That is some serious BS, I would have some serious problems with that company. Hopefully you can get the problem fixed and I might be down for one of those puppies :)

There is no way he would get those metalic cat's for 100 bucks or so. They are expensive at this time, but eventually the price will go down.

I am going to ask a specific question... How much better will a 3" metallic cat flow better than 3" ceramic "high" flow cat? Does anyone have a percentage factor showing the flow? I am running a DP, Stock cat, and a RB duel tip.

I asked for these figured when I built my metal substrate cat. Dynatech told me that the highest flowing ceramic cat flowed almost 400 cfm. They didn't specify other parameters of the test. Their Powercore metal cat flowed almost 500 cfm.

I can say that the difference between the Powercore and stock cat is unbelievable. You better have a boost controller because you will defnitely need it.

Sonny

My Random Tech metal substrate cat arrived this week. It's certainly small - called a 5" and installed on 3" pipe! Nice construction - all stainless including flanges and bolt kit.

So yesterday I went out and made some sound level measurements of my current setup - stainless downpipe, midpipe, HKS Superdragger. Idle at 85 dBA (c weighted), at 100 km/hr in 5th (just under 3k RPM) 95 dBA. Measurements taken at ear level inside cabin (beside driver) and that's loud in my books! It resonates in the car just over 100 km/hr and on long trips that forces me to travel at 120 km/hr (about 75 mph) where the resonance is less of a problem. The car has the stock turbo setup and uses a PFC.

I'll get the new cat installed in a few days and let you know how loud it is after, and if I notice any power drop. Guess I should take some photos now while it's in the hatch area ;-).

Awesome, David...keep us posted! I find that there is very little difference between the stock main cat and the metal cat that I made, but I am pretty sure that my Greddy/Trust exhaust is quieter than yours. Some noise test numbers would be great.

Sonny

Some metallic cat info here:

http://www.autocats.com/html/motorsport.htm

I have a boost controller (ProfecB). I want more than the stock cat allows without getting too noisy or getting into boost creep. I had SEVERE boost creep with a midpipe. I think the Metallic Cat will provide a good compromise between noise / flow and should have enough backpressure to limit creep.
Mike

Pettit streetport
Huge intercooler
Pettit intake, DB
RB duel tip
Pettit ecu
Profec B
Stock main cat
99 Spec turbo's

300 RWHP at 11.5 PSI (90 degree day)

Test Results
 

Before with stock cat and electric airpump running on 9V
reading Allowed
HC ppm 475 132
CO% 3.34 0.73
NOx 127 945

just tested with this "ceramic" cat with no airpump
reading Allowed
HC ppm 412 132
CO% 1.88 0.73
NOx 133 945

NOTE: other mods since first test
MSD 6A on leading coil
Changed the timing split (I believe from 10 -> 15)
Dropped base fuel pressure to 38psi (before ~43)
Added a catch can (before intake would suck the fumes straight)

NEXT TEST: Metallic Cat with resonator and air pump. I believe just the air pump with lower the HC ppm with in turn lowers the CO%...maybe not enough to pass, but I've still got some tricks up my sleeve. I'm not sure how I will bring the HC ppm down enough without alcohol?!?!? I'm open for idea's...

Just for reference this is a home (13)bREW engine...self built (aggressive port), DIY single, self tuned Haltech.

The car has really waken up after the install of this cat!! Not sure what I was thinking running a single with the stocker...sure was quiet though.

it might, but I would still get the wastegate ported....my set-up is almost identical to yours and creep killed my last engine, all it takes it one time

Pettit will port your '99s if you ask them

Just for reference, the first two pics above are my pictures of the Random metallic cat. The third picture is a Dynatech (I think with the 3" reducers cut off, and welded into a larger midpipe, with a v-band flange facing us in the picture).

I think the difference in flow between ceramic and metallic cats of the same cross sectional area is due to the metallic cat needing less material, and thus taking up less of the cross-sectional area with the structure of the substrate. For instance, if the structure of the substrate takes up 25% of the flow area with a metallic construction and 40% with ceramic, there will be more open area for the exhaust to flow with the metallic construction. I just made those numbers up, and they are NOT specifications from manufacturers or anything, but I tried to come up with something that would be reasonably close to reality. They probably sound high, but look up the % blockage values for simple screening material (pegasusautoracing.com has this info for the meterials they sell, this is the stuff you might install in front of a radiator or oil cooler) and you'll probably be surprised how high they are.

Certainly you could make a ceramic cat with an equally large cross sectional area (when compared to 4" metallic cat) that would have the same amount of flow area, but there's probably a point at which the cat starts to not work because the substrate is too big to get hot. The metallic cats should have an advantage here, too, since the metallic stucture conducts heat better and perhaps has less mass (or not?) to heat up.

-Max

I havent contacted these guys yet but do you think it is even possible for this one to be a real metallic cat at half the price of most places?
http://www.performancepeddler.com/de...T_ID=THU415250

That is the same exact cat I was using.

Did you notice the fine print at the bottom of that page?

"Disclaimer: The images below and descriptions below may not be the actual product image and/or correct descriptions for the product. Our manufacturers are always updating their products and we are not always notified."

