straight pipe or hollow out the cat?
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From: Valdosta, GA, US
Re: straight pipe or hollow out the cat? (Inextricabledrvr)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Inextricabledrvr »</TD></TR><TR><TD CLASS="quote">why do you suggest the straight pipe?</TD></TR></TABLE>
Becaue if you gut the cat you end up with the exhaust gases circling around in the cat and messing up the flow. a pipe will make it flow very nicley
Becaue if you gut the cat you end up with the exhaust gases circling around in the cat and messing up the flow. a pipe will make it flow very nicley
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From: Chicago, IL, USA
Re: straight pipe or hollow out the cat? (Inextricabledrvr)
any idea on what kind of o2 sim to run with a straight pipe? i have a pipe i fabricated myself - 2.5inch diameter w/ flanges for cat and rest of exhaust for removal before emissions test - with bung for o2 sensor - that i ran for a while but didnt like the check engine light or the incorrect a/f ratio due to CEL.
ps: i am willing to sell the pipe if anyone is interested....
ps: i am willing to sell the pipe if anyone is interested....
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From: SOCAL
Re: straight pipe or hollow out the cat? (afterburners)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by afterburners »</TD></TR><TR><TD CLASS="quote">none.. honda has a hi-flow cat stock... you only pollute the air and gain 0-1 hp</TD></TR></TABLE>Really? Can you back up your statement with some proof? Like some dyno graphs...because I have never seen only 0-1 HP gains from a straight pipe. Do you work for the EPA? 
To keep this on thread on track... I'd go with a straight pipe.
Modified by emoBB1 at 2:00 AM 3/18/2004
To keep this on thread on track... I'd go with a straight pipe. Modified by emoBB1 at 2:00 AM 3/18/2004
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From: Bay Area, CA, USA
Re: straight pipe or hollow out the cat? (Inextricabledrvr)
Highflow cat, you won't really feel any benefit to having a straight pipe in there other than a loud, smelly, obnoxious exhaust. Not to mention you'll be poisioning those around you with carbon monoxide. The only time where a straight pipe might be worth it is in a race where $$ is involved and you need that .1 sec that it might yeild. For the street, just leave the cat on.
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From: Betonwüsten, USA
Re: straight pipe or hollow out the cat? ()
If you hollow out the cat you are stuck with stock ID inlet and outlet. With a testpipe you can get your Inlet/outlet to 2.5" or whatever you like. Also the testpipe is lighter since it is not a cast piece.
TimeRacer: Since when has exhaust NOT been smelly? While sitting in traffic it does not matter what you are running, you are poisoning those around you with CO2, CO, NOX as well as a huge number of other nasty compunds inherent in any exhaust gas. Also I would not be so worried about emissions since you are only running a 2.2 liter engine that if you did things right you tuned to have a good A/F ratio. That means less emissions than Joe Blow American's 10 cylinder, 6 liter POS Diesel SUV that also has no cat. Testpipes also don't contribute to noise as much as some ricer exhaust tip.
Synopsis: get at test pipe and be done with it.
the Pirate
TimeRacer: Since when has exhaust NOT been smelly? While sitting in traffic it does not matter what you are running, you are poisoning those around you with CO2, CO, NOX as well as a huge number of other nasty compunds inherent in any exhaust gas. Also I would not be so worried about emissions since you are only running a 2.2 liter engine that if you did things right you tuned to have a good A/F ratio. That means less emissions than Joe Blow American's 10 cylinder, 6 liter POS Diesel SUV that also has no cat. Testpipes also don't contribute to noise as much as some ricer exhaust tip.
Synopsis: get at test pipe and be done with it.
the Pirate
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From: Monroeville, PA, USA
Re: straight pipe or hollow out the cat? (Inextricabledrvr)
So you want to stink up the air? Let me say that unless you have a chassis dyno you will probably see no real improvement in performance on a street engine To make this more clear-a hollowed CAT or straight pipe are illegal according to Federal Law. Most states will impose a fine or require the reinstallation of the parts for inspection. No car dealer is allowed to sell a car that is missing the parts.
