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how to make oem cat into a high flow one
:bowdown: Thanks to Stealth for this finding!!! You rock dude :bowdown:
All that are interested please see the gutting your cat thread in this section. Stealth told us his finding and I am passing it on. The thread has this info and I will tell you how I got it done in a shorter period of time. That 9" of "extra cat material" can be removed from the rear by just obtaining a 5ft section of 1/4 inch threaded rod from Home Depo/Lowes and ramming it repeatively into it. This size rod is thin enough to go around the bends of the assembly but strong enough to break up the ceramic.. Be sure to mark the rod to the dept you need(you dont want to go into the front section of the cat) and dont go past it. The rod can be bent on the end to increase the area it cleans as you go. Wear a mask when you are doing this as when you are shaking out the pipe to clear it --it can get a little dusty and I wouldnt think you want to beathe that stuff into your lungs. Damn good find. olddragger :rofl: |
Originally Posted by olddragger
:bowdown: Thanks to Stealth for this finding!!! You rock dude :bowdown:
All that are interested please see the gutting your cat thread in this section. Stealth told us his finding and I am passing it on. The thread has this info and I will tell you how I got it done in a shorter period of time. That 9" of "extra cat material" can be removed from the rear by just obtaining a 5ft section of 1/4 inch threaded rod from Home Depo/Lowes and ramming it repeatively into it. This size rod is thin enough to go around the bends of the assembly but strong enough to break up the ceramic.. Be sure to mark the rod to the dept you need(you dont want to go into the front section of the cat) and dont go past it. The rod can be bent on the end to increase the area it cleans as you go. Wear a mask when you are doing this as when you are shaking brout the pipe to clear it --it can get a little dusty and I wouldnt think you want to beathe that stuff into your lungs. Damn good find. olddragger :rofl: beers :beer: |
I used to do this for my Hondas when I was like 16. I'd use a grinder, crow bar and a large hammer....and just smash away. Just make sure you guys wear eye protection and some sort of HEPA filtration mask. If you inhale the ceramic dust...it can get ugly.
Oh yeah, and make sure you don't let any tree-huggers see you doing this. I got "reported" once when I was younger. I had to explain to the local fuzz that it was a science experiment... OD, But wouldn't it be better just to have someone weld some flanges on a "test" pipe? That way, if you ever need to smog again you could just throw the CAT back on? |
but you see--it passes emissions this way also. That is one of the good things about this.
ditto on dont breath this stuff in. I can tell a little differance in the car:) Sounds a little deeper (i have the RB catback). olddragger |
+1 on testpipe
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how would it still pass emissions if you knock out all the catalytic elements?
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Yeah - this def wont pass emissions.
Why not just buy a $200 cat delete pipe, and put your OEM one back in for emission testing. Switching a cat pipe only takes about 30 min. |
Originally Posted by BigOLundh
Yeah - this def wont pass emissions.
Why not just buy a $200 cat delete pipe, and put your OEM one back in for emission testing. Switching a cat pipe only takes about 30 min. |
Cat Man Doo.....
You are missing the point, the catalyst is STILL in place, works 100%, and will pass any emissions check - even a visual or a disassembly by the dealer.
O.D. ain't nobody's fool...... S |
The difference is Georgia doesn't have a sniff test, California does.
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BigOLundh and toxin440, with this mod you aren't removing *all* the cat material, the cat has two "walls" (excuse my english) one 7'' and the other 3'', you are just removing the 7'' one so the 3'' still works (it's there for safety when the 7'' is consumed) or something like that and you PASS emissions.
I'm trying a resonated midpipe shortly, if it's get too loud for my taste I'm doing this. |
exactly correct --you still have cat material left. you are only removing the part that is past the last o2 sensor. So it should pass a sniff test.
This cleans up a lot of really unnecessary restriction in the oem cat. Therefore making it like a high performance one if not just like one. olddragger |
so... we all know how the 8 is mods...
but, im in FL. im not worries about getting tested for emmissions... how many hp do you think can be freed up this way. and how about with removing all of the material? (7" and 3") |
Originally Posted by silverwolf
so... we all know how the 8 is mods...
but, im in FL. im not worries about getting tested for emmissions... how many hp do you think can be freed up this way. and how about with removing all of the material? (7" and 3") |
Has anyone else tried this?
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Originally Posted by Mazda-Rati
Has anyone else tried this?
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Clarity......