We've tested 4" dia. metal substrate cats on 3rd gens - they plug due to overheating. I'm now trying the Random 5" dia. So far so good, but I've only had it in for a week. It does hang down pretty low - as low as the front crossmember. I didn't notice any power loss compared to a mid-pipe. The car seems easier to drive, but that may be because it's quieter, therefore more pleasant. ;)

Are you sure it was the metal cat? I've had my 4" diameter Random metal cat on for 4-5 months now and it is still hanging in there running great. You might be melting the core if you have some flame-age on deceleration. Probably the biggest cause of clogged/melted cats is the flame-age on decel.

FLAMAGE RULES!!!!!!

no cats for me.....wheeeeeeee! :)

I had the RT HF cat installed inline at Sport Performance and have no complaints yet. The sound is a bit more tolerable at lower RPM's and the smell is cut by 80% easy. Hopefully some WB tuning to cut out some fuel will improve performance a bit, but the flow is still surprisingly good. I also had the WG plumbed into the DP. SP did a great job!

I will see about some dyno tuning over then next three weeks or so.

How does overheating cause plugging? What was doing the plugging? How long before plugging? Is this with or without air injection? How many cells per inch is the metal substrate? Is this tested on the street or track? Is there possibly a drop in FD metal cat replacement on the way? I'd like to hear anything else about your testing.

I bought the SMB (http://www.smb.net.au/fullsystemsmazdarx7.htm) cat and had Bryan at BNR supercars weld in a magna flow 5x8 oval muffler in just in front of the cat. He had to move the cat back to just before the flange but other than that it was a pretty quick install, just a few cuts and a few welds. It has worked great so far. I've got about 500 miles on it so far with no problems at all. The wife loves it now because my car is so quiet and doens't stink. I've been meaning to take some pictures of it but I haven't yet.
I'm also interested in the reasons for your plugging.

The car that had the problem went through two of the 4" units and they were the early metallic substrate cats, each lasted perhaps a month. It isn't my car, by the way. The car is set up with a Pettit ECU, I think running at 14 PSI, down-pipe, forget what cat-back. It's using the ASP large intercooler. Has been the fastest import in Edmonton last few years, until the owner got tired of repairing the damage caused by drag racing (blew an engine one year, next year exploded the diff - as in broke the housing, both while warming the tires). He decided he couldn't afford to race it anymore.

We've also been having trouble with RX-8s toasting the 4" metallic cats and have switched to 5" for them. We being Canzoomer. I do electronics work for my friends company from time to time.

I posted in another thread my noise measurements but I'll repeat here. First, my car has a PFC, stainless downpipe, had a mid-pipe, now the Random 5" cat, and an HKS Superdragger cat back, and runs at 12 PSI. I had a local performance muffler shop install the Random - they did an excellant job, and only charged me $80. The Random setup fit perfectly, comes in two pieces with a killer 3" stainless pipe clamp. The shop welded the two pieces together as it would seal better and be stronger, so I still have the "killer" 3" stainless pipe clamp. ;)

My noise readings were as follows, C weighted measured at drivers right ear:
Pre - cat - idle 85 dBA 100 km/hr (62 MPH) 95 dBA (too loud!!)
5" cat - idle 82 dBA 100 km/hr 92 dBA (still loud but better!)

That's a drop of 1/2 the noise power! I didn't notice any reduction in power, but the car is a lot more "fun" to drive. Maybe it has a little more low end torque, or maybe it's just more pleasant. Friends report they can't hear me coming any more until I'm 1/2 block away (instead of 2-3 blocks).

The cat is bolt in, comes all stainless, including bolts and flanges, and comes with the install kit (gaskets and bolts) for just under $490 US delivered in the US from Canzoomer. It also has a fitting for a wideband O2 installed so the sensor sits straight up between the trans and body (see in pic below). If you are interested e-mail Maurice at maurice@harddata.com. He can quote you on exact price and delivery. Here's a pic of the cat in the hatch waiting for installation.
https://www.rx7club.com/attachment.p...d=121202&stc=1
Because it's 5" diameter, it hangs down as low as the front cross member.

Random makes and recommends the 5" specifically for the RX8. It's on their web site. They found that the 5" generated less heat and better power than the 4" on the 8. For some reason, they didn't find the 5" make that much of a difference on the FD. Either that or the car is too old and limited numbers makes it less interesting to do R&D. As you stated, they had better results with the 5" cat on the RX8. I think they make a bolt on cat using the 5" also.

As for you going through 2 cats on that same 7, I suspect there might be an issue with the car? Either nice flamage on decel melting the core or the presence of oil or coolant in the exhaust coating the metal core and burning off melting the core under driving.

btw - Random has a some kind of warranty and will warranty the cat if it didn't fail due to the conditions above. Honestly, I don't think the EGTs are high enough to melt the core w/o the above stated conditions existing.

I just remembered the comment he (owner of car) made - friends following at night reported the exhaust was glowing red and sparks were coming out the back. I don't think there is anything wrong with the car, as it's still running fine a year later. It may be related to the Pettit ECU or the 14 PSI he runs, but I just don't know. I do think my car with the 5" should be fine. The cat works great - no more watery eyes when standing behind the car! ;)

I agree! Hope you enjoy it as much I have been. Best mod I've done since the Profec B on my last 7! :D

if the 4" plugs up that fast why would the 5" last much longer? perhaps a year at most with hard driving?

these cars crank out alot more heat than an RX-8, esp at high boost