BaronVonBigmeat

And don't forget about "grandfathered" industries. ie, congress has specifically exempted certain industries from having to upgrade their pollution controls until 2020 or something like that. Don't get me wrong, I'm very much pro-business, I'm just saying let's consider all the factors. Meanwhile, the EPA pushes cars to go from producing .0001% pollution to producing .0000001% pollution, which is not a very cost-effective way to clean the air.

Genom

Heh. You guys want ridiculous pollution? Try Mexico City. It's a valley surrounded by mountains about 2200 meters up. When I left 6 years ago all cars could NOT drive at least 1 day a week, and during elevated pollution (especially during winter) this was set to 3 days a week (2 weekdays and 1 weekend day). This was normal for about the previous 6-7 years. Everyday the pollution levels are unacceptable by international standards, creeping into dangerous about 60% of the time, and very dangerous about 15%, meaning schools closed, work suspended and car usage restricted.

And like in most other places, they curtail the private sector. But the public buses spew so much crap into the air you cant breathe near one, and the northern edge of the entire city is dedicated to factories that if they where relocated 30 miles north, on the OTHER side of the mountains, would cut pollution levels by 80%.

And have they? OF COURSE NOT. The .2% of the population that controls most of the money might be inconvenienced a bit by this and so the polititians do nothing about it.

Yeah, Mexico City is a craphole. You can say it. I sure know it. But most other places are cool.

Barnstormer

Has anyone thought about the fact that the car is an OBDII computer and removing/gutting the cat without modifying the signal from the second o2 sensor will trip the CEL and even if it's cleared it will show up again almost immeadeatly(sp)?

CraziFuzzy

Yeah, that's why in his original post, he stated that he wanted to install a dummy sensor...

Doctorr

Yes, I too was wondering what would happen if the second O2 sensor was not 'happy'......surely the computer wants to see some difference between sensors #1 & #2 ?

I am also concerned about the logic of tuning the engine so that it meets some upcoming federal standards, by riching out the mixture so that you use a tankful in 200 miles instead of 300....
Where is the greenhouse gas sensitivity in THAT?

The kicker is that some Euro countries tax the car on how much CO2 it puts out, so the tuning for the catalyst not only uses more fuel and costs more cash, it actually puts the car into a higher 'tax' bracket! Go figure.....
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doc

MazdaManiac

iTrader: (3)

If you tie the second O2 sensor input to the first sensor with a potentiometer, you can tune the relationship to the ECU's satisfaction.
That is how I did it on my Miata.

canzoomer

The EU monitors the cat by the use of 2 O2 sensors.
It expects a difference of levels.

O2 sensors typically output a DC voltage, whcih varies depending on reading.
If the cat is doing it's job properly it will convert CO t CO2, yielding a lower oxygen level after the cat than before. The O2 sensor monitoring allows theECU to tell if the cat is doing it's job properly. If you remove the cat, then the difference in readings will not be there and a ECU code will result.

The method of simulating that the cat is still there that is most effective is a simple logic device that reads the first O2 sensor, and produces an adjusted voltage controlled by this for the second O2 sensor input to the ECU.

It is quite feasible to make a midpipe with a higher flow cat that can take higher exhast temperatures, allowing for leaner mixtures and more ignition advance.
This does raise the exhaust temps, resulting in the need for a more robust cat.

However, such a setup will NOT pass the emissions requirements in some states, notable California.

rxeightr

Based upon your wording, am I to assume one does not exist yet? Will it need to made specific to the RX-8 to satisfy a specific configuration?

MrWigggles

Remember that the current cat is wedged in there pretty well (note the lump in the floor on the passenger's side. A high flow unit if it is bigger is going to cost you some ground clearance.

Canzoomer,

Would even a high flow unit not pass Cali? or where you refering to using a straightpipe?

For racing apps where you wanted to remove the cat, a simple voltage devider would work well to reduce the signal coming out of the second O2 sensor. You could mount the O2 sensor in the straight pipe replacement and with a couple resistors reduce the signal going to the ECU. I don't think you need a seperate logic circuit.

You could also just simply ground the connection and not use an O2 sensor, but that might be too clean as far as the ECU is concerned.

