Discussion
So I have been trying to get my noise levels down. I mentioned on another thread that I was having trouble and my new SR4 quiet box was anything but. I got out my noise meter today for some tests.
Note this is on a clubsport not an SR4!
Radical replaced my SR4 box with another as they couldn't believe that it was so loud. I have got the new one and a dongle to go on the back. Here are the results with 3 yellow lights (about 6k rpm I think).
Race box 113 dBA
Race box plus dongle 110 dBA
Quiet box 107 dBA
Quiet plus dongle 104 dBA
These are taken at 0.5m like they do at the circuits. So that is a problem to me, unless I can get it down to 100, I am pretty restricted on track days.
Anyone got any ideas? Anyone want a nice (but loud) 2 seater clubsport?
Graham
Note this is on a clubsport not an SR4!
Radical replaced my SR4 box with another as they couldn't believe that it was so loud. I have got the new one and a dongle to go on the back. Here are the results with 3 yellow lights (about 6k rpm I think).
Race box 113 dBA
Race box plus dongle 110 dBA
Quiet box 107 dBA
Quiet plus dongle 104 dBA
These are taken at 0.5m like they do at the circuits. So that is a problem to me, unless I can get it down to 100, I am pretty restricted on track days.
Anyone got any ideas? Anyone want a nice (but loud) 2 seater clubsport?
Graham
Hi Graham
I've sent you an email - I think getting a custom silencer made up will be the best bet. Tony Law reckons on a <100dB silencer for around £80+VAT & delivery, which is a no brainer given their reputation. He reckons getting down to 98dB will be real hard given the experience they've had with some other Radicals, and that there is a lot of induction noise.
Cheers
Phil
I've sent you an email - I think getting a custom silencer made up will be the best bet. Tony Law reckons on a <100dB silencer for around £80+VAT & delivery, which is a no brainer given their reputation. He reckons getting down to 98dB will be real hard given the experience they've had with some other Radicals, and that there is a lot of induction noise.
Cheers
Phil
I have just spoken to Paul (workshop manager) at Radical and it seems that with the SR4 track day box (which is the quietest) the following is expected:
95 dBA at < 4k rpm (not much use that one then!)
100dBA at just less that 5k rpm (get one yellow just flickering on the kawasaki engine).
Paul thought that this was the quietest that could be reasonably achieved as at that point a large proportion of noise would be coming from the induction.
So there are three choices:
1 lie really effectively about max revs and what the lights mean (will anyone believe that one yellow is 3/4 max revs?)
2 Go on loud days.
3 get really creative about exhaust systems and air boxes. I have been here before with my previous loud car - a Caterham R500 and it a/ gets expensive and b/ puts horribly complicated pipework everywhere which makes working on the car and taking bodywork off a real PITA.
Oh well, at least I know the options!
Anyone got a list of loud track days?
Graham
95 dBA at < 4k rpm (not much use that one then!)
100dBA at just less that 5k rpm (get one yellow just flickering on the kawasaki engine).
Paul thought that this was the quietest that could be reasonably achieved as at that point a large proportion of noise would be coming from the induction.
So there are three choices:
1 lie really effectively about max revs and what the lights mean (will anyone believe that one yellow is 3/4 max revs?)
2 Go on loud days.
3 get really creative about exhaust systems and air boxes. I have been here before with my previous loud car - a Caterham R500 and it a/ gets expensive and b/ puts horribly complicated pipework everywhere which makes working on the car and taking bodywork off a real PITA.
Oh well, at least I know the options!
Anyone got a list of loud track days?
Graham
Hi Graham, your number 1 option is the way to go, I have done many trackdays in my clubsport in the past and when they ask for 3/4 revs put your hand over the dash as if the sun is glaring off it and hold it at 1 or 2 yellows, once passed speak to someone in the know at the circuit and ask where the drive-by sensors are on track and just be mindful when driving past them i.e, back out of the throttle for a bit, its always worked for me, jobs a good-en !
