Need Advise on Cats

[Jagdpanzer]

Like a few of you guys I'm about ready to install a set of headers and performance exhaust system on my Z. However, in my case I'm still looking for the right cats to go with. On this forum I read where a lot of you have gone with Random Tech bullet cats. Here are a few questions I hope those of you with more experience can help me with:
What advantages do the RT bullet cats have over the others available?
Which particular RT model and size is best to use?
Which core type is better, ceramic or metal matrix?
Should some sort of flange connection be installed between header discharge and the cats or should everything be welded solid like Nick did? http://www.pnwzr1.net/Nick/Headers/Headers%20049.JPG (http://www.pnwzr1.net/Nick/Headers/Headers%20049.JPG)
Is heat insulation or shielding of the cat necessary?
Where is a good place to buy RT bullet cats?
Are there any other cat manufactures out there I should be also taking a look at?
Pics would be most appreciated
Thanks

[Jeffvette]

DO NOT WELD THEM IN!!! It makes for a huge headache when you need to remove the exhaust later on. Find a competent exhaust shop that can give you some flanges.

Take a look at the magnaflow cats. Cheaper than the RT cats, and they are the same thing. You can hold each in your hand and you can not tell the difference other than the name stamping.

[GrayZ]

I have RT'S but if i would have seen these below first, well...i dunno
meow

http://i76.photobucket.com/albums/j9/kmoudy/pod-1.jpg

[DMark]

..... Take a look at the magnaflow cats. Cheaper than the RT cats, and they are the same thing.....
Hey Jeff,

Would you happen to know the Magnaflow part # that would work with SW headers?

Thanks,

[tf95ZR1]

You can get them from a place like Summitt or Jegs.
Just name your diameter in and diameter out.
ie 3 in / 3 in

[kenthompson]

I have RT'S but if i would have seen these below first, well...i dunno
meow

http://i76.photobucket.com/albums/j9/kmoudy/pod-1.jpg

I can see where heat is going to be an issue. I hope the inlet/outlet size is appropriate. Do you think the noise issue will go away?:iamwithst

[tccrab]

I can see where heat is going to be an issue. I hope the inlet/outlet size is appropriate. Do you think the noise issue will go away?:iamwithst

Sorry, those Cats will cause you nothing but trouble. If they ever need replacing it will cost you a fortune!
:mrgreen::dancing

[Nick]

I don't mind the CATs being welded in. IF I ever need to drop the trans, I'll deal with the issue at that time (probably by removing the headers, which ain't all that bad a job; certainly no where near the hassle of removing the stock manifolds!). Having the CATS welded in beats having to replace leaky and noisy exhaust header collector gaskets every oil change, like I used to do on my '55 Bel Air when it had headers. :rolleyes:

[tf95ZR1]

Hey Nick
Flanges probably would be the neatest, but are they necessary?
My cats are slip fitted and clamped. They haven't loosened but
the day ain't over yet.......
:)
If there was a problem with loosening I'd just tack weld them in a
few spots. Easy to grind down for removal.
Ted

[Nick]

Ted, I think the slip fit with clamps is fine. A few small tack welds would be awesome, and certainly not permanent like mine.

[Aurora40]

My impression is the metal matrix cats flow better than traditional ceramic ones? I'd guess they aren't as efficient though, or manufacturers would be using them instead of ceramic ones.

Mine do not have any heat-shielding. They are slip-fit on the headers and flanged to the exhaust. Marc H. did the work.

I don't know how they fair in VA's emissions test as I have not yet had to go with this configuration. Will you be retaining AIR and EGR?

[Jagdpanzer]

Will you be retaining AIR and EGR?

The SW headers I have do not have the air tubes installed so I guess I will have to do the same thing most others have done, reduce the weight of the car.

[Hammer]

I think I read about these here before. Anyone tried them?
http://www.performance-curve.com/index.asp?PageAction=VIEWPROD&ProdID=1181

[Nick]

I think I read about these here before. Anyone tried them?
http://www.performance-curve.com/index.asp?PageAction=VIEWPROD&ProdID=1181
Never seen those before, John, but the price is right! :thumbsup:

[HAWAIIZR-1]

I think I read about these here before. Anyone tried them?
http://www.performance-curve.com/index.asp?PageAction=VIEWPROD&ProdID=1181

I bought a set but have not installed them yet. I'll comment when I get them on, but will won't be this month. I hope it's not get what you pay for, but I'm on a tight budget so oh well.

[Hammer]

I bought a set but have not installed them yet. I'll comment when I get them on, but will won't be this month. I hope it's not get what you pay for, but I'm on a tight budget so oh well.

Craig,

I look forward to hearing about these. Great cost savings if they work.

Thanks

[guinnessdood]

My impression is the metal matrix cats flow better than traditional ceramic ones? I'd guess they aren't as efficient though, or manufacturers would be using them instead of ceramic ones.

Mine do not have any heat-shielding. They are slip-fit on the headers and flanged to the exhaust. Marc H. did the work.

I don't know how they fair in VA's emissions test as I have not yet had to go with this configuration. Will you be retaining AIR and EGR?

