how to make oem cat into a high flow one
03-17-2007, 02:50 AM
#26
Originally Posted by 4 years to Supercharge
sosonic the area that gets pulled is not able to be seen without using a fiber optic camera.
Anyone have one?
MM?
that would solve that pesky last set of ports not opening ?
beers
07-17-2007, 05:36 PM
#29
Lubricious
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So, you reeeeally don't have a clue do you. Look I'm all for clean air, but if you would care to read about how our cat works you would find that the "cleaning" takes place in the first catalyst wall/barrier. As the exhaust has already been "cleaned", the second barrier does nothing more than hamper airflow and is only there to pick up cleaning duty after the first one fails and triggers a CEL. So, if the first one failed you would replace the cat to get rid of the CEL even though the second catalyst was doing the same job. It is redundant, unnecessary, and reduces high end power.
Interesting someone mentioned "better" flames after the mod. Flames come from ignition of unburned hydrocarbons.
07-17-2007, 05:48 PM
#30
Metatron
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You are probably correct, the effective zone could easily move much deeper under "heavy load".
However, there is no test (mechanical, electrical or rolling road) that would see it.
As long as the secondary sensor is happy, I'm happy!
Have over 20k miles on this mod, and just took it off to try my test-pipe (just a noisy failure, complete with CEL, so it is going back on) and was surprised by the condition of the honeycomb, still looks like new, will post a pic.
S
However, there is no test (mechanical, electrical or rolling road) that would see it.
As long as the secondary sensor is happy, I'm happy!
Have over 20k miles on this mod, and just took it off to try my test-pipe (just a noisy failure, complete with CEL, so it is going back on) and was surprised by the condition of the honeycomb, still looks like new, will post a pic.
S
07-17-2007, 06:02 PM
#31
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07-17-2007, 06:29 PM
#32
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07-17-2007, 07:04 PM
#33
the rear brick is simply an environmental safety backup in the event the primary front brick fails, end of story
when the front brick fails you are required by both tha manufacturer and the state/Federal laws to replace the entire assembly even though the tailpipe still sniffs clean due to the backup brick ... if the front brick efficiency drops below an acceptable limit the secondary O2 informs the PCM to throw the indicating CEL. The rear brick has nothing to do with this process except to cover for the primary brick failure/efficiency loss
also, read an EPA committee report where they have recognized that people are using O2 foolers, CEL delete software, etc., they are investigating ways to detect such things ...
when the front brick fails you are required by both tha manufacturer and the state/Federal laws to replace the entire assembly even though the tailpipe still sniffs clean due to the backup brick ... if the front brick efficiency drops below an acceptable limit the secondary O2 informs the PCM to throw the indicating CEL. The rear brick has nothing to do with this process except to cover for the primary brick failure/efficiency loss
also, read an EPA committee report where they have recognized that people are using O2 foolers, CEL delete software, etc., they are investigating ways to detect such things ...
Last edited by TeamRX8; 07-17-2007 at 07:09 PM.
07-18-2007, 06:54 AM
#34
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Ok, What if you perform the operation and cut your catalytic converter and then after some miles the remainder catalyst fails due to broken ceramic?
Do you think that dealer will still change your catalyst because you are under warranty?
I do not think so.
So it is better to swap your stock catalyst with an aftermarket that will save you from any future trouble.
Do you think that dealer will still change your catalyst because you are under warranty?
I do not think so.
So it is better to swap your stock catalyst with an aftermarket that will save you from any future trouble.
07-18-2007, 11:50 PM
#35
Ok, What if you perform the operation and cut your catalytic converter and then after some miles the remainder catalyst fails due to broken ceramic?
Do you think that dealer will still change your catalyst because you are under warranty?
I do not think so.
So it is better to swap your stock catalyst with an aftermarket that will save you from any future trouble.
Do you think that dealer will still change your catalyst because you are under warranty?
I do not think so.