There have been many folks who have argued this. Personally, I have a high flow fully legal cat and a cat-back on the Prelude. Our race CRX has a CAT even tho I am allowed to take it off at the track. I want clean air. The tests that have been done by various magazines led me to the upgrade rather than the other method-which I did try. Ready for this-it can actually hurt performance if you reduce back pressure too much. Think it over and go from there
There have been many folks who have argued this. Personally, I have a high flow fully legal cat and a cat-back on the Prelude. Our race CRX has a CAT even tho I am allowed to take it off at the track. I want clean air. The tests that have been done by various magazines led me to the upgrade rather than the other method-which I did try. Ready for this-it can actually hurt performance if you reduce back pressure too much. Think it over and go from there
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From: Norwalk, CT
Re: straight pipe or hollow out the cat? (95 lude)
The difference in performance between a high-flow cat & test pipe of identical diameters is almost not even measurable.
Courtesy of team-integra.net, an Integra Type R w/ CAI, SMSP header & exhaust, Toda B cams, and fuel tuning. Red line is w/ a 2.5" carsound cat, blue line is w/ a 2.5" test pipe.
Use a cat.
Courtesy of team-integra.net, an Integra Type R w/ CAI, SMSP header & exhaust, Toda B cams, and fuel tuning. Red line is w/ a 2.5" carsound cat, blue line is w/ a 2.5" test pipe.
Use a cat.
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From: Betonwüsten, USA
Re: straight pipe or hollow out the cat?
That is a 2.5" <U>High flow</U> cat that is aftermarket I am talking about STOCK. Also Let me know what that graph looks like after 100k miles when his seals and bearing are all worn and bleeding oil into the exhaust and the cat is clogged with carbon and creates a load of back pressure hindering performance causing further pollution.
A lot of pollution is from the people still running old inefficient carburated cars that have many miles and burn a hell of a lot of gasoline and oil due to sloppy tolerances. *cough**cough* Ford*cough.**SUV's*
Besides a 2 liter engine producing the same ratio of pollutants that a 6 liter engine produces does not make the 6 liter engine produce less pollutants. In fact it produces 3 times the pollutants. So my 2 liter honda can create 3 times more pollutution and still be on par with the 6 liter engine.
Also EPA regulations do not include total emissions, at full throttle or part throttle at all RPM's/Loads. There are certain standards for certain RPMs and throtle positions that the EPA looks at and car importers cater to those standards to be taxed at a lower rate.
AND all Honda cars are at least considered low emission vehicles from the factory, i think that Ford and GM don't really match those standards. SO who has the better design to begin with?
If I had $300 to spend on my car i would dyno tune it long before I would buy a cat.
People will do what they will but they should at least think about what they are saying. Before they subscribe to one platform over another.
the Pirate
A lot of pollution is from the people still running old inefficient carburated cars that have many miles and burn a hell of a lot of gasoline and oil due to sloppy tolerances. *cough**cough* Ford*cough.**SUV's*
Besides a 2 liter engine producing the same ratio of pollutants that a 6 liter engine produces does not make the 6 liter engine produce less pollutants. In fact it produces 3 times the pollutants. So my 2 liter honda can create 3 times more pollutution and still be on par with the 6 liter engine.
Also EPA regulations do not include total emissions, at full throttle or part throttle at all RPM's/Loads. There are certain standards for certain RPMs and throtle positions that the EPA looks at and car importers cater to those standards to be taxed at a lower rate.
AND all Honda cars are at least considered low emission vehicles from the factory, i think that Ford and GM don't really match those standards. SO who has the better design to begin with?
If I had $300 to spend on my car i would dyno tune it long before I would buy a cat.
People will do what they will but they should at least think about what they are saying. Before they subscribe to one platform over another.
the Pirate
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From: Bay Area, CA
Re: straight pipe or hollow out the cat? (PirateMcFred)
Daemione. where'd u get that graph from. 
but yea a highflow like the carsound does flow well but yea kinda like wut PirateMcFred says the high flow wont really last long before it ***** on you.
If you dont want to mess up the enviornment and want to have a long lasting cat talk to hy-tech. they take their highflow 2.5" cat from a Renault i believe its from the Clio. but anyways it flows very well and will last more then 100k. just get the straight pipe if you dont care about polluting.
but yea a highflow like the carsound does flow well but yea kinda like wut PirateMcFred says the high flow wont really last long before it ***** on you.
If you dont want to mess up the enviornment and want to have a long lasting cat talk to hy-tech. they take their highflow 2.5" cat from a Renault i believe its from the Clio. but anyways it flows very well and will last more then 100k. just get the straight pipe if you dont care about polluting.
