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Gtir Motorsport club » General Discusion » Gtir related Discussion » In car exhaust noise reduction systems

In car exhaust noise reduction systems

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1 In car exhaust noise reduction systems on 24th July 2016, 7:56 pm

DRC

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Hi guys , I was wondering if any of you fine chaps have thought about or even better used an exhaust noise reduction system like an Apei EVC , Varex number , an eBay valve or HKS EVC ?
I ask as I have a front exit pipe that is ok on long motorway drives and boosted fun , but it is just over the noise levels for where I live and this will draw unwanted attention ( senior citizens  going to the village committees ............ ) 
I don't want to really go back to a full exhaust system at this time  so that is not an option. As I am wanting to use the car for more day to day driving I would like the option of local shop run as apose to " you want so I will give it ya" ( in a Wealdstone raider style) . 

Thanks 
Dan

ROB_IOW

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the two star club
the two star club
My evo had the apexi system fitted .. quite good . I'm thinking about putting it on the pulsar but I think it's only 2.5 inch

3 Re: In car exhaust noise reduction systems on 24th July 2016, 10:04 pm

gtir_woody

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My mate has one, not sure of the brand, works great though and reduces the sound heaps.

4 Re: In car exhaust noise reduction systems on 24th July 2016, 10:14 pm

PartyPete

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the one star club
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I'm interested as I have a 3 inch side exit and would like to reduce noise for track days! What are these apexi systems you are on about?

5 Re: In car exhaust noise reduction systems on 24th July 2016, 10:21 pm

ROB_IOW

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the two star club
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Its just a butterfly in the exhaust . You pull a lever inside the car and it shuts the butterfly valve . Reducing exhaust flow and noise .
You can't drive with them shut . Far too much back pressure .

Evo wouldn't go above 1500rpm when it was shut

DRC

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With he Apexi system drilling a couple of small holes in the buterfly might help with the back pressure issue .
the Varex system looks best to me.

johnny gtir

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I have a manual one on my wide arch car 3"

DRC

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@johnny gtir wrote:I have a manual one on my wide arch car 3"

Johnny does it help bring the noise down ? If so which one did you go for as this is the main thing stopping me driving her as much as I want to . I will be ordering something this week .

nomad

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http://www.japspeed.co.uk/manual-exhaust-valve.html


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10 Re: In car exhaust noise reduction systems on 25th July 2016, 8:44 pm

DRC

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I see there are a few electrical ones on eBay but my worry would be that they are " cheap Chinese " variety that would pack up after a few months . The manual ones are simpler and less lghtly to go wrong . Thanks nomad for that I can't see if it's adjustable or just open or closed. Any ideas

11 Re: In car exhaust noise reduction systems on 25th July 2016, 8:54 pm

gtir_woody

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Good question I would have thought it was completely adjustable but it doesn't seem to indicate that in the description.

12 Re: In car exhaust noise reduction systems on 25th July 2016, 9:04 pm

nomad

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Are the electrical ones just on and off or adjustable .... i would think the cable ones you could adjust to a certain degree as i wouldnt want to just shut it off completely that wouldnt be good for your engine at all ... i guess like a 1/2 - 3/4 shut would minimise noise ....


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13 Re: In car exhaust noise reduction systems on 25th July 2016, 9:52 pm

DRC

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Looking around I think the mechanical one is adjustable looking at the locking device it looks like an old manual choke . The description I have see says " it can be modified on the on the fly" 
Manual sounds best to me. If it was only open or closed this could be  remedied by A : drilling a couple of holes or B : adjusting the cable so it always remains slightly open. Found one for 80 pounds on eBay.

14 Re: In car exhaust noise reduction systems on 26th July 2016, 6:28 am

nomad

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Thats what i thought it would be like an old choke style ... 80 quid is alright your have to chuck some pics up when you get it.... Wink


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15 Re: In car exhaust noise reduction systems on 26th July 2016, 7:05 am

ROB_IOW

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the two star club
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On the apexi one if you pull it out a little it closes a little .. more pull and it closes more ..

Only thing I noticed is after a couple of years of getting hot and sooty it became semi seized ..

