I have read the topic about backpressure - the result is that bacpressure in exhaust is bad (backpressure as resistance to flow). Should I replace my cat with some tube? I think that cat is just a resistance to flow => it is bad (?). Will the replace increase my power?

 

Yesh but don't forget you're in big **** if you get caught by a cop without it and you won't pass emissions either (atleast in VA).

 

Yes I know, thats why I want to REPLACE the cat, I dont want to destroy it. So the replace is good for performance? Somebody told me that I will lose bottom end.

 

What's your current setup?

 

My only mod is removed resonator and KN conical filter put on stock intake tube. I have a European F20A4 engine (it is 2.0 liter SOHC, 4gen).

 

Honestly there's no point in removing the cat in your case. Get some more stuff done and then we'll talk.

 

Why do you think it won't help? I think it could be clogged. I have bad acceleration and I dont know why (everything is set up, so I just wanna try it).

 

replace it with a carsound hiflow cat then.
some backpressure is necessary in N/A
no backpressure for turbo and other FI

 

thas only in CA or other strict places... i drove a friends toyota starlet with a perifiral port 13b running straight headers... and if u know wut that sounds like, then u'd have no prob w/a test pipe here

 

THe backpressure is minimal unless your cat has problems, put a new one on or a low restriction one. You won't give the cops a reason to write you up, you won't have the smog ***** after you and you wouldn't be hurting the enviroment either. Cats has come a long way since 1975. A little retriction helps your motor make power but a lot will hurt. staight pipes with no cat will give you a power loss.

 

That's a bit too general to say don't you think? Do you want a cat when you're boosting 12+ lbs? I sure as hell wouldn't. Same with a strong N/A build up - you don't want a cat. BUT, in this guy's case your post does apply, I just wanted to add some clarification.

 

He didn't say he was running a turbo. If he did I would have said he would have been beeter off with one of the High performance low restriction cats. Its a hell of a lot cheaper than the fine he would get if he got caught without a cat. and what would a low restriction cat cost hime in power with a turbo? maybe 2 or 3 HP? You would see more return by losing 10 lbs off the beer gut. Hell we get enough crap from the cops, why give them justification for the crap. And running without a cat can be a real steep fine and vehicle impoundment in some areas.

 

I have no turbo, just home-made intake. BUT i have a **** engine F20A4 (4 gen, year 1994) with only 130HP and I make 0-100kph (0-60mph) in looooong 11.5-12sec. This is horrible so I think if the cat is bunk up? Everything else is set up correctly, ECU tells me no errors. I have no money now for a new cat. My friend with the same engine, intake as mine, Sebring exhaust and no cat is doing this for 10sec.

 

Well we're telling you it's not worth it. Maybe it's just my 10 lb beer gut that's talking though...I dunno

 

if that the car you have, dont' do it.
not worth it.

what u want is a manual car
and a car with potential

 

If you think the exhaust is clogged up (or the Catalytic Converter is), then do a back pressure test. Take out the O2, stick in a low pressure guage and note the reading.

I wanna say it should be something like 1psi at idle. I'll have to check the manual when I get home for more accurate info, so do NOT take this figure to be anything but a guess from memory.

Point though is, you think you got an exhaust restriction, do a test.

 

i thought it's a FEDERAL requirement that all vehicles up to a certain GVW need a cat?


[Modified by YodaIsGod, 9:50 AM 3/7/2002]

 

Joshbm: was there any power loss at bottom end?

 

I live in alabama and it's not illegal to run without a cat. Infact i don't think we have any exhaust laws.