Gutting cats, good or bad???

KillaZ350 · 01-14-2001, 09:58 PM

I know my cars a little different from most of yours, but they should share the same side effects to certain mods, ive asked this on my camaro board but my question never gets answered.
I had Dual Cats, that goes into one 3in pipe into the muffler, then comes out the muffler in two pipes. Then the cats went bad and came apart inside so instead of paying $100 for two cats, i took my cats off and put a piece of pipe in each of their places.

The 1st few days it was a lot louder, didnt notice any performance difference, then after a few days it got a more quiet, and rode a bit more rough. I think i may be losing a little low end torque and back pressure, would this also mess up my EGR Valve? Like i said the power band and riding isnt as smooth as it was before....

------------------
1991 Z28 Camaro L98 5.7http://www.IROC-Z.org/3rdgen/BandetZ28-resized.jpg
http://www.IROC-Z.org/3rdgen/BandetZ28-2-resized.jpg

Skyman · 01-15-2001, 05:01 AM

Losing back pressure is always going to make you more topend HP. You may loose some lowend torque with less backpressure, but with a 350 Im sure its not bad. When I lost the cats in my car is made a WORLD OF difference. It was the very last thing I did, and probably added 40hp.

Skyler

------------------
-1989 Saleen Mustang #406-
TFS Heads, Edelbrock intake, E-303, 3.73's, 1 5/8 shortys, Offroad-H, 2chamber flows, 36psi FPR, 15degrees timing, 70mm tb, 73mm maf, 24lb inj, Crank pulley, MSD6A, Alum driveshaft.

On its way: Paxton Sn-89 with dyno tuning and long tubes.

Just added: B&M Ripper, Weldin Subframes, & Turn downs!
13.2@106mph

97snakedriver · 01-15-2001, 12:06 PM

How are the O2 sensors aranged in Camaros?

cobrayankee · 01-15-2001, 12:53 PM

Quote:

Originally posted by Skyman:
Losing back pressure is always going to make you more topend HP. You may loose some lowend torque with less backpressure, but with a 350 Im sure its not bad. When I lost the cats in my car is made a WORLD OF difference. It was the very last thing I did, and probably added 40hp.

Skyler

Added 40HP?!?!?! Is this a typo?

------------------
1997 Cobra (Black on black), C+L 80mm MAF, K+N filter, Pro 5.0 shifter, BBK Springs, Taylor Wires, 2 Chamber Flows, ASP Pulleys, BBK off road H pipe.

95mustanggt · 01-15-2001, 01:29 PM

I could see it adding a lot of horsepower. If that was the bottle neck you would see a lot more power added with no cats, especially with Sky's car and all his mods.

------------------
White 1995 Mustang GT
Dynomax Cat-Back, Offroad H-pipe, K&N Filters w/o Air Silencer
My 1995 Mustang GT

LS1JAY · 01-16-2001, 04:17 PM

I can answer this question for you, I just sold my 90' Formula 350(L-98) I took the cats off about 5 yrs ago, it did not hurt, it helped, it got me into the 13's, best ET before the motor work with bolt-ons, stock converter and 327 gears was 13.41 @ 102MPH! it did not cause EGR problems, but after I built it the motor to a 355, ported heads, ZZ-9(520 lift)cam, I got the code 33 a lot, changed the EGR and still got it! a cam could cause a code 33, but the cats off should not, but then every car is different, my car was speed density.

------------------
98'Trans Am LS1 273 gears Whisper lid,K&N,Whisper MAF ends,Flowmaster,Best ET on street tires 13.17 @ 106.49mph

Try Me · 01-16-2001, 04:37 PM

I don't want to argue with these guys, you won't get any gains on a stocker by gutting the cats.

The reason why these guys did see improvements is 'cause they have alot of mods.

Unless anyone has any dyno specs on a stocker like you, don't do it.
You're better off gutting the airbox :-)

LX XLR8R · 01-16-2001, 04:46 PM

what size pipes are on those..2 1/4" right..that 50 extra cubes trying to breathe threw what stangs have to..i say get rid of them..

------------------
1987 black notch(ex 4 banger)
DSS 306 w/ main support...Elderbrock 6028 heads..gt-40 intake..24# injectors...70 mm tb..77 pro-m...accel 300+..mac full legnth..tremec w/ pro5oh...full MAC exhaust,off road h-pipe,long tubes, catback...ron davis radiator..subframes, control arms...CFDF II..o yea holley FPR sucks..dont buy one..

LS1JAY · 01-16-2001, 09:22 PM

Not to argue with Try Me, but you will see some HP increase but not much if your stock, maybe 5HP or so, I did have headers, and a Flowmaster(on my 90' L-98) as far as the exhaust goes, I did get a little more ET and MPH without the cats about a tenth and 1MPH in the 1/4 mile! but I doubt you will see that much without headers, and a free flowing muffler!

------------------
98'Trans Am LS1 273 gears Whisper lid,K&N,Whisper MAF ends,Flowmaster,Best ET on street tires 13.17 @ 106.49mph

[This message has been edited by LS1JAY (edited 01-16-2001).]

