Drivetrain Headers without the cat?
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Headers without the cat?
I was interested in purchasing some headers when i started reading up on them a little more. How serious is this open and closed loop when purchasing headers without the cat. Is it going to give me a check engine light? I only ask because the difference in price can be like $800. Im just trying to figure out if its ok to get the headers without the cat? And does anybody have any good suggestions?
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From: Fresno, Ca.
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From: San Juan, PR
You will throw a code. I throw a code even with a racing cat.
I just ordered an o2 simulator from here: http://webstore.o2simulator.com/index.asp
If you order one, make sure you pick the one specified for the MINI.
I'm sure you already know this but if you buy a header without a cat it will be LOUD (and smelly too).
I just ordered an o2 simulator from here: http://webstore.o2simulator.com/index.asp
If you order one, make sure you pick the one specified for the MINI.
I'm sure you already know this but if you buy a header without a cat it will be LOUD (and smelly too).
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Joined: Nov 2004
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From: Downtown Denver
Why? Catalytic converters are on our cars for a reason. Yes, you can remove it and gain, oh, a half a horse, but your car will smell like crap and will have visibly more exhaust. awesome. 
Yes, a cat can be a restriction in the flow of the system, but the gases and exhaust it traps and converts are not things that should be in the atmosphere, and should not be justified so a car can be louder and gain barely no power.
The ONLY ONLY ONLY reason to do this is on a track car. Otherwise, spend your time getting power gains elsewhere. If you do track your car, think about getting a removable cat so you can install a stright downpipe when your tracking, then the cat for all other times. Mini-Madness has a header like that. There are options: fresh stock cat; lightly used stock cat (cut out); high flow cat (200 or 400 cell). . . or buy a header with a cat- Alta's is $750 with a high flow cat (which still probably won't pass CA CARB standards, but at least it's a cat, and still better than NOT running one.) MTH has a sweet looking header (they call it a manifold- english. . .
) with a 400 cell high flow cat, also.
Plus, here's what Randy Webb of Webb Motorsports says-
So, try not to be a total douche. Keep the cat. 
Yes, a cat can be a restriction in the flow of the system, but the gases and exhaust it traps and converts are not things that should be in the atmosphere, and should not be justified so a car can be louder and gain barely no power.
The ONLY ONLY ONLY reason to do this is on a track car. Otherwise, spend your time getting power gains elsewhere. If you do track your car, think about getting a removable cat so you can install a stright downpipe when your tracking, then the cat for all other times. Mini-Madness has a header like that. There are options: fresh stock cat; lightly used stock cat (cut out); high flow cat (200 or 400 cell). . . or buy a header with a cat- Alta's is $750 with a high flow cat (which still probably won't pass CA CARB standards, but at least it's a cat, and still better than NOT running one.) MTH has a sweet looking header (they call it a manifold- english. . .
) with a 400 cell high flow cat, also.Plus, here's what Randy Webb of Webb Motorsports says-
Originally Posted by Randy Webb
Why do you only use headers that have a catalytic converter?
Because I care for the environment - just kidding (not that there's anything wrong with that).
This question goes to how the MINI determines the A/F (Air/Fuel) ratio. There are two basic functional modes the ECU: open loop and closed loop. Closed loop is your friend, as it uses real time, actual fuel burn to determine the A/F ratio. This is determined through the O2 sensors, located in the header. The spent combustiable mixture passes out of the cylinder head and into the exhaust system. The O2 sensors can tell the ECU what the fuel ratio was, and the ECU trims accordingly to maintain the desired ratio. OBDII (On Board Diagnostics II) uses the O2 sensors to monitor catalyst efficiency.
Open loop is used when the O2 sensors can no longer handle the flow rate. This is pretty acuurately described as a "best guess" A/F determination. It is a very accurate guess, but real time data is always the best.
The MINI has two O2 sensors, one pre-cat and one post-cat. The sensors measure the temp difference and convert it to voltage, which is monitored by the ECU. Because of the OBDII, it needs to be sure the cat is functional. If there is no change in voltage, the O2 sensor assumes it has failed and the ECU functions in open loop.
