Stott
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 posted on 19/6/10 at 12:17 PM |
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IVA retest Monday - Noise Too High - HELP
Hi, this car below is going for it's retest on monday, the noise was 103.5 at 9000rpm, which it failed on. It has since been covered over and
all the covers at the rear lagged in sound deadening material, also another cat is in it, a db killer and it's still 101.
We tried moving the exhaust so it went up one side and exited behind the front wheel with another silencer in it but it's still 100.5
Any ideas what we can do asap? if there's anything we need to buy then we've only got today to run about really.
Any help appreciated, cheers
Stott
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graememk
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| posted on 19/6/10 at 12:37 PM |
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stuff the silencer with wire wool and security so it dosnt come out
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BenB
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| posted on 19/6/10 at 12:51 PM |
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Ooooooh nice!
9k is rather high to be doing the noise test. What did you put at your peak RPM?
Trouble is it'll be difficult to change it now for the test so you better start stuffing wire wool up the exhaust 
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Stott
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| posted on 19/6/10 at 02:20 PM |
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peak rpm was stated at 12k but peak power was put as 10500 ish
the tester is adamant that it needs to be 3/4 of 12k but we had heard it was supposed to be 2/3 of peak power meaning about 6700rpm, but who knows
it's not the exhaust that's the problem though, it's the mechanical engine noise that's doing it, the pipe is nearly silent
now! longer than std with the std cat in it, plus an additional cat, plus a noise insert!
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RichardK
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| posted on 19/6/10 at 02:36 PM |
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Think I'd be looking at temporily covering the engine area in some sort of vinyl cover with a foam/foil backing, trick will be making it look
permanent, fiberglass would be better but no chance of making it in time hence the vinyl suggestion.
Was thinking of something like a flintstone roof but further back!
Cheers
Rich
[Edited on 19/6/10 by RichardK]
Gallery updated 11/01/2011
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Dangle_kt
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| posted on 19/6/10 at 02:39 PM |
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Lag the air box in noise deadening mat - like you use to cover the firewall/door skin in a production car.
I lagged my airbox and it helped. Get the stuff that is fire retardent as it is near the engine.
If it is the mechanican engine noise then you either need to 1) move the end peice of the end can so that it is further away from the engine and
therefore the noise ..a bodge but the distance will help or 2) board off the entire back of the engine bay and lag in sound deadening mat
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PeteS2k
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| posted on 19/6/10 at 03:01 PM |
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According to the IVA manual, noise should be at:
75% of Max Power speed - 7875 rpm
or if max power speed not available (or I guess if the tester doesn't believe what you declared!)
2/3 of Max speed - 8000 rpm
So you should be able to save 1000rpm by querying that and referring to the manual. That should be worth a dB or two... with some of the other mods
you've already tried, that might even be enough.
Car looks superb, by the way 
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Stott
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| posted on 19/6/10 at 06:44 PM |
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The engine is covered from all angles in plastic, lagged with sound absorbing mat, we just used dynamat extreme on all the ali parts and scoops, floor
etc, we put absorbing mat on the rear of the seats to counter any reflected sound and it just measured 103 on our meter which is a bit suspect, it
showed 98 at idle just now. It's the £20 maplin one, dunno if it's any good.
The exhaust was moved to exit by the front wheel with another silencer but that made it louder!
The engine is solid mounted though which doesn't help matters at all. we've even used those jml vacuum bags stuffed in between the engine
and covers and the rear seats, full of expanding foam to fill all the voids............
We're trying to get hold of a better db meter now, if it still looks bad I guess it's cancel the retest and try to think about making
bodywork of sorts for it.
Cheers guys
Stott
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T66
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| posted on 20/6/10 at 09:49 AM |
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Tester sounds like a helpful prick !
good luck
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ed1801
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| posted on 23/6/10 at 08:45 AM |
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Well, did it pass?
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cloudy
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| posted on 23/6/10 at 08:52 AM |
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I see a certain amount of inspiration from my build! Well I suppose I should feel flattered  Good luck with the noise test, maybe think about some
temporary rear panels...
www.warnercars.com
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