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BEC Noise

Jubal - 26/6/08 at 06:51 AM

Seeing the other post about exhaust cans and my inbox this morning with news that Elvington airfield now has tougher noise limits than the public road has got me wondering.

Currently, most of us make do with bike cans and/or manufacturer supplied systems and it's clear that as time goes on this isn't going to cut it.

As well as Javelin, there are whispers from other TDOs about impending changes to noise limits. At many circuits they already test bikes differently to cars (static) with the same engine making it much harder to get through.

Racers spend 600-800 on a system to optimise power and I think it won't be long before we're spending the same to minimise noise. I'm just glad to have had a couple of years of relaxed rules.

smart51 - 26/6/08 at 07:01 AM

What is the new limit at Elvington? My BEC measured 96.1 dB(A) at Cadwell park last year, which is probably low enough for me to get in at Donnington. I have a very large silencer, though.

Jubal - 26/6/08 at 07:12 AM

Elvington has gone to 98 static and 87 drive by. My BEC measured just measured 91db at Cadwell but they tested it as a bike. I can see more Cadwell days coming up

If yours was measured properly at 75% of max revs then there's hope for us all.

bugsbunny - 26/6/08 at 08:31 AM

Hope is fading fast... :-( I got turned down in Croft and have since changed airbox, installed insulation and have a brans new exhaust. I still very much doubt I will get down to 98Db but I have high hopes...

MK9R - 26/6/08 at 04:14 PM

I failed at Combe on tuesday, i managed to cobble together a muffler and squeezed through. I'm sure their meter is dodgy though, i tested louder with the muffler on than off, so i left it 10 minutes and got through at 96 db!!!

So now i'm looking for a good silencer, where can i get something from??

Jubal - 26/6/08 at 08:11 PM

quote:
Originally posted by chris mason
edited to add, it's not impossible to get a bec quiet, 92db's is acheivable, it just takes a bit of thought and preparation.

Specifically, what steps would you take?

ChrisGamlin - 26/6/08 at 09:00 PM

Something big like a 30" x 7" (well made) can and an airbox should get most BECs below 98db. Mines currently got the silencer but still runs a foam air filter sticking through the bonnet and thats been tested at 98db at genuine 3/4 max revs. Driveby would be another matter with the air filter mind....

The problem is the inconsistency though, realistically to guarantee you get on 98db static days, you need to look to get around 95-96db because there will always be environmental variables as well as the odd over-reading meter to contend with.

carlgeldard - 27/6/08 at 07:13 AM

I don't want to sound thick. But exactly how do they test the noise on a track day. I've got a sound meter here at work.
So I might do a quick test tomorrow. Just to find out what mine is now like after all the SVA bits fell off. Which had to be
replaced with bits that I had in the garage if you know what I mean.

Carl

MK9R - 27/6/08 at 07:28 AM

The static test is done by holding the meter it next to the exhaust pipe at 3/4 max revs. Normally i tell the guy doing it my max revs are 9k (have got away with 6 ), but last time the guy knew about bike engines and made me run at 7.5k, at i hit 102 db.
They also montiro noise on the track by having a drive by meter set a certain distance away from the track. Its usually 20 meters i think, but again this differs

All tracks have different levels on different days for bith static and driveby so its worth checking.

I've just emailed a guy from a company called 2bular, his stuff is amazing (had it on my elise), and he really knows what he is doing, only downside is he is very expensive.

Jubal - 27/6/08 at 08:52 AM

quote:
Originally posted by MK9R
The static test is done by holding the meter it next to the exhaust pipe at 3/4 max revs. Normally i tell the guy doing it my max revs are 9k (have got away with 6 ), but last time the guy knew about bike engines and made me run at 7.5k, at i hit 102 db.

If you're going to replicate this at home then the static test is done from 0.5m at 45 degrees to the exhaust at the majority of tracks.

