: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:

: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:

breaking the law, you evildoer!!!!

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

how would it still pass emissions if you knock out all the catalytic elements?

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.

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.

and will save you money on the long run as well from having to pay off smog people or what not.

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.

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")

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")

If you remove all the material you have a midpipe, it'll trigger CELs, and won't pass emissions (and probable give more power too) but to have it that way it's better a normal midpipe because of the chamber shape.

Has anyone else tried this?

Has anyone else tried this?

I'm wondering the same thing as well..

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?

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.

Its not like theres any real power in dicking with emissions stuff

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. Freeing up a little more power theoretically would result in better gas mileage. Something we would all like.

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?

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.

:lol:

sosonic the area that gets pulled is not able to be seen without using a fiber optic camera.

Anyone have one? :D:

:lol:

sosonic the area that gets pulled is not able to be seen without using a fiber optic camera.

Anyone have one? :D:

that reminds me... does anyone here have a borescope??

MM?

that would solve that pesky last set of ports not opening ?

beers :beer:

emmisions?? it seems like a big issue in CA

Heh. I may do this when I take a trip back home to SC soon.

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.

Anyone have a source for this, besides someone's opinions? How about emssions test before/after the mod, with the engine under heavy load? Personally I think it's ridiculous to assume that 3/4 of the catalyst is redundant. Different amounts of catalyst surface will be needed depending on conditions. Just because the sensor is at the 1/4 position does not mean that the rear 3/4 is not doing a job until all of the first section is completely consumed. Sure, there's bound to be some margin built-in but I certainly would not assume that the effective zone of the cat is in a narrow band or even in a plane.

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

that reminds me... does anyone here have a borescope??

MM?

that would solve that pesky last set of ports not opening ?

beers :beer:

A borescope!!!!.....just what everyone has in their toolbox.....if you work on acft. engines.....pretty pricey for most back-yard mechs

A borescope!!!!.....just what everyone has in their toolbox.....if you work on acft. engines.....pretty pricey for most back-yard mechs

A borescope? Yeah I have 6 but wait that's because I work for Honeywell lol!

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.

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.

i think they would have no clue,, and if the cat made it back to mazda. it would never be checked..

beers :beer:

i think they would have no clue,, and if the cat made it back to mazda. it would never be checked..

beers :beer:

Unless Mazda was reading this thread and realized that some people may have performed this... :dunno:

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/catalytic-converter-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/catalytic-converter-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.

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.

How would our car sound like with half the cat missing?

any pics or better detailed instructions on how to do this? Does it also increase performance?

Does it also increase performance?

:uhh: thats the point.:icon_no2:

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."


I agree with this completely. And on top of that think about all the manufacturing facilities that belch out all kinds of nastyness everyday and would rather pay the EPA fines than comply with the regulations because it is cheaper for them that way.

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:

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.

The lake (Lake Michigan) is used for a drinking water source for a few million people in this area.

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:

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?

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.

wow is it really a 50 pound difference? Def worth going aftermarket if that's the case.

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.

fyi- stock cat/midpipe is 28.3 lbs... so i doubt I can save 50 lbs... prob more like 5-10.

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.

Are you talking about the CAT-BACK mazdaspeed exhaust? Because that actually has nothing to do with what people in this thread are doing. They're talking about (partially) gutting the cat, which is before the part the mazdaspeed replaces.

Are you talking about the CAT-BACK mazdaspeed exhaust? Because that actually has nothing to do with what people in this thread are doing. They're talking about (partially) gutting the cat, which is before the part the mazdaspeed replaces.

Oh. I thought they were talking about taking out the "bulged parts" and gutting them.

Oh. I thought they were talking about taking out the "bulged parts" and gutting them.

:lol2:

Don't you be touching my bulged parts...

Seriously though, this thread is about gutting the catalytic converter, which is under the car (yes, a bulged part... close to your transmission and what provides the cup warming effect)... It also happens to be the single most restrictive piece of the exhaust system, hence removing / gutting.

By the way, I seem to remember that the two parts of the cat actually clean the exhaust of two different gases, but for the life of me I can't remember where I read that.

Well, thinking about it:

7" of consumable catalyst, and 3" of safety catalyst.

