Silencers again
Discussion
Following the posts from ChrisV in March, I've just had a system made for my SR3 by Neil Handbury Racing. 98db static (7500rpm) at Castle Coombe earlier this week, but revs much better than my old system, which was the Radical "quiet" silencer with another silencer attached. Very nicely made and fitted.
I need to do something,
107db at brands yesterday at static at 7500rpm,101 was the limit.
I "lowered the rev limit" to 8000 and he let it pass.....just revving at 6000rpm.
I altered the dash lights and kept it below 8500 all day and was never black flagged by tripping the driveby. Interestingly I did go full revs for several laps at the end and no one batted an eyelid.
There was a palmersport JP something or other there, with an interesting clip on with no spanners required that didn't seem to be too restrictive and kept it quiet. I may see if I can find the thing and try it.
107db at brands yesterday at static at 7500rpm,101 was the limit.
I "lowered the rev limit" to 8000 and he let it pass.....just revving at 6000rpm.
I altered the dash lights and kept it below 8500 all day and was never black flagged by tripping the driveby. Interestingly I did go full revs for several laps at the end and no one batted an eyelid.
There was a palmersport JP something or other there, with an interesting clip on with no spanners required that didn't seem to be too restrictive and kept it quiet. I may see if I can find the thing and try it.
I was discussing the noise of the SR3 with Neil Hanbury the other day and he said that when they were testing the new system, by holding the clutch down when noise testing reduced the results by 2dB (so a significant drop when you are in the 100+ dB range). When I go to noise testing, I tend to put the car in neutral, so maybe in neutral with the clutch down is worth a try!
I was also at Brands yesterday and got higher readings than I have got at other circuits.
It seems to me that SR3's always have problems with the static test but not the driveby.
I think it is all the noise from the drivetrain and intake that echoes around the engine bay so the idea of pushing the clutch in makes sense.
It must be the frequency as some of the other cars are consiederably noisier on the driveby than the SR3's but still pass the static.
It seems to me that SR3's always have problems with the static test but not the driveby.
I think it is all the noise from the drivetrain and intake that echoes around the engine bay so the idea of pushing the clutch in makes sense.
It must be the frequency as some of the other cars are consiederably noisier on the driveby than the SR3's but still pass the static.
I did find halfway through the day, the 4 rubbers holding the airbox to the throttle bodies were not connected any more and thus not filtering air. Possibly caused by me removing the clam solo.
Maybe I had a lot of induction noise from this that I didn't notice before. Never gone 107 before.
Maybe I had a lot of induction noise from this that I didn't notice before. Never gone 107 before.
We also had to bulls
t our way through the static test on a 101db day as we were getting over 102 at only 4K on our SR1. They did reluctantly let us onto the GP circuit and it was fine all day even giving it the full beans. In contrast there were two Litchfield GTR's both passed the static but both were black flagged during the morning. I think on the Radical its partly due to the everything being at the back. We have just purchased one of Radicals 'very quiet' boxes but it is a really tight fit but does seem to drop readings by 10db or so on my simple IPhone app. Will test at Bedford soon..
t our way through the static test on a 101db day as we were getting over 102 at only 4K on our SR1. They did reluctantly let us onto the GP circuit and it was fine all day even giving it the full beans. In contrast there were two Litchfield GTR's both passed the static but both were black flagged during the morning. I think on the Radical its partly due to the everything being at the back. We have just purchased one of Radicals 'very quiet' boxes but it is a really tight fit but does seem to drop readings by 10db or so on my simple IPhone app. Will test at Bedford soon..Atom Ant said:
We also had to bullst our way through the static test on a 101db day as we were getting over 102 at only 4K on our SR1. They did reluctantly let us onto the GP circuit and it was fine all day even giving it the full beans. In contrast there were two Litchfield GTR's both passed the static but both were black flagged during the morning. I think on the Radical its partly due to the everything being at the back. We have just purchased one of Radicals 'very quiet' boxes but it is a really tight fit but does seem to drop readings by 10db or so on my simple IPhone app. Will test at Bedford soon..
