Jump to content
SAU Community

Recommended Posts

Hi all,

Just a quick question, I recently bought a 3" greddy power extreme II cat back exhaust system with a 3" front pipe, the thing looks great and really isn't that loud (if compared to whats around) but has a nice grunty sound when you accelerate(not a droning noise), Now I thought I would be Pro active and go to an exhaust outlet that is a EPA approved noise tester and get a noise test done to my exhaust at EPA standards, just to see how I would fair, to my dismay the exhaust had a sound pressure reading of 93db(a) (90db being the legal limit), just 3db over the limit !!

Question: Is there anything that can be done to easy that sound pressure down a little?? any tricks of the trade?? can the exhaust be wrapped to help deaden the noise ? or is there anything else that might help drop the sound pressure down just a fraction? please help ....

PS Please dont post stupid obvious responses like, put your stock exhaust back on, or you will get a public :dry: for your troubles...

Thanks all.

Edited by immortal^

ok this might sound stupid (and i wouldnt recommend for street) but my freind put some steel wool in the zorst to clear EPA...basically took ALL the sound out (and probs kept all the exhaust gases in)....a silencer will do the job easily

I wouldnt worry about it that close, theres usually a tolerance allowed for machines such as these i.e. as a result of other noise interferance, position when taken (wave patterns/nodes cancelling in/out), plus more. I would say +/-5% easy which would make your exhaust comply with EPA

Otherwise, stick some steel wool in there, it will deaden the sound enough to pass a epa test and will burn out after about a week. Doesnt harm exhaust at all..... o/wise goto motorbike shop and get internal fibreglass baffle to suit 2 stroke muffler and stuff that in there (you'll have to dig that out cos it wont burn like s/wool)

Unfortunately if you wrap the exhaust you'll just force more noise out the back straight into the device :thumbsup: (it will make it quieter in the car for you) only way to quieten it is improving the internal baffle (increases turbulence) hence above.

Alternatively you may be able to buy/fabricate a restrictor for your muffler. These fit into the tip and increase backpressure at the outlet causing the sound to bounce back into the muffler, in turn cancelling some frequencies and disapating more noise through the baffle

all these methods will increase your backpressure obviously and decrease your peformance at high rpm.

fit a restrictor in between pipe one and two. Tkes less than 2 mins to remove and replace.

think normal gasket but with a 2" hole instead of a 3" hole... works a treat for epa noise testing :)

post-34927-1192760368_thumb.jpg

I wouldnt worry about it that close, theres usually a tolerance allowed for machines such as these i.e. as a result of other noise interferance, position when taken (wave patterns/nodes cancelling in/out), plus more. I would say +/-5% easy which would make your exhaust comply with EPA

Well your wrong there unfortunately.

93 is 93. There is no "variance" allowance. Never has been.

So moving on, you probably need to look at changing a muffler to a better one.

3db is reasonably easy to knock out and keep it flowing.

Hell my 3.5" made 93db aswell, so easy to get it a bit quieter with a better muffler or whatever.

You can weld in restrictors, but thats a pin in the ass each time. Although with 93db its highly likely that you wont be pinned.

I wouldnt worry till you get the letter in the mail as 93db is much quieter than the usual 100+ systems that most people have.

A guarantee you rekon? I dont think so.

I know a number of people who have installed hot-dogs thinking it would work... and in the end had little-to-no impact to the overall db, the 'drone' is affected more than the outright noise based on what ive seen

to get mine passed i made up a reducer in the back of the cannon , it slipped in side the tip had one little rivet up from the bottom to make sure it didnt come out during rego check , in steed of a 5 inch hole in the cannon it was like 3.5inch or something didnt look stupid , used another piece of ss pipe to go down the canno bout 3 inchs and then a bit of pate tig welded to the end of the 3.5 inch piece and then put it in the lathe to machine it round and bore the internal dia out. worked for me easy to take in and out , made an easy 5-10db difference that what i did any way cheers

I personally wouldnt worry, 93 db is exactly twice the sound pressure of 90db. 90 db is really quiet, to got my Z32TT to 90 db i had to bolt in restrictors and heaps of steel wool, it sounded like a sewing machine, and i didnt boost it as it felt terriable, just wait for the letter, and hopefully it never will.