I'm guessing you're gutting it for a little extra horsepower (if not for acoustic purposes). So you mean..., the longer I drive this thing, the more power I get...? That honestly sounds farfetched.

Why is why I thought you guys should just get a MazdaSpeed exhaust.

what the hell do you mean the longer you drive this thing the more power you will get? where did that come from?

And I am going to assume this is your first rotary vehicle? They run quite a bit louder than piston motors naturally so you can really tell Mazda used a very baffled muffler and cat from the factory to get the car as quiet as it is. With as much as the cat itself quiets down the car there is a good amount of restriction in that piece. You will see the biggest improvement in power by replacing the cat as compared to a cat back exhaust, header, intake, u/d pullies, etc.

anyway- I'm probably going to tackle this project tomorrow and see what kind of gains I can get. I figure if I REALLY screw something up, I can always buy a supercat like I was originally planning. I'll take pictures for everyone's enjoyment... maybe do a little DIY :-)

So, this is my first Rotary engine. I have been perusing the posts for about 2 months now to find out what kinds of mods i can do to get more audio/visual flare out of my car for little money (gotta love military salary). This seems like a good candidate as it sound fairly cheap and effective.

Question though: the flames, when do you start to see flames coming out...and is that only with an aftermarket muffler, i am thinking about making a custom exhaust come out the center, would this cat mod make a single exhaust too hot?

Nope, I've gotten flames with a completely stock exhaust. The most effective way of producing them though is getting a hi-flow cat or midpipe. The stock muffler isn't too restrictive.

Will give it a try this long weekend. PRAYING everything goes OK!!!!!!!!!!!!

Wifes already seen me putting car on jackstands. "Now what-ya doing to your car??:banghead:


:lol2: :lol2: :lol2:

Silver- I'm doing mine tomorrow... if you get to yours beforehand, or if you're near your computer, please post your progress and any tips you may have!

: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:

Right, I'm new to all this cat stuff. Can someone point out to me what we're doing?
From what I get you take a 5ft 1/4 inch threaded rod mark it, then hammer it into the _______ on the cat?

How deep do you need to go when your braking up the ceramic? 9"?

Shaking out the pipe to clear it. What pip? the one I'm useing to brak up the ceramic?

About how much time will this take?

Thank you

Right, I'm new to all this cat stuff. Can someone point out to me what we're doing?
From what I get you take a 5ft 1/4 inch threaded rod mark it, then hammer it into the _______ on the cat?

How deep do you need to go when your braking up the ceramic? 9"?

no further than the end of the rear brick of ceramic. or no further than the opening for the 02 sensor.

Shaking out the pipe to clear it. What pipe? the one I'm useing to brak up the ceramic?

the piece of pipe the catalytic is welded too. If you unbolt the section of pipe the cat is on and look at it the directions will make complete sense.

About how much time will this take?

hour. maybe 2. did this on an old car.


Thank you
you're welcome.

I'm getting sick of you real quick.













Thats just too quick lol thanks!

what?

That was sarcasm ;)

Can you point out the part that we are hammer into? please.
1. Front of car is to the left
http://img508.imageshack.us/img508/867/p9010930fr8.jpg
2. Mid
http://img508.imageshack.us/img508/5617/p9010931kd3.jpg
3. Rear
http://img410.imageshack.us/img410/1880/p9010932mr3.jpg
Thanks

First you have to take it out, and stand it upright, "front" part up.

The first pic shows the O2 sensor , this is the hole I used. Rods curved towards the back, smashed the ceramic substrate, the pieces fall out thru the resonator (pics 2 and 3)

Olddragger went in thru the resonator, with a carefully measured rods.

The piece of catalyst that must remain is in "front" of the O2 sensor space.

S

Will give it a try this long weekend. PRAYING everything goes OK!!!!!!!!!!!!

Wifes already seen me putting car on jackstands. "Now what-ya doing to your car??:banghead:


:lol2: :lol2: :lol2:


^^^^I thought I was the only one to hear that!! :rolleyes:

First you have to take it out, and stand it upright, "front" part up.

The first pic shows the O2 sensor , this is the hole I used. Rods curved towards the back, smashed the ceramic substrate, the pieces fall out thru the resonator (pics 2 and 3)

Olddragger went in thru the resonator, with a carefully measured rods.

