Noise Testing

[graham harvey]

Hi all,

As I was passing Brands Hatch on Saturday, I popped in for a noise test as I am looking at booking up Trackdays for June, July, August and although aware that 98db days were out I wanted to check what my reading was. I have a decat and cup pipe with standard final box. I was shocked that my reading were 115db and 1111db.
Judging from the forum my mods are fairly common, so are these limits not enforced much on the day or is there some sneaky tick I am missing.
Really wanted to get the car on the track this year but it seems that it is now out of the question. The tester's exact words were, 'not a hope in hell mate' !!

Any advice would be welcome.

Regards

Graham

 

[iangray100]

I think you mean 111db ...not 111db ..not even the space shuttle is that load on takeoff !!!

All I can say is..change the exhaust back to STD ....worked for me to get it on the track ...aircooled engines are by design a lot nosier than watercooled engines so we have less tricks to play with !

 

[graham harvey]

Hi Ian,

Yes 111db ! Yes I think, i'll have to remove the cup pipe. About 4 years ago I did a track day at Brands and one at Snetterton with the same mods but there was no testing.

 

[Steve Brookes]

I would say they made a bad job of the readings especially since they got one of 111 and 115 - that's a huge difference between two readings! It should be done at 3/4 revs (about 4800 rpm), 0.5 M from the exhaust at 45 degrees. My configuration is the same as yours except that I have a cat. My reading is consistently 102 db. I would expect a decat to take it to around 105/106 which is OK for most tracks (bedford and goodwood excepted).

 

[graham harvey]

Thanks Steve, that is interesting. I did think the difference was odd but also he had me rev it to 5,500.

 

[964rh]

106-106db on mine with the same set up Graham, this was done at one of the Oulton RS days by their noise police, so no hiding the rev counter as they were leaning in the window!

 

[graham harvey]

Thanks Rob - Was that at 4,800 revs ?

 

[964rh]

yep, on the dot as the person doing the testing virtually had their nose on the rev counter

 

[graham harvey]

Ah thanks Rob - think that explains it. At Brands they had me hold it at 5,500 - which would account for higher figure.

 

[Sean_Jaymo]

Had mine measured today at Castle Coombe, Standard system with cat removed and replaced with straight through pipe. 106db.

 

[mcgc0]

Used to have to go through this in my FIA Historic Rallying days.. Always though (MSA regs) as 0.5m and 4.5k revs. Not sure what is meant or implied by 3/4 revs though in this instance.

Also a recent MSA scrutineering bulletin is reminding of dasterdly wire wool tricks (I've seen it done too!) and extra diligence being asked of them. Rev counter accuracy does vary between the car's own, and then (like we had) a dashtop pro one. There is a case for (re)connecting whicever one gives the lowest reading ;-) But I am course not suggesting anyone does.