Took the cats off.....
Thread Starter
Melting Slicks
Joined: May 2000
Posts: 2,161
Likes: 17
Took the cats off.....
I got the cats taken off yesterday......car sounds mean as hell (like NASCAR), but unfortuneately smells disguisting.....
I have no doubt in my mind that I will be putting them back on - my car is a daily driver and I think its fun to mod the car into a "street-driven race car", but in my opinion taking the cats off takes away from the car......unless it is track-driven only.
I have no doubt in my mind that I will be putting them back on - my car is a daily driver and I think its fun to mod the car into a "street-driven race car", but in my opinion taking the cats off takes away from the car......unless it is track-driven only.
Thread Starter
Melting Slicks
Joined: May 2000
Posts: 2,161
Likes: 17
Re: Took the cats off..... (ModifiedC5)
was there a noticeable performance difference when you took the cats off? Did you dyno b4 and after by chance? :cheers:
Drifting
Joined: Dec 2002
Posts: 1,472
Likes: 1
From: Reynoldsburg oh
Re: Took the cats off..... (OliverM5)
Do you still have the stock exhaust on. I cant believe it didnt throw any codes. I am also wanting to do that but I am not sure if I need o2 sims or not.
Pro
Joined: May 2000
Posts: 713
Likes: 4
From: Salt Lake City UT
Re: Took the cats off..... (OliverM5)
.
How much weight savings in removing the cats? There must be an exhaust leak for you to smell anything . .
I got the cats taken off yesterday......car sounds mean as hell (like NASCAR), but unfortuneately smells disguisting.....
Team Owner
Joined: Mar 2000
Posts: 29,564
Likes: 0
From: Nassau NP
Tropical Moderator
Cruise-In 1-5 Veteran
St. Jude Donor '03-'04-'10-'11
Re: Took the cats off..... (OliverM5)
I'm running TTS Headers, NO CATS, X-pipe and Corsa's.
The sound is WICKED!!
The smell does not bother me at all.
And yes, you will need the O2 sims...you WILL throw codes, it's simply a matter of time.
FWIW...the O2 SIMs are the same ones used in the 97+ Grand Prix's...you just need TWO of them instead of one. You can get them for a fraction of the price if you go to some performance stores that sell the sims for the Grand Prix. I just went to a vendors page...not going to say which one, and they want $199.00 for a pair. A quick net search turned up $45.00 each...I seem to recall getting them cheaper than that.
:seeya
The sound is WICKED!!
The smell does not bother me at all.
And yes, you will need the O2 sims...you WILL throw codes, it's simply a matter of time.
FWIW...the O2 SIMs are the same ones used in the 97+ Grand Prix's...you just need TWO of them instead of one. You can get them for a fraction of the price if you go to some performance stores that sell the sims for the Grand Prix. I just went to a vendors page...not going to say which one, and they want $199.00 for a pair. A quick net search turned up $45.00 each...I seem to recall getting them cheaper than that.
:seeya
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Team Owner
Joined: Mar 2000
Posts: 29,564
Likes: 0
From: Nassau NP
Tropical Moderator
Cruise-In 1-5 Veteran
St. Jude Donor '03-'04-'10-'11
Re: Took the cats off..... (BatMobile)
BTW...just went to TByrne's site...
http://www.tbyrnemotorsports.com/c5/c5exhaust.html
They have a pair of sensors for 89 bux...much more reasonable.
FWIW
http://www.tbyrnemotorsports.com/c5/c5exhaust.html
They have a pair of sensors for 89 bux...much more reasonable.
FWIW
Drifting
Joined: Dec 2001
Posts: 1,808
Likes: 19
From: Little Rock, AR
Re: Took the cats off..... (sprayedc5)
Did you have to put on your o2 sims or not
http://home.insight.rr.com/samsc5/goodpic%203.JPG
:eek: Holy smokes sprayedc5 thats one of the best signature pics ever. Ahhh Oh yeh OliverM5, I'm running with no cats on mine and I haven't noticed any smell unless I'm behind the Vette. Maybe a exhaust leak somewhere?
[Modified by RobsC5, 1:58 PM 12/10/2002]
[Modified by RobsC5, 1:59 PM 12/10/2002]
http://home.insight.rr.com/samsc5/goodpic%203.JPG
:eek: Holy smokes sprayedc5 thats one of the best signature pics ever. Ahhh Oh yeh OliverM5, I'm running with no cats on mine and I haven't noticed any smell unless I'm behind the Vette. Maybe a exhaust leak somewhere?
[Modified by RobsC5, 1:58 PM 12/10/2002]
[Modified by RobsC5, 1:59 PM 12/10/2002]
Former Vendor
Joined: Nov 2000
Posts: 5,607
Likes: 1
From: Houston TX
Re: Took the cats off..... (OliverM5)
When I took the cats off my stock CI motor, I lost about 5rwhp/rwtq instead of gaining. The car was dynoed at the same shop, but the before and after dynos weren't on the same day so the temperature might have something to do with it.
With the new motor, I plan on taking the cats off because it's about 20-30rwhp on a big motor. If I do, I will also swap out the Corsa Indy for Corsa Touring or Stock Z06 exhaust.