The piece of catalyst that must remain is in "front" of the O2 sensor space.

S

OK cool. So I should not start from this point right?
http://img407.imageshack.us/img407/600/dscf21542028large29tf2.jpg
and crap like this should fall out right?
http://img236.imageshack.us/img236/4918/image2818429ij5.jpg
Thanks

Absolutely not!

....of course, that would be WAY too easy!

Your cat should still look pristine like that when the job is finished, or you get a big fat FAIL!

Yes, the pieces will look like that. If you work thru the resonator, be SURE that stuff doesn't get rammed into that first bed.

S

Absolutely not!

....of course, that would be WAY too easy!

Your cat should still look pristine like that when the job is finished, or you get a big fat FAIL!

Yes, the pieces will look like that. If you work thru the resonator, be SURE that stuff doesn't get rammed into that first bed.

S

Right but I'm not and you said to take it off so my next question is; Can I use something to drill it out vs ramming it? wont that compromise the front ceramic structure?
Thanks

I'm not proud of the technique I used, almost ANY other method would be easier/work better/faster.

You aren't trying to do it all from that position, are you?

S

No I hear you but, what I'm asking is;
If I take my cat off and do what you said;"First you have to take it out, and stand it upright, "front" part up." then I should be ok drilling out from the back of the cat starting with the part that is facing the back of the car right?

That make sense?

I mean can just drill the end out useing a drill bit on my black and decker and start drilling from the back of the cat up to the front where the O2 sensor is right? but dont pass the O2 sensor right?

**Thanks STL thats what I was looking for**

Started mine. Tight exhaust bolts is an understatement! After checking it out, DAM the 02 sensor hole is small! After about an hour of crunching from the 02 hole. Still unable to reach the rear portion of cat material, I did'nt have a long bar handy. Found my dewy gun cleanning rod would work. Will start later this afternoon when its cooler and start working it from both ends.

***For you people who already done this mod. Theres no way all the rear 9" portion of the cat can be cleanned up entirely(Clean). You're just doing this mod to increase flow. Right? Or is there more to this mod?***

No I hear you but, what I'm asking is;
If I take my cat off and do what you said;"First you have to take it out, and stand it upright, "front" part up." then I should be ok drilling out from the back of the cat starting with the part that is facing the back of the car right?

That make sense?

I mean can just drill the end out useing a drill bit on my black and decker and start drilling from the back of the cat up to the front where the O2 sensor is right? but dont pass the O2 sensor right?

**Thanks STL thats what I was looking for**


No, its not that easy! Craw under your car and check it out. From the rear end the rod has to snake through the resanator to reach the rear portion of the cat.

***THIS IS NOT AN EASY JOB!!!***

Thanks but STL beat you to it ;)
See pic
http://img409.imageshack.us/img409/5402/vecchio20catef1.jpg

It will all come out clean, the ceramic is held in place by fibre around the edge, once it's broken up, the fibre falls out too.

Silverguy is right, don't start this unless you have a couple of days free......

As projects go, this rates up there as

".....fuck - this IS impossible!"

or

"Jeebers, I wish I'd never STARTED this shit!"

You should also have the right size (metric) thread-tap on hand to clean up the sensor hole, because you WILL smash the threads.

S

^Yup and thats why I was picking this apart. I want to know ex what the hell I'm doing befor I start. This way I know how long it will take me to do the job. This will have to wait till another time.
I thank you all for the great info and being patient with me. Now I just need some advil.

what the hell do you mean the longer you drive this thing the more power you will get? where did that come from?

It was a conclusion I drew from a few observations I made from your posts (your, as in forum users). I'm just wondering WHY you'd want to do this. Does it make the car go faster? Does it make it sound better?

If it makes it go faster, that means that the more catalyst you use (ie, the more you drive), the faster it goes. Sounds ridiculous to me.

Which brings me to another gain: audio. If you want better audio, get a MazdaSpeed exhaust.

And I am going to assume this is your first rotary vehicle? They run quite a bit louder than piston motors naturally so you can really tell Mazda used a very baffled muffler and cat from the factory to get the car as quiet as it is. With as much as the cat itself quiets down the car there is a good amount of restriction in that piece. You will see the biggest improvement in power by replacing the cat as compared to a cat back exhaust, header, intake, u/d pullies, etc.