So, the reason I use only cat-equipped headers is so I don't lose the accurate closed loop ECU function.
Because I care for the environment - just kidding (not that there's anything wrong with that).
This question goes to how the MINI determines the A/F (Air/Fuel) ratio. There are two basic functional modes the ECU: open loop and closed loop. Closed loop is your friend, as it uses real time, actual fuel burn to determine the A/F ratio. This is determined through the O2 sensors, located in the header. The spent combustiable mixture passes out of the cylinder head and into the exhaust system. The O2 sensors can tell the ECU what the fuel ratio was, and the ECU trims accordingly to maintain the desired ratio. OBDII (On Board Diagnostics II) uses the O2 sensors to monitor catalyst efficiency.
Open loop is used when the O2 sensors can no longer handle the flow rate. This is pretty acuurately described as a "best guess" A/F determination. It is a very accurate guess, but real time data is always the best.
The MINI has two O2 sensors, one pre-cat and one post-cat. The sensors measure the temp difference and convert it to voltage, which is monitored by the ECU. Because of the OBDII, it needs to be sure the cat is functional. If there is no change in voltage, the O2 sensor assumes it has failed and the ECU functions in open loop.
So, the reason I use only cat-equipped headers is so I don't lose the accurate closed loop ECU function.
Last edited by sandtoast500; Jul 26, 2007 at 09:01 AM.
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From: Cincinnati, Ohio
I currently have an ALTA Catless header, and I like it. I bought an o2 sim from o2simulator.com and got the MINI specific one. It is true that is is a lot louder than stock, and yes you can smell it, but I happen to like it, so it doesn't bother me. And as far as running a CAT....yea sure, I'll help the environment, but someone better PM me and pay for a CAT and pay to have it installed. Then I'll run one.
-Cody
-Cody
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From: Downtown Denver
Well, a cat WAS installed on your car. 
Why should you be subsidized to put it back on when you took it off? Don't you have emmisions in Ohio?
If you still have your stock header, you can take it to get the cat cut off and welded onto your header. Should be $200, tops. With all the other mods you've paid for, how about one that benefits everyone else, mr. greedy pants?
Why should you be subsidized to put it back on when you took it off? Don't you have emmisions in Ohio? If you still have your stock header, you can take it to get the cat cut off and welded onto your header. Should be $200, tops. With all the other mods you've paid for, how about one that benefits everyone else, mr. greedy pants?
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I currently have an ALTA Catless header, and I like it. I bought an o2 sim from o2simulator.com and got the MINI specific one. It is true that is is a lot louder than stock, and yes you can smell it, but I happen to like it, so it doesn't bother me. And as far as running a CAT....yea sure, I'll help the environment, but someone better PM me and pay for a CAT and pay to have it installed. Then I'll run one.
-Cody
-Cody
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From: Downtown Denver
You should be lucky YOU don't have to pay to have it put on ON TOP of a fine for violating the EPA standards. . .
I am not following the logic here. . . what is the point? You couldn't afford a header with a cat, so you bought one without, disregarding emissions standards for. . . what. . . some extra decibels and a half-horse? Why didn't you install the stock cat during installation?
Don't you feel just a little bit guilty for being so inconsiderate? Maybe a tiny bit?
If not, then you may also be the type of person that blatantly litters out the window of vehicles; improperly disposes of motor oil, paint buckets and batteries; and calls environmentally conscious people "tree-huggers." Blah.
I'm not completely directing this at you, Polizei, but you have chosen to defend these haughty actions.
I am not following the logic here. . . what is the point? You couldn't afford a header with a cat, so you bought one without, disregarding emissions standards for. . . what. . . some extra decibels and a half-horse? Why didn't you install the stock cat during installation?
Don't you feel just a little bit guilty for being so inconsiderate? Maybe a tiny bit?
If not, then you may also be the type of person that blatantly litters out the window of vehicles; improperly disposes of motor oil, paint buckets and batteries; and calls environmentally conscious people "tree-huggers."
