removed mine never thru a code.
pup cat removal
Team Owner
Joined: Apr 2001
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From: S.W. Ohio. . . . . . NRA Life Member
Le Mans Master
Joined: Sep 2000
Posts: 6,097
Likes: 43
From: ABQ NM
Cruise-In II Veteran
I've heard removing the pre-cats is worth about 5 hp. I also remember reading an article regarding a tuner dynoing with hollowed out pre-cats, and that leaving the hollowed-out chamber messed up the exhaust flow and actually cost hp. Ergo, if you're going to do this, remove them completely, not just their guts....
Instructor
Joined: Aug 2003
Posts: 220
Likes: 8
From: A little place called Macungie PA
Having sat through flow dynamics classes I completely understand that the empty shape of the pup cat should disrupt flow through the pipe but I wonder if the disruption is worse than the actual restriction of the cat material itself. Has anyone done flow tests or does anyone have back to back dyno runs with and without pup cats.
I've thought of removing them in the past to get just a little more noise not so much because I was worrying about 5 hp but if it's going to hurt my power numbers then more noise be darned.
I've thought of removing them in the past to get just a little more noise not so much because I was worrying about 5 hp but if it's going to hurt my power numbers then more noise be darned.
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Team Owner
Joined: Apr 2001
Posts: 54,204
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From: S.W. Ohio. . . . . . NRA Life Member
I hear ya, but in a pressurized setup... where the enlarged pipe is not at the end of the system... there is no "flow distuption". Near equal pressure on both ends of the enlarged section (which happens a few seconds after startup) eliminates any of this theory concern (the theories are not nonsense... but they don't apply here - or it's soooo miniscule that it's a moot point).
And I'm talking about gasses, not heavy liquids.
And I'm talking about gasses, not heavy liquids.
Last edited by Mike Mercury; Nov 20, 2007 at 11:45 AM.
Melting Slicks
Joined: Feb 2001
Posts: 2,791
Likes: 355
From: Northville, MI
On a Z06, they gained about 2.5 hp from 2001 to 2002 according to the chief engineer on the project. He told us that when the 2002s were introduced. He was talking about where the 20 hp difference came from.
Team Owner
Joined: Apr 2001
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From: S.W. Ohio. . . . . . NRA Life Member
2.5 hp is not a lot; but I gutted mine for two reasons:
1. to add some depth to the exhaust tone.
2. It was a free mod
3. to give ulcers to the environ-mentalcases who force this craap on us to begin with.
Team Owner
Joined: Apr 2001
Posts: 54,204
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From: S.W. Ohio. . . . . . NRA Life Member
post #3 links to a web page with a pic you can compare yours too.
In 2001, all C5's had them. Starting 2002 they were on all C5's - except the Z06.
Before 2001 they were installed on some C5's destined to be delivered in certain areas of the country. So, it's hit/miss; best way to determine is through a visual inspection.
Drifting
Joined: Feb 2007
Posts: 1,993
Likes: 7
From: LaPine Oregon
swapped exhaust to '02 Z
The answer to your initial question is No to throwing codes.
But because of the possible problems with flow disruptions and exhaust tone I opted to swap out the entire '01 Z for an '02 Z exhaust for $350.
From 1997 to 2000 just the California destined cars had 'pups' to meet CARBs LEV standard. This in fact reduced advertized HP by approx 5 horsepower in California cars. In 2001 the Californai Z06 also had 'pups'.
The 2002 model year brought out the new primary one (1) brick CAT design which meant that the 'pup's and the old two (2) brick CATs could be dropped for a reduction in back pressure ( 2 inches of mercury drop) and an increase of approx 5 hp.
The addition of the larger opening on the fresh air intake box and descreening MAF brought another 5 hp.
But because of the possible problems with flow disruptions and exhaust tone I opted to swap out the entire '01 Z for an '02 Z exhaust for $350.
From 1997 to 2000 just the California destined cars had 'pups' to meet CARBs LEV standard. This in fact reduced advertized HP by approx 5 horsepower in California cars. In 2001 the Californai Z06 also had 'pups'.
The 2002 model year brought out the new primary one (1) brick CAT design which meant that the 'pup's and the old two (2) brick CATs could be dropped for a reduction in back pressure ( 2 inches of mercury drop) and an increase of approx 5 hp.
The addition of the larger opening on the fresh air intake box and descreening MAF brought another 5 hp.
Team Owner
Joined: Apr 2001
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From: S.W. Ohio. . . . . . NRA Life Member
I've been running my 2002 coupe for 5 years with the pup-cats gutted; and people are still amazed at my 1/4 times - compared to my small list of mods.
The 2002 model year brought out the new primary one (1) brick CAT design ...
on the Z06 only
on the Z06 only
Melting Slicks
Joined: Feb 2006
Posts: 2,172
Likes: 103
From: Des Moines Iowa
Quote:
From 1997 to 2000 just the California destined cars had 'pups' to meet CARBs LEV standard. This in fact reduced advertized HP by approx 5 horsepower in California cars. In 2001 the Californai Z06 also had 'pups'.
Fact is that ONLY the 2000 C5 targeted for California or Northeastern USA Sale / Delivery were fitted with the pup cats. All other 2000 C5s, like mine, did NOT have pup cats. No pup cats at all, on pre-2000 C5s.
From 1997 to 2000 just the California destined cars had 'pups' to meet CARBs LEV standard. This in fact reduced advertized HP by approx 5 horsepower in California cars. In 2001 the Californai Z06 also had 'pups'.
Fact is that ONLY the 2000 C5 targeted for California or Northeastern USA Sale / Delivery were fitted with the pup cats. All other 2000 C5s, like mine, did NOT have pup cats. No pup cats at all, on pre-2000 C5s.
Melting Slicks
Joined: Feb 2006
Posts: 2,172
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From: Des Moines Iowa
Team Owner
Joined: Apr 2001
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From: S.W. Ohio. . . . . . NRA Life Member
interesting.
I looked at my GM parts list and they show one camshaft part-number for all 2000 C5's.
ding... ding... ding; we have a winner !
Burning Brakes
Joined: Oct 2004
Posts: 931
Likes: 31
From: Rowlett, Texas
Jovette, right you are. The 2000 48-state had no pups, but had the
.500-lift cam. I went to a lot of dyno days with my Texas 2000, and these 2000's routinely dyno'd a few HP more than the '98,'99's.
If you can find a used 2000 48-state midpipe, it will bolt right on
the later years, just like a '02-'04 Z will.
As far as gutting the Pups, you might get a raspy, hissing sound through the exhaust that you can hear in the car. My '87 made that noise when I gutted the pups. Not loud, just raspy and unpleasant.
DG
.500-lift cam. I went to a lot of dyno days with my Texas 2000, and these 2000's routinely dyno'd a few HP more than the '98,'99's.
If you can find a used 2000 48-state midpipe, it will bolt right on
the later years, just like a '02-'04 Z will.
As far as gutting the Pups, you might get a raspy, hissing sound through the exhaust that you can hear in the car. My '87 made that noise when I gutted the pups. Not loud, just raspy and unpleasant.
DG