Yes, its my first rotary. However, this concept of a "quiet" RX8 is completely alien to me, since I have a MazdaSpeed exhaust, and you can hear Rena coming before you ever see her. Not to mention that the purr of the rotary + MazdaSpeed exhaust is just so freakin orgasmic I see music in the stereo as an obstacle (hence I turn them off and just listen to the symphony that my right foot tells the engine to play. IT'S BEAUTIFUL!).

If it makes it go faster, that means that the more catalyst you use (ie, the more you drive), the faster it goes. Sounds ridiculous to me.


It sounds ridiculous cos it ain't so... During normal operation catalyst gets "burned through" (the chemicals are used up) but the solid stuff still stays to impede the exhaust flow. The point of this to remove this extra "stuff" that some people believe serves no purpose (I am still not convinced).

As for power gains, it will not be anything dramatic, but if any exhaust mod will yield power this one certainly will. Not sure how this would stack up against a high-flow cat, though...

Well I'm done:puke: All StealthTL stated above is TRUE! I was thinking what the fuck have I started! Could've been cruzing around or watching a movie. Cars all put together but its to late and I'm too dirty & tired to start or drive my car. Will report back tomorrow.

Estimated time to complete 29hrs with long breaks in between. My breaks were needed because two times I almost just wanted to punch-out the the whole cat material out from the front end which would have made this job a 1-2hr job.

***If you have the extra cash laying around dont do this mod, just buy a supercat or something. But if your short on cash or saving for something else(Like me:) ) maybe this mod maybe for you.****

I have really been thinking of doing this mod.... unfortunately, I lack the time AND patience to do this so... anybody wants to do it for me? :rolleyes:

Maybe at SSX.... just maybe...

Silver_Surfer, See thats why I was all questions on picking this apart for the ones like you and me that dont have 3-4, or more days time to complete this mod.
I was going to do it but after going over what has to be done; Time vs money, well money wins. I'll just buy a full exhaust system.

Well My breaks were needed because two times I almost just wanted to punch-out the the whole cat material out from the front end which would have made this job a 1-2hr job.

That's a good point, anyone done just that and turned it into a CATless midpipe w/giant resonator? It certainly looks like the OEM resonator may be more effective than the small diameter things on some midpipes. Wonder if it's enough to quiet it down (to 90db) when using a CAT back exhaust?

Results: No cell:) Revs alittle faster, butt dyno feels alittle better. I would say from the way people describe the gains are about the same as a AP underdrive pulley but with alittle more deeper sound(I like!) I 'm not going to dyno it but I would guess its about the same or on par as a A/M supercat.

If anyone is going to do this mod buy a 4ft section of springsteel rod(I used my expensive nylon coated dewey rifle cleanning rod:Eyecrazy: ) After stroking the rod back & fourth(Having sex with my cat with no climax:banghead: ) for awhile I came up with an idea. I bent the front 1.5in section to about 75-80 degrees, pushed the rod into the back of the cat, hooked the other end to my drill and "Roto-Rotered it. Made quicker work.

Silver_Surfer, See thats why I was all questions on picking this apart for the ones like you and me that dont have 3-4, or more days time to complete this mod.
I was going to do it but after going over what has to be done; Time vs money, well money wins. I'll just buy a full exhaust system.

Yeah, I hear you!
I striped one of the front exhaust studs taking the cat off. Was a bitch to change. I did save a bunch(Geico) of cash but would I do it again? I just dont know.

Well considering a supercat is about $400 new, it may be worth the trouble for someone who cannot devote unlimited funds to their car. For me it comes down to the fact that I have about $500 to spend on my next mod, and this way I can have a high-flow cat AND a nice cat-back.

PS- didn't get to it this weekend. Silver- did you take any pics?

Well considering a supercat is about $400 new, it may be worth the trouble for someone who cannot devote unlimited funds to their car. For me it comes down to the fact that I have about $500 to spend on my next mod, and this way I can have a high-flow cat AND a nice cat-back.

PS- didn't get to it this weekend. Silver- did you take any pics?