So it is better to swap your stock catalyst with an aftermarket that will save you from any future trouble.
beers
07-19-2007, 12:05 PM
#37
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boy there are a couple people that just do not understand how cat converters work, if they think the 2nd section is a back up.
In fact saying so, TeamRX8 and StealthTL is clearly mis-information and wrong. People get Banned at the RX-7club for making stuff up like that.
Here is some very very basic info for those that think the 2nd section of the main cat converter is a back up to the failure of the 1st section:
So in other words... if you rip out the back section and your state has CO and HC testing, you will fail a sniffer test. Sure your NO will still be low, but that is all that will be.
Flames, are a clear indication of unburned Hydrocarbons which will fail sniffer tests.
And StealthTL ... the "coating" does not wear off. Only over or underheating a cat converter can distroy the coating. Current Cat converters will last the life of the car if they don't get too clogged with other metals or fried by an improper mixture (and even fried- the honeycomb melts down. The rare earth metals that comprise the honeycomb do not wear off.
In fact saying so, TeamRX8 and StealthTL is clearly mis-information and wrong. People get Banned at the RX-7club for making stuff up like that.
Here is some very very basic info for those that think the 2nd section of the main cat converter is a back up to the failure of the 1st section:
How Catalytic Converters Reduce Pollution
Most modern cars are equipped with three-way catalytic converters. "Three-way" refers to the three regulated emissions it helps to reduce -- carbon monoxide, VOCs and NOx molecules. The converter uses two different types of catalysts, a reduction catalyst and an oxidation catalyst. Both types consist of a ceramic structure coated with a metal catalyst, usually platinum, rhodium and/or palladium. The idea is to create a structure that exposes the maximum surface area of catalyst to the exhaust stream, while also minimizing the amount of catalyst required (they are very expensive).
A three-way catalytic converter: Note the two separate catalysts.
There are two main types of structures used in catalytic converters -- honeycomb and ceramic beads. Most cars today use a honeycomb structure.
Ceramic honeycomb catalyst structure
The Reduction Catalyst
The reduction catalyst is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce the NOx emissions. When an NO or NO2 molecule contacts the catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the form of O2. The nitrogen atoms bond with other nitrogen atoms that are also stuck to the catalyst, forming N2. For example:
2NO => N2 + O2 or 2NO2 => N2 + 2O2
The Oxidization Catalyst
The oxidation catalyst is the second stage of the catalytic converter. It reduces the unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over a platinum and palladium catalyst. This catalyst aids the reaction of the CO and hydrocarbons with the remaining oxygen in the exhaust gas. For example:
2CO + O2 => 2CO2
But where did this oxygen come from?
The Control System
The third stage is a control system that monitors the exhaust stream, and uses this information to control the fuel injection system. There is an oxygen sensor mounted upstream of the catalytic converter, meaning it is closer to the engine than the converter is. This sensor tells the engine computer how much oxygen is in the exhaust. The engine computer can increase or decrease the amount of oxygen in the exhaust by adjusting the air-to-fuel ratio. This control scheme allows the engine computer to make sure that the engine is running at close to the stoichiometric point, and also to make sure that there is enough oxygen in the exhaust to allow the oxidization catalyst to burn the unburned hydrocarbons and CO. Many newer systems will utilize a second oxygen sensor in the converter itself, to monitor the oxygen provided by the first stages output.
Most modern cars are equipped with three-way catalytic converters. "Three-way" refers to the three regulated emissions it helps to reduce -- carbon monoxide, VOCs and NOx molecules. The converter uses two different types of catalysts, a reduction catalyst and an oxidation catalyst. Both types consist of a ceramic structure coated with a metal catalyst, usually platinum, rhodium and/or palladium. The idea is to create a structure that exposes the maximum surface area of catalyst to the exhaust stream, while also minimizing the amount of catalyst required (they are very expensive).
A three-way catalytic converter: Note the two separate catalysts.
There are two main types of structures used in catalytic converters -- honeycomb and ceramic beads. Most cars today use a honeycomb structure.
