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

[andrew_mx83]

So i have been bitten by the damn noise test notice.
Knowing the car was way too loud i fitted a baffle plate after the cat with a few holes in and also pulled a lot of ignition timing out. the car was no quieter under 3000 rpm but noticably quieter from there up. it comes on cam around there and usually starts to get very loud if under load.
Todays produced a test result of 100.5db. so no dice, and not by far.

what are my next options? i want to avoid cutting the exhaust up if at all possible. im thinking of stuffing steel wool in in front of the baffle, does this work?

basic specs:
mx83 with a mild 7m-ge. 10.8:1 comp, 40thou over pistons, balance, blueprint
5 speed conversion - car got a LOT louder after this. im running a very light flywheel/clutch combo so it revs up quickly and has quite a bark.
intake cam retarded 3 deg
cai
exhaust is: 3-2-1 extractors to a 2.5" collector -> 2.5" high flow cat -> 2 x offset straight thru magnaflow mufflers. all stainless with mandrel bends all the way.

the car is usually quite loud. people that know me hear me from 2-3 suburban blocks away if im giving it some stick.


any thoughts??

ill try and get an extension out of the epa but if not i have until thursday to clear it.

[PlacentaJuan]

7mge lol

do ya think you got much more horsepower out of this engine with a huge zorst?

[Stefan]

Your car is obviously undermuffled, even though your are using 2.

Try a better and/or another muffler. My 1G w/ 3" mandrel exhasut was too loud for me with a single stright-through oval muffler, ended up adding another smaller one. And that's with a turbo in the way...

[Jt_70R]

you could always grab a stockie system from the manifold back, and fit that for the test. that way you dont have to carve up anything.

theres always plenty of gramps-spec mx83s being wrecked in the classifieds section.

[andrew_mx83]

for sure. 11ty billion hp gain from the exhaust.
2.5 aint huge on a 3 litre

[Kedderz]

1inch restrictor plate before cat, do test, win, take plate out.

[andrew_mx83]

putting on another whole system is starting to sound good. ill look into rounding one up.

is a plate with a 1 inch hole going to shut it up much more than what i have now (same thing but with about 10 small holes)? i can do that pretty easy. before cat is better than after?

[benjamin]

Stainless mufflers? They are always louder. Stainless is a much harder metal (more brittle) and doesn't "give" as much as a normal mild steel muffler or system for that matter. This is generally why they have more bark, as you say, because the exhaust pulses are being transmitted along the exhaust instead of being absorbed by the softer metal.

So, if all other options fail I would try fitting mild steel mufflers.

[CrUZida]

Get the rear muffler flanged and put on a baffle or turbo muffler to get it passed.
Then just shelve the muffler until you get defected again.

Shouldn't cost more than 300 clams.

[brett_celicacoupe]

i found the r32 gtr standard muffler is very good at silencing. the minimum throat diameter inside the muffler is no less than 2.75" too.

[oldcorollas]

is a plate with a 1 inch hole going to shut it up much more than what i have now (same thing but with about 10 small holes)? i can do that pretty easy. before cat is better than after?

plate with holes in it does almost buggerall for noise... tried this already

what would realyl help, is to throw away the shit "mufflers" you have...

get a good resonator fitted soon after cat, then get a big reverse flow muffler for back.. i mean biggest chamber that will fit under car in the space, and large enough in/outlets...
if you have 2.5 now, put a 3" reverse flow muffler

or the R32 muffler

Benjamin, the difference in strength and hardness between mild and stainless is buggerall when you consider the strength of the pulses.... neither is "soft" and stainless won't make it louder or have more bark. that is totally due to the design of the mufflers..

[The Real Roadrunner]

Benjamin, the difference in strength and hardness between mild and stainless is buggerall when you consider the strength of the pulses.... neither is "soft" and stainless won't make it louder or have more bark. that is totally due to the design of the mufflers..

I would actually argue that OC, each time i put on a stainless system it seems to have a much more "tinny" noise to it than the same setup in mild steel.

Matts, IS200 was always "tinny" with the stainless system but the same engine combo in a different car but with a mild steel system (same design, sizes etc) was alot deeper in its note with less raspiness.

cheers
linden

[julzy_quads]

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

[oldcorollas]

I would actually argue that OC, each time i put on a stainless system it seems to have a much more "tinny" noise to it than the same setup in mild steel.

Matts, IS200 was always "tinny" with the stainless system but the same engine combo in a different car but with a mild steel system (same design, sizes etc) was alot deeper in its note with less raspiness.

cheers
linden

you think that is from the piping? or from the muffler itself? is the staino muffler made form thinner sheet? different design?
i'm not saying it doesn't happen, just that strength is not the issue (they are about the same strength i suppose)
i wonder why?

[mrshin]

Come see me, I think I've got my old stocky MX83 system kicking around too. Best option though is to flange the rear, and make up a 2" tri-flow muffler for the sake of a noise test.

Michael
Unique Exhausts
(03) 9762 9930

[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