View Full Version : Managing exhaust noise limits - teased from Japfest thread
Japfest thread had some interesting discussions on exhaust noise at circuits, I wanted to create a more focussed thread. I have a lot of events coming up and I want to tailor my exhaust emission for each venue.
a great big silencer from Jetex in the cat position.
Jez, any chance you can tell me where you got this and for how much?
I have 3 silencers on my car and still got kicked off :furious:
98db 1st sesh
102db 2nd sesh
:confused:
any ideas
Tone, what setup is you have with 3 silencers in there?
I've got a custom (APT cut and shunt :)) S14 downpipe into very cheap (it split on the welds after 48 hours!) S14 decat silencer which has been spliced into an S13 Nur Spec back system.
Ideally I would like to have something I can change easily. Looked at these options;
Apexi Exhaust Control Valve
http://www.apexi.com/product_exhaust_detail.asp?id=251&pageNum=1
But it kills power too much.
SUPERTRAPP Clamp On Disc
http://www.demon-tweeks.co.uk/catalogue/product_detail.asp?CLS=MSPORT&TLGRP=M006&CODE=MSD344-1705&PGRP=MP095&GRP=MP095&PCODE=MSD344-1705
Again this could potentiall kill power too much
If I had 2/3 silencers I could swap into the decat space, each giving me 96/98/100db's that would be ideal.
driftking
23-05-2005, 00:11
Good thread, maybe a sticky in the making?
For the record, i got kicked off Bedford autodrome for a 20m drive-by noise of 90dbs, the limit was 87.5. I have S14, and was running std downpipe, cat and nur spec WITH THE BUNG IN! I was on about 9psi too... The bloke reckoned it was the wind carrying the noise, i reckon it was bullsh1t but those are the regs laid down by the local council, so didn't bother to argue the toss. I'd bet my bottom dollar there were cars there that were louder. :indiff:
Sorry, rambled. :rolleyes: But hope this is useful expirience.
Edit, just read that back, i'm not bitter, not really, just gutting when you pay £200 to do 4 1/2 laps. :censored: Las, where are you? Back me up!
I got an S14 decaqt silencer from Bren. Makes a huge difference to my NUR-Spec. :)
I think your easiest option will be the exhaust valve! I for one would no tlike to change a red hot silencer if it was a fraction too loud :no:
a bung makes a huge difference to my car's noise output.
archenemy.co.uk
23-05-2005, 01:45
Sports cat + mongoose = straight through :thumbs:
Why bother having 3 options, just get it as quiet as you can without loosing power :confused:
a bung makes a huge difference to my car's noise output.
You didn't see the disapproving looks you got from my neighbours :D
Seriously though, what noise level would be considered appropriate, and/or tolerable for a residential situation, rather than just a track?
I'm aware that whilst being "too loud" on a track can get you pulled in, or prevented from going out at all, I think we should also bear in mind keeping good diplomatic relations with the people we live by. :)
Something I've been wondering about is whether residential situations would tolerate a louder exhaust than a track situation. On a track there are many cars creating noise, whereas on a single road there's just you. Any thoughts?
Papa Lazarou
23-05-2005, 02:05
Theres the ATP boost operated exhaust valve thingy. Still might be a problem if you have noise monitored on the track all the time though.
http://www.atpturbo.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=ATP-ACS-010&Category_Code=BCS
I got my silencer from Merlin Motorsport - you can view the range of silencers here: www.jetex.co.uk, in the universal parts section.
I went for the biggest 3" silencer they do (Its a straight through design, so shouldn't impede flow too much) with a cat back 80mm Nur Spec. Never had a prob with noise so far.
Sorry, but how does this work? :confused:
http://www.demon-tweeks.co.uk/resources/images/zoom/MSD344-1705.jpg
The Apexi Active Tail Silencer is another good option!
http://www.prostreetonline.com/news/apexi%5Factive%5Ftail%5Fsilencer/
It goes on the end of the exhaust pipe - quite effective, but makes the backpressures quite large.
You didn't see the disapproving looks you got from my neighbours :D
Seriously though, what noise level would be considered appropriate, and/or tolerable for a residential situation, rather than just a track?
I'm aware that whilst being "too loud" on a track can get you pulled in, or prevented from going out at all, I think we should also bear in mind keeping good diplomatic relations with the people we live by. :)
Something I've been wondering about is whether residential situations would tolerate a louder exhaust than a track situation. On a track there are many cars creating noise, whereas on a single road there's just you. Any thoughts?
you haven't heard the dissapproving shouting from my neighbouring streets when I fire it up at night without the bung ;)
Mr Yeager Sir...
The noise your tyres were making on Saturday morning in the Travel Inn car park drowned out your exhaust ;)
[assuming it was you arsing about doing doughnuts at 7am :p ]
:notworthy
PhilMorrison
23-05-2005, 10:32
I got my silencer from Merlin Motorsport - you can view the range of silencers here: www.jetex.co.uk, in the universal parts section.
I went for the biggest 3" silencer they do (Its a straight through design, so shouldn't impede flow too much) with a cat back 80mm Nur Spec. Never had a prob with noise so far.
Doh.. I've just PM'd you asking for all these answers lol :wack:
Doh.. I've just PM'd you asking for all these answers lol :wack:
LOL - just replied. And you're more than welcome to come on a track session where grip is a priority ;) :D
LOL - just replied. And you're more than welcome to come on a track session where grip is a priority ;) :D
Dont confuse him! Im not sure his noggin could cope with the idea of grip :eek: :eek: :smash:
Excellent drifting btw phil, got some nice footage ill put it up soon :)
Butuz
PhilMorrison
23-05-2005, 10:53
Actually as I was just saying to Mr Jez, maybe we can learn something from each other. I'd be very keen to learn to grip a little better, I think it could do wonders for my drifty antics :).. Butuz, I look forward to the footage mate :thumbs: Cheers :thumbs:
Its a pity all the footage was taken from behind the fence on the corner by the bit where you enter/exit the track - i bet you got some good stuff going round by quarry etc :D
http://www.butuz.net/200sx/Japfest/Phil-Drifting-HQ.wmv
There ya go - pity i didint get you in the wet :)
Butuz
Actually as I was just saying to Mr Jez, maybe we can learn something from each other.