I would say the manufacturers use ceramic because they are cheaper...

Here's a word of experience about ceramic substrate cats...I had them in my car...notice the key word...HAD. My PROM (a Z-Industries PROM) was installed at the same time that I installed the headers/cats/Corsa. After about 2 weeks...i was driving the car at lunch time (driving on the base...so no hot rodding) and one of the cats caught on fire. I was able to put the fire out with minimal damage to the car. When we put the car up on the lift and removed the flanges from the headers...we could see that the ceramic substrate had completely melted in both cats and shelled out the cats. The cats were completely destroyed. I sent the PROM to Corey henderson and he analyzed it and said it was no wonder the cats caught fire considering how rich my PROM was allowing my car to run. He recalibrated my PROM with the same settings as Ron Hanselmans (or really close to that)...I replaced the cats with 3" I/O Random Tech metallic substrate cats and have not had a problem since. That was 3 years ago. So...buy metallic substrate cats...AND get a PROM from someone who knows the LT5 intimately.

My cats have custom heat shields and the exhaust installation was done by a true meticulous professional. Very nice work...but he lives here in Utah...

[Hammer]

Uly,

The description on the website is below. Wondering how they might compare with yours. The description says metallic, that why I was inquiring about them.

Thunderbolt cat's are designed to give high performance in limited spaces. This high flow converter features a Metallic brick with 300 holes per square inch. This 100% EPA legal OBDII catalytic converter is designed for engine's up to 5.9L / 6000 lbs. (Not for use in California)

Part # - 415300
Length - 11"
Body - 4" Round
Inlet - 3"
Outlet - 3"
Brick Type - Metallic
Material - 409 Stainless Steel

[Aurora40]

Hey Uly, I'm not sure that's a failing of the cat? The better the cat is, the more heat it will generate. That's what they do, turn excess fuel into heat. I would guess your "tune" was extremely rich, right?

I don't think a metal-based honeycomb matrix would be less likely to melt than a ceramic one, though. And OEM cats are not cheap. If there was something that worked better and allowed new cars to make more power while meeting the strict emissions requirements, you can bet they'd jump on it. On our cars, new car emissions regs are irrelevant. So more power is enough from metallic substrate cats.

RT's website describes metal matrix cats as such:
Random Technololgy also offers metal matrix catalytic converters designed for maximum flow capacity. These high flow converters are designed specifically for use in sanctioned race classes that require the use of catalytic converters.

[guinnessdood]

All I'm saying is that the combination of the ceramic and lousy PROM were not good...I also believe that the metallic cats will "flow" better..based on what RT uses...why would they use metal if ceramic flowed better? They wouldn't. I'm not really too sure why car manufacturers use ceramic or even if they are ALL still using ceramic as their substrate of choice...anyone know if the new ZR1 uses ceramic or metallic substrate cats?

I know there are other cheaper cats that seem to be quite similar to the RTs and I have seen some folks on here say they used them and they worked fine. I would say that they are very similar to the RT cats (the Thunderbolts), but I have no experience with them. I definitely like the price better than the RT cats! I bought mine from Martel Brothers if I recall. What the hell...if you're in need of some cats...for the price I'd try them...if they suck...you're not really out much...and if they work good...WOOHOO!!!

[HAWAIIZR-1]

Craig,

I look forward to hearing about these. Great cost savings if they work.

Thanks

John,

I won't have anything to compare them to other than the install. I'm going to slip them over the headers and use clamps initially as recommended by Jeff and others with hope of no leaks. I'm sure there is a benefit of getting the high quality RTs as I have used on all my other cars, but I thought I would give these a whirl since I can't imagine feeling or seeing the difference. They look high quality on the outside, but I don't know the technical differences on the inside. I decided to do all my mods at once so therefore the delay.

[Aurora40]

I also believe that the metallic cats will "flow" better..based on what RT uses...why would they use metal if ceramic flowed better?
I believe that too. In fact, it's the first sentence in the first time you quoted me. :)

What I doubt is that they both flow better, and catalyze better. Otherwise OEMs would use them.

As to your PROM, there is a good chance it would have killed any catalytic convertor. If it was rich, and the cat had air, it will turn all that extra fuel the PROM was dumping into heat. That heat will superheat the catalytic convertor until it eventually is destroyed. Running rich will kill just about any cat, and could be a pretty big fire hazard too. :cheers:

[Hammer]

John,

I won't have anything to compare them to other than the install. I'm going to slip them over the headers and use clamps initially as recommended by Jeff and others with hope of no leaks. I'm sure there is a benefit of getting the high quality RTs as I have used on all my other cars, but I thought I would give these a whirl since I can't imagine feeling or seeing the difference. They look high quality on the outside, but I don't know the technical differences on the inside. I decided to do all my mods at once so therefore the delay.

I helped Demps install new headers on his blue car and we used a bit of anti-seize. he mentioned it helped seal things up. Keep it away from the O2 sensors or anything that might allow it to get on them. We used a real light coating on the gaskets. I guess it could burn off and mees the sensors up. Once again, looking forward to your post(s) on how they work.