Is there really anything to gain by eliminating the catalytic converter on a 2200 OHV engine with a stock tune? Or is the loss of back-pressure and subsequently torque not worth the trouble? Seems like this is something everyone talks about doing but I don't see how it can really help unless it's already hopelessly clogged before you eliminate it. I understand the emission issues and the trouble codes, but that's not what I'm asking. Any words of wisdom?
"In Oldskool we trust"
unless you're boosted, there's rally no gain whatsoever to be had by eliminating the cat. also; losing backpressure is a good thing. there is no such thing as too little backpressure.
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I thought torque was affected by back-pressure on these little engines. is that a myth?
"In Oldskool we trust"
People often confuse back-pressure with scavenge effect.... Scavenge effect is what you want....back-pressure need not apply.
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
I hear this alot and I've done this on my car,
Removing your cat will give a small boost in the higher rpm range, but really hurts you low end torque. Losing power in this range is bad for a stock driven street car.
You can view a article about this at
http://umods.angelfire.com/mods
Import tuner tested three diffrent set ups:
No cat
oem cat
and a hollowed out oem cat to see what was the best and dyno'd each
They found that no cat saw a loss of low end but made up for it in the high end
and the worst thing you can do is hollow out the oem cat, it lst power through out the rpm range. The hollowed out cat made more back pressure due to the design.
The flow of exhaust starts to swirl inside and slowed down.
Also a bit of advise:
Unless you are planning to build a turbo ride leave on the cat! The noise and smell will get on your nerves after about a day.
I did everything to max out flow, removed the cat, did a straite pipe, no cat with mufflers, all of it.
The best for a mild/stock ride (just my thoughts don't want haters getting mad)
is 2 1/4 inch exhaust with a modified stock cat.
For my build I did a custom header back system with 2 1/2 inch down pipe and 2 1/4 pipes any where a bend needed to be made I used 2 1/2 inch pipe to make for the bend.
For the cat i tried a few things and the best way to make larger pipes fit it is to cut it flush and cut slits in the exhaust pipe you are going to insert. You can either weld it together or get some JB and let it set.
I dont have a muffler on any more just straite pipe w/ 2 1/2 outlet.
2 1/4 is best if you don't have mods up to 2.8L anything bigger can use a 2 1/2 inch pipe
http//www.umods.org/drift.html
umods@live.com/ddiaz@umods.org
Doing that gives you a little better torque up high at a cost of down low because the exhaust cant scavenge for crap down low in the RPM band without a cat but can at higher RPMs..
But just pulling the cat isnt going to do anything worth while... just make your car sound like crap and not run quite as well.
I cut my cat in half, beat the guts out of it and put a 1 3/4 pipe through the cat welded all back together. After i was done it looked completely stock. Did i do a good thing or @!#$ er solid. tell me
I cut my cat in half, beat the guts out of it and put a 1 3/4 pipe through the cat welded all back together. After i was done it looked completely stock. Did i do a good thing or @!#$ er solid. tell me And will it make my car smoke bad?
without any other modifications, it will hurt you in the low rpm range (sub 4000), but
can help above that. as for the smoking, sounds like you either A) used a pipe with some oil in it (common, as they're usually packed in shippin oil to prevent rust) or B) had a pre-existing issue that the cat was burning off more completely. i'm leaning towards A.
Edited 1 time(s). Last edited Tuesday, January 05, 2010 6:22 PM
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It is true that there is no such thing as too little back-pressure. However, if you eliminate back-pressure, you usually lose exhaust gas velocity. When you lose velocity you lose the scavenging effect.
In a perfect world you would have an infinitely small amount of back-pressure, and an infinitely fast exhaust gas velocity. This is part of the reason why people wrap their exhausts. It is not necessarily to keep under hood temps down (although that is a plus), it is to raise velocity. Hot air weighs less than cold air, so it moves quicker.
As an example of this: when Joe Shmoe puts a 4 inch cat back on his civic and complains that he lost power, it isn't because he lost back-pressure. It is because he los exhaust VELOCITY.
It really comes down to what you want your car to do. There is such a thing as too large of an exhaust, or too little exhaust velocity for a given application.
Most people seem to be slightly confused about this, I thought I would clear things up.
Wes
my cat is gone, because it was all broke up inside, my low end feels great lol
i want to do an Aftermarket cat, my stuck is all mangled due to winter n lack of maintanance on the citys part. Any suggestions? I alsa want to replace the rear, its been 6 years for the pacesetter and it too is mangled. the header and down pipe are good. I was thinking of just straght pipe, and a glasspack but i kn ow how it will sound, terrible! so i am going to man up n buy one.Still looking around for the best bang for my buck. 2.25 is what i want, it sees to be the best exhaust diameter forthe car. Any recomendations let me know!
Fireboy153
Brady Fire Co. - Station 150
Long Live The Sunflower! (yea its not so "cool")
I finally decided on a exhaust system after messing around with it about a billion times and what I finally did was a full header back system w/ 2 1/2 bends plus 2 1/4 pipes and a Cherry Bomb exstream muffler( not a glasspack) and placed it at the end of the car fits nice in the stock location. Sounds really nice and I just removed the cat all together I had cracked the core doing diffrent things to the exhaust system and it was spitting out stuff.
I'm up loading the pictures to my photo bucket account and I'll post the links when its done. But if you want more information and pics pm me and I'll send you more information.
http//www.umods.org/drift.html
umods@live.com/ddiaz@umods.org
on my 92 cavy with the 2.2 for about 2 weeks i was running the manifold with nothing but a 2 foot downpipe. Not counting the moise it sucked balls, I had a large loss of power before roughly 4000rpm and my gas mileage went to hell. I went from this to a gutted cat with 2 inch pipe going thru and a thrush turbo muffler. i noticed not too much gain from these vs the stock setup.
If you lost MPG from having no exhaust piping it was from your heavy foot, I had mine like this while I was fixing some parts on it and I had plenty of power all round. I think what was happening was that the noise was so loud and annoying that you didn't want to press the gas and you felt like you were losing power cuz you were hearing more noise then you were power. Trust me I went through this issue twice and it is all mind games!!
After this spell of noise and then fixing the parts I felt a little less power on the mid-high range but about the launch was the same.
http//www.umods.org/drift.html
umods@live.com/ddiaz@umods.org
http//www.umods.org/drift.html
umods@live.com/ddiaz@umods.org
Haha I always had a heavy foot with that turd of a car. i quite literally spent twice the money for gas those 2 weeks driving the same drive as usual. As far as power I could not accelerate past 35 in a merge lane that i usually could hit 50 in. Perhaps the cars ecu was wierd and it was an isolated experience but it really did happen.
Now the Z loved a header and just a little downpipe.
