kevin
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Side exhaust in UK?

Post by kevin »

Does any one know if you're allowed an after market side exhaust in the UK if it conforms to the correct decibel level .
We used to have a rule that the exhaust could not point left like on our old alfa spiders as the exhaust gas was aimed at pedestrians .
Also what is the legal decibel limit in UK for road .
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Giuliettaevo2
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Re: Side exhaust in UK?

Post by Giuliettaevo2 »

Don't know what the rules are in the UK. But there are also production cars, vans and trucks with side exit exhausts and those are not illegal. See the Viper or some AMG Mercedes models for instance. :wink:
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Re: Side exhaust in UK?

Post by Steve R »

Yep it's perfectly legal in the UK, see here:

http://www.youtube.com/watch?v=4iEai0_pdgM

Had that on for several years, passed MOT's no problem as not too loud when ticking over. Also never stopped by police either as it was a "reasonably" sane sound when driving slowly or legal motorway cruising speeds.

CSC manifolds into twin 2" pipes, straight into an un-baffled Jetex box that merged into single 2.5" then out to the passenger side in front of the rear wheel as a 63mm pipe.

There are no decibel measurements for UK MOT, but the written regulations say something like it mustn't be noticeably louder than the factory component. However, the MOT man told me as it's a 30 year old car, who can say for sure what it used to sound like!

So basically MOT and police no problem, the only issue I had was reduced ground clearance - they like speed bump round here.
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Re: Side exhaust in UK?

Post by kevin »

I'm trying to find the right product ie after market end piece that I can interchange on my side exit exhausts . It will need to be about 400 mm long max and 70 mm diameter as that all the room I have if I cut and make joint near the end of the side exits . I can always put sleeve pipes on and clamps then attach new end piece to body just like I have now .
. Trackday DB is my problem not MOT and also I think my neighbours ( or even neighbourhood) are about to raise the issue .
I really don't want to suffocate the engine just merely trim it by plus minus 5db to get it around 97 . My side exits are 50mm . Has any one had to add anything to their cars just to take th edge off ?
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75evo
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Re: Side exhaust in UK?

Post by 75evo »

Probably the best thing is to get twin adjustable electronic valves. Keep it 3/4 closed in town and for MOT tests and wide open for the track. Also if you add the V-band clamps after the electronic valves, you can replace it with very restrictive 1.5" resonated pipes. But I think the valves alone should help keep the noise levels down.
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Re: Side exhaust in UK?

Post by kevin »

I don't have room above box for the electronic actuator as there normally very high . Maybe I have not seen the tight product here . Ironically track day db is the problem as its not to bad up to 4000rpm . It already had two small boxes on . I guess its the 100mm pistons that create that deep noise down the pipes .
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Re: Side exhaust in UK?

Post by 75evo »

You can mount the actuators in any orientation, so the gap between the pie and the body is not a problem. I just noticed that you said you have no room above the box, I'm assuming you meant the center muffler. I don't think you mount it there. You can mount this type of valve (attached pics) after the muffler
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.

But it looks like the gap between the 2 pipes is small and that could pose a problem as the valve body itself is a bit bulky. You could try a mechanical valve as the valve body is slimmer.

This one functions on vacuum.

http://www.amazon.com/Weldable-Stainles ... B00HPC1P00

Install this on one of the pipes. When it shuts off, that pipe acts like a helmholtz resonator and should take out the low frequency. And for the other pipe just restrict it down by 0.5". Or install a turndown with a cone like ones from dynatech.

http://pitstopusa.com/i-5069645-dynatec ... e-3-5.html

Or if that doesn't work out for you, this varex muffler could work out for you if you replace your current muffler. Get the 2 in 2 out version (a bit expensive), but the mounting of the actuator doesn't seem to take too much room under the body.
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Re: Side exhaust in UK?

Post by kevin »

In order to have a dual in and out with an actuator the box becomes very big . I don't want to restrict the air flow by reducing diameter to reduce noise . I have been sent some links to jetex and custom chrome which can make end pieces to take off a few DB . I'm going to email them and see what they come up with .
I have looked at moroso spiral flow and jetex inserts but these appear to increase back pressure hugely . I probably need to increase volume to reduce DB without affecting back pressure .
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Re: Side exhaust in UK?

Post by 75evo »

Try replacing the 2 front small mufflers with cat converters. The metal ones won't really affect performance. They will take the edge off the sound.

http://www.mandrelbendingsolutions.com/ ... %22/Detail

Then, as you said, try to increase the main muffler volume. But it sounds really difficult with the space restriction..