I think we could - as soon as I get my car at all sideways I try to correct it straight away rather than letting it go. Mainly because I'm scared :ghey: and usually end up spinning. Would be good to be able to cope if I get more sideways than planned :) And of course drifting looks like a really good laugh :)
I agree. I think learning to be in total control of the car when the back end steps out would be invaluable. Probably more so than those pfiffy advanced driver "dont cross your hands" courses that people rave on about.
Most people crap emselves when the back end steps out, and do things wrong such as lift off suddenly, or brake, or over correct. Being able to correct a slide without thinking puts you in far better stead should you ever need it on public roads.
Drifting is something i really want to give ago - ive got 4 spare wheels and tyres now, ill have my GTR brakes sorted soon, all i really need then is an uprated WMIC and new clutch, after that ill have no excuses to stop Phil from dragging me kicking and screaming onto the track :p
Butuz
on topic? :)
Use a valve, or get burned hands :nod:
Decat silencer should make a little bit of a difference, but I find at full chat it just can't cope with the volume of gasses :totallydeaf:
Use a valve, or get burned hands :nod:
Not keen on the ristrictiveness of a valve. I would be changing the silencer at the circuit, I would know the noise level before hand and throw on the relavent silencer the night before. In all honesty I don't think i'll need more than one because I think the combination of decat silencer, decat pipe and bung would give me some variation on noise.
Not keen on the ristrictiveness of a valve. I would be changing the silencer at the circuit, I would know the noise level before hand and throw on the relavent silencer the night before. In all honesty I don't think i'll need more than one because I think the combination of decat silencer, decat pipe and bung would give me some variation on noise.
Ah :)
Personally I can't see how a bung and valve differ in restrictiveness. They both reduce the diameter of the exhaust pipework to create more back pressure, and therefore reduce volume.
The only difference I can see is the bung is right at the end of the exhaust, so the engine can fill the pipework with gas before it becomes restricted - whereby with the valve it only has the pipework prior to the valve to fill before it becomes restrictive.
How about fitting a valve at the last join in the exhaust, and running without a bung? At full-open, a valve would be very unrestrictive (compared to a bung). Otherwise, fitting the largest possible silencer would be the best option. I don't think a silencer could sap much power - so I wouldn't want to be changing them all the time when one would suffice :) :i'malazybastid:
EDIT: Or buy another NUR back box, and plumb in twin back boxes - one per side :cool:
Back off topic - I saw you driving the pink machine to work on Friday Si :) I was in the Pug, and too tired/slow to flash you before you'd gone...
You were nearly as late as me! :wack:
Bean Bandit
23-05-2005, 12:50
a mate just tested his dB level of the Megan Cat-Back on his S14 - with bung in and CAT he got ~78dB on a drive by measurement - this is with 0.8bar of boost on the stock engine though... regulations for street (we don't have any tracks) are so mad I'd need to hit a max of 76dB with the S13 to get trough which is ridiculous as about every other new or old sportscar is louder... but I'll have to match the original item...
anyone fitted the complete silencing setup bren offers (i.e. donwpipe silencer etc)? and took a measurement?
Back off topic - I saw you driving the pink machine to work on Friday Si :) I was in the Pug, and too tired/slow to flash you before you'd gone...
You were nearly as late as me! :wack:
I saw you coming down the chesham road onto the 413 ;) in my s13.
I saw you coming down the chesham road onto the 413 ;) in my s13.
With the black headlights? Ah, think I saw you too :)
With the black headlights? Ah, think I saw you too :)
twat :p :wave: she is looking good!
I got 106Db with my Nur Spec and 2 3/4" downpipe. I threw the bung in and got 105Db although it's worth noting that I was parked a car's width closer to the wall for the second reading. With Pointblank's massive bung I got 90Db although the power suffered :(
you haven't heard the dissapproving shouting from my neighbouring streets when I fire it up at night without the bung ;)
Lol, and nor have you :D
I got my silencer from Merlin Motorsport - you can view the range of silencers here: www.jetex.co.uk, in the universal parts section.
I went for the biggest 3" silencer they do (Its a straight through design, so shouldn't impede flow too much) with a cat back 80mm Nur Spec. Never had a prob with noise so far.
Why did you choose this make? Is the construction good? Did you slot the silencer into the same space an S14 decat pipe would go? If so, which unit did you get?
http://jetex.co.uk/Jetexwebsite/universalparts/boxes3inch.htm
I said it would crack and said that the seam should be welded before it went on the car. Theyre pants and we are sending them all back.
Bigtone got a Jetex silencer and he was still over the limit.
Im going to order one Jetex U307600 and one U447600 (if it looks like it will fit) tommorrow and see if I can stick one into the front pipe (S14) and the other where the current (2.5") decat silencer lives.
The last time I fitted one of our larger decat silencers it dropped the db reading by 7, on Sat it dropped it by just 4 :rolleyes:
Why did you choose this make? Is the construction good? Did you slot the silencer into the same space an S14 decat pipe would go? If so, which unit did you get?
http://jetex.co.uk/Jetexwebsite/universalparts/boxes3inch.htm
I got the largest box at the bottom of that page. I got that make because I couldn't find anywhere else that did 3" silencers on their own. They're fairly well made and coated in tough paint/plasticy stuff that hasn't burnt off. There may well be better alternative but at the time that met my needs :)
I made my own front exhaust section and incorporated that silencer into it. Its a bit big and my exhaust hangs down a bit low. Not really a problem. I don't think any of the Jetex range would be a direct swap for any nissan parts, so you'd need fabricate something to get it to work.
Its a pity that the holes are offset :( Did you fit that where the original cat would have sat?
Its a pity that the holes are offset :( Did you fit that where the original cat would have sat?
Yeah, roughly. The fact that the holes are offset actually helps. Having said that - the section of the exhaust that I made is quite bodged...
I said it would crack and said that the seam should be welded before it went on the car. Theyre pants and we are sending them all back.
shh i wasn't going to mention where I got it from! ;) We didn't have time to do the welding and it seems we never needed the darn thing in the end! But Wild Trax is going to be very very concerned about noise...