Sorry no pics. But pics really wont show anything except rods sticking out of the cat. One tool I used that really helped was a 3-4 ft stainless rod. I had it shaped into a straighten Z with one end sharpened to stab and pry at the cat material through the 02 hole. The other end(shorter was my handle. The pointed end of the rod had to keep being reshaped as working deeper into the cat untill reaching all the way through. At first I was only working from the 02 sensor hole but the shit had nowhere to go so I had to figure a way to make a hole all the way through so the stuff would fall through. Thats where the springsteel rod came in use.

Thanks man- I'll give it a go when I put my new catback on.

[QUOTE=Silver_Surfer;2038810]Results: No cell:) Revs alittle faster, butt dyno feels alittle better. I would say from the way people describe the gains are about the same as a AP underdrive pulley but with alittle more deeper sound(I like!) I 'm not going to dyno it but I would guess its about the same or on par as a A/M supercat.


***Update*** I just got finished installing my AP underdrive pulley. I had more gains with the cat mod than the AP underdrive pulley. Heck, felt little to no gains on the butt dyno. Wish someone could do a dyno test on both cats.

alright to be honest i have no idea what you guys are talking about????first of all can someone tell me where i can get info on how an exhaust works....and how it differs from a straight pipe, and how it differs from a hi-flow,and what exactly a midpipe does and what exactly is a muffler then???im still in the process of understanding fast cars, i wasnt really interested in how a car goes fast untill my friend got an evo8, then i startd to ask myself how does this work, so i have very little knowledge on how the exhaust systems work....can some fellow 8 drivers give me some helpful info, hints, and advice....

alright to be honest i have no idea what you guys are talking about????first of all can someone tell me where i can get info on how an exhaust works....and how it differs from a straight pipe, and how it differs from a hi-flow,and what exactly a midpipe does and what exactly is a muffler then???im still in the process of understanding fast cars, i was really interested in how a car goes fast untill my friend got an evo8, then i startd to ask myself how does this work, so i have very little knowledge on how the exhaust systems work....can some fellow 8 drivers give me some helpful info, hints, and advice....

Go slow and research! Dont do any mods/changes that cannot be reversed and you'll be OK.


And DONT DO THIS MOD!!!!!!!!!!!!!:)

so, exactly how much more power/better mileage am I gonna see if I fornicate the cat converter with an Iron rod, sorry if this is old but I'm a noob

so, exactly how much more power/better mileage am I gonna see if I fornicate the cat converter with an Iron rod, sorry if this is old but I'm a noob

To be honest. Very little!

it will come in handy also if you supercharge! it also helps the cat run cooler if you track your car.
olddragger

it will come in handy also if you supercharge! it also helps the cat run cooler if you track your car.
olddragger

True on the supercharger, but if you have that big a budget you might as well buy a high-flow unit and spare yourself the headache... or just get a midpipe...

If you do alot of tracking, a midpipe would be a good investment also, even if you only put it on for track days.

Not saying don't do it, just think of the options :)

already did it and i have a midpipe for the track----we think alike
OD

Mines goin bye-bye this weekend, hope I don't catch any flak at the shop here on post...


I kinda miss the muscle car...it was so much more straight-forward


Thanks for all the info guys

i plan on doin this tonight when i get off of work ... i hope to do it about four or five hours with the cut in two and weld back together method... any suggestions before i dive in ?

Using the chop-n-gouge method loses one of the advantages of this method - undetectability. The weld will be fairly obvious, unless you can get the heat shield off/replaced in good shape.

unless he cuts and rewelds on the original seam.

i live in iowa.... no emission testing what so ever ... i just want the no CEL otherwise i would just punch it or get a mid pipe

Y'all never cease to amaze me with the creative genius. I have nothing to offer but a NT style "Good Job!"

Carry on. :)

I believe someone alluded to this on the first page of the thread. I had the cat cut out behind the front flange and in front of the stock resonator. A straight pipe was the welded in w/o2 bung for future use. Only cost me $35 and the guy who did it said if I ever need the stock cat to bring it back and he'll weld it back in. The best part is the car sounds just like stock.

I'm thinking using an air hammer could make this a little easier. Anybody have trouble with doing this??

hi.

I did this and reinstalled, sounds good, drives good, but when it idles some whiteish smoke comes up into the engine bay. I think its some of the fiberglass packing. Should I worry or will it burn itself out?