Re: alfa-digest V8 #956

[George Graves <gmgraves@domain.elided>]

On Thursday, July 25, 2002, at 03:04 PM, alfa-digest wrote:

> Date: Thu, 25 Jul 2002 14:04:44 -0700
> From: "Derek Ealy" <dealy663@domain.elided>
> Subject: Headers cause emissions changes, why?
>
> Hi,
>
> I live in California, and own a pretty nice Milano. One of the things
> that I really don't like about it is how low the exhaust system hangs
> under the car. At some point in the future I will lower the car with
> sport springs and can imagine that it will be an even greater concern as
> I pass over dips and bumps.
>
> Last week I saw a cool article on Alfa Centro about some great looking
> headers for my car from some place in England. On top of adding a bit of
> power, and a cool sound they also give you a bit more ground clearance.
> As they are from England I'm sure they aren't legal here in sunny CA and
> it got me to wondering why is it that headers almost always will 
> increase
> a car's emissions and make it fail our smog tests? I wouldn't think that
> changing the shape of the exhaust tubes in a way which adds power (which
> would seem to result from more efficient combustion) would raise the
> amount of bad stuff coming from our engines.
>
> Does anyone know why this is the case? I've seen very few aftermarket
> headers which are legal in CA, matter of fact I can only think of one,
> for my old Miata.
>
>
>
> Derek
Actually, if anything, headers *should* reduce emissions because by 
making the all the exhaust paths the same length from each cylinder, 
they decrease back-pressure and make for more efficient combustion. The 
problem is that the part of the exhaust system from the cylinder head to 
the O2 sensor is considered part of the "smog equipment" and therefore, 
by law, cannot be modified or changed from the approved equipment that 
came on the car when new. In other words, its an arbitrary rule that has 
nothing to do with the actual operation of the car. You could buy some 
"magic headers"  which would reduce your car's emissions to NOTHING, and 
it would still be illegal to fit them to your car. That's the legal 
answer. Now here's reality. Nobody who smogs your car is going to notice 
(or care) that the headers aren't stock. All that is, ultimately, 
important, is that your car still passes the smog test with the new 
headers fitted. So, let your conscience be your guide.
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