Ive got to sort something before the weekend as we are at Croft on Sat so Ill post up the results :)
disco-tom
23-05-2005, 19:52
I saw a few cars going round the track - notabley the 240Z's - with extra silencers attatched to the end of their exhausts. they look a little dorky, but are easy to stick on for track days and do their job.
Haven't looked for anywhere that supplies them, but I assume they are just normal silencers like the ones in the link Jez posted. Would have to have some form of adaptor pipe made up before being able to attatch it to the jap spec exit pipes, but could be a usefull idea?
With reference to what Angelus posted.
Those noise baffles are completely useless for our cars. I put one on at Bedford, but first lap out i got black flagged...not worth getting at all. They seem to work on NA cars though.
btw i've got Apex Single box cat back, de-cat and front pipe all courtesy of Bren.
Cheers,
Las
*edit* also got black flagged at Donnington on Satuday..noise increased 1st lap to 100dB then 101dB then 102.5dB...nice comment from the steward..."yeah mate, we've had a problem with noise on these skylines...." :smash: :smash: :rolleyes:
mambastu
28-05-2005, 13:02
Just been down to Goodwood to have my car noise tested. Very friendly and helpful people down there :thumbs:
I mentioned that my car had a Skyline engine in it and they said that they have a lot of problems with Skylines and noise levels. An early bad sign was the guy shaking his head as I drove it up to him.
Measured at 5300 rpm I achieved.....115 db
I think I almost broke the fookin sound meter :wack:
I have a NUR Spec R cat back rear system with a custom built twin 2.5" into 3" front pipe. The odd thing is that if anything it actually sounds quieter inside the car with the bung out than it ever did with the same exhaust on the CA.
Jez, any idea what db's your car was before and after you fitted the additional silencer in it ?
Ah bugger, not sure that I'm going to be able to get that down to sub 105 levels even with an extra silencer and to be honest it sounds so nice with the current setup I don't really want to. Silly low noise limits :(
Jezz_S13
28-05-2005, 13:03
115db LOL. Woops. :D
John Bennett
28-05-2005, 13:06
:D :notworthy
As a nerdy aside, I was reading the Skyline service manual, and on one model there seems to be a system on the twin-exit exhaust to electrically shut one of the exits? Akyone know if this was for noise issues, and did it ever work well?
mambastu
28-05-2005, 13:08
:D :notworthy
As a nerdy aside, I was reading the Skyline service manual, and on one model there seems to be a system on the twin-exit exhaust to electrically shut one of the exits? Akyone know if this was for noise issues, and did it ever work well?
Yeah, it was fitted to some of the R33 GTS-T's but I've never seen it on a car over here. Some Mitsubish GTO's also have it.
And Chris was telling me how it was quieter after the RB lump went in :confused: :p
mambastu
28-05-2005, 13:44
And Chris was telling me how it was quieter after the RB lump went in :confused: :p
Thats the thing, I'm sure it does sound a fair bit quieter than it did with the CA with the same NUR Spec R with the bung out when you're driving around normally (and Chris is nodding as I type this). I've never fitted the bung in it since the RB went in and with the CA I used to drive with the bung in most of the time because of the resonance and noise.
I guess at 5,000 rpm you tend to leave a lot of the sound in your wake so you don't appreciate how loud it really is.
Jez, any idea what db's your car was before and after you fitted the additional silencer in it ?
No, fraid not - I've only ever run this engine with the big silencer in.
Sounds like you're never going to get your car on track :( Bit of a shame and waste...
mambastu
28-05-2005, 14:23
Sounds like you're never going to get your car on track :( Bit of a shame and waste...
Its hardly a waste as it was never intended to be a dedicated track car. Its my comfy (compared to my bike) daily used road car. ;)
Just chatting to Chris about it and we've got a few options to explore before GT-Battle.
Just winding you up mate ;)
Comfy at 115db?
mambastu
28-05-2005, 14:41
Comfy at 115db?
Well....drier than the bike then ;) :D
We have a selection of silencers here now to try out :)
Why did you choose this make? Is the construction good? Did you slot the silencer into the same space an S14 decat pipe would go? If so, which unit did you get?
I make s14/a decat silencers using Jetex units -there was one fitted to Slipstream Ian's car at Japfest. Think he still used the Nur bung as well to be on the safe side though, so not a very useful experiment! The difference is apparent on the road though.
I use the largest oval section that will fit. It's no lower than any other part of the Nur, but of course in the centre of the car so more of a problem for speed bumps.
Jetex have a good reputation but they aren't cheap if you want stainless. Get what you pay for though :)
We have a selection of silencers here now to try out :)
how did you get through the croft noise restrictions at the weekend? :confused:
We didnt get kicked off, although Kev said we were getting comments from spectators about the car being loud.
s13girly-
31-05-2005, 11:46
I don't see the issue its not like you're all in the middle of a housing estate is it!!
Can't imagine F1 races being halted by some little t**t running along behind the cars with a db meter!!!!!
;) ;)
We didnt get kicked off, although Kev said we were getting comments from spectators about the car being loud.
did you play with silencers/bungs/the whole system :confused: . or did they just not test ;)
I don't see the issue its not like you're all in the middle of a housing estate is it!!
Can't imagine F1 races being halted by some little t**t running along behind the cars with a db meter!!!!!
not really the point is it. if a racing circuit wants to keep its licence then they have to comply with local regs. and like it or not, wherever you put a circuit, there are going to be local residents who don't want noise.
They just didnt test :)
:thumbs:
I fitted a silencer from Jetex for this weekend at Wild Trax. My Nur Spec system without it was 108db without the bung and 104 with, fitting this new box in the same place as the decat pipe gave me 97ish without the bung and a whopping 86ish with it!! :D RESULT
Not that much performance loss with the in and the bung out either...
Same setup as me - works well dunnit :)
mambastu
12-06-2005, 23:34
Finished my 'track' exhaust yesterday.
I've used a secondhand R32 Super Drager 3.5" centre section with silencer which PTS kindly modified so that its a straight swap for the intermediate section of the NUR Spec R. The Super Drager silencer is about three times the size of the NUR spec's tiny bullet silencer so we expected it to make quite a difference to noise levels but it only actually made 1db difference when combined with the NUR Specs tailbox (i.e 114db) ! Chris then made a new rear section using the biggest 3" Jetex oval silencer from DT which has surprisingly knocked it down to 98db, we thought we would probably have to go to three boxes.
