hey guys i drive a 2001 Z 24 pretty much stock im going to go get magnaflow exhaust on my car next week and have the catlytic converter taken off so i have straight pipes i have been thinking about maybe having them put wider pipes underneath i know it can help to a point b4 it starts causing u to lose hp about what size would u all suggest?? thanks
2 1/4" and why are you removing the cat?
Just go with a magnaflow high flow cat from car sound. Legal and flows just as much as dropping the cat.
well i was under the impression it causes uneccesary restriction causing loss of hp is it gonna hurt my car to take it off??? so are we all kinda thinking 2 1/4 is about what im thinking and do u all know what size the pipes are stock on my car by any chance???
Ummmm are you not aware of the function of the catalytic converter? It converts harmful gases (CO, etc.) into harmless ones. Meaning your car is now illegal. Also meaning it's a smog machine. Yes 2.25 is the biggest you wanna go N/A, though some say backpressure is unnecessary. Generally removing your cat also results in a CEL, because your O2 sensor isn't being used. This could lead to improper air-fuel mixtures. Get an O2 simulator if you're bent on removing it, or weld the bung into the pipe and keep the sensor.
i wish could get an answer without having to hear the tree huggers perspective on things but i guess thats why its a forum to get everybodys opinion i dont want my car quiet and the amt of stuff coming out of a 2.4Lengine is not gonna make your air unbreathable seriously and i dont want to hear every litte bit helps anyways if the high flow keeps it legal then whatever and just out of curiosity about the air-fuel mixture how does that work if its exiting the car im not tryin to be smart i really dont understand like does that hurt gas mileage or what if its just air exiting i dont exactly understand how that works ......
i ran 3 in manifold back no cat on my 04 cavi. i lost some lower end power but got more power on my top end
Ben Sandoval wrote:i wish could get an answer without having to hear the tree huggers perspective on things but i guess thats why its a forum to get everybodys opinion i dont want my car quiet and the amt of stuff coming out of a 2.4Lengine is not gonna make your air unbreathable seriously and i dont want to hear every litte bit helps anyways if the high flow keeps it legal then whatever and just out of curiosity about the air-fuel mixture how does that work if its exiting the car im not tryin to be smart i really dont understand like does that hurt gas mileage or what if its just air exiting i dont exactly understand how that works ......
what happens is the second O2 sensor measures the amount of oxygen...if its too high or too low it will tell the ECU to adjust the fuel mixture to get the right amount. Well with the cat gone you also remove the O2 sensor...no sensor = check engine light which also causes the car to run in limp mode which automatically makes the car run rich.
Also even if you weld in a bung you can still get a CEL because of the increased speed of the exhaust gases. honestly a high flo cat is cheap...buy a good one and correct one and it will save you hassles in the end.
Quote:
i dont want my car quiet
Oh lord. Everyone put on your earplugs.
acidburn1022 wrote:what happens is the second O2 sensor measures the amount of oxygen...if its too high or too low it will tell the ECU to adjust the fuel mixture to get the right amount. Well with the cat gone you also remove the O2 sensor...no sensor = check engine light which also causes the car to run in limp mode which automatically makes the car run rich.
Also even if you weld in a bung you can still get a CEL because of the increased speed of the exhaust gases. honestly a high flo cat is cheap...buy a good one and correct one and it will save you hassles in the end.
Actually, that is not true. The secondary O2 sensor in the cat does not communicate to the ECU to change the fuel mixtures. Only the primary O2 sensor in the exhaust manifold has anything to do with changing the fuel mixture. The secondary O2 sensor is really only there to trip the CEL if your cat is clogged and not working properly.
2010 Subaru Impreza WRX Limited
1999 Cavalier Z24 Supercharged
1999 Grand AM SE (Beater Car)
1997 GMC Sierra
2007 Honda CBR 600RR
2005 Honda TRX450R
Luke Heier wrote:acidburn1022 wrote:what happens is the second O2 sensor measures the amount of oxygen...if its too high or too low it will tell the ECU to adjust the fuel mixture to get the right amount. Well with the cat gone you also remove the O2 sensor...no sensor = check engine light which also causes the car to run in limp mode which automatically makes the car run rich.
Also even if you weld in a bung you can still get a CEL because of the increased speed of the exhaust gases. honestly a high flo cat is cheap...buy a good one and correct one and it will save you hassles in the end.
