Just another question......... Dad decided while doing some minor engine work, that he would take the catalytic converter out of my exhaust system. I was just wondering if there are any drawbacks from doing this or not. Thanks......

 

Isnt that illegal? I mean doesnt that violate some emissions laws or sumtin?

 

I will not hurt anything. Should give you a slight hp boost.

 

Slight? depending on the car, you will get AT LEAST 5-8 hp form BONE stock. Do it, especially if you don't have to smog it. It will be a seat of the pants improvement.

If you have a dual cat car, I would not recommend it though, no point really unless you are running some wicked power.

 

while a new cat flows BETTER then a open pipe, they can clog up easily and quickly.... causing a slight restriction there...

if you can pass inspection and emmissions(if you have either of them) with it off, sure.. take it off..

after all these years, they tend to clog it up somewhat and people then realize a power increase..


athough the "responcable" and correct thing to do would be to put a replacement cat back on there... they cost from 60 to 80 dollars..

 

How can a catalytic converter flow better than an open pipe of the same size?

 

I dunno bout 8.

 

Thankfully they did away with emission test in Florida about 3 years ago, so no worries there . I appreciate all the info guys!!!

 

On my new Trans Am, they hoolowed out my stock cat, and combined with some other light mods, got another 20-some horses at the wheels, I'll definately say that 10-12 of those ponies was from the hollowing of the cat. That's like 14-17 ponies or so at the crank, so I think 8hp is not too far off.

 

On the early cars with cats hollowing them out or replaceing them with a piece of pipe will make a significant difference, mainly becasue they stock motors were breathing through straws on both sides (2.25" single exhaust on some and rediculously restrictive air cleaner assemblies). Nowadays cats are mush better and much less restrictive.

 

I have an LG4 with the cat removed, and it sounds better than alot of stock 350 tpis that i have heard...and by the way my exhaust is stock.

 

If you cat is clogged to begin with then you might see some noticeable gains by gutting it on a stock engine. I gutted the one on my Iroc and saw zero gains in trap speed. I did it more for sound though and wasn't expecting any real performance gains anyway.

 

because a cat can have a larger area inside then a straight pipe...

if the honeycomb is nice and clean, it should flow thru it with almost no restriction... so little restriction with the wider area of it lets it flow better..


keep in mind though, that only applys to modern Cats... older cats dont use the same type of scrubbers and dont flow that well..

 

An exhaust system is only as good as it's smallest point. Also going from a small area to a large area back to a small area will only cause unneeded turbulance in the exhaust and probably cause backpressure, not to mention the honey comb inside will hurt flow as well. Where as one smooth, unblocked pipe of the same size will flow nice and smoothly.

 

while you're at it, why dont you say the usual volicity thing too?







its a fuggin street car... take a **** before you get in and the weight change will have the same diff..



*** i hate **** people.

 

Before you **** me off, why don't you just quite spouting off **** you have no idea about, like saying a cat flows better than an open pipe. I could go on and on, but I'll try to be nice. What velocity thing would you be referring to?

 

Maybe he's reffering to the thread rx7speed started.he might be trying to say turbulance will rob the system of velocity therefore making it less efficient ,if he picked up on that.
on the point you made about the smallest part of the exaust, thats my understanding too, a pipe is only good to it's smallest part. Like going to a bigger system without haveing mandrel bends is almost pointless. The olny thing i did'nt like about hollowing cats is the way they make your car sound. I just yank em off and take the gamble of getting cought.on another note, It's usually the people like mr_dude_1 that get guzzled at the lights. the people with the biggest mouths have the slowest cars in most cases

 

no wonder why I have to do a search of my name everynow and then


somebody is always talking about me


but yes I agree with 25th

sure might not make much difference

but the straight section without the cat prolly would do a little better I would think.
but with how modern cats are anymore it prolly won't make THAT Much of a difference
if you have the old style cat that might be another story
or like my car with 3 cats it's another story
but new ones eh prolly going to come ABOUT even anyway with straight pipe ahead I'm sure
but for me I would do it anyway cuase I like the sound of a straight pipe vs a cat


and the thread I made was more based on technical shiz then based on ok lets take my little lg4 and put all this work on it to make it gain a whole 5hp

 

i went from a 15.9 to a 14.7 and that was all because of my gutted catalytic converter.....buuwahhaah L69!!

 

heh, yea rx7speed I know all about the 3 cat situation, a call to racing beat will remedy that

 

then your cat was extremely clogged.