Ceramic honeycomb catalyst structure
The Reduction Catalyst
The reduction catalyst is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce the NOx emissions. When an NO or NO2 molecule contacts the catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the form of O2. The nitrogen atoms bond with other nitrogen atoms that are also stuck to the catalyst, forming N2. For example:
2NO => N2 + O2 or 2NO2 => N2 + 2O2
The Oxidization Catalyst
The oxidation catalyst is the second stage of the catalytic converter. It reduces the unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over a platinum and palladium catalyst. This catalyst aids the reaction of the CO and hydrocarbons with the remaining oxygen in the exhaust gas. For example:
2CO + O2 => 2CO2
But where did this oxygen come from?
The Control System
The third stage is a control system that monitors the exhaust stream, and uses this information to control the fuel injection system. There is an oxygen sensor mounted upstream of the catalytic converter, meaning it is closer to the engine than the converter is. This sensor tells the engine computer how much oxygen is in the exhaust. The engine computer can increase or decrease the amount of oxygen in the exhaust by adjusting the air-to-fuel ratio. This control scheme allows the engine computer to make sure that the engine is running at close to the stoichiometric point, and also to make sure that there is enough oxygen in the exhaust to allow the oxidization catalyst to burn the unburned hydrocarbons and CO. Many newer systems will utilize a second oxygen sensor in the converter itself, to monitor the oxygen provided by the first stages output.
Flames, are a clear indication of unburned Hydrocarbons which will fail sniffer tests.
And StealthTL ... the "coating" does not wear off. Only over or underheating a cat converter can distroy the coating. Current Cat converters will last the life of the car if they don't get too clogged with other metals or fried by an improper mixture (and even fried- the honeycomb melts down. The rare earth metals that comprise the honeycomb do not wear off.
Last edited by Icemark; 07-20-2007 at 12:09 AM.
thats the point.
07-29-2007, 02:22 PM
#41
I refuse to have a country that produces 50% of its electric energy by burning COAL tell me about emissions... Here's a choice quote: "America's traditional coal-powered plants pump 2.3 billion tons of carbon dioxide into the air each year — twice the amount cars produce."
And then a little closer to home you have all the "off road only" construction equiptment and other heavy machinery that not only don't have to comply with any emmisions standards they don't have to use the low sulfer diesel. And on top of that there are no emissions requirements for most types of pro racing series like NASCAR or CORR off-road truck racing.
I'll worry about the emissions out of my single automobile when those that produce the most noxious gasses worry about theirs. Cars are such a small piece of the pie that its obsurd how much of the attention they get as compared to the heavy polluters.
EDIT: and to illustrate my point this is on the front page of my newspaper today:
Originally Posted by nwitimes
The Issue with BP
A new permit allows the refinery to release 54 percent more ammonia and 35 percent more total suspended solids into the lake (Lake Michigan) daily, which means it could send an average 1,584 pounds of ammonia and 4925 pounds of total suspended solids a day into the lake.
A new permit allows the refinery to release 54 percent more ammonia and 35 percent more total suspended solids into the lake (Lake Michigan) daily, which means it could send an average 1,584 pounds of ammonia and 4925 pounds of total suspended solids a day into the lake.
Last edited by mac11; 07-29-2007 at 02:37 PM.
07-29-2007, 03:04 PM
#42
Metatron
iTrader: (1)
Thanks, Icemark, for your imaginative, yet erroneous, take on how three-way catalysts work.
That's why real engineers don't rely on Wiki or that kids site - "How-Stuff-Works".
According to Johnson-Mathey and DCL (they invented the TWC) they are not seperate beds, they are designed (and work just fine) as one bed. The only reason to have two would be to measure efficiency part way through the bed.
Obviously at full throttle the gas velocity through the (now much shorter) passages can overwhelm the ability of the cat to work properly, that would be why flames shoot out my ***-end.
