exhaust query

helpimcrap

helpimcrap

helpimcrap

Soldato
Joined
13 Jan 2004
Posts
12,776
Location
Leicestershire
this is for a turbo car, namely Sierra RS Cosworth.

why do loads of people seem to cut the middle box out and weld a straight pipe in instead?

how would this affect performance as i thought having less back pressure would affect a turbo system which relys on exhaust gases to work?

:confused:
 
Its a ***** way of making the car louder, plus may give a bit of a power boost.


Turbos work on a pressure differential, I.e high pressure engine side and low on exhaust side. As pressure tries to equal itself the exhaust gas moves from high to low pressures.
Removing as much back pressure as possible is beneficial in a turbo car as it reduces pressure on the exhaust side (I.e around ambient obviously not below)

Very basic explanation btw :)
 
why would it be a ***** way of doing it? its removing possible restriction (im not into fords, i couldnt say if that specific middle box is a restriction). definately cheap but not necessarily bad
 
They're removing the catalytic converter, these restrict flow. The less restrictive the exhaust is the more gas can flow and the turbo can spool quicker.

It's a bit ***** as obviously it worsens your emissions, the other option is to use a less restrictive sports catalytic converter.
 
Minstadave said:
They're removing the catalytic converter, these restrict flow. The less restrictive the exhaust is the more gas can flow and the turbo can spool quicker.

It's a bit ***** as obviously it worsens your emissions, the other option is to use a less restrictive sports catalytic converter.
Click to expand...

No, they're removing the centre box. Not all Cossies had a cat anyway.
 
ah right cool, so it's a cheaper way of improving it by the sounds of it and what you are saying makes sense to somebody who has never had a turbo car so thanks. :)
 
less back pressure is a good thing on turbo cars.

Thats why you see imprezas and evos with 3.0 inch exhausts with as little sound deadenning as possible.
 
Let me clarify by what I ment by *****.

Its is a more ***** way of modding your exhaust than buying a purpose built SS turbo back system.

Not saying its not worth doing on a budget mind...
 
Correct me if i'm wrong. Its legal to have no cat as long as you declair it on insurance and stays within legal co2 levels. Fail a co2 test and its a £1000 fine?.
 
Philz0r said:
Correct me if i'm wrong. Its legal to have no cat as long as you declair it on insurance and stays within legal co2 levels. Fail a co2 test and its a £1000 fine?.
Click to expand...

Catalytic converter has nothing to do with CO2 levels, it's Carbon Monoxide (CO) and unburnt hydrocarbons (HC) that are measured.

If it passes the MOT emissions test then currently it legal, but it is proposed to check for the presence of the cat under revised MOT rules.
 
so obviously, if someone puts the cat on for an MOT, passes and MOT then removes the cat afterwoods, they're breaking the law and result in a fine if found out?
 
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