996 gt3 rs dB level ?
Discussion
fisky13 said:
just got measured at cadwell park at 104dB, bog standard car,this cant be right ?but does anybody know what it should be , going on some 101dB track days,could i have any problems?
i was on the same day at cadwell. my standard 205 gti is normally 96dB @4500, but it measured 99dB that day. it was very cold and i have a suspicion that they were measuring it wrong...squirejo said:
there were 2 standard ones lapping bedford autodrome on Saturday, which has had a well publicised clamp down on noise. Which makes me conclude your reading was abnormally high.
I was in one of them. Both of us had issues with static and had to let the chief instructor drive our cars past the most difficult meters.I was asked to rev to 4.5k for my reading and off side pipe was 101db. Near side pipe was 105 db! On driveby I was fine all day and that was going past the most difficult meter at 7500 rpm next to another car.
My friend was in the other car and had similar issues although they only asked him to rev to 4k...
Couple of things that are remarkable :
- They've started measuring both pipes which is a shame as they used to only do the off side which is quieter on both the RSs that were there on Sat.
- My friend with a noble failed static and driveby. He then came back 2 hours later and they re-static tested him. This time his reading had dropped by 5db! His car was warm both times and they double checked with 2 meters on the retest. Both showed the same reading so I don't think the meters were out. The day had warmed up a little, but a change in 5db is enormous over a couple of hours. I can't understand it unless he had trouble applying correct revs for the reading.
- I've never failed static there before. No idea why I did this time. My car now has 18.5k miles on it, and my mates has well under 10k.
If it was simply atmospherics affecting the static reading by 5db, I'm not sure how we are meant to work around that. The reading is taken from right by the exhaust pipe and such a massive variance is a nightmare to work around.
fisky13 said:
just got measured at cadwell park at 104dB, bog standard car,this cant be right ?but does anybody know what it should be , going on some 101dB track days,could i have any problems?
What revs were you measured at? Do you have your own meter to test at different revs to see if you get the same as tehm or different?Bert
screwloose said:
Keeping in mind that the db scale is a logarithmic scale a difference of 5db is HUGE!
For example 100db is twice as loud as 90db!!
Err, no. 100dB is 10 times as loud as 90dB. Yes, the scale is logarithmic, but it doubles for every 3dB, not for every 10.For example 100db is twice as loud as 90db!!
http://en.wikipedia.org/wiki/Decibel#Acoustics
It may be that whoever was operating the meter, above, had it on the wrong weighting. SPL [Sound Pressure Level, i.e. "noise"] meters have several different weightings to account for the fact that the frequency response of the human ear is not flat.
Edited by Zumbruk on Saturday 23 February 11:24
Edited by Zumbruk on Saturday 23 February 11:24
Zumbruk said:
screwloose said:
Keeping in mind that the db scale is a logarithmic scale a difference of 5db is HUGE!
For example 100db is twice as loud as 90db!!
Err, no. 100dB is 10 times as loud as 90dB. Yes, the scale is logarithmic, but it doubles for every 3dB, not for every 10.For example 100db is twice as loud as 90db!!
http://en.wikipedia.org/wiki/Decibel#Acoustics
It may be that whoever was operating the meter, above, had it on the wrong weighting. SPL [Sound Pressure Level, i.e. "noise"] meters have several different weightings to account for the fact that the frequency response of the human ear is not flat.
Edited by Zumbruk on Saturday 23 February 11:24
Edited by Zumbruk on Saturday 23 February 11:24
DanH said:
Sean Edwards said:
I was at Bedford today with a client in a 996 RS and he was measured at 101 static and 78.5 drive by.
Did they do both his exhaust pipes and what rpm?Mate, standard 996 RS never gets thrown off Bedford. Porsche's are always bad on static, but fine on drive by!
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