The car sounds bloody boring now. Can't believe how quiet 98db is, sounds as quiet as a standard S13 and its taken a noticeable performance hit with the big silencer....grrrr.....twatty noise levels :rant:
I've got a trackday at Brands the week after GT Battle and after that the NUR spec's going straight back on. :nod:
The car sounds bloody boring now. Can't believe how quiet 98db is, sounds as quiet as a standard S13
Sounds like permanent hearing damage to me :nod: ;)
It's interesting reading through this, though. I used to work in live sound reinforcement, where there's a limit of 120 dB SPL A weighted from the speakers. Which, quite honestly, is unbearably loud. We used hearing protection for health and safety reasons! The biggest PA I worked on ran off three phase mains, and could be heard a mile and a half away outside the building it was in!
That does take me to my point though, at those sorts of volumes, shouldn't you be using hearing protection?
As a nerdy aside, I was reading the Skyline service manual, and on one model there seems to be a system on the twin-exit exhaust to electrically shut one of the exits? Akyone know if this was for noise issues, and did it ever work well?
Yeah, it was fitted to some of the R33 GTS-T's but I've never seen it on a car over here. Some Mitsubish GTO's also have it.
Had one on my R33. Didn't really do a lot as it only worked on one side. Quite over-engineered setup for what it did really, with lots of cams and cable going from the boot to the exhaust.
mambastu
13-06-2005, 00:33
That does take me to my point though, at those sorts of volumes, shouldn't you be using hearing protection?
Eh ? ;) :D
It would be more of a problem if I had a seat behind the exhaust at 5300 rpm +
From inside the car its no-where near that loud.
That does take me to my point though, at those sorts of volumes, shouldn't you be using hearing protection?
Sorry? I can't hear you :D
Something went past where I work off Rabans Lane on Friday, going (watch out for the sound effects :D )
vrrrooooOOOOOOM BANG VRRRRROOooo BANG vrrrrrrr pop pop pop-pop-pop-pop vrrrrrr pop-poppopopop
Was that you? :)
Good work, looks like I'll also have to invest in one of those big Jetex silencers.
Anybody have anyproblems with the big one being offset? (bottom one)
Has anybody tried the 630mm long one, not oval, non-offset. (second one)
http://jetex.co.uk/Jetexwebsite/universalparts/boxes3inch.htm
it looks like I will also have to buy one due to the police in the north of scotland having a zero tolerance on performance exhausts, my only hope it to make it as quite as a standard exhaust.
I was also thinking of enlarging the exit on my bung so that it will reduce back pressure a little but still quiten the system down.
glens14a
13-06-2005, 13:15
I have a Jetex U447600R on my system 3" bore stainless steel 125mm x 250mm
It's made a big difference as I have a 4 branch/elbow and no cats
http://server3.uploadit.org/files/jediimp-jetex.JPG
I have a Jetex U447600R on my system 3" bore stainless steel 125mm x 250mm
Sure? thats the 630mm version
U457600 is the 250mm one.
glens14a
13-06-2005, 13:47
Sure? thats the 630mm version
U457600 is the 250mm one.
:nod: your correct it's a U457600R :annoyed:
PhilMorrison
13-06-2005, 14:01
I fitted the largest of the Mild Steel universal Jetex box's last week, it's made the car far to quiet :(.. It's not actually sapped that much power though. Definatly slower, but not to bad. To fit this box where the cat would normally, I had to get a bit inventive with the floorpan with the aid of a 20kg sledghammer :eek:
sroberts
13-06-2005, 14:06
On a intersting note, it would be interesting to get dB reading for Dans titanium GP Sports exhaust. Its a single box system and its far far quieter than my nur spec and appears to not sap power.
Si :)
Isn't anyone, especially people running big power concerend by changing silencers effecting the fuelling of the car?
People have mentioned a loss in power which will be straining things and car specific maps on stand alone management wouldn't compensate for this?
I've also got a concern of the screamer pipe which is loud. What can be done about this?
Feed the Screamer back into the exhaust somewhere further down the exhaust, or get a long 2" silencer for it.
Fuelling should only be effected on MAP-sensor equipped cars, then only nominally, the VE will only alter slightly.
We have a selection of silencers here now to try out :)
I have the Scorpian de cat from Bren. With Front Pipe, main cat and Apexi GT Spec I got around 114dB. With the Scorpian in it was the same, maybe 115dB :)
Drifter that can't be right, you are saying with the GT spec zorst with cats in gave 114dB, thats is louded than a jet plane on takeoff.
mambastu
13-06-2005, 17:41
Isn't anyone, especially people running big power concerend by changing silencers effecting the fuelling of the car?
People have mentioned a loss in power which will be straining things and car specific maps on stand alone management wouldn't compensate for this?
Can't speak for everyone else but I've noticed mine runs slightly richer in certain parts of the rev range with the new quiet exhaust so I'm going to re-map it slightly.
Drifter that can't be right, you are saying with the GT spec zorst with cats in gave 114dB, thats is louded than a jet plane on takeoff.
:D Not measured very technically though. 3000rpm and tested close to the tip with a *cough..cough* Nokia mobile phone :p It certainly doesn't sound loud, just a very deep rumble, kinda like an earthquake :cool:
it wont be that loud, my apex single silencer system was 103db @ 4k rpm
How has everyone tested their dB's. Don't really want to ask the local plod ;)
thats a good point, I really don't want to ask the local plod as they are the one who are giving me grief, was hoping that my local tuner and RR could do it but they don't :(
mambastu
13-06-2005, 19:28
How has everyone tested their dB's. Don't really want to ask the local plod ;)
Tested mine at Goodwood first as a benchmark and then used a Nokia mobile at the same distance and RPM and it was 1db lower on the Nokia so they're reasonably accurate. They don't test db's by sticking it up the exhaust, its a set distance and angle away from the end of the exhaust tip.
what phone does dB limits?????
what phone does dB limits?????
Dont know the number. It is the Nokia jobbie for builders, in a tough rubber case. It also has a torch and level :p
what phone does dB limits?????