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From: Monroeville, PA, USA
Re: straight pipe or hollow out the cat? (PirateMcFred)
Well Pirate-you hit it square on the proverbial head didn't you. But the fact is that a High Flow CAT is better than a stock one from the standpoint of all-out competition use due to the fact it is freer flowing and nothing more. Do they clog-eventually as would a stock one. The law says they have to work for 50k miles from the getgo, unless you are stupid enough to run leaded gas or certain additives-voids warranty.
I agree with those that suggest that the gain from an open or testpipe are not really worth the effort. This is particularly true for street engines. My CRX had a stock CAT and passed emissions with 175K on the clock-was it ever replaced-I do not know, but it was a stock unit. The upgrade included a custom everything from the head back to the tip (manifold, CAT, and mufflers) in 2.5". Does the engine breathe a little better than stock-yes it does.
Everyone here has the choice to do as he/she pleases.
I agree with those that suggest that the gain from an open or testpipe are not really worth the effort. This is particularly true for street engines. My CRX had a stock CAT and passed emissions with 175K on the clock-was it ever replaced-I do not know, but it was a stock unit. The upgrade included a custom everything from the head back to the tip (manifold, CAT, and mufflers) in 2.5". Does the engine breathe a little better than stock-yes it does.
Everyone here has the choice to do as he/she pleases.
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From: TurboDandees, Mirror, USA
Re: straight pipe or hollow out the cat? (Inextricabledrvr)
I enjoyed what i did... Keep the stock exhaust and get a cutout from http://www.quicktimeperformance.com and install it before ur catalytic converter... super stock sound with no exhaust fumes with it closed and with a flick of a switch, dumped exhaust... racecar sound. with it closed, i made 162.8whp and 138.1tq. opening it up bumped me to 178.5whp and 148.2tq and lost no bottom end ... lost no power anywhere(bone stock motor on hondata). It's just nice to rev up to someone sounding nice and stock... and when the light turns green... slapping them with "open header". Sucks if u still lose though. hahaha 
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Re: straight pipe or hollow out the cat? (PirateMcFred)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PirateMcFred »</TD></TR><TR><TD CLASS="quote">That is a 2.5" <U>High flow</U> cat that is aftermarket I am talking about STOCK. Also Let me know what that graph looks like after 100k miles when his seals and bearing are all worn and bleeding oil into the exhaust and the cat is clogged with carbon and creates a load of back pressure hindering performance causing further pollution.
Also EPA regulations do not include total emissions, at full throttle or part throttle at all RPM's/Loads. There are certain standards for certain RPMs and throtle positions that the EPA looks at and car importers cater to those standards to be taxed at a lower rate.
</TD></TR></TABLE>
I don't know what state you live in but in Metro NY emissions tests are conducted on a dyno where your car is driven at various speeds, load and RPM. The before and after w/ and without cat differences are huge. And without a cat on a car that is tuned for a cat (stock ecu) it will fail. So you are polluting more and the car is going to smell like crap all things being equal(mostly stock). I had no probs passing with 170k w/stock cat BTW.
So I don't really care if you do or don't run a cat. If I had a turbo car I'd say it might be worth it but for not for a street driven NA Honda..
Also EPA regulations do not include total emissions, at full throttle or part throttle at all RPM's/Loads. There are certain standards for certain RPMs and throtle positions that the EPA looks at and car importers cater to those standards to be taxed at a lower rate.
</TD></TR></TABLE>
I don't know what state you live in but in Metro NY emissions tests are conducted on a dyno where your car is driven at various speeds, load and RPM. The before and after w/ and without cat differences are huge. And without a cat on a car that is tuned for a cat (stock ecu) it will fail. So you are polluting more and the car is going to smell like crap all things being equal(mostly stock). I had no probs passing with 170k w/stock cat BTW.
So I don't really care if you do or don't run a cat. If I had a turbo car I'd say it might be worth it but for not for a street driven NA Honda..