The last one is probably to turn the exhaust downwards at the tips.
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Re: Side exhaust in UK?

Post by Grdi »

hi all...do you have by chance any draw/dimensions for the AR75 side exhaust build?
or some web (maybe post here?) where to find some this example?!
Decibel level is not the issue, as louder as better :D performance and weight only related mod...

I talk about 3.0 24v engine...

Thanks!
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75evo
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Re: Side exhaust in UK?

Post by 75evo »

I have my old side exhaust (absolutely no muffler). Believe me it was obnoxiously loud. It takes away from your driving experience. It had 11mm cams, open intake, CSC headers into X pipe then 2 pipes out the side. You need one muffler, not a big one, but you need just one. Probably a 2X 2" in and out with a small 4" casing. Then the sound would be loud but not obnoxiously loud like my old side exhaust.

I can snap some photos of it. Probably all rusty now. It needs 90 degree bends but to go under the 75's frame rails it also needs slight pipe offsets which can be done by combining a few bends.

If you have a cage, and take off those rails underneath the body, then it becomes easier. Just cut the skirting on the side a bit to avoid melting it.

Here's the video:

https://www.youtube.com/watch?v=VKZFL7SgB2U

Actually you made your own custom multi chamber muffler didn't you? Try to get the low frequency out, and retain most of the high end. The low frequency stuff is seriously annoying. The standard absorption muffler won't do it. It takes away the high frequency sound! At least that's what I think based on the many mufflers I used before.
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Re: Side exhaust in UK?

Post by Grdi »

Thanks 75evo!

Headers are stock 164 24v headers tuned for rwd accommodation. From there I have 2x2.16'' (55mm) with flexi part (or maybe 2x2'' not sure anymore?!) into mid muffler (somehow standard, not open), then 2 in 1 (aka Y), becoming 1x2.36’’ (60mm), rear muffler (more open than standard versions) and back out.
So, this is somehow standard 3.0 setup done by the local exhaust specialist according my draw.

Now I want to remove completely rear back muffler (I don’t want weight and heating on the back and want to open rear bumper).
Plan is to go straight from the first muffler (will make new muffler more open, or even full open), Y part and side exit before rear tire.
Is it smart after muffler to do first Y and then one 2.36’’ pipe on side or w/o Y but two parallel 2.16’’pipes on the side, somehow like Kevin’s picture above?!

Noise I don’t care, helmet on the head and focus is on driving, particularly in hillclimb, regular race track forgiving mistakes, hillclimb as rally, never :)


one flyby on the track with current setup...car sounds like regular louder street car...I want loudness, side exit and nothing to lose on performance...any hints are welcome

http://www.youtube.com/watch?v=NA9VkbSAkw8
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Re: Side exhaust in UK?

Post by 75evo »

I read somewhere, that the merge collector helps exhaust scavenging. To what extent, that I'm unsure of. You then split it back to 2 pipes because 2 2" pipes are easier to fit under the car when you want to go to the side. So I think an X pipe is the best solution. The muffler absorbs some energy I think, so the scavenging effect may decrease if you put a muffler before merging (my theory). I would put a nice compact 2 in 2 out muffler under the car and then make it go out like Kevin's car.
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Re: Side exhaust in UK?

Post by kevin »

What worked for us was a 55mm x2 into center box then out the side . The one pic is not ideal for two reasons as it has a resonator boxes close to manifolds where you want a long clear section before the first silencer box . I had to have this to bring down the noise but it did not really help that match . Secondly my bends after silencer are pretty sharp but I needed my side pipes to clear the jacking point on the four post lift . Sound is really beautiful and by keeping twin pipes helps with clearance . You can do the same with the 75 no problem . Make sure you have two flexijoints in .
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Re: Side exhaust in UK?

Post by Grdi »

Thanks Kevin!

As always, picture worth 1000 words 8)
I just did (don’t look draw quality, done in .ppt :oops: ) how this should look like?!

Image

Wondering why you took hard 90deg exit and didn’t use more flat e.g. 100-120deg to finish somewhere in front the rear left tire (on right side is gas pump, at least in my case).
Most probably some accommodation issue below the car, right :?: I can’t right now virtualize the picture of the car below…my idea is to go more flat towards rear side of the car :idea:

Would be great if you can share the movie how your car sound with this setup?! Or if movie is available already here in forum please share the link.

Thank you guys!
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