 4200rpm. he said it only hit 90 on onverrun but it looked a bit more to me. either way its a pass so im happy.

thanks for the suggestions guys

[NME308]

If you arn't already blackbooked by the cops for pull over on sight, then you will be once the old lady who dobbed you in in the first place does it again a couple of times

Believe me when you get just a little bit older you will realize that some dumb noggin screaming sideways into your street waking you up with the thought that the aforesaid moron is coming through your bedroom wall will give you the understanding to quieten the damb exhaust down voluntarily.

I have been there and done that... And I can guarantee you that horsepower can be made quietly even naturally aspirated. Even if you think you like the exhaust note right now (remember rotor heads seem to like the satanic racket their junk makes) it will be much easier long run to shut it up! Even traffic light duels are much easier and more enjoyable with an understated exhaust note (not that we condone traffic light duels)...

cheers

[Duk]

Years ago I added a 'Gonzo' (sounds rather porno) resonator to my SC AW11 MR2 to help knock a few decibels off the exhaust racket. They seem to work well and the exhaust guy I buy my stuff from says they flow well but (at the time) he couldn't get flow bench figures from his supplier. I certainly didn't notice any reduction in on the road performance .
Anyways, it took my car from 97dB down to about 93/92dB . I was happy, Mr Plod was happy, win win .
BTW, they don't use any internal insulation/absorption material so the stainless steel 1's should damn near last for ever.