16 Re: In car exhaust noise reduction systems on 26th July 2016, 9:31 pm

johnny gtir

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Mine is style as per link. At first I thought it did not but it dose it takes the burble right out of it so it's a lot more effective than you think when you just stand next to it

17 Re: In car exhaust noise reduction systems on 26th July 2016, 10:07 pm

mreguest

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Anything that restricts airflow effects engine performance. At low rpm the valve things do reduce a fair chunk of noise but they are a disaster waiting to happen. I reduce noise for a living and would lose my job if I recommended anything like that because the risk of someone upping the rpm and not opening the valve is too great, ticking time bomb... I help design noise reduction systems on an industrial scale but the science is the same. Some silencers are really huge:
https://goo.gl/images/4pZ0rU

The trackday tail pipe silencers shave off a few decibels but stick them on the dynamometer and you'll lose some top end power.
If you want less noise and maintain bhp you need a silencer with the same cross sectional free area through middle of it as the rest of your pipe work.
Silencers (attenuators) work because they have a perforated steel tube through the middle which should be the same diameter as the rest of your pipe, without getting technical the outer casing simply needs to be as long and wide as you can fit in space available. There are other fancy types of attenuators but the perforated pipe method is easiest and cheapest to consider...
Longer attenuators have better lower frequency and therefore overall sound reduction, wider outer case diameter absorbs more sound so there is a proportional balance to be had, length versus case diameter versus shape too, oval better than round simply because you tend to fit more oval under a car.  Between the perforated inner pipe and outer casing is fireproof soft material which absorbs sound energy through the perforations, this deteriorates (burns out) over time.
There is alot more to it considering number and size of perforations etc too where you target specific resonant frequency response... How do you want it to sound and at what rpm...

Look on jetex.co.uk and work out what silencers you can fit and where... Quite easily figure out a swappable/interchangeable combination of silencers and straight pipes, they have a huge range of flanges and stuff...
The valve things are being wrongly advertised. They were designed as bypass valves for 'sports mode', ie to bypass the restrictive silencers put in modern exhaust systems to meet stricter eu/eec type approval.
Think lambo/ferrari etc, they have to pass the same drive by noise levels as a Renault clio. Simply press the button to unleash the fury, bypass the silencers and get full engine performance. Grey area whether pressing the button on the street is legal or not.
You can get electronic boost controlled bypass system too that I'd love to replicate on the pulsar so it's super quiet off boost and loud as fook at 1bar Smile

18 Re: In car exhaust noise reduction systems on 26th July 2016, 10:34 pm

shroom

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You seen the Armytrix exhaust systems there imense lol

19 Re: In car exhaust noise reduction systems on 27th July 2016, 6:00 am

johnny gtir

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Very good post mreguest I use mine to get in and out the estate at stupid o clock in the morning or stationary mine dose not fully shut as car could not breathe. After that noise dose not bother me but I did look at both diverting via a silancer/rear back box with a valve and twin smaller pipes running down the car like the skylines used to ie 2x 2 inch pipes but never got round to trying it

20 Re: In car exhaust noise reduction systems on 27th July 2016, 5:47 pm

nomad

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Admin
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Very informative post .... but would it be that restrictive on such a short pipe run as he has a front exit ... dont think there is much room to y pipe it anyway .....


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21 Re: In car exhaust noise reduction systems on 27th July 2016, 5:58 pm

DRC

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Yes a very detailed response there .
I intend to fit it just behind the drivers side bumper where the exit pipe comes out of the small in line silencer .
As mentioned above it is just to get me and out of the village / Built up areas at unsocial hours. For me personally big power is nice but I want to use the car for normal duties so cutting a power off up top is not an issue if needs be.

I will post up my set up review when it arrives .

22 Re: In car exhaust noise reduction systems on 27th July 2016, 8:52 pm

DRC

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Just to add I received the control valve and it looks like a fairly well made item and yes it is fully adjustable . The Spring tension is hi and when it's released it snaps open . I will need to find a solid mounting point for the adjuster as it does need a bit of force to adjust it . I will have it fitted on Friday all going well .

23 Re: In car exhaust noise reduction systems on 27th July 2016, 9:38 pm

mreguest

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If you are using it to poodle around estate to avoid antisocial noise then you're probably doing a good thing for social reasons. At low rpm a physical restriction in the system has good effect on noise. But if you put your foot down and essentially you have a blockage in the system then the gas flow is restricted, power is reduced and the overall strain on the engine components can be increased.

Note, diameter of pipe is not all, the velocity of gas flow is key to success, read - http://www.gomog.com/allmorgan/exhaustbackpressure.html

It is near impossible to judge the effect on the above parameters from aftermarket car exhaust equipment manufacturers because they rarely have any meaningful test data. It is a totally unrestricted free for all market largely full of misleading adverts and bullshit.  

The law simply states that it is illegal to change your exhaust to one that is louder than the manufacturers original kit, and the onerous is on you the consumer.

Luckily for us GTIR Pulsar import folk there is no test data available and as such only need to comply with IVA import rules. I think it is 102dBA static position noise measured at 1 metre at 3/4s rpm. Simply put this is loud, and a UK Sunny will of been about 90dBA to pass UK rules. 10dBA quieter is a lot quieter...