Blah.I'm not completely directing this at you, Polizei, but you have chosen to defend these haughty actions.
My little dose of LITHIUM
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Well, sandtoast500 has taken up the banner, which normally falls to Dr Obnxs, or me, occassionally. I ran catless for about 2 weeks while waiting for a new header and then an appointment at the shop to weld up a Magnaflow. I never detected any bad smell, but it sure was loud in a noisy way. The problem is that it really gets you very little, if any, power increases.
So the economist in me wonders: benefits=loud, little to no extra power; costs=noisy, illegal, bad for the environment. I'm no tree hugger, so don't misinterpret what I'm saying here--it's just that running catless doesn't pass the old Benefit-Cost test. Unless you're a selfish, self-centered (insert quote from Red Hot Chili Peppers here--rhymes with Rick.) of course.
So the economist in me wonders: benefits=loud, little to no extra power; costs=noisy, illegal, bad for the environment. I'm no tree hugger, so don't misinterpret what I'm saying here--it's just that running catless doesn't pass the old Benefit-Cost test. Unless you're a selfish, self-centered (insert quote from Red Hot Chili Peppers here--rhymes with Rick.) of course.
I love how people get all bent out of shape when someone here decides to not run a cat. I'm sure the few number of MINI's that are running without cats are far less polluting than say a school bus, some tool in a lifted diesel truck with 7" exhaust shooting out black smoke, semi-trucks, cars 15+ years old etc. Go bark about that instead, its a much bigger issue.
I took my cat out when my OBX was installed and I ended up adding a cat simply for noise reasons, nothing else. Being legal and "green" was simply an added bonus.
I took my cat out when my OBX was installed and I ended up adding a cat simply for noise reasons, nothing else. Being legal and "green" was simply an added bonus.
Last edited by ThumperMCS; Jul 26, 2007 at 02:23 PM.
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From: Downtown Denver
Originally Posted by ThumperMCS
I love how people get all bent out of shape when someone here decides to not run a cat.
You sound like your 16. . .So, your logic is "just because there are trucks", you shouldn't run a cat? I'd like to see what on officer or the EPA has to say about that. Sure, just one more person doesn't make a difference. . .
But, add another MINI with no cat to the number of other idiots with Civics, Accords, CRXs, beat up Cavaliers, etc. that are doing it and it adds up.WEAK. . . .
It's like saying, "there are huge landfills, therefore, I can throw my trash on your lawn and it doesn't matter." That is a foolish fallacy and bad logic.
By the way, diesel trucks may seem to spout more crap in the form of black smoke, but most cars emit more "clear" pollution. . . All US cars made after 1975 have a cat. . . so that's probably 98% of everything on the road. And, there are standards for all vehicles, including yours. Also, things ARE being done about those "large" vehicles- More public and city buses and vehicles are going to alternate and hybrid technology. So, I guess that voids your arguement. Sometimes people getting "bent out of shape" is the only way things ever happen.
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From: Fresno, Ca.
I love how people get all bent out of shape when someone here decides to not run a cat. I'm sure the few number of MINI's that are running without cats are far less polluting than say a school bus, some tool in a lifted diesel truck with 7" exhaust shooting out black smoke, semi-trucks, cars 15+ years old etc. Go bark about that instead, its a much bigger issue.
I took my cat out when my OBX was installed and I ended up adding a cat simply for noise reasons, nothing else. Being legal and "green" was simply an added bonus.
I took my cat out when my OBX was installed and I ended up adding a cat simply for noise reasons, nothing else. Being legal and "green" was simply an added bonus.
+1 I love all theses people and there holier than thou attitudes.
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Seriously? What a smart ***, ignorant thing to say! You sound like your 16. . .
So, your logic is "just because there are trucks", you shouldn't run a cat? I'd like to see what on officer or the EPA has to say about that. Sure, just one more person doesn't make a difference. . . But, add another MINI with no cat to the number of other idiots with Civics, Accords, CRXs, beat up Cavaliers, etc. that are doing it and it adds up.