Nokia 5100
http://www.mobile-phones-uk.org.uk/nokia-5100.htm
Nokia 5140
http://www.mobile-phones-uk.org.uk/nokia-5140.htm
Nokia 5140
http://www.mobile-phones-uk.org.uk/nokia-5140.htm
:nod: Thats the one
...there was one fitted to Slipstream Ian's car at Japfest. Think he still used the Nur bung as well to be on the safe side though
My mistake, apparently he got one the track with the silencer but without the bung -whereas before the bung was needed. It wasn't even the largest jetex silencer that I put in (no hammering of the floor pan needed :) ).
was a very well made pipe..............
Lol. And apparently his sex life got better for the duration it was fitted, and people in the street stopped him to congratulate him on his choice... etc.
Lol. And apparently his sex life got better for the duration it was fitted, and people in the street stopped him to congratulate him on his choice... etc.
It was bloody noisey before...... :wack:
Well I have an Apexi ECV which I used for japfest at CCoombe. I closed it a bit to get tested (94db) and then opened it up on track.. job done:thumbs:
Slipstream_ian
27-07-2005, 11:20
It was bloody noisey before...... :wack:
im borrowing it again for the UJC track day to so im hoping that will still get me though as it was 100DB bang on the nose
skyshack
27-07-2005, 19:20
OK have they got in for me? I just get the home page for all the Jetex links.
BeerBringer
25-10-2005, 11:47
We have this problem in Sweden also. Usually there is a 95 dB limit on our tracks. I don't know how many cars were blackflaged on "JapMeet" this summer due to beeing to loud, but it was ALOT!
Almost all aftermarket systems seem to be to loud. If not they have an ugly as tailpipe...
I'm still on stock but I'll probably build my own to keep the noice down.
Anyone got any pics of these jetex boxes fitted :)
I'll take some photo's of mine, I'm not very tolerant of excessive noise but the Jetex silencer mad quite a differance when it replaced the tiny mid-box of the Apex old style twin box system. I'll see if I can get some dB figures :nod:
And I only added this one
http://www.jetex.co.uk/website/images/U307600box.jpg
I'll take some photo's of mine, I'm not very tolerant of excessive noise but the Jetex silencer mad quite a differance when it replaced the tiny mid-box of the Apex old style twin box system. I'll see if I can get some dB figures :nod:
And I only added this one
http://www.jetex.co.uk/website/images/U307600box.jpg
I have the same box, it made a huge difference. Took it out now because I wanted the power back :)
I dont think I lost any power :no:
I dont think I lost any power :no:
I had a definate decrease in response and power. Although not tested, infact it's never been on the rollers, yet, I would say about 10-15bhp was lost, ish.
archenemy.co.uk
27-10-2005, 19:21
Eh Its a straight through silencer, not baffled how can you loose that much if any. Me thinks you imagined it :nod:
Eh Its a straight through silencer, not baffled how can you loose that much if any. Me thinks you imagined it :nod:
Well... I was a bit baffled (heh) when we fitted it and the response didn't seem the same. So the day I removed it I went for a run down a DC, removed the silencer, went back, and there was a marked difference.
However maybe the increased noise made it SOUND faster :)
I need a 3 inch decat silencer, bren is kind of stuck at present with the ones he was going to do.... any suggestions of places to get one made? :thumbs:
Well I reckon Graham @ TopGearNW Did a cracking job on mine, I'll speak to him on Sat :nod: Mines in the mid-section but I reckon it could easily have been in the decat :nod:
Well I reckon Graham @ TopGearNW Did a cracking job on mine, I'll speak to him on Sat :nod: Mines in the mid-section but I reckon it could easily have been in the decat :nod:
Cheers :thumbs: let me know ;)
mambastu
27-10-2005, 22:33
Eh Its a straight through silencer, not baffled how can you loose that much if any. Me thinks you imagined it :nod:
I lost a shit load of power (and response) when I used the Jetex boxes even after a re-map to allow for the fuelling changes. I had one 3" bore small oval with one 3" bore large oval as a rear box.
They might be straight through boxes but they take a chunk of power away on mine. Couldn't wait to get the Blitz back on.
Its ironic that the slowest the car will ever be is on a race track :rolleyes:
I'm using the largest 3" silencer with a Nur Spec on my car. Going to make up a straight through pipe. See if I can crack 500bhp ;)
Also going to measure the back pressure before and after - should be quite interesting.
Mine did, using an Apex twinbox catback, I reckon it dropped to low 90's but I also have a decat silencer. I replaced the small mid-box with the Jetex one, it made it lower to the ground (by ~1") but it fitted fine, slight angle to avoid the prop :nod:
ScottieS13
21-11-2005, 23:02
lol untill i learned that it could kill the seals in my turbo i was planning on running a scafolding bar straight out the back of the car. but i suppose its a good thing asi wouldnt get very far on a track day if this was the case
If anyone is looking for an oval 3" Jetex silencer, I've got one spare - I was going to make it into a decat silencer, but it didn't happen before the car went...
the silencer is the same size as the exhaust so wouldnt slip over it very well :confused:
if he twised the box a bit to clear the prop the ground clearence would be just 2" and if i hit a speed bump i could rip the exhaust off :wack:
he said would be £70 + vat :whip:
i dont know what to do now :confused:
SM got any pics of yours so i can see if it inside or outside the exhaust also hows your ground clearence with that silencer box :)
Yep, they are the same size, you need to flare one end, any good exhaust maker should have a flarer.
Yep, mine is slightly twisted, and the lowest part of the car.
I got mine done by a board member on here, Graham from TopgearNW, (TopGearNW on this BB) www.topgearnw.com and was MUCH less than £70, he is also about to do somwething similar with SteA's car but not with a JetEx silencer as he has sourced some other genuine 3" bore silencers to test.
Has anybody got any experience of the apexi active tail silencer, they sound too good to be true.
http://www.apexi-usa.com/product_exhaust_detail.asp?id=217&pageNum=1
http://www.apexi-usa.com/graphics/products/2173.jpg
We have batch of Jetex silencers (straight decat replacement on the s14s) that we are testing at the moment and have some of the Apexi active tailpipes coming to see how well they work :)
Would the Jetex silencer get the single box through castle coombe without the bung?
My single box appears to be about 10db above other decatted ones for some reason too, probably the manifold. Also worried that with the bung being so restrictive and the amount off boost that the backpressure will blow out my turbo gaskets.