Some police have no idea or don't care what the noise rules are, they can simply issue a Section 59 notice which you cannot appeal on site. It's a licence to print money and stop dickheads screaming through esates.
Some innocent people in import cars get caught up because some police take offence to some cars.
Think about it, you drive slowly through an esate in a pulsar or an American car of the same noise level, who is gonna get the Sec59 tickets from the police for noise? Very expensive to fight Sec59 in court, you'd probably win but, it is far cheaper to get a quieter exhaust than to fight the powers that be...

When aftermarket exhaust people are asked they usually say "every car & engine ever produced is slightly different and therefore we don't test anything properly because you cannot copy and paste the test results from one car to the next..."

Well that is total bullshit, they don't do it because proper testing is expensive. FYI in the power and construction industry, i.e. diesel generators, power stations, turbines, diggers etc, it is totally regulated (ISO/BS/EN/EU/EEC/DIN tested) and the exhaust gas flow, silencers and noise data is accurate and works, and is interchangeable across manufacturers.

I've never seen Armytrix before but take for example someone similar:
http://www.fi-exhaust.com/product/mclaren/mp4-12c.html

These are advertising an exhaust that is 'incredible loud!', probably very expensive and they probably don't have any meaningful bhp test data. Would you put an unregulated and untested exhaust on your $100,000 car? Yes of course you would, just in the same way we put mongoose on GTIRs, it's all relative and good fun pub talk...

The Fi youtube video seems to demonstrate noise test data and to the untrained eye I can see why people feel like it makes sense, but it is nonsense. Why?

Well first off the sound level meter (Type 2) they use is £16 on ebay:
http://www.ebay.co.uk/itm/LCD-Digital-Sound-Level-Decibel-Meter-30-130dB-Noise-Monitor-Pressure-Test-0G7B-/172059759055

The one I use costs £5,000 and measures full frequency response data. This is overkill for trackdays etc but if you are going to publish 'test data' then you probably want to spend a few hundred £££s on some proper (Type 1) noise equipment.

Also in the video they state dB values, well they don't understand what a dB is. Decibels need to have more parameters attached to them. dB 'A', 'C' or 'Z' is common and must be quantified by a distance too. Think if a car company said we can do 27MP... Well MP what? MPG or MPH?
The A, C, Z is a frequency weighting. Humans hear in 'A' weighting and dBA is what trackdays reference. Trackdays also reference a distance of 0.5m or 1m from exhaust at 3/4s rpm. Typically from 98 - 105dBA, some also have driveby levels.

Personally I would actually consider using a £16 one if you are simply curious before a trackday. If it left the factory 'calibrated' properly (most do) then worst case Type 2 might be 3dBA away from Type 1 measurement. Set it to dBA, fast, max hold, and give it a blast at what ever you need distancewise/rpm for your track day.

My car with full mongoose was 104dBA at 0.5m 5625rpm. I put a 500mm long 250mm oval simons silencer in the system and it is now 90dBA. 14dBA drop is hugely quieter and the gas flow will be pretty much the same because the cross sectional free area through it is the same.

Back to above Fi exhaust company - "Frequency Intelligent Valvetronic Exhaust System technology offers our cutting-edge intelligent ECU exhaust control valve, with an emphasis on the optimization of both acoustics and performance."
In summary they don't seem to have useful noise data and i doubt there's dynomometer test results. Those readings in the video I reckon are dBC and about 2m from exhaust.
Reality they have removed some silencers and got a black box to open the valves at a single preset rpm to completely bypass the tiny silencers. I doubt they will pass any UK track day noise levels and the police could Sec59 the shit out of them...

Sorry for the massive rant, lol, just flows out sometimes! Smile

Does anyone have any pictures of the side exit exhausts that frequent the pulsars? Would love to see them not on a car?

Surely you can come out the turbo, turn 90 degrees and pass straight through a silencer (big as possible) and out the bumper... bit of good welding and you can make some small and quiet stuff.

Cheers,
Adam

24 Re: In car exhaust noise reduction systems on 28th July 2016, 6:23 am

johnny gtir

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Just to add dose anyone want to take a guess at what anths 100% stock sunny Gtir was at Bedford on the pre track sound test

I only read half the above post and was going to come back to it and now I have the question has been mentioned

Rep point for the above both rant and info in the same post gets my vote

25 Re: In car exhaust noise reduction systems on 28th July 2016, 6:34 am

johnny gtir

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This is not a test just a question so keep the is the same to keep gases flowing fast what your thoughts on hole sizes distance between them position in silences ?

And difference between a retinator and silencer

Like I say I am not testing you just curious as I have worked with the lad and built lots of different exhausts/ boxes for my Gtir's and thinking on the latest one instead of side exit infront of drivers wheel go back to full system for the look of the car. I just know my current side exit out performs any full system I have had but it's no louder than my full systems I have had.

Ps my mate is more of a very good welder than a exhaust builder and I test mine with my work fire alarm Db tester so it's just same distance readings nothing flash

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