Exhaust decibels

[TNT ANDY]

http://assets.dft.gov.uk/publications/trl-report-ppr506-proposals-for-in-service-exhaust-noise-testing/trlreportexhaustnoisetesting.pdf

Here's a starting point for the readers amongst you.

[paul b]

So, all we need to know is what was the dB srat for a standard 5Gtt back in 1987, LOL, not a chance,,,,
the figures they are working from are only used if the original dB rating was known, other than that then it's back to the old ,. "too noisy" test if over 99dB...:)

[TNT ANDY]

Quite right ol bean. I'd like to agree, and like other info I've found it would be more a case you will get puled for having an excessively loud exhaust if you're being a nob.

Has anyone on here got an oe set up we can check?

[Adey aka Ewok]

is there an upper limit of noise already in place?

might just adjust the ecu settings for the honda so it will limit revs to 3k when stationary, thatll feck em off some more lol

[TNT ANDY]

is there an upper limit of noise already in place?

might just adjust the ecu settings for the honda so it will limit revs to 3k when stationary, thatll feck em off some more lol

No there isn't it seems that you could be bound and gagged for having a 90db 5gtt as a 120db tvr rips by. Seems a tad unfair to me. After all the issue is noise, not who made your car otherwise it's a case of if you're rich you can buy your right to be abusive (if that's what it is) I've been in London City pleanty of times and seen and heard a Lambo / Ferrari screaming through Oxford street - pure bliss (and incredibly loud) - but it's legal???

Hows that work?

[Os8472]

Switch in the fuel pump wiring, " oh no officer, I've broken down, can you give me a push?" see how quick they leave :)

[Renault 5 GT Turbo]

I will measure the db level of my standard car in a mo and post it here shortly

[Os8472]

I will measure the db level of my standard car in a mo and post it here shortly

Make sure it comes out at 105db :)

[Brigsy]

Standard exhaust is quiet, id guess 60-70db for a static test??

Im starting to get paranoid about my van getting noise tested now as its loud with the gt series blower and side exit with no baffles left, 105db+ at a guess

[markey b]

i got nailed for mine being 104 in the 'official' police test.

mine is a sidey with one tiny silencer, if you have a normal system it should be quieter

[Dave Reed]

You sure this isn't an April fool :)

[markey b]

You sure this isn't an April fool :)

not at 20:36 andy is too sharp to be a fool

[Coops]

isn't it basically a disturbing the peace type offence, as in not even governed by traffic laws but more public order policies??

and I agree with the unfairness of it, I live just outside matlock bath in the peak, try to have a conversation down there as the Harley Davidson crew rock through, or some **** on a superbike with a carbon can on a piece of scaffolding. then some poor sod in a car that's 1/4 as loud gets pulled.

[markey b]

isn't it basically a disturbing the peace type offence, as in not even governed by traffic laws but more public order policies??

and I agree with the unfairness of it, I live just outside matlock bath in the peak, try to have a conversation down there as the Harley Davidson crew rock through, or some **** on a superbike with a carbon can on a piece of scaffolding. then some poor sod in a car that's 1/4 as loud gets pulled.

:ashamed: i've just cut the exhaust on my bike in half to make it louder... sorry :laugh:

[TNT ANDY]

Did anyone measure the standard 5's exhaust?

I've just done mine and it's come out as follows:-

1000 rpm - 81.1 db
2000 rpm - 89.2 db
3000 rpm - 95.3 db
4000 rpm - 97.3 db

reving upto 6000 rpm - peak 105.7

I suspect a drivebye at full chat will be much louder. I've got another silencer which I will install and also will be getting rid of the bobbin mount at the rear of my sidey as it transmits too much noise into the car through that mount and see how I get on.

I have a 2.5" K-Tec jobby with an enlarged elbow and down pipe for reference.

[Romil Davda]

Can you get the reading for 4500rpm, as this is what I had to hold the car to at, at Oultan Park.

Also, I believe the drive by figures are actally lower! I'm sure someone can confirm?

[TNT ANDY]

Can you get the reading for 4500rpm, as this is what I had to hold the car to at, at Oultan Park.

Also, I believe the drive by figures are actally lower! I'm sure someone can confirm?

Sorry I didn't get it at 4500, I can do, but looking at it I'd say it will be around 100 db.

What's your limit?

[Romil Davda]

What's your limit?

Limit was 105db, which is about the same for most tracks.

Many thanks.

[TNT ANDY]

Removed the rear bobbin hanger tonight and replaced with 2 x heavy duty rubber mounts one either side to hopefully take some of the additional vibration out of the dide exit through the old bobbin mount.

http://www.rtoc.org/files/Miscellaneous/Stotto/DSCF3907.JPG

http://www.rtoc.org/files/Miscellaneous/Stotto/DSCF3906.JPG

I'll get out in it over the weekend, hamerite'd now and will get some underseal on it tommorow.

