Cat vs No Cat

Gizmo · 10-13-2005, 11:46 AM

I've been reading and talking around and I always thought cat converters hindered hp as well as put a lot of heat into the engine bay. Yet I've found some things stating that they take away very little hp if any. I'm talking about stock cats not high performance ones.

So which one is it do they or do they not take away hp

battlestylespl · 10-13-2005, 12:02 PM

i dont have any "dyno proven" figures...but i prefer no cat.

krystar · 10-13-2005, 12:08 PM

cats are most definitely an exhaust restriction.

flip240 · 10-13-2005, 12:35 PM

the older cat types that are parrallel to the ground are good, thats how mine is mounted

Gizmo · 10-13-2005, 02:00 PM

The one on my daily driver is perpendicular to the ground right under the headers. I wanted to go with a 4-1 header set up and get rid of the cat but I wanna make sure I can fix the check engine light when the second o2 sensor is all messed up. The car is a Hyundai Elantra 00

XRoll2000 · 10-13-2005, 03:00 PM

Depending on the car, you can lose backpressure, low end torque and definately fail emmissions. No cats, it will be loud and/or raspy, again depending on the car. You don't lose much hp with the cats. Catalytic converters were installed for a reason.

Gizmo · 10-13-2005, 03:42 PM

Would I be good with going with possibly a high flow cat?

ghettoRoadster · 10-13-2005, 04:27 PM

on the S2K. testpipe is one the cheapest ways to squeeze what lil extra hp u can get. so i bought one.

Turk · 10-13-2005, 04:49 PM

Quote:

Originally Posted by Gizmo

Would I be good with going with possibly a high flow cat?

No, all stock cats are pretty much high flow cats. Even if aftermarket cats gain u a few hp, it's never worth the money. Also, no cats gain u HP only if u keep your a/f ratio right. The 02 sensors have a lot to do with how much fuel will be going into the engine, if u mess that up you'll lose a lot of hp.

89cupe · 10-13-2005, 06:01 PM

I ran .5 slower/4 mph slower w/ cat H pipe rather than Offroad H pipe on 302... However , it couldve had something to do with 100% humidity and around 80 degrees out...

krystar · 10-13-2005, 06:15 PM

i know when i got my race header, there was a def dyno difference.

steve · 10-24-2005, 05:05 PM

Doug02GT · 10-24-2005, 06:52 PM

You are not going to notice the difference between a high flow cat and no cat. Stay legal. My Mustang had an offroad X and I sounded like a bus going buy. Now I have an SLP X-pipe with cats and it is so much better. No smell, no worrying about cops, no power loss.

ChitownGST · 10-24-2005, 09:40 PM

Yeah, what ^^^ said is true. Most DSMers can tell the difference either. And we're turbo! Just roll with one.

KAR 101 · 10-26-2005, 03:13 AM

cats were put on a car for emissions nothing else. while they do restrict air flow and silence the exhuast a bit, depending on what car who knows how much/or little you can pick up on hp. dont know first hand on gaining hp but i would asum so. about the O2 sensor, its the first O2 before the cat that relay's air fuel ratios so you wont be messing that up but what the second O2 sensor is for is to tell the computer if the cat is working or not for emissions. with out the cat in the car and stock second O2 you will def through a check engine light inless you get the simulater O2 sensor for that. have fun.

MIKES3 · 10-27-2005, 01:31 PM

Quote:

Originally Posted by Gizmo

I've been reading and talking around and I always thought cat converters hindered hp as well as put a lot of heat into the engine bay. Yet I've found some things stating that they take away very little hp if any. I'm talking about stock cats not high performance ones.

So which one is it do they or do they not take away hp

I dont have a cat as well, but thats only because I have a custom down pipe on my car. The cat will give you maybe 2-3 more HP at the max. It makes your car quite loud w/o the cat. Not that much of a restriction

To sum it up I think it only makes a little difference on aspirated cars

What car are we talking about anyways. There are ways to pass emissoons w/o a cat & 02 sensor. I know I can. You have to get a tuner

Gizmo · 10-27-2005, 02:19 PM

Alright don't laugh but its a 2000 Hyundai Elantra that I'm just doing basic intake and exhaust stuff on its my daily driver. I wanted to go with out a cat seeing as I also think that I have two don't know why but I wanted to get rid of the first one. However, I'll most definatly throw a check engine light. What I wanted to do was get a simulator for it to put out the light or get the computer reflashed. Since it's after 96 the only plug it into the computer and don't put it on the rollers. If there is no code no problem I'm just not sure of a company that sells simulators or reflashes ecu's

We did an AEM intake Apexi Cat-back and off road Kamikaze headers on my dad's focus and picked up 28hp at the wheels. All I had to do to pass emissions was put his simulator in and it was fine. I'd like to do pretty much what I did to his car.

oudi · 11-12-2005, 02:44 PM

they are better if its a straight pipe but u need a cat to pass inspection.