Is my exhaust Legal? MOTable?

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charliepinto
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Is my exhaust Legal? MOTable?

Postby charliepinto » Thu Dec 27, 2018 6:40 pm

Hello all,

I've been messing around with my exhaust, trying to find the coolest format and note. I found it in the form of a short straight pipe.
From the down pipe I've got a 1m pipe going straight back and then a angled end pipe which directs the exhaust to the ground. There are no heat issues or fume issues. The pipe angles down before the rear axle. There seems to be quite a grey area with what makes an exhaust MOT worthy. I've had my landrover MOT'd for 5 years with just an open down pipe. I know to a degree it depends on who is doing the test as well. Should my Capri exhaust meet requirements? It is within the decibel rating.

Thanks all :lowrider: :beer:

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D366Y
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Re: Is my exhaust Legal? MOTable?

Postby D366Y » Fri Dec 28, 2018 10:37 am

I think you technically are still meant to have it emissions tested as well but again it depends on where you go as I never have mine checked

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andyd
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Re: Is my exhaust Legal? MOTable?

Postby andyd » Fri Dec 28, 2018 11:25 am

D366Y wrote:I think you technically are still meant to have it emissions tested as well but again it depends on where you go as I never have mine checked

My MOT tester always does the emissions.

Exhaust laws https://www.motester.co.uk/mot-test-of- ... emissions/

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D366Y
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Re: Is my exhaust Legal? MOTable?

Postby D366Y » Fri Dec 28, 2018 12:35 pm

andyd wrote:My MOT tester always does the emissions.

Exhaust laws https://www.motester.co.uk/mot-test-of- ... emissions/


In that case so does mine :lol: :whistle:

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Re: Is my exhaust Legal? MOTable?

Postby Fordoholic Nick » Fri Dec 28, 2018 1:21 pm

D366Y wrote:
andyd wrote:My MOT tester always does the emissions.

Exhaust laws https://www.motester.co.uk/mot-test-of- ... emissions/


In that case so does mine :lol: :whistle:


Danny I would keep quiet about that then mate ;) :lol:
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Re: Is my exhaust Legal? MOTable?

Postby Fordoholic Nick » Fri Dec 28, 2018 1:32 pm

D366Y wrote: it depends on where you go as I never have mine checked


:agree: I been going to my mot tester for 20yrs+ inc my previous laser and he is still pretty old skool when I bring in the Capri. He is different with the Fiesta but he deffo gives more leeway with the Capri and uses a bit of common sense.
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Re: Is my exhaust Legal? MOTable?

Postby fordperv » Fri Dec 28, 2018 2:15 pm

You could still do the emissions check on that exhaust anyway just insert the probe whilst is elevated on the ramp

As with is it legal, it all depends whether your tester takes offence to being deafened

If not your ok

If so it can be failed on section 8.1 of the testers manual

Exhaust noise from the vehicle must not be unreasonably above the noise level you'd expect from a similar vehicle with a standard silencer in average condition.

https://www.mot-testing.service.gov.uk/ ... ection_8.1

Also I'm quite confused at how a short straight pipe would be in the correct decibel range for the specified limit which is a maximum of 82db iirc, also I'm not going to ask about how it's affected the performance by having no back pressure

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Re: Is my exhaust Legal? MOTable?

Postby Not_Anumber » Fri Dec 28, 2018 3:15 pm

It would be interesting to know what difference to performance and economy the absence of back pressure would make.

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Re: Is my exhaust Legal? MOTable?

Postby charliepinto » Sat Dec 29, 2018 3:51 pm

Not_Anumber wrote:It would be interesting to know what difference to performance and economy the absence of back pressure would make.



I can't comment on economy as I haven't really done enough miles in it since to gauge that properly. In terms of performance, It drives better than ever...
I used to have a aftermarket performance exhaust which was fine, sounded nice but went quite quiet at the high revs. When you first start the car up, it runs rougher than it did when it had the whole exhaust. Its not bad by any means but a bit rougher. When the engine is warm though it idles perfectly. I've noticed that it is noticeably better at accelerating. I haven't experienced it at very high speeds yet so can't comment on that. The whole back pressure question is always one of debate, the most accurate thing I've been told which coordinates with my experience of running not far off an open down pipe is that you will experience better performance in the low revs and acceleration but perhaps a bit less power at the top end. But again from experience I've never noticed much difference in a cars performance when running it open down pipe, the capri has been the most notable change. But still not worthy enough of everyone cutting there exhaust off half way! :lol: :roll:

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Re: Is my exhaust Legal? MOTable?

Postby 340truck » Sun Dec 30, 2018 10:04 am

Not_Anumber wrote:It would be interesting to know what difference to performance and economy the absence of back pressure would make.


Absolutely fuck all difference to anything. This has been discussed at length previously, on a four stroke commercial engine back pressure simply does not exist. End of story.
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Re: Is my exhaust Legal? MOTable?

Postby stevemarl » Sun Dec 30, 2018 1:40 pm

For what it`s worth, (Construction & use regulations)
Silencers

54.—(1) Every vehicle propelled by an internal combustion engine shall be fitted with an exhaust system including a silencer and the exhaust gases from the engine shall not escape into the atmosphere without first passing through the silencer.

(2) Every exhaust system and silencer shall be maintained in good and efficient working order and shall not be altered so as to increase the noise made by the escape of exhaust gases.

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Re: Is my exhaust Legal? MOTable?

Postby fordperv » Mon Dec 31, 2018 9:50 am

Most of us are screwed at the last part of section 2 :lol:

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Re: Is my exhaust Legal? MOTable?

Postby D366Y » Mon Dec 31, 2018 10:56 am

fordperv wrote:As with is it legal, it all depends whether your tester takes offence to being deafened


I think I'm in luck with my tester then!! :lol:

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Re: Is my exhaust Legal? MOTable?

Postby Not_Anumber » Fri Jan 04, 2019 4:23 pm

The way the rules about exhausts are interpreted does seem very subjective

For example the majority of kit cars have loud and often entirely unbaffled exhausts, usually exiting at the side of the car and sometimes with a long sidewinder type exhaust box running down the outside of the car. Each kit car build has had to pass an IVA / SVA individual approval check, something that frankly makes the average MOT test look like a drive by inspection by Stevie Wonder and yet exhaust noise is one of the few things these vehicles just dont get failed on. The thinking amongst inspectors seems to be that so long as it's not louder than an extremely loud motorbike then its absolutely fine.

I think much of it at MOTs relies on the Testers expectation of what a certain type of car is supposed to sound like.

Because most MOT testers have no idea now how loud or quiet a production Capri exhaust is supposed to be I think its very unlikely our cars would fail from having relatively loud exhausts, so long as they can see the system fits properly and doesn't leak.