I couldnt say for sure, I dont have db ratings for the suilencers yet. Will have soon though :)
Just been down to Goodwood to have my car noise tested. Very friendly and helpful people down there :thumbs:
I mentioned that my car had a Skyline engine in it and they said that they have a lot of problems with Skylines and noise levels. An early bad sign was the guy shaking his head as I drove it up to him.
Measured at 5300 rpm I achieved.....115 db
I think I almost broke the fookin sound meter :wack:
I have a NUR Spec R cat back rear system with a custom built twin 2.5" into 3" front pipe. The odd thing is that if anything it actually sounds quieter inside the car with the bung out than it ever did with the same exhaust on the CA.
Jez, any idea what db's your car was before and after you fitted the additional silencer in it ?
Ah bugger, not sure that I'm going to be able to get that down to sub 105 levels even with an extra silencer and to be honest it sounds so nice with the current setup I don't really want to. Silly low noise limits :(
115dp are you sure? You'll struggle every 4db means a doubling in volume you would have to reduce the volume to less than 25% it's current level. I have a feeling the gauge or it's casing may be sesetive to a certain fequency causing a dodgey reading. Maybe the skyline just happens to hit that frequency more easily than other cars...
anyway just athought
mambastu
31-01-2006, 23:49
115dp are you sure? You'll struggle every 4db means a doubling in volume you would have to reduce the volume to less than 25% it's current level. I have a feeling the gauge or it's casing may be sesetive to a certain fequency causing a dodgey reading. Maybe the skyline just happens to hit that frequency more easily than other cars...
anyway just athought
115dp ? No, 115 db ;)
Yes, I'm sure. One of the marshalls at Goodwood kindly tested it for me before GT Battle last year with one of their handheld noise meters. I also used a friends Nokia with built in noise meter just to see how accurate it was in comparison and it recorded 114db.
I think you might be right about the frequency because it does sound very different to a CA's or SR'd 200SX (higher pitched) and the guy at Goodwood said they have a lot of problems with Skylines on trackdays. I had to get a custom exhaust made up to get it under 105dbs but it does rob a fair bit of power as previously mentioned so I'm looking at another solution.
The car is reasonably noisy at idle but when its revved it gets much much louder. You can literally hear the car howling from a couple of miles away when its on full chat. The weird thing is I don't get the uncomfortable resonance inside the passenger cabin that I used to get with the Nur Spec R when I had the CA in the car which makes the exhaust much more bearable with the bung out than it used to be......er....either that or I've gone deaf :D
Theres a vid I did last year of the car doing a few standing starts and it'll give some idea of the sound difference compared to a normal 200 http://mambastu.mysite.wanadoo-members.co.uk/Standing_starts_01.mpg
This is what BaT use on their caterhams to get the noise down.
http://www.supertrapp.com/product_sections/cat.asp?CatID=27
Dont know if it would work on our turbo nutter barges.
:( They don't work at all for our cars.
I rented one of these from a garage outfit that was at a Bedford trackday last year. I didn't even manage a single lap till i got black flagged...I was running an Apex type 1 cat back with de-cat and front pipe...
They work on N/A cars but not turbo'd ones.:(
Our S13 ran 100 yesterday with one of our new decat silencers. Thats a drop from 107ish :)
Our S13 ran 100 yesterday with one of our new decat silencers. Thats a drop from 107ish :)
Wondered how you passed the 105dB limit :wack:
Is that a Apex single box, or twin box, system + decat silencers.
I had it in my head you were running a silenced front pipe + single box system only.
Twin box with one of our new 3" decat silencers :) I measured it as 95db, as did gary. Ann says BAT measured ti as 100db but maybe shes wrong seeing as both Gary and I got 95. Its certainly not anywhere near as loud as it used to be.
115dp ? No, 115 db ;)
You can literally hear the car howling from a couple of miles away when its on full chat. The weird thing is I don't get the uncomfortable resonance inside the passenger cabin that I used to get with the Nur Spec R when I had the CA in the car which makes the exhaust much more bearable with the bung out than it used to be......er....either that or I've gone deaf :D
[/url]
Yeah I found that with mine. First time I heard it I couldnt believe it!!! It sounds like a bike!!! :D And youre right about the incar bit. ITs nowhere near as bad:confused:
Ideally I would like to have something I can change easily. Looked at these options;
Apexi Exhaust Control Valve
http://www.apexi.com/product_exhaust_detail.asp?id=251&pageNum=1
But it kills power too much.
If I had 2/3 silencers I could swap into the decat space, each giving me 96/98/100db's that would be ideal.
I have an APEXi ECV fitted but I took it to an engineering factory first and had the bore increased to 3 inch so as not to kill power. They charged me all of £20 to do it. It's my intention to have the valve "flap" itself increased to 3" to match so I can close the zorst right up if I want but at the moment it takes the DB right down to 94 with only the 67mm valve in the new 3" hole. I have been on track at CCoombe and Silverstone with this fitted and all I did was open the valve again when I got on track. I was never stopped or tested again but if I was tested again I would just pull the valve shut again:D
archenemy.co.uk
13-02-2006, 08:41
I have an APEXi ECV fitted but I took it to an engineering factory first and had the bore increased to 3 inch so as not to kill power. They charged me all of £20 to do it. It's my intention to have the valve "flap" itself increased to 3" to match so I can close the zorst right up if I want but at the moment it takes the DB right down to 94 with only the 67mm valve in the new 3" hole. I have been on track at CCoombe and Silverstone with this fitted and all I did was open the valve again when I got on track. I was never stopped or tested again but if I was tested again I would just pull the valve shut again:D
Don't go to a place like Bedford
There are no second chances on the drive by tests, you pass a station, too much noise = bye bye :(
Drive by tests? what, on a public road or do you mean on a track?
As far as I'm aware the track at Bedford has a 101db noise limit and quite frankly my car would pass that without any form of silencing and thats with well over 300bhp and a GT Spec zorst(3.74inches). I think it's usually the cheap exhausts that make over 101db... oh yeah, and the nur spec..
archenemy.co.uk
13-02-2006, 09:17
As far as I'm aware the track at Bedford has a 101db noise limit and quite frankly my car would pass that without any form of silencing and thats with well over 300bhp and a GT Spec zorst(3.74inches). I think it's usually the cheap exhausts that make over 101db... oh yeah, and the nur spec..
