tegwin
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| posted on 29/5/08 at 01:42 PM |
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BEC noise on a track day?
To those of you with BECs, how well does your car cope with the (relativley) strict noise resitrctions on general track days?
Im trying to work out what exhaust setup is best for my trackday car, and obviously need to design it for power, but keeping it within the noise limit
might also be kinda handy..
So what do others do?
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Paul TigerB6
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| posted on 29/5/08 at 01:55 PM |
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A lot of noise comes from the induction side so need to look at that too. My plan is to go for one of those shiny Pipercross airboxes on my own car
when i get that far but basically the standard airbox is much quieter than a sausage filter
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Jubal
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| posted on 29/5/08 at 01:56 PM |
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Historically I've never had a prob being under 105db with either the MK can or an R1 can and a standard airbox. The car now has a second hand
can off a megabusa/blade, which seems OK noise wise but not properly tested yet.
A mate of mine has just returned from a 95db "road silenced" day where he was told by the organiser that limits were on the way down
inside the next few years so I guess we all need to think about this.
There's some chat on PH about it now:
quote:
The problem with many BECs is that owners just slap on an aftermarket bike can and expect it to be sufficient because they're used on the
road. Road bike noise levels are measured completely differently to trackdays though, so just because the can has a BS kite mark stamped on it to
signify its useable on the road, doesnt mean it will get through trackday noise regs
Unless you don't have room for a decent sized can on the side (Furys and Phoenixes etc spring to mind), there's no real reason for a BEC
to be be excessively loud though. I fitted a 29" x 7" repackable can to my R1 BEC and despite still having an open filter that sticks
through the bonnet (therefore more induction noise), it can happily pass a 98db static test at genuine 3/4 revs. It would currently struggle with a
Donny / Goodwood drive-by with the open TBs allowing too much induction noise out, but an airbox should resolve that and make it safe for most
events.
I decided to ring Oulton yesterday and find out how differently they measure cars and bikes:
quote:
It's a good point. I rang MSV about it today and they would test my engine at 5500 revs at 0.5m at a 45 degree angle if the engine was in
a bike. So clearly there's a big penalty for the fact the engine's in a car.
In the car it's at 75% max revs!!
[Edited on 29/5/08 by Jubal]
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wheezy
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| posted on 29/5/08 at 02:05 PM |
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There is no substitute for size If you want to get below 100Db and still keep a straight through system you will need at least a 7" can, the
longer the better. I have just managed to squeeze in a 7" can but at 24" long it may still be to noisy.
With a standard MK can I only managed 110db at 3/4 revs. You can fit a baffle but you will loose power in the higher rev range.
Dave
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PAUL FISHER
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| posted on 29/5/08 at 02:59 PM |
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Its the driveby now whats the big killer at trackdays,one of the worst being Donnington,there you can pass the static 98db's,but then get black
flaged on driveby noise ,as stated above induction noise is usually the cause of this.
So when ever possible keep your standard induction setup,and fit as bigger silencer as you can,MK now supply such a silencer,the trade off is it is
quite heavy,but I have no problem passing noise tests,it also can be repacked,not cheap,but neither is a black flag on a track day.
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tegwin
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| posted on 29/5/08 at 05:20 PM |
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Chears for the input.
I have a zx9R engine as well...Has a really nice sausage filter on it, but thats going to end up in the scrap pile I suspect
So any info you, or anyone else has on a locost airbox would be awsome!!
[Edited on 29/5/08 by tegwin]
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Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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smart51
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| posted on 29/5/08 at 05:26 PM |
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I had a 6" dia x 26" long straight through can on my R1 BEC at Elvington and it measured 102 point something Db. I fitted a 6" dia
x 5" long can in between the original and the manifold and it measured 96 point something at Cadwell park.
For drive by noise, your induction road is almost as loud as a loud silencer.
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