Actually, that is not true. The secondary O2 sensor in the cat does not communicate to the ECU to change the fuel mixtures. Only the primary O2 sensor in the exhaust manifold has anything to do with changing the fuel mixture. The secondary O2 sensor is really only there to trip the CEL if your cat is clogged and not working properly.
thanks for correcting me,
I thought the 2nd o2 sensor also helped with the A/F ratio.
so basically if i dont put a CAT in its gonna get loud and then it will be illegal but as far as screwing things up its okay since the first sensor is b4 the CAT anyways?????? anybody have any suggestions on CAT brands or anything or where to get them? thanks for the help guys
Ben Sandoval wrote:so basically if i dont put a CAT in its gonna get loud and then it will be illegal but as far as screwing things up its okay since the first sensor is b4 the CAT anyways?????? anybody have any suggestions on CAT brands or anything or where to get them? thanks for the help guys
He just told you where to look....
Rich Grayo Jr. wrote:look here
http://www.j-body.org/forums/read.php?f=50&i=26968&t=26968
acidburn1022 wrote:thanks for correcting me, I thought the 2nd o2 sensor also helped with the A/F ratio.
Hey, no prob. That's what we are all here for.
Back to the post, if you run without a cat, you won't have any problems as far as functionality goes. You will just have an annoying CEL all the time. I don't have a cat in my car, and I don't have a CEL either :-) You can fake the computer by putting in a mechanical simulator. The instructions are floating around here somewhere. I can expalin if need be. Anyway, no CEL, and no cat. However to compensate for the noise, I put two 20" resonators inline with each other to cut down on the noise, which the cat usually does. However, to be COMPLETELY legal, go with a Magnaflow High Flow cat. They can easily be found here on the .org, or on eBay, or on a number of sites that sell j-body stuff.
2010 Subaru Impreza WRX Limited
1999 Cavalier Z24 Supercharged
1999 Grand AM SE (Beater Car)
1997 GMC Sierra
2007 Honda CBR 600RR
2005 Honda TRX450R
jack saves the day again! But u wanna hear loud? come to Orlando Florida and ride next to me with ur window open and let me floor it... Stright header it is soon to be fixed by TTR sweet GP
5 seconds to find another street...
MadJack wrote: All the "Hoopla" over the CAT causing a loss of power comes from the original style of CATs. The first style basically used pellets packed into a large can, they were very restictive. The new style cats all use a honeycomb or square pattern grid, that is straight through. You can tell these types of CATs, by looking through them, you can see all the way through the grid pattern, out the other side. The grid helps maintain most of the exhaust velocity, with only a loss of maybe a couple of horsepower, at the most. The reason you want to replace the CAT with a high flow CAT is to maintain a consistant diameter. The stock CAT's inlet and outlet are less than 2", which would restrict the exhaust gas flow.
As for the size, read ]"What is the best size exhaust pipe?", from the FAQ Library.
For those who say you need backpressure, please read this. [/color
Finally, MadJack is 110% correct. Your stock cat is pretty much a High Flow Cat and the only reason one should replace it is to keep the diameter of the exhaust piping the same to not create a bottle neck. Anyway you can get a Mangaflow cat or I have a Catco one that I got from Summit w/ a resonator and it sounds amazing and there are no CEL's. Good luck w/ the exhaust and remeber...just cuz its loud doesnt mean its fast.
luke,
no offense or anything, but everytime i see your sig i laugh. i know that one on the left is a girl. but the one on the right is that a guy or gal.
theres no easy way of asking so i just have to ask.
actually, removing the cat entirely on the j-body will cause a LOSS of power. madjack is correct, the stock cavvy cat is a high flow. but dont cut it off entirely. i had a 96 sunfire and i did that, and it got REAL loud, and didn't help a bit if you lose too much backpressure, it causes you to lose power. remember that. and it will cpst you more than one improper silencer ticket. i installed an rk sport dual exhaust, and it sounded sh***y. go with the magnaflow cat if you must. its only ,like, $80 or something like that. besides, messing with the cat will only cause you to lose power, and replacing it wil only cause you to gain maybe 2 hp (SuperStreet's tenth anniversary edition will tell you that
). if you want real power out of the 2.4, go with a hahn supercharger, then a 2.5" exhaust.
What?! They are both pics of the same girl... Not sure how she looks like a guy..
2010 Subaru Impreza WRX Limited
1999 Cavalier Z24 Supercharged
1999 Grand AM SE (Beater Car)
1997 GMC Sierra
2007 Honda CBR 600RR
2005 Honda TRX450R