-Mr. Wigggles

SuperRex

In California you have to pass a visual test as well... they physically check if the cat under yur car is the cat it left the dealership with.

canzoomer

The converters exist.
We have to implement them in mid pipes and test them to verify they work properly in this application and survive.
To monitor function we have to add sensors for temperature after the cat, and then run it for a month or so to verify it survives under hard use.
This is not going to be an overnight process.
Who wants to get a high-flow cat, only to find out it fails in a month?

I am sure there may be others working on this too.
We are about to build a couple for testing, and Random Tech in Atlanta want to build one as well.

If you are in the area of Atlanta Georgia, and would like to be a guinea pig, email me off-list and i will hook you up with Random.

Omicron

Speaking of Random Technologies, Canzoomer, have they had any luck with developing a high-temperature cat yet? I'd love to find one that would survive your Stage 2 mod.... :D

canzoomer

The stock cat is kind of poorly implemented in the RX-8. It is mounted and shielded in a rather kludgy way.

You can just see it was not the one they originally designed for.
It is the lowest point by far on a stock RX-8 already.
Our design will not stick out any further, and one of the design goals is for it to stick out less, so it is not the obvious damage point if you bottom out.
I personally think that by makiong the cat stick out in this fashion is awful design by Mazda. Having a $1,800 item as the low point is a design disaster!
I doubt that anything other than the stock, or similar to it , will pass in California. Personally I find it ludicrous that doing this makes your car illegal in California, but you can legally purchase a diesel pickup that make 8 times the pollution as the RX-8.
But then i live in Canada, not California, and we have our own share of legislative idiots up here too..
That is essentially wehat I meant. You also want to add a diode and an opto-isolator to prevent feedback and noise, and to reduce the chance of damage from a high voltage spike feeding back from static and frying the ECU.
It is. I tried it already. It gets unhappy after about 15 minutes on the road and throws a check engine.

canzoomer

Dave from Random has sent me two cats to test in my prototype midpipe designs.
Once I have some mileage on them I will know more.

We are going to be running two cars with two different setups using these.

Random makes a couple of units good to 2000F+, which is a lot higher than the stock one that can take about 1,750F.

However these take a LOT longer to heat up to full operating temperature, so will never pass the new 5 minute warmup used in Califonia.

canzoomer

Here is a source of interesting reading materials on Catalytic converters and regulations:

http://www.epa.gov/otaq/cert.htm

canzoomer

Of special interest is this spec set:
http://www.epa.gov/otaq/stds-ld.htm

canzoomer

And here is what goes in to effect for 2004.
This is the new Tier2 emissions schedule, which Mazda had to meet with the RX-8 release.

http://www.epa.gov/oms/tr2home.htm

canzoomer

Perhaps most importantly, if you consider using an aftermarket exhaust on the road, there is a federal law that governs this.
I suggest that you read and become familiar with THIS DOCUMENT.

It quite clearly expains the law.
It also clearly explains a LTO about catalytic converters in layman's terms.


http://www.epa.gov/otaq/cert/factshts/catcvrts.pdf

Omicron

Now that's really encouraging! 2000F+ might just survive your Stage 2 mod..

I'm not in CA, so I don't have to worry about the same requirements they do. :D

canzoomer

We think it will, but have to do some testing first.

One cautionary note about the emissions, as of now 2004 model year cars come under the new EPA regulations for catalytic converters and emissions.

I really suggest reading this:
http://www.epa.gov/oms/tr2home.htm

Buger

The EPA OTAQ (Office of Transportation Air Quality) website has a tremendous amount of information and it is one of the main sites where I have done a fair bit of reading in the last few months.

Unfortunately, there is so much information there that not too many people will end up reading much of it.

I've tried to summarize some of the information in the below thread:

https://www.rx8club.com/rx-8-discussion-3/rx-8-emissions-1341/

Hopefully it will be helpful to some people.

Brian

deadrx7conv

And tons of other vehicles.... Some just leave the 2nd Cat monitoring o2 in the vehicle with the resistor circuit which mimics having that cat. All you gotta do is monitor the output of the 2nd o2 sensor, with and without the cat, and select the appropriate resistor.

When going for emissions tests, just reinstall the original cat that you saved in storage for this purpose.