Re: cat removal?

[walter@quattro.corp.inmet.com (Walter Meares)]

> ------------------------------
> 
> From: PDQSHIP@aol.com
> 
> An empty cat on a turbo car will pass emissions (and infact, I'm running half
> of what is allowed on the 3 tests in my state, so I still feel that I'm a
... 
> I know my state is pretty strict and so is Dan Bocek's and we both pass
> emissions with flying colors, no reverse mods.....
> 
> 
> Scott

> From: glen.powell@smc.com
> Date: 11 May 1995 08:27:18 -0400
> Subject: Re: cat removal?
> 
>   On killing the kitty.....

>   As to the morality of cat removal or hoggin' out the cat, I've found that
>   the '85
>   ur-Q passed the tough Taxxachusetts emission tests without the cat, but
>   also
>   found that 1/4 mile times were the same with and without, when the car
>   was
>   in a basically stock state of tune. So if you are basically stock, there
>   is little
>   to be gained by removing the cat, and, if you do, the environmental
>   impact
>   is not large. I think it would make a lot more sense if the
>   powers-that-be would
>   look at regulating diesel emissions on everything from cars to the
>   largest
>   trucks and leave the few modifiers and enthusiasts alone, IMFO.
> 
>   -glen
> 

I think you'll find, if you check out your tailpipe emissions results
with/without the cat, that it makes a *big* difference.  The mfrs didn't
put them on their for no reason, and as far as I know, the Clean Air Act
specifies emission levels, not technology by which to achieve it.  EPA's
rules revolve around protecting the technical solution (among other things);
since the cat is a key piece of the technology right now, they address it 
directly in their rules.

Typically test levels are set (even in CA or MA) to catch really grossly
out-of-tune cars.  You can remove the cat and still pass these tests.  But
you'll make probably an order of magnitude more ppm emissions this way. For
example, it seems to me that if I'm tuning my 4ksq using the access port
before the cat, I'm supposed to adjust the mixture for say 1-2% CO.  But my
smog check will show perhaps .1% CO or less after the cat.  I don't think these
are exactly the right numbers, but you get the idea...  it would be similar
for HC and NOX.

I can't imagine why having a turbo would make a difference in regard to this.

Not moralizing here, just pointing out the facts...  As the owner of a 1974
Datsun 260Z, a car with one of the worst conglomerations of vacuum/electric/
spring loaded valves and doodads to reduce smog (not so mention the worlds
worst incarnation of the SU carberettor), I have always been 
extremely frustrated by the laws which make it so hard to improve these
cars with newer technology, especially in states with draconian enforcement
and visual inspection like CA.

Walter

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