WEAK. . . .
It's like saying, "there are huge landfills, therefore, I can throw my trash on your lawn and it doesn't matter." That is a foolish fallacy and bad logic.
By the way, diesel trucks may seem to spout more crap in the form of black smoke, but most cars emit more "clear" pollution. . . All US cars made after 1975 have a cat. . . so that's probably 98% of everything on the road. And, there are standards for all vehicles, including yours. Also, things ARE being done about those "large" vehicles- More public and city buses and vehicles are going to alternate and hybrid technology. So, I guess that voids your arguement. Sometimes people getting "bent out of shape" is the only way things ever happen.
You sound like your 16. . .So, your logic is "just because there are trucks", you shouldn't run a cat? I'd like to see what on officer or the EPA has to say about that. Sure, just one more person doesn't make a difference. . .
But, add another MINI with no cat to the number of other idiots with Civics, Accords, CRXs, beat up Cavaliers, etc. that are doing it and it adds up.WEAK. . . .
It's like saying, "there are huge landfills, therefore, I can throw my trash on your lawn and it doesn't matter." That is a foolish fallacy and bad logic.
By the way, diesel trucks may seem to spout more crap in the form of black smoke, but most cars emit more "clear" pollution. . . All US cars made after 1975 have a cat. . . so that's probably 98% of everything on the road. And, there are standards for all vehicles, including yours. Also, things ARE being done about those "large" vehicles- More public and city buses and vehicles are going to alternate and hybrid technology. So, I guess that voids your arguement. Sometimes people getting "bent out of shape" is the only way things ever happen.
When the world ends and we all die from "global warming"...it will be everyones fault who took their cat out because they installed a cat-less header! 
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From: L.A ca
When I first put on my Jackson Racing header I did not have a cat for a brief time. I had a race cat on order but there was a delay . I like my toys loud but this was insanely loud . I also had issues with warning lights as I did not have a simulator. I cut the header to allow the installation of the stock cat and all was well. I was going to use the race cat but when it showed up i realized that the stock one was actually not too bad. This was all done over 40,000 trouble free miles ago. I noticed ZERO performance between running with and without it.Here in Cali it is a huge fine to run catless and for the most part something attempted by the younger generation.
Randy
M7 Tuning
Randy
M7 Tuning
Last edited by maxmini; Jul 26, 2007 at 06:45 PM.
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From: Fresno, Ca.
I was interested in purchasing some headers when i started reading up on them a little more. How serious is this open and closed loop when purchasing headers without the cat. Is it going to give me a check engine light? I only ask because the difference in price can be like $800. Im just trying to figure out if its ok to get the headers without the cat? And does anybody have any good suggestions?
Sorry guess we should get back on topic, I'm not sure where you live but in Cal It's a $10,000 fine. might be something to look into too.
My little dose of LITHIUM
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From: Albuquerque New Mexico
So despite all the rhetoric and hyperbole, my Benefit:Cost analysis still holds, and remains unchallenged. Show me proof, on a Mini Cooper S, that running a header with, and without, a catalytic converter, makes a measurable performance difference, and I'll *then* consider the data and make a decision. Btw, one of the GODS of NAM runs cat-less: MSFITOY. Sid is totally unapologetic about it, too.
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I think everyone is misunderstanding me i am not talking about removing the cat. I will keep the stock cat on there i am simply replacing the headers themselves. I am concerned about keeping the car on an open loop. Running the air/fuel to rich. Im not really sure, thats why im asking but i will not be removing the cat.
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you know i am actually new to this site. I am also farely new to owning a mini cooper. Its probably the most fun car i have owned. But of all the cars i have owned and all the forums i have posted on in the past for my other cars i would have to say you are the most ignorant bunch. And now i dont mean this to all of you but the majority of you. Because you have to think most of us are getting on here trying to get help. You could almost saying we are looking up to some of you. We think that you might have some answers. But when someone calls me a DOUCHE-----what?