:cheers:
With the new motor, I plan on taking the cats off because it's about 20-30rwhp on a big motor. If I do, I will also swap out the Corsa Indy for Corsa Touring or Stock Z06 exhaust.
:cheers:
Racer
Joined: Oct 2002
Posts: 366
Likes: 0
From: DesMoines Iowa
Re: Took the cats off..... (OliverM5)
I have a 99 FRC, took the cats off and runn B&B exhaust with BBK headers car sounds great and runs even better. I threw code the next day and the car is considerably louder inside than it was before also have smelled kind of strong fuel smell sometimes when gettin' after it and the windows down.
Le Mans Master
Joined: Nov 1999
Posts: 7,695
Likes: 51
From: Imperial Beach CA
Re: Took the cats off..... (Bad Bob)
Witnessed dyno before and after with little to no power increase. This guy had long tube headers, X pipe and cat removal and got less than 8 rwhp. Go to Charlie Hoyts web site and look for Radue's dyno results.
Melting Slicks
Joined: Sep 1999
Posts: 2,521
Likes: 0
From: Houston, TX
Re: Took the cats off..... (Bad Bob)
I'm with you Oliver....I put high flow cats on after running without for a couple months. The stench made the driving experience less pleasurable. I only lost 2 horses and 5 footies after the change. I did change from SVO 30's to '02 28 Lb injectors as well. Now I can get on it more as well because the exhaust note is a lot less obnoxious.
:cheers:
:cheers:
Racer
Joined: Sep 2002
Posts: 420
Likes: 0
Re: Took the cats off..... (C5Cemo)
Cats NEVER add power - they are strictly for emissions.
That being said, you might not thing the added power is worth the smell/sound.
I, personally, love the sound of my '02 Z w/FLPs and no cats - sounds like one of the fastest American-made muscle cars - they way it should sound!
If someone dynoed and without cats and lost power, they lost it in spite of having no cats, not because they had no cats - with cats their power loss would have been greater.
That being said, you might not thing the added power is worth the smell/sound.
I, personally, love the sound of my '02 Z w/FLPs and no cats - sounds like one of the fastest American-made muscle cars - they way it should sound!
If someone dynoed and without cats and lost power, they lost it in spite of having no cats, not because they had no cats - with cats their power loss would have been greater.
Drifting
Joined: Jul 2000
Posts: 1,289
Likes: 0
From: Newport Beach, CA, USA
Re: Took the cats off..... (OliverM5)
Here is the deal on CATS based on my experience:
1. If you have a stock motor and no real mods, the difference in power will not likely be that much.
2. With a bigger motor things change--a lot! When you build a big motor, you get custom tuning and the custom tuning typically pushes the timing and other settings for as much as you can go without detonation and based on the octane you will be running. If you have it tuned this way, you have the best power you can get.
If you then add "high-flow cats" (3" in my case), two things happen: (a) you have added an impediment to exhaust flow; and (b) the CATs add heat which affects detonation. In my car, the dyno difference was 20-30rwhp/trq. I think it was both (a) and (b). I think the difference is so great because in addition to the (a) difference (which should really be about 10-12rwhp/trq), the (b) difference causes the PCM to retard the timing.
I have much less fuel smell after having the section from the header flange to the Corsa Touring Mufflers re-fabricated to be very smooth. However, when you get on the car and then come to a quick stop, you do get some blow-back smell, but not that bad. A 600hp N/A car will never be a Lexus in overall comfort--that is part of the allure.
The CATS are off only for offroad use BTW.
Good luck!
1. If you have a stock motor and no real mods, the difference in power will not likely be that much.
2. With a bigger motor things change--a lot! When you build a big motor, you get custom tuning and the custom tuning typically pushes the timing and other settings for as much as you can go without detonation and based on the octane you will be running. If you have it tuned this way, you have the best power you can get.
If you then add "high-flow cats" (3" in my case), two things happen: (a) you have added an impediment to exhaust flow; and (b) the CATs add heat which affects detonation. In my car, the dyno difference was 20-30rwhp/trq. I think it was both (a) and (b). I think the difference is so great because in addition to the (a) difference (which should really be about 10-12rwhp/trq), the (b) difference causes the PCM to retard the timing.
I have much less fuel smell after having the section from the header flange to the Corsa Touring Mufflers re-fabricated to be very smooth. However, when you get on the car and then come to a quick stop, you do get some blow-back smell, but not that bad. A 600hp N/A car will never be a Lexus in overall comfort--that is part of the allure.
The CATS are off only for offroad use BTW.
Good luck!
Le Mans Master
Joined: Aug 1999
Posts: 5,411
Likes: 2
From: N Carolina 08 Z51 Coupe
Re: Took the cats off..... (Mako)
The stock cats flow very well.. You need to do some heavy mods to the engine before the cats will be restrictive.
Don't forget.... some back-pressure is good for low end torque..
mike
Don't forget.... some back-pressure is good for low end torque..
mike
Melting Slicks
Joined: Oct 2002
Posts: 2,855
Likes: 0
Re: Took the cats off..... (Mako)
I took off my cats and put o2 sims, we got apprx 20rwhp and similar torque, this was before my SC when I was heads/cam package only. I think it would make more diff with my SC.