Hello All,

I was just looking at mini-design.com and noticed that they sell a cat replacement, and I was wondering if anyone here had any experience with that. And please, no flames, old school performance mods are not for everybody. Here is a pic from there site:



If you look carefully you can see the o2 sensor is attached to the replacement, but i'm not sure how or if they have found a way to get past the check engine light always coming on. I had this problem with my a4 when I put a race cat on. Look forward to hearing about anyone's experience with this matter.

Blake

 

Blake,

There are two parts to the cat system, a pre-cat followed by the cat. These pieces don't just bolt up, so I'm wondering how they made that pipe - did they flange the original header?

The O2 system has two sensors, the first, before the pre-cat to determine the mixture for the ECU. The second is emmisions related, and checks that the pre-cat is there, so you probably would have an issue with the check engine light. It looks like the pipe has this second lambda sensor fitting, so they might know how to trick the system voltage. I'd be interested to hear if that's what they did.

You can also buy an O2 simulator that tricks the system.

My thoughts are that if you have to cut and weld, you may as well get a Supersprint or some other header without the cat that includes the flex line. You are going to deal with the check engine light either way, so why not get the optimized flow?

Let me know what you hear either way, I'm curious if they are just driving around with the light on or not.

Randy

 

O2 simulator? What kind of magic is that? More important where do I get one?

 

since any rocking of the transverse engine will cause fore and aft and up and down movement of the header, tht flex mount seems very important if you want to avoid cracked joints.

 

Part of the magic of owning a MINI is that you're doing as little environmental damage as one can by driving a car (other than a hybrid). Please don't do this mod on your daily drivers! You'll be spewing more noxious gas than a Ford Excursion!

 

Like I said in previous posts, we all own mini's for our own personal reasons. Some of us bought mini's not as an environment statement, but instead because it is a street legal go-kart that brings some life into daily commutes. To each his own, but if I wanted a green vehicle I would of bought a honda insight and been on my mary way.

 

Two Lambda sensors.. They both are for emmissions. All current vehicles use Oxygen sensors for one measurement only, 14.7/1 Air fuel ratio. This ratio is used to foster catalytic converter light off and is best for emmisions. The rear O2 is there to verify catalyst performance. The front and rear readings are compared, if the voltage oscillations get too close then the check engine light will illuminate. At wide open throttle, neither O2 is used for fueling adjustments, but are ignored because they are only capable of measureing one AFR.
A O2 simulator is a device that sends the ECU a oscillating signal (generally between .2-.7 volts) that mimics a functioning o2. The key is that the rear sensor must oscillate slower than the front, wether simulated or real.

 

Can someone explain exactly what the converter does?
I know carbon monoxide comes out the tailpipe??? but
does the converter change this or just break it down??

 

>>Like I said in previous posts, we all own mini's for our own personal reasons. Some of us bought mini's not as an environment statement, but instead because it is a street legal go-kart that brings some life into daily commutes. To each his own, but if I wanted a green vehicle I would of bought a honda insight and been on my mary way.

I'm not making judgement here...but it's worth pointing out that your MINI is no longer street legal in any of the 50 states if you remove the cat. But, you knew that.

Furthermore, I believe that in many states if you're caught driving your MINI on public roads with this modification, your car will be impounded and you might suffer a similar fate. But you knew that too.

 

Impounded? What, are you high? In states with annual vehicle inspections, your car will be evaulated for emissions at the tailpipe. If it fails you will be denied your sticker until it is repaired to pass the tests. BTW, if leaned out and ran hot your "Ford Excursion" would pass the emissions test. While not trashing our planet is a priority, knee jerk reactions usually don't cause productive results. But, I'm sure someone did a comparative study between the mini and the excursion prior to posting.

 

yes I do know that removing your cat makes your car not street legal. I knew that when my 300hp 65 mustang was running straight pipes, and I also new that when I used a high flow cat on my 250+hp audi a4. I also know that if you have a bolt on replacement pipe that you can take it off and replace it with the cat in a matter of about 20 minutes, thus eliminating the problem with inspection. And no you would get thrown in jail, the only times you get questioned about your exhaust are if you are running without a cat or mufflers and your car sounds like something right out off nascar (like my 65 mustang, who never got me any tickets and most cops response was "damn that sounds mean as hell, whatcha got in this bad boy&quot Also I have a magnaflow exhaust with a resonator so the change in the exhaust note is minimal. So if you don't like performance mods that's fine, just don't come into the performance mods forum and get upset that people are talking about performance mods. I don't mean to be a ****, but it's just like people who complain about what's on tv or the radio, if you don't like it just turn it off, no one is forcing you to listen to "gangster rap" or watch tv show where there is vulger language.

 

Aren't some high-flow cats probably actually cleaner than the OEM one? More expensive too, but cleaner...? That's what my dealer told me anyways. My dealer is working on getting a high-flow cat for the MINI.

 

Once again grinder, you are correct. There are so many restrictor on stock exhaust systems that it is not uncommon to see improvements in gas millage when switching to a less restricted exhaust, thus using less gas to go the same distance, thus proving the point that just because you modify your car, doesn't mean you are burning down the rainforrest or clubbing baby seals.

Blake

 

Good Points... If you locate the performance cat, please start a thread.

 

>>Can someone explain exactly what the converter does?
>>I know carbon monoxide comes out the tailpipe??? but
>>does the converter change this or just break it down??


Here you go... all you care to know about cats (converters that is).

 

Modern high flow cats are rated at such a high CFM that removing that running without a cat is really not needed. I think the fine for running without a cat is around 2500 dollars so hey its up to you if you want to take the risk.


Of course if you have been paying attention to the current research on exhaust systems and back pressure you would know that some cars actually make more HP with cats, mufflers or some other type of device that produces a little backpressure.

Many cars don't run well with very little or no backpressure. I would like to see some chassis dyno data on the same MINI running a stock system, cat back only, high flow cat/muffler and full race set up with no precat, cat or muffler.

I won't argue that a lot of the EPA rules are stupid because I think they are. As long as a vehicle can pass a tailpipe test for the year it was made it should not matter what has been done to the motor.

 

">>Two Lambda sensors.. They both are for emmissions. All current vehicles use Oxygen sensors for one measurement only, 14.7/1 Air fuel ratio. This ratio is used to foster catalytic converter light off and is best for emmisions. The rear O2 is there to verify catalyst performance. The front and rear readings are compared, if the voltage oscillations get too close then the check engine light will illuminate. At wide open throttle, neither O2 is used for fueling adjustments, but are ignored because they are only capable of measureing one AFR.
>>A O2 simulator is a device that sends the ECU a oscillating signal (generally between .2-.7 volts) that mimics a functioning o2. The key is that the rear sensor must oscillate slower than the front, wether simulated or real."


Here is a link to how to make your own simulator, maybe that will help the folks making the headers
http://jdmfan.com/technical/performa...sor_simulator/

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