Youre wrong
The drive by is 89db I think
We went to have a test the other week see the Bedford thread in the MS section for details
Apex single exhaust needed a bung and a decat silencer to pass, only just
Youre wrong
The drive by is 89db I think
We went to have a test the other week see the Bedford thread in the MS section for details
Apex single exhaust needed a bung and a decat silencer to pass, only just
I was looking here (http://www.trackdays.co.uk/tracks/bedford.htm) where they clearly state it's 101db.. Maybe they adjust their limits for different track days?
If it was 89db then thats not really worth doing as most people certainly on here would just fail even with a silencer..
Ah I see, the other test is measured 20 metres from the car....
That is low, i need to sort this out early this year or i'll have problems...
Maybe you could bung up but increase boost made?.. Like for example when you close your exhaust opening you actually make it much more difficult to get boost but would increasing your settings bring the power back? It makes me wonder how big production cars manage with such low noise?..
archenemy.co.uk
13-02-2006, 09:52
They have 2 ways of metering the noise, the static one is the 101 IIRC and the drive by, which is the important one is 89db. very difficult to fool this one all day, with 2 metering stations round the track and a no tolerance rule.
Thats why we took a trip up there - check it out now avoid dissapointment later. Me with Mongoose and sports cat breezed through
I remember passing you 2 up at castle combe (even though you did you best to hold me back and knock me off) Chil so its not too slow either :)
Look Phil. in principal I agree with the general message of what you have tried to say but making stupid accusations is not the thing to do and it's completely out of order. Do not accuse me of trying to "knock" someone "off" a track. That's wrong and certainly is not a joke!
archenemy.co.uk
13-02-2006, 10:08
Blah Blah blah ;)
archenemy.co.uk
13-02-2006, 10:22
dum de dum :)
OOh look, a japfest piccy!!:D
http://www.sxoc.com/vbb/attachment.php?attachmentid=28063&stc=1&d=1139952828
archenemy.co.uk
13-02-2006, 10:32
nothing to see here :no:
archenemy.co.uk
13-02-2006, 10:36
Raspberry Raspberry
Well what do you expect?;)
http://www.sxoc.com/images/dynamic/memberimgs/lores/2005524184615.jpg
archenemy.co.uk
13-02-2006, 10:44
:)
Steady on please guys, we gone on from noise issues now.
Look Phil. in principal I agree with the general message of what you have tried to say but making stupid accusations is not the thing to do and it's completely out of order. Do not accuse me of trying to "knock" someone "off" a track. That's wrong and certainly is not a joke!
Woah there man... how can you have a username like cHiL and be bleating on like a teenager with his cock stuck into the back of a lamb?
My silencer was very effective from jetex. It also took quite a lot of abuse last year, it has a few dints it in and the core has survived well and still does a good job.
with 2 metering stations round the track and a no tolerance rule.:)
There are actually 3 points on the track at Bedford where they meter the noise.
Woah there man... how can you have a username like cHiL and be bleating on like a teenager with his cock stuck into the back of a lamb?
Hi yeager :wave: "cHiL" is one half of a surname, I haven't been a teenager for 21 years and I'm neither "welsh" nor beastial ;)
Slipstream_ian
24-04-2006, 12:55
Well on saturday i had car messused at combe with the bung in it was 96.9 and with it out 101db
this is still with my nur spec and cresey de cats last year it was 100 db with the bung in so work that one out
I was at Donington on the Friday before the show. I'm now running a scorpion decat and the apex type II exhaust (cat-back). When exiting the final corner (onto the home straight), I got measured at 102 dB!!!:eek:
I thought the apex II exhaust was meant to be quieter than the type I. I got the same reading last year when I had a straight through system with the type I exhaust on!
I then changed gear at the point where the noise meter is and that sorted it out!
i'm a women i know i put a pillow over my mouth that silences me or use your imagination
I have been asked to review the Apexi N1 exti by pm so I thought I would post it up here. I think bren can do them for around 600 with varying lead times. I think Im the only SX owner with one in this country or at least very few people.
I dont have a digital camera on me at the moment so I wont be able to take a pic but its on the american website. It is 80% stainless steel its just the rear box that is titanium and has an "apexi" brand stamped in it. Its not as loud as the GT spec but is slightly louder then the N1 evo. The reason I got it is its a JASMA quiet exhaust and does not rust unlike the standard N1. The N1 evo is fully stainless but it wont fit the active tail silencer in. The N1 exti fits the active tail silencer in no problems. It also comes with a slash cut collar that fits over the back box exit, this has a nice blue flame effect that would be good to pop on when showing the car but unnecessary otherwise.
I would recommend this exhaust if you want a reasonable volume JASMA (less then 98db) exhaust which can fit the active tail silencer in for additional track time sound suppression without affecting power too much. If you dont have strict noise regulation and dont want the active tail silencer the N1 evo is the one to go for although slightly heavier.
Apexi exhausts that dont rust - N1 evo, N1 exti, GT spec
Apexi exhausts that do rust - Dual N1, N1 (about 2-3 year life)
Apexi exhasts that work with the active tail silencer - GT spec, N1 exti, N1
Apexi exhausts over 98db (jasma) - GT spec
All of the above exhausts should cope with 4-500bhp
I disagree that the non stainless exhausts only have a life of 2-3 years. The origiunal Nissan exhausts are only mild steel and they can last in excess of 10 years :)
Ive had some bad experiences with mild steel in the past. I bought a Jetex back box that was meant to have all sort of super coatings on, it holed in 3 years. One of my friends had another english brand, that last 1.5 years he managed to get 3 out of it but by the time he sold the car it was more putty and patches then metal. I have heard people having similar experiences with HKS mild steel exhausts. Maybe apexi are better as ive not had any bad storys of holed exhausts.
Fair comment, Im just going on standard type systems :)
Another person PMing me about exhaust
pic -
http://www.sxoc.co.uk/vbb/attachment.php?attachmentid=36226&stc=1&d=1155040198
VoodooRhythm
08-08-2006, 20:45
As asked earlier, what other places are there that could do a quick noise test??? I'm really worried about the level of mine as i'm running 3" turbo elbow + front pipe, 4" expansion de-cat, and Apex single box system.
