Exhaust noise, track days, blah blah.....
Discussion
I happened to be at Bedford Autodrome yesterday to drive the Megane 250 for a forthcoming test. Anyway, I went in the 4.0 and as the chaps were noise testing the Renaults I asked if I could try the Chim as I was interested in the reading, despite it not going anywhere near the track that day.
They agreed and I held it at 4500rpm, getting a reading of 109/10db, but as I lifted off it 'popped' and I ended up with a reading of 120db as they measured that too.
So while I can probably get the exhaust quieter if I want to (ACT have been recommended?), do you guys lift from the accelerator s-l-o-w-l-y to avoid any pops or bangs at noise test time or do they always record that as part of the overall noise output of the car?
Needless to say, with that reading I won't be going on track for a while, although we did drive around the circuit to get to the pit lane and it was popping like a b
d as I lifted.
By the way, I don't know what exhaust I have fitted as it was on the car when I bought it (dealer was unsure too) and while it is rather loud it does have the cats in.
They agreed and I held it at 4500rpm, getting a reading of 109/10db, but as I lifted off it 'popped' and I ended up with a reading of 120db as they measured that too.
So while I can probably get the exhaust quieter if I want to (ACT have been recommended?), do you guys lift from the accelerator s-l-o-w-l-y to avoid any pops or bangs at noise test time or do they always record that as part of the overall noise output of the car?
Needless to say, with that reading I won't be going on track for a while, although we did drive around the circuit to get to the pit lane and it was popping like a b
d as I lifted. By the way, I don't know what exhaust I have fitted as it was on the car when I bought it (dealer was unsure too) and while it is rather loud it does have the cats in.
Garlick said:
I happened to be at Bedford Autodrome yesterday to drive the Megane 250 for a forthcoming test. Anyway, I went in the 4.0 and as the chaps were noise testing the Renaults I asked if I could try the Chim as I was interested in the reading, despite it not going anywhere near the track that day.
They agreed and I held it at 4500rpm, getting a reading of 109/10db, but as I lifted off it 'popped' and I ended up with a reading of 120db as they measured that too.
So while I can probably get the exhaust quieter if I want to (ACT have been recommended?), do you guys lift from the accelerator s-l-o-w-l-y to avoid any pops or bangs at noise test time or do they always record that as part of the overall noise output of the car?
Needless to say, with that reading I won't be going on track for a while, although we did drive around the circuit to get to the pit lane and it was popping like a bd as I lifted.
By the way, I don't know what exhaust I have fitted as it was on the car when I bought it (dealer was unsure too) and while it is rather loud it does have the cats in.
Generally the regs for noise testing are 3/4 of max RPM limit for car at 1ml form tailpipe. 105db is the max limit at most places and a good benchmark to aim for.They agreed and I held it at 4500rpm, getting a reading of 109/10db, but as I lifted off it 'popped' and I ended up with a reading of 120db as they measured that too.
So while I can probably get the exhaust quieter if I want to (ACT have been recommended?), do you guys lift from the accelerator s-l-o-w-l-y to avoid any pops or bangs at noise test time or do they always record that as part of the overall noise output of the car?
Needless to say, with that reading I won't be going on track for a while, although we did drive around the circuit to get to the pit lane and it was popping like a b
d as I lifted. By the way, I don't know what exhaust I have fitted as it was on the car when I bought it (dealer was unsure too) and while it is rather loud it does have the cats in.
N.
Indeed, not that I plan to do extensive track work mind you.
The main thing is avoiding the lift off 'crackle' as that was what sent my reading sky high. I assume a quieter pipe and a more gentle removal of foot from accelerator would help.
Made the noise test guy jump out of his skin mind you
The main thing is avoiding the lift off 'crackle' as that was what sent my reading sky high. I assume a quieter pipe and a more gentle removal of foot from accelerator would help.
Made the noise test guy jump out of his skin mind you
Bedford is notorious for being gestapoish on the noise front, shame as the Gran turismo circiut (I think thats what it is named) is a nice circuit. Act track day silencers do work well but have found they dont reduce overrun noise just db's. Supertrapps do reduce overrun and db's but use all 10 discs per side with 2mm washers between each disc and hey presto you will be back on any track. You may need to know a tig welder to get them to fit!. I have no cats no silencers just straight through pipes and supertrapps for my track day's and got tested at Coombe at 98db. Demon tweeks sell them. They are handy to have as a back up.
I managed to get my old S3 through the Brands noise test by easing the revs very gently up and down. I may have also chosen a slightly conservative 3/4s maximum revs. 
At least one standard Cerb got through without additional silencers that day and I've seen a standard Sagaris run during an evening session at Bedford. However, most of the TVR people were bolting on extra cans.