MK9R - 27/6/08 at 09:32 AM

quote:
Originally posted by Jubal

quote:
Originally posted by MK9R
The static test is done by holding the meter it next to the exhaust pipe at 3/4 max revs. Normally i tell the guy doing it my max revs are 9k (have got away with 6 ), but last time the guy knew about bike engines and made me run at 7.5k, at i hit 102 db.

If you're going to replicate this at home then the static test is done from 0.5m at 45 degrees to the exhaust at the majority of tracks.

I know thats what they state, but i've seen them just stick the bloody thing in the end of the exhaust! No wonder there is variation in the results!! Its a joke that you can spend so much on a day, just fot it to be a complete waste of monmey and time because someone has drop the sound meter, or some numpty is holding it in the wrong place!

[Edited on 27/6/08 by MK9R]

Jubal - 27/6/08 at 01:47 PM

quote:
Originally posted by MK9R
I know thats what they state, but i've seen them just stick the bloody thing in the end of the exhaust! No wonder there is variation in the results!! Its a joke that you can spend so much on a day, just fot it to be a complete waste of monmey and time because someone has drop the sound meter, or some numpty is holding it in the wrong place!

Are you sure? I'd have complained. Most meters are ready mounted onto a pole of the required length. The pole is what gets stuck in the end of the exhaust.

bigrich - 27/6/08 at 10:19 PM

As Chris said i had my zx10r tested at 8000rpm at 92Db on sva using standard R1 silencers from an 04-06 bike. I also use an enclosed airbox to reduce intake noise. It is very quiet for a BEC but this was part of thethings i wanted for this car, haveing had the full on noisy blade BEC previously

MK9R - 1/7/08 at 06:44 AM

Just won an 1999 R1 end can on ebay for Ł15, si i'll whack that on and see what difeerence it makes

Jubal - 1/7/08 at 10:19 AM

quote:
Originally posted by bigrich
As Chris said i had my zx10r tested at 8000rpm at 92Db on sva using standard R1 silencers from an 04-06 bike. I also use an enclosed airbox to reduce intake noise. It is very quiet for a BEC but this was part of thethings i wanted for this car, haveing had the full on noisy blade BEC previously

This is the answer. Two cans are clearly better than one. Have you any pics of the manifold/link pipe routing?

MK9R - 1/7/08 at 10:20 AM

its a standard stuart taylor manifold, so not brilliant

MK9R - 1/7/08 at 10:24 AM

[img]http://www.locostbuilders.co.uk/photos.php?action=showphoto&photo=scoopz_com_l7_red_19_crop.[/img]

[Edited on 1/7/08 by MK9R]

[Edited on 1/7/08 by MK9R]

MK9R - 1/7/08 at 10:26 AM

bugger why won't that display!

MK9R - 1/7/08 at 10:26 AM

bugger why won't that display!

Jubal - 1/7/08 at 01:20 PM

I was asking bigrich...his setup is great with the cans coming out of the back but I wanted to see how/where they connect up underneath and at the front of the car.

pennpromo - 3/7/08 at 12:50 PM

I was at Castle Combe last week with my CBR1000 engined car. I have a Tony Law Exhaust, 4 into 2 into 1 then a big can. Measured 97.6 DBa at 0.5 metres static at 7,500 revs. Was quite surprised how quiet it was. It was a 100Dba day so I was easily clear. You can't beat a custom made system for the application when you tell the guy you want under 100Dba when he makes it. If it's too loud, don't pay !

Jubal - 3/7/08 at 01:06 PM

quote:
Originally posted by pennpromo
You can't beat a custom made system for the application when you tell the guy you want under 100Dba when he makes it. If it's too loud, don't pay !

That puts it quite succintly. Pretty much the thrust of what I was saying by starting he thread.

bigrich - 3/7/08 at 02:07 PM

Jubal, drop me a u2u wth your email address and i will forward you some pictures if thats ok with you

Rich