[Os8472]

Looks good fella :agree:

[TNT ANDY]

Looks good fella :agree:

:laugh: I wouldn't go that far Oli - but I hope it takes some of the noise / vibration out all the same.

[Os8472]

:laugh: I wouldn't go that far Oli - but I hope it takes some of the noise / vibration out all the same.

Ok it doesn't look good but it's better the OE item

[TNT ANDY]

Right, got the primary silencer on ( from Jetex) and run it up, although not had it out of the garage yet, it seems to have taken a fair bit of noise out. I'll take it for a run on Sunday and measure the Db's again.

http://www.rtoc.org/files/Miscellaneous/Stotto/Exhaust/DSCF3911.JPG

http://www.rtoc.org/files/Miscellaneous/Stotto/Exhaust/DSCF3909.JPG

[TNT ANDY]

Been out - sounds much more civilised now, and there has been a significant DB output as follows:-

1000 - 73.6db
2000 - 82.6db
3000 - 87.6db
4000 - 88.3db
4500 - 90.8db

Reving upto 6000 - 95.8db

Which was nice

[TNT ANDY]

Just so as I get this right, is 2db twice as loud as 1 db, but 3db is 4 times louder than 1db ?

[TNT ANDY]

BTW - the wiki stuff doesn't help :eek:

http://en.wikipedia.org/wiki/Decibel

[andybond]

Guys ,

Has anyone tried the diesel style exits on the five ? It helps keep the noise down by firing it into the floor. Same lack of restrictive centers etc , but without the volume.

Bit like Ronnies car

http://www.racingexposure.com/blog/wp-content/uploads/2010/10/TASN1670.jpg

[James5]

Guys ,

Has anyone tried the diesel style exits on the five ? It helps keep the noise down by firing it into the floor. Same lack of restrictive centers etc , but without the volume.

Bit like Ronnies car

http://www.racingexposure.com/blog/wp-content/uploads/2010/10/TASN1670.jpg

My old powerflow sidey had diesel tip and it was still fecking noisey:laugh:

[TNT ANDY]

The silencer I put on had no restriction in it at all, just a straight through pipe with loads of holes in it through to a large wadded section, unlike the centre section as displayed in the recent 'Anti-lag' post. I'm amazed at how much noise has been removed. As for pointing it at the ground, I did this on my last side exit and it mad no difference apart from it made an annoying fluffing noise when thrashed.

[rs250nut]

Sod the exhaust that car is the tits, thanks for posting it:agree:

[Os8472]

How much clearance have u got on your gear linkage with that second silencer in place Andy?

[HAndy]

good info there andy:)
could you confirm turbine size and ar housing for those readings;)might give other peeps something to compare with running sideys and same sized turbo's, also did you notice any difference in turbo spool up?? (very minimal i guess )

with a lot of tracks heading towards lower db limits (less than 105db) , fear that most of us will be needing to double up on silencers or change to bigger items long term :scared::scratch:

[HAndy]

Guys ,

Has anyone tried the diesel style exits on the five ? It helps keep the noise down by firing it into the floor. Same lack of restrictive centers etc , but without the volume.

Bit like Ronnies car

http://www.racingexposure.com/blog/wp-content/uploads/2010/10/TASN1670.jpg


yep, been there tried that , thought at the time that would stop the plod from being able to carry out a road side noise test on my car:cooter::ashamed: it use to blow patches/holes in the shingle drive on start up and giving it any more than 1/4 throttle:laugh::laugh:

it made the exhaust louder, deflection of the floor and surrounding area;)

[TNT ANDY]

Sod the exhaust that car is the tits, thanks for posting it:agree:

Thanks for that. It's not as good in the flesh, but I'm happy with it.

[TNT ANDY]

How much clearance have u got on your gear linkage with that second silencer in place Andy?

Loads - no issues there, however, the bottom of this can hangs lower than the existing one and catches on 1 or 2 speed humps. My car is -50mm I may have to stick some -35mm springs on there if it becomes an issue.

[TNT ANDY]

good info there andy:)
could you confirm turbine size and ar housing for those readings;)might give other peeps something to compare with running sideys and same sized turbo's, also did you notice any difference in turbo spool up?? (very minimal i guess )

with a lot of tracks heading towards lower db limits (less than 105db) , fear that most of us will be needing to double up on silencers or change to bigger items long term :scared::scratch:

All I know about my turbo is it's a large T25 whatever that means, I had it built for 200bhp optimal performance. I'll have a look and see if I can dig out any info on it. Spool up - negligible.

[TNT ANDY]

All I know about my turbo is it's a large T25 whatever that means, I had it built for 200bhp optimal performance. I'll have a look and see if I can dig out any info on it. Spool up - negligible.

.49 rear
.64 Front
55 trim

I've no idea what this means