It is a definite downside to the glorious noise. The thread caught my eye as I'd need to double check I can silence it down to track day compliant levels before contemplating a return to TVR ownership.
At least one standard Cerb got through without additional silencers that day and I've seen a standard Sagaris run during an evening session at Bedford. However, most of the TVR people were bolting on extra cans.
It is a definite downside to the glorious noise. The thread caught my eye as I'd need to double check I can silence it down to track day compliant levels before contemplating a return to TVR ownership.
heightswitch said:
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Generally the regs for noise testing are 3/4 of max RPM limit for car at 1ml form tailpipe. 105db is the max limit at most places and a good benchmark to aim for.
N.
Thats race days and noisy days, a lot of trackdays want <100db My chim had no cats but a stock exhaust, sounded louder than most sports exhausts but only ever registered 99db.Generally the regs for noise testing are 3/4 of max RPM limit for car at 1ml form tailpipe. 105db is the max limit at most places and a good benchmark to aim for.
N.
You'll also find a lot of placed i.e. donny (RIP) and goodwood have driveby tests as well. you need to lift off before you go past the mics.
as for lift of crackles on the noise test. when we noise test the race cars i slowley build the revs and slowly let them off.
Noise is a real pain, so much so on the Sag race I think im going to run two separate exhausts down each sill rather than the one. that way i can run two big boxes
Garlick said:
They agreed and I held it at 4500rpm, getting a reading of 109/10db, but as I lifted off it 'popped' and I ended up with a reading of 120db as they measured that too.
Kewlio 
Dunno what the problem is - many dream of such a reading.
If you're not serious about tracking it, enjoy it.LordGrover said:
Garlick said:
They agreed and I held it at 4500rpm, getting a reading of 109/10db, but as I lifted off it 'popped' and I ended up with a reading of 120db as they measured that too.
Kewlio Dunno what the problem is - many dream of such a reading.
If you're not serious about tracking it, enjoy it.I may well want to do the occasional track day though as PH offers a calendar of events, and as I'll be there it would be rude not to do a lap or two, so I'm just looking for solutions.
Garlick said:
LordGrover said:
Garlick said:
They agreed and I held it at 4500rpm, getting a reading of 109/10db, but as I lifted off it 'popped' and I ended up with a reading of 120db as they measured that too.
Kewlio Dunno what the problem is - many dream of such a reading.
If you're not serious about tracking it, enjoy it.I may well want to do the occasional track day though as PH offers a calendar of events, and as I'll be there it would be rude not to do a lap or two, so I'm just looking for solutions.
I used to run the ACT track silencers and they were pretty good, dropping around 5-6 db, but when I put the charger on, I found they didn't work so well and they were causing a fair amount of choking at the top end as they couldn't cope with the increased flow.
I had a word with Tim at ACT and had some new jobbies made up. They are basically a pair of fat slash cut tail pips with silencing in them - about 40cm long. I then lopped off about 35cm from the existing tail pipes and these slide over and bolt on. They bring the noise from 109/110db to 100/101db (tested several times). With no loss in power whatsoever (tested using a fully set up datalogger on track). To go back to noisy mode, I have a matching pair of tail pipes (40cm) without any silencing in which can be swapped over in about 5 minutes as there is only 1 slimline exhaust clamp per pipe.
Looks fantastic, works brilliantly and didn't cost very much as I recall (can't remember the figure though). They're not on the website obviously so if you're interested in replicating them then give Tim (ACT) a call.
I had a word with Tim at ACT and had some new jobbies made up. They are basically a pair of fat slash cut tail pips with silencing in them - about 40cm long. I then lopped off about 35cm from the existing tail pipes and these slide over and bolt on. They bring the noise from 109/110db to 100/101db (tested several times). With no loss in power whatsoever (tested using a fully set up datalogger on track). To go back to noisy mode, I have a matching pair of tail pipes (40cm) without any silencing in which can be swapped over in about 5 minutes as there is only 1 slimline exhaust clamp per pipe.
Looks fantastic, works brilliantly and didn't cost very much as I recall (can't remember the figure though). They're not on the website obviously so if you're interested in replicating them then give Tim (ACT) a call.
Bedford has changed its attitude to become very unfriendly. First time I went, the tester came back round to the side of the car with a big smile and said "Beuatiful sound". The last time I went I had to fit the ACT cans (ony place I have been where this has been necessary) as they claimed I was 106dB. I queried this as every other track measures my car at 100dB or less. Quick as you like I was told to pi55 off if I didn't like it. Customer? Me? Together with the vicious speed bumps on the way in, I won't bother with Bedford again. Shame, as I only live a few miles away.
Suggest you give Donnington (also strict, but not nasty), Cadwell, Oulton - all nice(er) tracks too.
Suggest you give Donnington (also strict, but not nasty), Cadwell, Oulton - all nice(er) tracks too.
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