You can hire one from Bookatrack - if you are a trackday customer, or pop to most racetracks.
Anyone got a fix for noisy external wastegates other than plumbing it back into the original system?
Anyone got a fix for noisy external wastegates other than plumbing it back into the original system?
This may sound like a silly suggestion, but can you not just attach a silencer to it?
Thats what I tried to get SX Sam to do the other month - but he plumbed it back in.
Bren told me he was going to silence his screamer - surely its just an extra exhaust, make it side exit, and as its longer you'll probably have to step up the bore to stop creep (I guess, anybody know? )
This may sound like a silly suggestion, but can you not just attach a silencer to it?
Yeah but I wondered if anyone had any experience of it I was going to have to do the research from scratch :)
Id imagine a bit difficult as there wont be the room for it under the car.
Has anybody got any experience of the apexi active tail silencer, they sound too good to be true.
http://www.apexi-usa.com/product_exhaust_detail.asp?id=217&pageNum=1
http://www.apexi-usa.com/graphics/products/2173.jpg
No news on these yet? Anyone got db readings for a ca with this on?
Straightliners will noise test your Cars at Elvington on the 11th of March the noise test is free just pay to get in to the RWUB event £10 if you want to enter the event it is open to cars and bikes just bring a crash helmet and your driving licence Regards Bishop (Straightliners)
I find it all well silly personaly, I have a nur spec R and front pipe from apex with some sort of silencer where the cat is, before i went to fit this lot I tought I'd phone my local police department up in Milton Keynes and ask them if they could tell me what my legal limmit is for the ROADS ? After 20 mins of talking to people in the DVLA and with the police, they basicly said, they most certianly dont no of any law, and they deffiantly dont have any equipment for mesureing exhaust loudness, so as far as they no they are currently not enforeceing it. So this crap about noise limmits on the track is just corporate laws placed on them to make life harder for the guy who owns the track, its aload of bullshit I say, and we should just race on the roads, they soon change the limmits then hehe.
I have an Apex 3" system from the elbow-back (I have the bung from Apex too). Does anyone know the sort of dB level these produce? Quite worried now I have a track pass for combe at the end of april.... :wack:
Apex 3" full system is 105dB on mine at 4500rpm. 98dB with decat silencer. I havent tried it with a bung though.
Purplepower
04-05-2007, 21:06
Interesting reading about the RB25 skyline / resonance issue mentioned on this thread..
Anyone have any more experiances with the apexi tail silencer?
Mista Weava
19-07-2007, 11:04
This is my solution.
it is a little restricitive - more-so depending on the requirement to use exhaust packing.
i recorded a 5 decibel loss to get down to 92db static from 97db WITHOUT PACKING.
http://img.photobucket.com/albums/v325/mistaweava1/Bung/Bung001.jpg
http://img.photobucket.com/albums/v325/mistaweava1/Bung/Bung002.jpg
http://img.photobucket.com/albums/v325/mistaweava1/Bung/Bung003.jpg
http://img.photobucket.com/albums/v325/mistaweava1/Bung/Bung004.jpg
http://img.photobucket.com/albums/v325/mistaweava1/Bung/Bung005.jpg
http://img.photobucket.com/albums/v325/mistaweava1/Bung/Bung006.jpg
the red "X"shows the "X" that i had fitted later on, so i could put exhaust packing behind it to lower the noise as necessary. basically it was two bars welded in this shape to stop the packing blowing out.
i have not tested the bung with packing yet on a noise meter, but i made provision for its use, in case i got stung at a track; the theory being, that whilst it may be restrictive i would still be getting track time. i can confirm that it lowers the noise level DRAMATICALLY with packing in.
http://img.photobucket.com/albums/v325/mistaweava1/Bung/Bung008x.jpg
http://img.photobucket.com/albums/v325/mistaweava1/Bung/Bung009.jpg
the bung is stainless and copied from that of a mates inpreza. the bung had to be bespoke as i have a small diameter tail pipe (i hate channel tunnel tail pipes). i got a mate at the local fabricators to knock it out in lunchtime.
the great thing is being able to remove it in seconds, and also the ability to add and remove packing to tailor the noise level to suit the track.
crude? maybe.
cheap? definitely!
effective? :nod:
:thumbs:
Ive got an Apexi active tail silencer for sale. Reduces noise but not power due to being active.
Don't know how ontopic this is but on the Nürburgring there is also a limit but they never measure it, my open exaust is REALLY loud and they never said anything but I'm not the only one, the M3 CSL's, Caterhams, 911's all roar their ass off and just get to go on.
So don't bother silencing it if you are going to the Ring :)
BackEndOut
09-05-2008, 01:48
Right i've just read thru this whole topic and haven't actually got a FINAL SOLUTION. Can someone tell me what is the best exhaust system that i can buy/create with maximum performance and minimum noise. The tracks I will be goin on allow 95db. Can someone tell me the answer to maintaining 300-350hp and the 95db limit.
95 static, or 95 drive by?
S13 or S14?
Basically you want big 3" straight through silencers, these usually have to be welded into most aftermarket exhausts, you can buy a silencer installed in a decat pipe for ease of install.
BackEndOut
09-05-2008, 14:16
S15 actually :thumbs: erm wot is normally louder? static or driveby? So if i went for a 3inch turbo back with Nur Spec and a Jetex 3inch Silencer in the decat region...i'd be good for 95db?
I'm running pretty standard S14, Apex'i Induction, Standard Downpipe, CAT, Custom 2 1/2inch centre, HKS Super Dragger Backbox. I hardly notice I've got massive 4.5inch tailpipe. Ticks over with lovely grumble, when I'm driving its not killing my ears. I'm really impressed. Will a Decat make it louder if I don't get the silenced one?
Cheers guys
We are currently testing a prototype Apex S14 track exhaust. The car running it was at Cadwell Park last week and recorded 87Db at 4500rpm. Apparently. Although Im more inclined to think their testing meter was broken!
Powered by vBulletin® Version 4.1.9 Copyright © 2012 vBulletin Solutions, Inc. All rights reserved.