explain exhausts to me!- silencer?

[beau]

now just been thinking about car exhausts and i have got slightly confused!

ok, so you need to have a cat after year 1992/3?

so do you have to have a silencer? do you even have to have a back box?

just explain everything about exhausts to me! so i might just about understand them, and whats legal and not.

 

[arc]

needs to be below noise limits and you dont need a cat either - but u have to ope able to pass the emissions test for yr car as if it had a cat if itemseant to have one

 

[NumanR]

There are no noise limits for an exhaust system, as it would mean extra equipment for an mot station to have. Currently the MOT tester has to use his judgement as to whether the noise is reasonable, now an MOT tester and a Police Officer may disagree, both of them giving you a ticket for the same exhaust level!!!
Regarding emmissions, the exhaust must be sealed, (slight seapage through joints and drain holes is allowed), and must be hung on all mountings, any mountings missing or broken is a reason for failure of an MOT. Also the exhaust systems since 1992 would almost definately require a catalytic convertor to meet emission limits, its technically possible to pass limits without one but extremely difficult, also on newer cars the limits have been reduced making it even more difficult for a catless vehicle to pass.

 

[Chas Uno]

I'm pretty sure that all new cars registered after January 1993 MUST have a catalytic converter fitted. The original date was January 1992, but it was a bad time for car sales (middle of the recession), so the manufacturers had loads of unregistered cars that were built without cats. For that reason the date was moved back a year to allow the unregistered cars time to sell.

A catalytic converter has one job, and that is to 'clean' certain pollutants produced by the exhaust cycle. That is why the emissions are much stricter for cars registered after January 1993.

A cat is NOT a silencer. It is in effect a pollutant filter. Therefore a car still needs a silencer in the exhaust system to keep noise levels down. Depending on the design, some cars get away with just a back box, whereas some cars need an additional silencer after the cat.

There are some noise levels as dictated by the EU, though as Arc mentioned the MOT test doesn't have a DB meter to check for this. It is down to the judgement of the MOT tester as to whether the noise is acceptable or not.

You're not going to buy a performance exhaust system are you Beau?!!!!!

 

[PNL]

now just been thinking about car exhausts and i have got slightly confused!

ok, so you need to have a cat after year 1992/3?

so do you have to have a silencer? do you even have to have a back box?

just explain everything about exhausts to me! so i might just about understand them, and whats legal and not.

Buy a book of E bay

 

[beau]

You're not going to buy a performance exhaust system are you Beau?!!!!!

i have bought a powerflow back box for my sis, but i was reading about silencers and getting all confused!

 

[arc]

I'm pretty sure that all new cars registered after January 1993 MUST have a catalytic converter fitted.

wrong mate. trhey have to pass then sqame emissions test but f it can do it wihtout a cat then it is ok

 

[GhostWKD]

powerflow backbox now lmao! is she going to want the extra noise?

 

[beau]

powerflow backbox now lmao! is she going to want the extra noise?

dave said his is quiet so hopefully her one will be would be nice if it maked a little noise, maybe i should fit a cherry bomb and de-cat to her car hehe

 

[GhostWKD]

if that selecta gets a decat i'll make my next mod a decat not one to be outdone me

 

[beau]

lol, would a de-cat make her selecta have much more power? i have heard that it sounds better but dont know about performance upgrade?

 

[AppleSei]

dave said his is quiet so hopefully her one will be

Well unless daves changed his exhaust, ive been in daves punto and the exhaust certainly isnt quiet

 

[Trancendental]

wrong mate. trhey have to pass then sqame emissions test but f it can do it wihtout a cat then it is ok

You sure about this? I'm sure I've read in Construction and Use that all vehicles after 1993 MUST have a CAT.

even though CATS produce N2O which is more harmful then CO to the environment

 

[chaos]

even though CATS produce N2O

A cat can, I believe, convert NO to N2O, but this is minor compared to the benefits of removing NO and NO2 from the exhaust gases.

A cat also oxidises carbon monoxide into cardon dioxide.

A cat isn't effective until it reaches approx 200C and can they can go up to temperatures of about 700Cish.

A cat could never be used in a leaded engine - lead is a poison to platinum.

 

[Chas Uno]

wrong mate. trhey have to pass then sqame emissions test but f it can do it wihtout a cat then it is ok

Ok then. Show me a car built AFTER 1993 which DOESN'T have a Cat and can still pass the MOT emissions test!

 

[arc]

You sure about this? I'm sure I've read in Construction and Use that all vehicles after 1993 MUST have a CAT.

it will be obvious from the emissions that there is no cat, wrong proportion of stuff coming out - but if you can get the emissions of nasty things to below the requirments for the test without using a cat, then it is fine to not have one.

MOT tests as we all know include emissions testing. They do NOT include looking to see if the cat is there or not. They will however inspect the exhaust system generally for leaks, security, and excessive noise*

The fact that a cat has been eliminated from the exhaust system will be picked up by the emissions testing equipment if the vehicle is 1994 (L) or later.

Precise parameters are laid down by the ministry regarding acceptable emission levels for vehicles built at differing periods in time. (ie they wouldn't expect a vehicle built in 1920 to meet with 2006 parameters).

If you can remove your cat AND maintain acceptable emissions your car will pass it's MOT.

*Although noise is one of those grey areas. We don't have a decibel meter, and I don't know of any test centre that does. So find a deaf tester

thats from an MOT tester type person