Cat Placement??
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AudiWorld Member
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Cat Placement??
Is there any differance in placing the cat closer or further from the turbo? I notice that in most car the cat is further down from the down pipe, not like the audi's. The audi cat bolt directy onto the turbo. any info is welcome.
thanks
thanks
AudiWorld Super User
Joined: Mar 2000
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no...
usually the cat is further down because there is a nice accessible space to locate it.
not sure why audi tucked it in...
could get into a big theory argument about ehy...but it would be speculation without any real data so i will leave it at that.
not sure why audi tucked it in...
could get into a big theory argument about ehy...but it would be speculation without any real data so i will leave it at that.
Thread Starter
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In most cars i driven the cat is some ways...
down from the headers/exhust manifold.
IMO thinking that a cooler cat produces a better flow through the cat.
I'm not a themophysic or any thing but when molecules are heated. The molecules moves erratic all over the place thus making the flow less smooth.
my2sence
IMO thinking that a cooler cat produces a better flow through the cat.
I'm not a themophysic or any thing but when molecules are heated. The molecules moves erratic all over the place thus making the flow less smooth.
my2sence
Junior Member
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Yup..cold start emissions.
The cat only works at temps above...some value.
The exhaust gasses heat the cat, but with the turbo in front of the cat it basically cools the exhaust before it hits the cat. The further the cat is from the turbo, the more heat is lost, the longer it takes the cat to light.
Many NA cars have cats either very close to, or part of, the exhaust manifold.
The exhaust gasses heat the cat, but with the turbo in front of the cat it basically cools the exhaust before it hits the cat. The further the cat is from the turbo, the more heat is lost, the longer it takes the cat to light.
Many NA cars have cats either very close to, or part of, the exhaust manifold.
AudiWorld Super User
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From: Minneapolis, MN 'burbs
Subaru has taken this to the extreme with the new WRX....
...which has a total of three catalytic converters. The first catalytic converter is placed in front of the turbo (i.e., between the exhaust manifold and the turbo). All in the name of clean emissions. The WRX is classified as a UL (Ultra Low) emissions vehicle.
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