I very much doubt it'll be 10dB with a proper noise meter; if it does, it should have sounded about half as loud to your ears and that's an awful lot; as I understand it, according to psycho-acousticians, a non-exact rule-of-thumb is that every 10 dB increase is a doubling of perceived loudness.t our way through the static test on a 101db day as we were getting over 102 at only 4K on our SR1. They did reluctantly let us onto the GP circuit and it was fine all day even giving it the full beans. In contrast there were two Litchfield GTR's both passed the static but both were black flagged during the morning. I think on the Radical its partly due to the everything being at the back. We have just purchased one of Radicals 'very quiet' boxes but it is a really tight fit but does seem to drop readings by 10db or so on my simple IPhone app. Will test at Bedford soon..Is that 'very quiet' box a new product? An evolution of the 'supposed to be quiet, but not very often in reality' box?
I think you're right about all that noise at the back; I reckon that even if the exhaust were piped out of range of the meter (as an experiment), it'd still be 85plus dB. Likewise if there were a load more holes on top of the rear bodywork, I reckon overall noise would reduce considerably.
splitpin said:
I very much doubt it'll be 10dB with a proper noise meter; if it does, it should have sounded about half as loud to your ears and that's an awful lot; as I understand it, according to psycho-acousticians, a non-exact rule-of-thumb is that every 10 dB increase is a doubling of perceived loudness.
Is that 'very quiet' box a new product? An evolution of the 'supposed to be quiet, but not very often in reality' box?
I think you're right about all that noise at the back; I reckon that even if the exhaust were piped out of range of the meter (as an experiment), it'd still be 85plus dB. Likewise if there were a load more holes on top of the rear bodywork, I reckon overall noise would reduce considerably.
The exhaust is in fact titled as 'Extra Quiet' and on the Radical parts list on their on line shop EX0031 - Exhaust Silencer. It does not have a straight through design but has the outlet offset. On our test you could immediately hear a significant reduction in noise so will be interesting to test at Bedford, I'll report back on this.Is that 'very quiet' box a new product? An evolution of the 'supposed to be quiet, but not very often in reality' box?
I think you're right about all that noise at the back; I reckon that even if the exhaust were piped out of range of the meter (as an experiment), it'd still be 85plus dB. Likewise if there were a load more holes on top of the rear bodywork, I reckon overall noise would reduce considerably.
This whole thing IMO makes the static testing a bit of a waste of time, I have a GT3 that blows 102db static on a good day but once on track its fine all day long. The static just provides a ball park measurement.
Here is a pic of EX0031
I also repacked the race exhaust with no noticeable difference to the ear, still its worth a go
Hi all, just to follow on from my last post and this may be of interest, we officially tested the new exhaust at Bedford and it gave a reading 93dB static at around 6K so that's a massive reduction in noise. Noise levels in the car were just as loud but there was a noticeable reduction in performance as the engine felt 'corked' but still plenty quick enough on the day with no noise worries to meet 101dB static.
I had loads and loads of trouble with my 'quiet' track-day silencer around various tracks. Ended-up with all sorts of botched solutions in order to pass scrutineering, including a serpentine pipe sticking upwards out of the back at Combe. Then I did a Radical day at Snetterton last year and talked to them about it. They suggested they took the silencer away with them to send back to manufacturer.
I then heard from Mike Beech at Radical who said that it was completely screwed and that the manufacturer had replaced it free of charge. I've then not been able to use the car for over a year due to work commitments. Fired it up only yesterday with the new silencer installed and it's MUCH quieter. I really think it'll pass any scrutineering now, even Castle "More than me job's worth" Combe.
I'm at Donington this Saturday so I guess I'll find out...
Anyway, the moral of the story is that Radical's so-called 'quiet' trackday silencer isn't always as quiet as it's meant to be. If you're having problems then it might be worth you returning yours too.
I then heard from Mike Beech at Radical who said that it was completely screwed and that the manufacturer had replaced it free of charge. I've then not been able to use the car for over a year due to work commitments. Fired it up only yesterday with the new silencer installed and it's MUCH quieter. I really think it'll pass any scrutineering now, even Castle "More than me job's worth" Combe.
I'm at Donington this Saturday so I guess I'll find out...
Anyway, the moral of the story is that Radical's so-called 'quiet' trackday silencer isn't always as quiet as it's meant to be. If you're having problems then it might be worth you returning yours too.
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