As for the sound, I find it just perfect - for the last month I've had my resonated race-pipe on, but it's loud, obnoxious and annoying. The hi-flo cat is a lot quieter at cruising throttle positions on the highway.
The race-pipe is loud ALL the time, I hate to be alongside someone and add a TINY bit more throttle, only to have the exhaust note go from "buurrr...." to "BWWAAAAA!"......not Stealthy at all.
The straight pipe experiment was to see if there would be a noticeable performance difference between the three different pipes, but I certainly don't feel anything - even from full cat to empty. My only conclusion was that I couldn't live with the straight pipe.
I would write up a DIY, but truthfully, any way you choose to do it would be better than how I did it (with a ground-down dental mirror and some bent stainless rods, through the secondary O2 port.) I fracked up the threads and made a general mess. I think "old-dragger" had a better method, via the outlet.
S
That's why real engineers don't rely on Wiki or that kids site - "How-Stuff-Works".
According to Johnson-Mathey and DCL (they invented the TWC) they are not seperate beds, they are designed (and work just fine) as one bed. The only reason to have two would be to measure efficiency part way through the bed.
Obviously at full throttle the gas velocity through the (now much shorter) passages can overwhelm the ability of the cat to work properly, that would be why flames shoot out my ***-end.
As for the sound, I find it just perfect - for the last month I've had my resonated race-pipe on, but it's loud, obnoxious and annoying. The hi-flo cat is a lot quieter at cruising throttle positions on the highway.
The race-pipe is loud ALL the time, I hate to be alongside someone and add a TINY bit more throttle, only to have the exhaust note go from "buurrr...." to "BWWAAAAA!"......not Stealthy at all.
The straight pipe experiment was to see if there would be a noticeable performance difference between the three different pipes, but I certainly don't feel anything - even from full cat to empty. My only conclusion was that I couldn't live with the straight pipe.
I would write up a DIY, but truthfully, any way you choose to do it would be better than how I did it (with a ground-down dental mirror and some bent stainless rods, through the secondary O2 port.) I fracked up the threads and made a general mess. I think "old-dragger" had a better method, via the outlet.
S
08-08-2007, 02:42 PM
#43
Stealth
I really want to do this! Working through the 02 hole, Did you have enough angle to punch all the way through the 7" portion of the rear cat? Besides cat material was there any steelwool material? I have gutted other cats(mostly nissan) and found steelwool rings around both ends of the cat material.
I really want to do this! Working through the 02 hole, Did you have enough angle to punch all the way through the 7" portion of the rear cat? Besides cat material was there any steelwool material? I have gutted other cats(mostly nissan) and found steelwool rings around both ends of the cat material.
08-08-2007, 02:51 PM
#44
Metatron
iTrader: (1)
I used curved stainless barstock and a hammer.
The packing was ceramic fibre, didn't put up too much fight.....
Once I had a small hole thru to the back I was able to stand it up so material fell thru the resonator and out.
I chewed up the sensor threads pretty good, had to 'chase' the threads to clean 'em up.
Not rocket science, more like orthoscopic surgery!
S
The packing was ceramic fibre, didn't put up too much fight.....
Once I had a small hole thru to the back I was able to stand it up so material fell thru the resonator and out.
I chewed up the sensor threads pretty good, had to 'chase' the threads to clean 'em up.
Not rocket science, more like orthoscopic surgery!
S
08-30-2007, 09:02 PM
#46
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For those of you who tried this: how long on average did it take you? My 8 is my daily, so I can't afford to go 3 days without it. I'm wondering if this is feasible in a few hours' work?
08-30-2007, 10:23 PM
#49
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Ya know..., you guys can chalk up $500 for a MazdaSpeed exhaust. I have one, and god damned, it makes Rena purr. I've seen many RX8s around town, but none sound as good as Rena. It has an authentic rumble to it, unlike cheap "custom jobs" that any fool can tell from afar that you did it in your garage.
Last edited by dothackRAVE; 08-30-2007 at 10:26 PM.