PS the sound test is done not under load, thats how all the "factory" V8's and the like pass, hold them at a steady 3000rpm and their quiet(thats where the test is done), give them a stab, and they bark.

fit a restrictor in between pipe one and two. Tkes less than 2 mins to remove and replace.

think normal gasket but with a 2" hole instead of a 3" hole... works a treat for epa noise testing :thanks:

+1

Really easy 5 minute fix to make the problem "go away" why its getting tested. I would only muck around with mufflers if it was annoyly loud. 93db isn't very loud at all.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Dear folks My family members have 4 different cars : Triton 2015 and Corolla 2011 and Mazda3 2012 and Hyundai Elantra 2014 Looking to buy engine oil funnel spill free What I found are are below  https://www.amazon.com/gp/aw/d/B0BBTTJNKX?ref=ppx_pt2_mob_b_prod_image&th=1 https://www.ebay.com.au/itm/145553221359?srsltid=AfmBOoqYBU6Ptw0LU_bAp_k67U3qkF97HHvePkA7iHZw8vUmiwoIRaRr https://www.amazon.com/gp/product/B09X23TCS5?th=1 Is there a funnel with attachment that fits most cars ? Don't mind to spend for a decent quality  Thx  
    • Stock ECU (or more accurately stock tune) absolutely refuses to go over 10psi and behaves like you have seen. The Nistune is the same if it is the stock tune. If the Nistune chip has been tuned, the resulting tune could be literally anything for any combination of parts. The Nistune just makes the stock ECU Tunable.
    • So stock ECU does not like anything above 10 psi?  That Nistune one is just for "try" if it will be any different, I know it need to be tune for that. I know but YOU may know about these problem but i/we dont. They few little Skylines here let alone people who know anything about tham so that is why iam asking here  
    • So now we have a radiator with no attachments whatsoever. It lifts up with a particularly tight spot between the drivers side air box mount and the lower radiator outlet, but if you've got this far you will sort that too. This is the lower mounts with the rad out so you can see where the rubber bushes go, it is a straight shot upwards Done! Assembly is the reverse of disassembly, with blood less likely to be shed.
    • Right, onto the second last trick. The Air Con condenser is mounted to the front of the radiator and stays in the car when the radiator is removed. There are 2x 10mm headed self tappers holding the top of the condenser to the radiator, remove those The bottom of the condenser is attached to the radiator with clips. You need to lift the condenser out of those clips and clear (up, then forward). f**ked if  could work out how to do that last bit with the front bumper on. I hope you can, and you share the trick.  Bumper removal probably deserves its own thread one day once I've recovered the will to live, but basically you need to remove the wheels, front inner guard liners (clips and 10mm headed bolts), the self tapper between the guard and the bumper at the rearmost point of the bumper (same as an R32 that bit), any remaining clips at the top/front of the grill, an absolute bastard design with a plate that holds the top of the bumper above the headlight each side (only 1 bolt which is tricky to get to, but the plate catches 2 places on the bumper and must be removed....carefully!) and push clips between the bumper and guard under the headlight. If you've done all that you will be faced with wiring for the fog lights on both sides and in ADM Q50 RS at least, 4 nasty tight plugs on the driver's side for the ADAS stuff. So, the clips at the bottom look like this on drivers side (looking from the front) And on the passenger side (also from the front), you can see this one is already out Clearance on both of these are super tight; the condenser needs to move up but the upper rad support mount prevents that, and the radiator can't move down far because it is (rubber) mounted. Once you achieve the impossible and drop the condenser off those mounts so it does not stop the rad moving, you are good to go
×
×
  • Create New...