Exhausts for track days

[John]

Hi,

I am looking at changing the exhaust on the bike and I want to still do track days. I live very close to castle combe, which has an extremely strict noise limit 105dB (0.5m from exhaust at 75% of max revs(excluding redline)), this means even the stock exhaust would likely fail. I was going to try to go ultra quiet but I think I have now come to the conclusion that the s1krr no mater what exhaust it has will never be quiet enough for them.

So the question how is how strict are the other tracks? Silverstone, Brands, Donington, Cadwell, Snetterton, etc

If I can get away with it I think I would now like the AR GP3, which with the v2 or v3 can should make 106dB and 101db with the baffle in(not sure how it was tested but is listed on AR site). For this setup, which tracks do you think I would have problems at? As there seems to be a lot of inconsistencies with the testing method, e.g. position, % of rev limit, etc

 

[RossHarper]

Castle Combe is round the corner from me as well. Mine is Decat with Akra stubby and it fails miserably at CC. But mine with Cat and normal exhaust did pass at Castle, I never tried with CAT and Akra stubby.

Castle Combe is very strict on Db levels. I believe most people on here don't have a problem with Decat and a normal length can (not a stubby) at ACU guideline tracks

 

[John]

So with the baffle in a short exhaust like this would fail most tracks still? Most of them seem to list the limit as 105, which if they use the same measuring method as AR this should pass with the baffle in

 

[Wild Pete]

Full Leo Vince exhaust and baffle in recorded 103db. W/out it was just at 105db. I got blacked flagged on the last run without the baffle last year at Snetterton.

 

[andybarsblade]

Full akro with baffle is 99db so I had to mod my baffle a little to make it safe. I find its not the engine noise but more the bangs from the quick shifter that cause the problems?

 

[unionjack]

Full Leo Vince exhaust and baffle in recorded 103db. W/out it was just at 105db. I got blacked flagged on the last run without the baffle last year at Snetterton.

The microphone is on a pole at the start of the pitlane, just don't give it full beans until past it.

 

[bananaman]

Most manufacturers give a conservative db reading, they need to sell em ! I had an ar with ultimate side exit which needed 2 baffles to just get through but that just restricted it to fk. Changed in the end to get through noise test, was always touch and go whether it would get through or not and ruin the day.

 

[bananaman]

Oh, and not all tracks use the same testing method. Silverstone for example test at 75% of revs, 10,500?

 

[Burner]

This is an interesting one. My old GSXR thou with Moriwaki system which has never had a baffle blows 98db on the ACU test (5.5krpm, 45degrees, 0.5m distance). From what I remember from Silverstone last year it was an on track 102db drive-by. If you pinged the meter it was off if you'd not bothered to fit a baffle, if you had then I think you had a chance to pass the static test, which I'm sure even a road system would struggle to pass.

I've a full Ti Arrow system on the S1, it's full length pipework but the can's quite stubby. It blew 103 and 102db on recent trackdays, baffle in. 108 with baffle out, all under ACU test conditions. Rode the bike minus baffle at an unsilenced day at Donington a couple of weeks ago and my dad said the only bike any louder was Gino Rea's Moto2 bike......

I've a track day a silverstone in a few weeks. Do they still operate the 102 drive by as the first line of noise policing or is it a static test before being allowed out?

 

[bananaman]

I was tugged in pitlane waiting to go out, think it was the look of it that drew attention, fortunately I had the standard with me, lost a session changing it back. I understand rules are rules but the attitude sucked "change it or fk off" attitude. It was Silverstone staff, they wont be getting anymore of my money.

 

[Godzilla]

I was tugged in pitlane waiting to go out, think it was the look of it that drew attention, fortunately I had the standard with me, lost a session changing it back. I understand rules are rules but the attitude sucked "change it or fk off" attitude. It was Silverstone staff, they wont be getting anymore of my money.

You changed a full system in an hour or so? Impressed.

 

[baz]

Full Akrapovic system(long can)with baffle shouldn't cause a problem anywhere(98/99db)and only loses 2hp with the baffle in.

Silverstone tend to use the fly-by but if you have a stubby can you are asking for trouble and will probably be static tested.

 

[andybarsblade]

Full Akrapovic system(long can)with baffle shouldn't cause a problem anywhere(98/99db)and only loses 2hp with the baffle in.

Silverstone tend to use the fly-by but if you have a stubby can you are asking for trouble and will probably be static tested.

I get black flagged with mine at Donny but as I said I think its the QS pops that do it

 

[bananaman]

You changed a full system in an hour or so? Impressed.

LMAO ! no it was an AR system so slid the mid pipe off and re-fitted the cat and oe can

 

[bananaman]

I get black flagged with mine at Donny but as I said I think its the QS pops that do it

wheres the fly by at Donny? am there in a couple of weeks

 

[Godzilla]

Beginning of the start finish straight I believe, on the pits side of the track so short shift there and stay over to the right.

 

[Burner]

Silverstone tend to use the fly-by but if you have a stubby can you are asking for trouble and will probably be static tested.

The can's not too short, about 300mm. I've made an extra baffle that fits to the back of the standard baffle. It's made from some perforated stainless tube, 2 slits cut into the sides 180degrees and 30mm apart, then the upstream wall bashed in with a ball peen. This catches the gasses, throws them out and then they have to negotiate the perforations to exit the can. Tested it straight thru', standard baffle, then standard baffle plus homemade effort, with an iPhone db meter. Waste of time.....! All 3 measured between 100-102db at 5.5/6k. Homemade effort was much quieter with the mark-one ear lug though. Confines of the back yard didn't help much I'm sure.

Just checked the silverstone trackday T&Cs and they state a static test before being let out...... 105db is loud but a s1000 at 10krpm is loud too!

 

[Runout Rodney]

I used to do track days at Castle coombe on my 1000rr , It wouldnt pass with the stock pipe, so i put an Austin Racing silencer on it and it passed ! Their noise test is 3/4 throttle with the tester a meter away
105db limit. This set up gave 103db but make sure the bikes as hot as possible before you get it tested.

I now have a Acrapovic fitted, so i use my speed triple at coombe and 1000rr everywhere else.

 

[fatbob]

Full arrow system with baffle in 98........... Wouldn't bother testing without baffle as it simply wouldn't pass

 

[Runout Rodney]

Full arrow system with baffle in 98........... Wouldn't bother testing without baffle as it simply wouldn't pass

Is that at 10,000 revs with the noise meter, a meter away ?