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From: Norwalk, CT
Re: straight pipe or hollow out the cat? (PirateMcFred)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PirateMcFred »</TD></TR><TR><TD CLASS="quote">That is a 2.5" <U>High flow</U> cat that is aftermarket . . . </TD></TR></TABLE>
Did I state otherwise?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">Besides a 2 liter engine producing the same ratio of pollutants that a 6 liter engine produces does not make the 6 liter engine produce less pollutants. In fact it produces 3 times the pollutants. So my 2 liter honda can create 3 times more pollutution and still be on par with the 6 liter engine.</TD></TR></TABLE>
More like 10+ times the pollutants when running without a cat. And the mantra that "other people probably pollute more, so that makes it okay for me" simply doesn't work. Pretty selfish way of thinking, if you ask me. **shrug**
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">AND all Honda cars are at least considered low emission vehicles from the factory, i think that Ford and GM don't really match those standards. SO who has the better design to begin with?</TD></TR></TABLE>
Modern domestic engines meet the same emissions standards Hondas do.
All I'm saying is that for a totally reasonable expense (<$100 installed), a high-flow cat will not hinder performance in any way, will help you avoid potentially massive fines, and is much better for the environment. Oh yeah, and your car won't smell like rotten eggs.
Did I state otherwise?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">Besides a 2 liter engine producing the same ratio of pollutants that a 6 liter engine produces does not make the 6 liter engine produce less pollutants. In fact it produces 3 times the pollutants. So my 2 liter honda can create 3 times more pollutution and still be on par with the 6 liter engine.</TD></TR></TABLE>
More like 10+ times the pollutants when running without a cat. And the mantra that "other people probably pollute more, so that makes it okay for me" simply doesn't work. Pretty selfish way of thinking, if you ask me. **shrug**
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">AND all Honda cars are at least considered low emission vehicles from the factory, i think that Ford and GM don't really match those standards. SO who has the better design to begin with?</TD></TR></TABLE>
Modern domestic engines meet the same emissions standards Hondas do.
All I'm saying is that for a totally reasonable expense (<$100 installed), a high-flow cat will not hinder performance in any way, will help you avoid potentially massive fines, and is much better for the environment. Oh yeah, and your car won't smell like rotten eggs.
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From: allmotor, power, USA
Re: straight pipe or hollow out the cat? (Daemione)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Daemione »</TD></TR><TR><TD CLASS="quote">Oh yeah, and your car won't smell like rotten eggs.</TD></TR></TABLE>
what if it already does? ive been told by many people that when i drive in front of them pushing it or not, that it smells like rotten eggs. this is why i plan to go obd1 w/ a testpipe
what if it already does? ive been told by many people that when i drive in front of them pushing it or not, that it smells like rotten eggs. this is why i plan to go obd1 w/ a testpipe
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From: Chicago, IL, USA
Re: straight pipe or hollow out the cat? (superjunprelude)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by danmanh22 »</TD></TR><TR><TD CLASS="quote">
ps: i am willing to sell the pipe if anyone is interested....</TD></TR></TABLE><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by superjunprelude »</TD></TR><TR><TD CLASS="quote">how much and what year lude did it came out of
?</TD></TR></TABLE>
My test pipe is off of my 2000 Honda Prelude Base. It's made from steel, flanges are steel, no corrosion on the pipe, and it's 2.5" diameter. It will probably fit a 4th gen also, but I can check on a friend's car to be 100% certain if someone needs me to do so.
I'll sell it for $25 bucks plus shipping - the flanges i made don't have cutouts for those crush-ring exhaust gaskets, so ill include a pair of new Mr. Gasket high-temp gaskets (new ones) with the set.
It has a cutout for the o2 sensor also.
E-mail me if u r interested... dmaziar@purdue.edu
ps: i am willing to sell the pipe if anyone is interested....</TD></TR></TABLE><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by superjunprelude »</TD></TR><TR><TD CLASS="quote">how much and what year lude did it came out of
?</TD></TR></TABLE>
My test pipe is off of my 2000 Honda Prelude Base. It's made from steel, flanges are steel, no corrosion on the pipe, and it's 2.5" diameter. It will probably fit a 4th gen also, but I can check on a friend's car to be 100% certain if someone needs me to do so.
I'll sell it for $25 bucks plus shipping - the flanges i made don't have cutouts for those crush-ring exhaust gaskets, so ill include a pair of new Mr. Gasket high-temp gaskets (new ones) with the set.
It has a cutout for the o2 sensor also.
E-mail me if u r interested... dmaziar@purdue.edu