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hollowed out my cat

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Old Dec 30, 2007, 05:26 PM
  #31  
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Originally Posted by Tristar Racing
Still waiting for those dyno results, especially on stock-to-mildly modified car...
dyno results will be irrelevant for this mod, the gains from a testpipe are within the fluctuations in power from dynoing on different days and different weather conditions.


the correct way to make a comparison would be to put the car on the dyno for a baseline, gut the cat, then dyno it again immediately
Old Dec 30, 2007, 05:31 PM
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Originally Posted by justboosted02
that is a ceramic substrate cat, it is pretty restrictive, you can probably expect 10-20whp from gutting it depending on your mods.

to the guy who made the comment that testpipes are only worth 5hp, this is correct but only when you are running a metallic substrate cat like the perrin or the random tech.

kudos to you for the free mod, super stealth
I couldnt disagree more. Having engineer friends in the automotive industry (and a mechanical engineer myself), I can tell you modern cats are NOT as restrictive as you think.

And if different dyno conditions will hide the gain, how much are you really gaining? Oh yea, plus the issue of polluting and possible fines if caught...
Old Dec 30, 2007, 05:46 PM
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Originally Posted by Tristar Racing
Anyone have dyno results to back any of this up? The leaded gas comment makes sense, I guess, because leaded gas will ruin the cat anyhow. But Ill er on the side of caution and say leaded gas in an engine that isnt designed for it might cause other damage.

If your car is a track rat fine, but is it worth the possible fine and polluting for 5 hp? Im thinking improved driving technique and better tuning will more than offset the power gained by a lack of a cat. Thats just me though. I however appreciate what catalytic converters have done for air quality in major metropolitan areas. Go to Mexico city, and tell me you dont.....
I did back to back testing with the cat in and out....It was negligible ~5 hp (although I did have to adjust the tune to get the same results).....I'll try to find the dyno plots later...(That was a stock 9 with 3" TB)....I imagine with a 30R or 35R a test pipe would make a bigger difference.

I will soon be testing with a 50trim.
Old Dec 30, 2007, 05:55 PM
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nice job
Old Dec 30, 2007, 05:59 PM
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there's always so many different opinions on this forum that i don't think anyone can ever do anything right, anyways thanks for the comments guys lol
Old Dec 30, 2007, 06:04 PM
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Originally Posted by aznj
there's always so many different opinions on this forum that i don't think anyone can ever do anything right, anyways thanks for the comments guys lol
Sorry man, but I disagree with you on this one... A post about how one destroys a functioning catalytic converter to create a test pipe ??? Not only is this DIY post stupid and illegal, it will yield not gains for a stock car. (Especially for someone living in Seattle, Wa.....)

Last edited by cij911; Dec 30, 2007 at 06:09 PM.
Old Dec 30, 2007, 06:05 PM
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thats funny, we did this today to my friends lol.....

That looks like my dad's cigarette filters EWWWW

Last edited by kaonashi; Dec 30, 2007 at 06:09 PM.
Old Dec 30, 2007, 06:37 PM
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Our county got rid of emissions testing starting this year, I might have to do this
Old Dec 30, 2007, 06:56 PM
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CT emissions FTW, this would pass just as long as there is no CEL.
Old Dec 30, 2007, 07:41 PM
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^ Unfortunately you are missing the point....You won't get more power + your car will stink up in traffic....There are so many clueless posts about running catless...Do us all a favor and keep your cat on...
Old Dec 30, 2007, 07:48 PM
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Originally Posted by cij911
^ Unfortunately you are missing the point....You won't get more power + your car will stink up in traffic....There are so many clueless posts about running catless...Do us all a favor and keep your cat on...
Finally someone gets what I was saying in my posts...
Old Dec 30, 2007, 08:01 PM
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I ran a test pipe for a while and the gains are not worth the smell and possible of a $1,500 fine. Got to love CA.
Old Dec 30, 2007, 08:27 PM
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no need to get offended cij, i wasn't just talking about this thread. I did it, it's too late, how many people here are running test pipes. I really just did this to see how it would turn out, and i like the way the car drives now so i'm going to leave it that way. and another thing, no one said my car was stock.
Old Dec 30, 2007, 08:31 PM
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nah, its an aftermarket already there worth like 10 bucks for scrap
Old Dec 31, 2007, 06:36 AM
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Thanks god for TX, our air already smell's like toxic **** and we live in an area filled with plants so emissions are a damn joke where i live.

BTW have you ever drove past a plant and your a/f go crazy? i have ethonal FTW lol


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