cat-less exhaust

[seanjuan]

Here's the deal
i really had no need for the Thermal R&D exhaust that i bought and installed on my 92 civic LX so i traded it to my friend for his civic rims and his stock exhaust. he has a 96 civic but with brief inspection i saw that the exhausts matched up
upon actually swapping exhaust we found out that his doest have a catalytic converter in the same place mine does and his midsection pipe is just a straight pipe where mine has a cat
but since they were the same lenght we swapped anyway
it actually seams like my car is faster with the stock cat-less exhaust than it was with the aftermarket exhaust with a cat

what i'm wondering is is this could cause any problems down the road. Minnesota doesn't do emissions testing anymore so that shouldn't be a problem, i'm just concerned about engine life and fuel consumption

thanks
Sean


PS.
i also installed a Solo short throw shifter while i had the exhaust off and it was a snap, i love the shifter!

[94_AcCoRd_EX]

I wouldn't worry about it if you don't have emissions, though it is illegal. I'd like to gut my cat someday, so I say leave it.

[slowEJ6]

why gut your cat? it wont help you much whatsoever to be honest - if even help.

[94_AcCoRd_EX]

Originally posted by hybrid3do0rcx
why gut your cat? it wont help you much whatsoever to be honest - if even help.

Really? I was under the impression that a gutted/high flow cat would help. Thanks for the info.

[Accord Man]

Dont do that.. its really bad for the environment.. Save up the cash and get a high flow cat.

[4jacks]

NO WAY !!! Gutting your Cat will give a LOT more performance gains and get you MUCH better Gas milage. The ONE and only thing your Cat does is clean up the air. Is does nothing but hinder your cars performance..

there's no way i'm going be able to find any Dyno's to prove HP gains, but you will definatly get a noticable increase. I'm gutting my cat, I just have to get an extra to swap if I ever need to pass emissions.

[94_AcCoRd_EX]

Originally posted by Accord Man
Save up the cash and get a high flow cat.

Yeah, that's actually what I'd end up doing... I was just saying that I thought the lack of a cat would improve performance.

[4jacks]

I bought a "Supposedly" Hi flow Cat for my probe and didn't notice anything.

Q??? Are you suppose to be able to see thru a High Flow Cat ?? Cause if you can't ... What makes it any better than a regular Cat. ??

I couldn't see through the one I had Bought, for my probe... I was thinking.. the guy just ripped me off and sold me a regular Cat.

[slowEJ6]

Originally posted by 4jacks
NO WAY !!! Gutting your Cat will give a LOT more performance gains and get you MUCH better Gas milage. The ONE and only thing your Cat does is clean up the air. Is does nothing but hinder your cars performance..
not true. ive seen stock cat and high flow cat dynos in person and a couple in SCC.....the gains were less than minimal. not worth swapping out unless yer gonna be pushing quite a few more horsies.

[4jacks]

I still disagree... I've known two people that have straight piped it, and they said it was noticable. And I'm a little skeptical as to whether SCC would publish that they did something that illegal.
at any rate, I'm still doing I got me a ULEV so i hope to still pass MD emissions with out it.

[slowEJ6]

theres nothing illegal about a high flow cat. SCC didnt do anything illegal.

straight pipe = losing backpressure. if you dont have a lot of power thats not a good thing at all.

did they actually DYNO the car to see the difference? the butt dyno doesnt tell all cuz sometimes you just "think" it does something.

my friend with a 00 eclipse GT ran consistent 15.3's.....after gutting his cat his car smelled weird and he still ran 15.3's...

[94_AcCoRd_EX]

Originally posted by hybrid3do0rcx
theres nothing illegal about a high flow cat. SCC didnt do anything illegal.

I think you have to have 100k miles on your car or have a damaged cat before you can legally replace it in the US. Then you have to have the mechanic sign a paper, etc. That's what I read on a site that was selling them.

[PabloHoney]

Originally posted by hybrid3do0rcx
theres nothing illegal about a high flow cat. SCC didnt do anything illegal.

straight pipe = losing backpressure. if you dont have a lot of power thats not a good thing at all.


Ok...back-pressure = bad. You don't want backpressure. What you do want is higher exhaust velocities [sp?] Gutting a cat may give better flow, but could actually slow down the exhaust, thus doing nothing for your car.

did they actually DYNO the car to see the difference? the butt dyno doesnt tell all cuz sometimes you just "think" it does something.

my friend with a 00 eclipse GT ran consistent 15.3's.....after gutting his cat his car smelled weird and he still ran 15.3's...


Hahahaha, the butt dyno =) Very very true though....more often than not, people will change something, claim it feels faster, when it actually does nothing. Face it people...you can't FEEL 5 hp.

[slowEJ6]

Originally posted by 94_AcCoRd_EX


I think you have to have 100k miles on your car or have a damaged cat before you can legally replace it in the US.
the car had over 100k miles..... :cool:

[Quist]

actually I have heard that the cat is the fastest flowing part of your exhaust. Since the cat becomes extremly hot after only a few seconds of running, the air passing through it is heated creating a "thinner" air that may pass through the cat quicker. Not sure about the last part (it was off the top of my head), but I have heard reports about the CAT flowing the best out of you entire exhaust system. dunno???

Gutting a cat would just hinder air flow and create pockets of air that will end up slowing everything down, due to jagged pieces of metal and left over shiznt inside.

[Grey16]

I had a staight pipe on my civic and I had to put the cat back on for emmisions and there was no difference at all. Maybe if you have serious boost, removing ,gutting want ever to your cat is probly not going to do anything or much at all. Thats just my 2 cents.

[4jacks]

Okay... I had to educate myself a little, but I'm back to argueing again...

This is what I found out !

The precious metal catalyst is bound to an extruded ceramic honeycomb
substrate. The ceramic has hundreds of flow channels that allow the exhaust
gasses to come in contact with a maximum amount of surface area where the
catalyst reaction takes place. The catalyst must come in direct contact with the
exhaust gasses for the reaction to take place.

And this is where I found that info.. and a little more
http://www.bobsmuffler.com/conv_works.htm

Of Course everyone knows that's Bob's Muffler.com is the ONLY place to Go with your Automotive Queries. .... It was the first thing to come up okay !

But it's enough to prove my thought process. Basicly if you open up a Catalytic Convertor, it is jammed packed with all this ceramic coated layers and layers and layers. The only description I've heard before is from my 7th grade sceince teacher who suggested taking the darn thing off for better gas milage (great earth freindly science teacher) He said it looks like a million little BB's that just fall all over the place.

now with the proven fact that your exhaust gases have to pass through all this crap. You can't say that this isn't the MOST restrictive part of your whole exhuast system. I forget who it was, but one of you speed junky's even told some new person not to buy a 5-zigen exhaust, becuase the extra bend being all slanted, was unnecessary and caused extra restriction. Well if that extra bend is restrictive your CAT is 500 times worse.

I'm not claiming straight piping the cat will give you 45 Hp... but It is definatly going get you more than puttin on a free flow muffler.

And to quist's credit... (learned this on the page also) most cats have a pre warmer thing that heats the air, Warm air moves faster. But this got me thinking... If I can keep the Pre warmer and take out the ceramic honeycomb layers... it'll be that much better.

So anyway... I'm going bore my CAT , and gain 50 HP outa it... and slap another Really Huge Type R sticker on my Car... you all can do what you want.