To clear up some confusion here, this is the text of the original post O.D. is referring to -
I solved this problem for myself two years ago. While getting my car fitted for a wide-band O2 sensor, I noticed that the secondary sensor sits in a space between blocks of catalyst. A little probing with a dental mirror showed that the cat is made of a front "bed" about three inches deep, then the space, then a rear bed about nine inches deep. The principle is that the cat works from front to back, as the coating wears out, the reaction takes place deeper inside, until the sensor sees no difference in the gas between the first and second readings, at which time it lights the CEL for "failed cat". The only reason to have the second bed is so the car will still be OK to drive, even if you ignore the light for years. When only the first quarter of the cat is used up, the sensor will be on. So my answer was to remove the second catalyst bed, cutting 3/4 of the material out, while maintaining full functionality, 100% legality, pass any emissions check - including a visual. Even a dealer/mechanic could not detect any problem, unless he had x-ray eyes! Car sounds better, runs better, throws 'large' flames when prompted, and has been working like that since October 2004. The actual removal was not as easy as it sounds - the best way would be to attack the material from its outlet instead of inlet, but that is thru the resonator and around two good bends. That way proved impossible. I succeeded by chipping away thru the sensor hole. That is also much harder than it sounds, took three days - the hole is roughly the same size as a sparkplug hole! If I were to do it again, I would cut the assembly in two at the back of the cat body, allowing easy removal, then get my friendly stainless steel welder buddy to put it back together. S |
thanks Stealth--I should have done that on starting the thread--rather than saying "refer too".
I can verify my seat of the pants"runs better" and it does seem to pull stronger in the top end. again this is seat of the pants and an old butt setting in them. olddragger. |
Any pictures in progress?
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Originally Posted by LionZoo
The difference is Georgia doesn't have a sniff test,
..yet. Every month a new law goes into effect somewhere concerning emissions. Clean areas are getting dirtier air everyday, and with it comes the EPA clean air rules. Smog checks..mod like you have em to protect your investment for later. Its not like theres any real power in dicking with emissions stuff. |
Originally Posted by Speedtoys
Its not like theres any real power in dicking with emissions stuff Enthusiasts are looking to improve their cars tuning for more power. More power is gained by better tuning that more efficiently burns fuel which lowers emissions. Tuners are good for the environment ;) |
Wow this sounds like a great idea. Anyone up for making a DIY?
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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."
Emissions laws should govern production, mass-market cars, but there's no reason to dump on the automotive enthusiasts... How about this: all cars come with all the regular emission stuff, but allow people to remove it if they wish. I bet that 99% of people still would not do it, because it smells like shit... < / rant > That put aside, if this "mod" doesn't affect the emmissions performance, then I might think about it... Sounds like quite a hassle though... Here's a great idea - someone should take a supercat, one of these, and dyno to see the difference :-D (yes, I am just trying to get someone to do the work for me...) |
Pictures please.
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:lol:
sosonic the area that gets pulled is not able to be seen without using a fiber optic camera. Anyone have one? :D: |
Originally Posted by 4 years to Supercharge
:lol:
sosonic the area that gets pulled is not able to be seen without using a fiber optic camera. Anyone have one? :D: MM? that would solve that pesky last set of ports not opening ? beers :beer: |
emmisions?? it seems like a big issue in CA
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Heh. I may do this when I take a trip back home to SC soon.
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Originally Posted by musclecarconvrt
(Post 1753771)
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. |
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 |
Originally Posted by swoope
(Post 1784860)
that reminds me... does anyone here have a borescope??
MM? that would solve that pesky last set of ports not opening ? beers :beer: |
Originally Posted by spigot52
(Post 1974659)
A borescope!!!!.....just what everyone has in their toolbox.....if you work on acft. engines.....pretty pricey for most back-yard mechs
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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 ... |
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. |
Originally Posted by rotaryPilot
(Post 1975333)
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. beers :beer: |
Originally Posted by swoope
(Post 1977118)
i think they would have no clue,, and if the cat made it back to mazda. it would never be checked..
beers :beer: |
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: 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). http://static.howstuffworks.com/gif/...er-cutopen.jpg 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. http://static.howstuffworks.com/gif/...r-catalyst.jpg 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. |
How would our car sound like with half the cat missing?
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any pics or better detailed instructions on how to do this? Does it also increase performance?
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Originally Posted by rowteree
(Post 1991742)
Does it also increase performance?
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Originally Posted by CnnmnSchnpps
(Post 1781222)
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. |
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 ass-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 |
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 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 |
Thanks for the quick reply!:wavey:
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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?
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Of course, one advantage of going with an aftermarket cat as opposed to partially gutting the stock one is that the aftermarket one will be about 50 pounds lighter.
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wow is it really a 50 pound difference? Def worth going aftermarket if that's the case.
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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.
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fyi- stock cat/midpipe is 28.3 lbs... so i doubt I can save 50 lbs... prob more like 5-10.
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