Regards
Tony.
Regards
Tony.
Graham,
I do exactly as Tony mentions with my SR4 on track days. I've had mine at Goodwood where they are strict and have sensors all around the circuit. With the quiet silence we drove all day, no issues. My 911 C4S was actually louder and failed on the static, but they did et me on as they said it would pass the drive by. Very nice of them.
I do exactly as Tony mentions with my SR4 on track days. I've had mine at Goodwood where they are strict and have sensors all around the circuit. With the quiet silence we drove all day, no issues. My 911 C4S was actually louder and failed on the static, but they did et me on as they said it would pass the drive by. Very nice of them.
Well, I'll give it a go, but having just been kicked off a day where the sound man knew the revs and lights better than me on the Rad at Combe and where the sound man at Hullavington knew the revs on my caterham and neither were up for being blagged, I think I may be just too honest for track days :-))
shooomer said:
PhilboSE,
Can you email me the details of the quiet silencer.
Many thanks.
Paul
Hi Paul
It's just a new backbox about 27" long that will be "perfectly" packed to give the maximum possible sound deadening. It'll be 6" diameter same as standard to fit in the car. It'll stick out the back a bit but should still be plenty of clearance.
When I get it I'll give it a go and report back.
Phil
Hi,
There was a problem with the initial order with Tony Law and so I don't have the new box yet. I'm away for August now so I will have to progress it when I'm back.
However, from speaking to others, I'm thinking that you'll be really struggling to get a Radical down quiet enough to pass at Combe. The exhaust noise is bad enough but conceivably could be silenced with a big/complex enough back box, however after a certain point the induction noise and the reverberations around the bodywork at the back of the car that acts as a soundbox take over in the noise stakes, and they're much more gnarly problems to solve.
Donington still does some noisy days however. It's my understanding that when the factory take Radicals to Combe for a testing day, the noise limits are considerably higher than for normal track days.
Phil
There was a problem with the initial order with Tony Law and so I don't have the new box yet. I'm away for August now so I will have to progress it when I'm back.
However, from speaking to others, I'm thinking that you'll be really struggling to get a Radical down quiet enough to pass at Combe. The exhaust noise is bad enough but conceivably could be silenced with a big/complex enough back box, however after a certain point the induction noise and the reverberations around the bodywork at the back of the car that acts as a soundbox take over in the noise stakes, and they're much more gnarly problems to solve.
Donington still does some noisy days however. It's my understanding that when the factory take Radicals to Combe for a testing day, the noise limits are considerably higher than for normal track days.
Phil
Collcted my car from Cheesman's last night, silecer is 27 1/2 " long and 8" dia. look enormous, but can be quickly changed to original where noise restrictions not a problem.
Makes no noise ! But my God does the engine sound mechanical now !!! Will post some photos on Monday, and will pop to Goodwood next week for a noise test.
Tim.
PS Havent been billed yet.
Makes no noise ! But my God does the engine sound mechanical now !!! Will post some photos on Monday, and will pop to Goodwood next week for a noise test.
Tim.
PS Havent been billed yet.
Sorry fellow Radicalistas !
Did a Goodwood sprint on Saturday, an amazingly dissapointing 103dB with three lights on, no attempt at cheating, and thats just engine noise as the exhaust note is totally muted. My pal was doing the driving this weekend and noticed no performance drop off. The new system appeared to be the cause of a body support frame breakage, one tube broke away at the weld, right in the corner where four tubes meet, so some gusseting appears to be the order of the day !
Regards.
Did a Goodwood sprint on Saturday, an amazingly dissapointing 103dB with three lights on, no attempt at cheating, and thats just engine noise as the exhaust note is totally muted. My pal was doing the driving this weekend and noticed no performance drop off. The new system appeared to be the cause of a body support frame breakage, one tube broke away at the weld, right in the corner where four tubes meet, so some gusseting appears to be the order of the day !
Regards.
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