01-14-2001, 09:58 PM	#1
KillaZ350 Registered Member Join Date: Mar 2000 Location: Columbia, South Carolina Posts: 214	Gutting cats, good or bad??? I know my cars a little different from most of yours, but they should share the same side effects to certain mods, ive asked this on my camaro board but my question never gets answered. I had Dual Cats, that goes into one 3in pipe into the muffler, then comes out the muffler in two pipes. Then the cats went bad and came apart inside so instead of paying $100 for two cats, i took my cats off and put a piece of pipe in each of their places. The 1st few days it was a lot louder, didnt notice any performance difference, then after a few days it got a more quiet, and rode a bit more rough. I think i may be losing a little low end torque and back pressure, would this also mess up my EGR Valve? Like i said the power band and riding isnt as smooth as it was before.... ------------------ 1991 Z28 Camaro L98 5.7http://www.IROC-Z.org/3rdgen/BandetZ28-resized.jpg http://www.IROC-Z.org/3rdgen/BandetZ28-2-resized.jpg

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
351W headache or good idea?	5.0PiMpin	Windsor Power	7	04-17-2002 10:01 AM
Good Radiator	Patrick Boetticher	Windsor Power	15	02-27-2002 01:51 PM
Track Last Night!! (Good and Terrible)	CobraConv99	Stang Stories	6	11-09-2001 12:59 AM
Competition Engineering(Moroso) anti-sway bar opinion/pics....not good!	8850	Windsor Power	10	11-08-2001 11:47 AM
Good race with a new V6 stang...	Skyman	Stang Stories	6	01-01-2001 06:06 PM

01-15-2001, 05:01 AM	#2
Skyman I need 110mph Trap Speed! Join Date: Feb 1999 Location: So, CA Posts: 4,315	Losing back pressure is always going to make you more topend HP. You may loose some lowend torque with less backpressure, but with a 350 Im sure its not bad. When I lost the cats in my car is made a WORLD OF difference. It was the very last thing I did, and probably added 40hp. Skyler ------------------ -1989 Saleen Mustang #406- TFS Heads, Edelbrock intake, E-303, 3.73's, 1 5/8 shortys, Offroad-H, 2chamber flows, 36psi FPR, 15degrees timing, 70mm tb, 73mm maf, 24lb inj, Crank pulley, MSD6A, Alum driveshaft. On its way: Paxton Sn-89 with dyno tuning and long tubes. Just added: B&M Ripper, Weldin Subframes, & Turn downs! 13.2@106mph

01-15-2001, 12:06 PM	#3
97snakedriver Registered Member Join Date: May 1999 Location: Blacksburg, VA Posts: 1,526	How are the O2 sensors aranged in Camaros?

01-15-2001, 01:29 PM	#5
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	I could see it adding a lot of horsepower. If that was the bottle neck you would see a lot more power added with no cats, especially with Sky's car and all his mods. ------------------ White 1995 Mustang GT Dynomax Cat-Back, Offroad H-pipe, K&N Filters w/o Air Silencer My 1995 Mustang GT

01-16-2001, 04:17 PM	#6
LS1JAY Registered Member Join Date: Jan 2001 Location: Central Florida Posts: 102	I can answer this question for you, I just sold my 90' Formula 350(L-98) I took the cats off about 5 yrs ago, it did not hurt, it helped, it got me into the 13's, best ET before the motor work with bolt-ons, stock converter and 327 gears was 13.41 @ 102MPH! it did not cause EGR problems, but after I built it the motor to a 355, ported heads, ZZ-9(520 lift)cam, I got the code 33 a lot, changed the EGR and still got it! a cam could cause a code 33, but the cats off should not, but then every car is different, my car was speed density. ------------------ 98'Trans Am LS1 273 gears Whisper lid,K&N,Whisper MAF ends,Flowmaster,Best ET on street tires 13.17 @ 106.49mph

01-16-2001, 04:37 PM	#7
Try Me Registered Member Join Date: Jul 2000 Location: Ottawa, Ontario, Canada Posts: 465	I don't want to argue with these guys, you won't get any gains on a stocker by gutting the cats. The reason why these guys did see improvements is 'cause they have alot of mods. Unless anyone has any dyno specs on a stocker like you, don't do it. You're better off gutting the airbox :-)

01-16-2001, 04:46 PM	#8
LX XLR8R Dirk Diggler Join Date: Feb 1999 Location: SLOATSBURG, NY Posts: 1,931	what size pipes are on those..2 1/4" right..that 50 extra cubes trying to breathe threw what stangs have to..i say get rid of them.. ------------------ 1987 black notch(ex 4 banger) DSS 306 w/ main support...Elderbrock 6028 heads..gt-40 intake..24# injectors...70 mm tb..77 pro-m...accel 300+..mac full legnth..tremec w/ pro5oh...full MAC exhaust,off road h-pipe,long tubes, catback...ron davis radiator..subframes, control arms...CFDF II..o yea holley FPR sucks..dont buy one..

01-16-2001, 09:22 PM	#9
LS1JAY Registered Member Join Date: Jan 2001 Location: Central Florida Posts: 102	Not to argue with Try Me, but you will see some HP increase but not much if your stock, maybe 5HP or so, I did have headers, and a Flowmaster(on my 90' L-98) as far as the exhaust goes, I did get a little more ET and MPH without the cats about a tenth and 1MPH in the 1/4 mile! but I doubt you will see that much without headers, and a free flowing muffler! ------------------ 98'Trans Am LS1 273 gears Whisper lid,K&N,Whisper MAF ends,Flowmaster,Best ET on street tires 13.17 @ 106.49mph [This message has been edited by LS1JAY (edited 01-16-2001).]