How noisy is a cat ??
Thread Starter
Drifting
Joined: Sep 2004
Posts: 1,307
Likes: 1
From: Milford Haven Pembrokeshire
How noisy is a cat ??
Thrown my 81 cat in the bin - and about to choose a dual system and was just wondering if the cat had any noise reducing qualities as well as power reducing ones ??
Safety Car
Joined: Apr 2004
Posts: 3,997
Likes: 1
From: WAY DEEP INSIDE AMERICO,YES YOU LIVE HERE TO!! TX
Safety Car
Joined: Jun 2002
Posts: 4,756
Likes: 2,506
From: Buckeye, AZ
St. Jude Donor '12-'13
I spent a lot of time on this one......the cats will act as additional mufflers even high flows. The high flows will allow your exhaust to be more "rumbly" but still tone down the volume some. To get the true 60s rumble you have to get rid of the cats, but where I live that makes you non-EPA compliant and you won't pass the test. For that reason I put the high flows. The exhaust sounds good now.
Safety Car
Joined: Jun 2004
Posts: 4,371
Likes: 223
From: Beecher Illinois
Just replacing the factory cat on my white 79 with a "test pipe" improved the exhaust sound considerably. Don't need emissions testing where I live but I could always easily return the cat if needed.
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Drifting
Joined: Apr 2002
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From: New Baden Illinois
Race Director
Joined: Jan 2000
Posts: 12,399
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From: San Jose CA
I see no reason NOT to run cats, it's a $200 investment and a huge relief on the environment. Lose about 5 hp but give back to everyone in the world.
Le Mans Master
Joined: Oct 2005
Posts: 6,247
Likes: 471
From: Glen Allen, VA
My 81 Z28 that I used to have a 2 into 1 back into 2 exhaust, where it went to 1 pipe to go through the converter. That car had no mufflers when I got it, but I added them and the noise level hardly decreased, so the cat was obviously doing the bulk of the sound deadening.
Burning Brakes
Joined: Jul 2006
Posts: 830
Likes: 1
[QUOTE=Shark Racer;1558562856]~440 rwhp, and I THINK it only has 2 cats but don't quote me on that. You can quote me on the RWHP though. 505 at the crank.
QUOTE]
Nope. It has 4 cats. I saw the z06 do 550+ at the rear with my own eyes at our Vette Dyno Day. I'll post the dynosheet. It's on the Pacific NW board titled "Dyno Day results." Granted, you are somewhat correct, it is NOT straight from the factory, but...it's just a slight "tuning" at a tuner shop with slight mods.
Pretty amazing.
You'll notice, that it reads "stock" the only tweeking done was "tuning" of the beast. There is NO SuperCharger, no nitrous.
-From the thread.
Once we have the dyno video uploaded I will post it as well. Mind you these numbers were made through the STOCK MUFFLERS! Of course I added a new set of header to the combination, but the owner wanted it quiet, I did however add a bypass switch for the Bi-Mode exhaust system so that he can open the exhaust valves manually at his will. All in all it was a fun day.
http://forums.corvetteforum.com/show...no+day+results
QUOTE]
Nope. It has 4 cats. I saw the z06 do 550+ at the rear with my own eyes at our Vette Dyno Day. I'll post the dynosheet. It's on the Pacific NW board titled "Dyno Day results." Granted, you are somewhat correct, it is NOT straight from the factory, but...it's just a slight "tuning" at a tuner shop with slight mods.
Pretty amazing.
You'll notice, that it reads "stock" the only tweeking done was "tuning" of the beast. There is NO SuperCharger, no nitrous.
-From the thread.
Once we have the dyno video uploaded I will post it as well. Mind you these numbers were made through the STOCK MUFFLERS! Of course I added a new set of header to the combination, but the owner wanted it quiet, I did however add a bypass switch for the Bi-Mode exhaust system so that he can open the exhaust valves manually at his will. All in all it was a fun day.
http://forums.corvetteforum.com/show...no+day+results
Last edited by OregonVette80; Jan 18, 2007 at 12:42 PM.
Melting Slicks
Joined: Dec 2005
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