David Beale

I'll have to check on what they finally did and get back to you, perhaps as late as tomorrow, as I only have the cat in my mid-pipe section (pics. were posted in another thread). I just called Maurice, but he's out right now. Again, if I were doing it again I would purchase this combo from Random - their welding is exquisite - it's a shame to bolt it under the car it's so pretty! Even the flanges are stainless!

neit_jnf

iTrader: (17)

I knew about this, I had emailed canzoomer about it before. The resonator is separate from the metallic cat midpipe and has to be welded to the catback section. Supposedly they couldn't make the cat and the resonator fit together in the midpipe

AgentSpeed

I haven't dyno'd mine since but if I'm able to make it to the next Kan tuning session, I'll through it on for a pull or two and see.

alberto_mg

You might want to consider the 5" diameter one that Random made for the RX8. Iirc, Random said it flowed a bit more. Random was actually very helpful in determining the appropriate size when I spoke with them. You might want to give them a call and try to get one of their techs on the line to discuss your power output and have them recommend something.

NuTbAgSaN

ive been looking at the smb for my fd, but today i realized this could be a solution to a problem of a friends 2nd gen as well. what we got is full exhaust, so i was thinking just have a metal sub cat put in with the system. ive been reading alot, and just want to clarify, do these pass emissions without the airpump. i can see they work well for a ton of people, but as far as the emission thing i havnt seen too much.

AgentSpeed

I have to pass this coming Feb. I hope it will pass, I've heard it will without the airpump.

alberto_mg

could be. all you need to do is weld it into the midpipe around where the old cat used to be.

there were about 3 people who have passed emissions with these metal cats. i think 1 was out in CA. try searching for those threads in the 3rd gen section.

David Beale

Regarding the 5" Random metallic cat I just installed.
One other thing I noticed on my trip to the coast. When I left, after about 1hr of running at 120 km/hr on cruise, I noticed the console was getting quite hot. Not hot enough to do anything bad, but hot to the touch (my arm noticed it!). I was a little worried, of course. It didn't trip the "exhaust overtemp lamp" - first thing I looked at when I noticed the temp. After a few hours it returned to normal "warm" temps. It never recurred on the trip.

After thinking about it for a few days (yeah, I'm slow), I suspect it was the cat burning off buildup that accumulated with a few weeks of driving in the city. Perhaps this is a warning that you could clog the cat if you don't burn it clean with a nice highway run once in a while. BTW, I don't have any heat shields on the thing that were originally on the stock cat - only heat shields left are the ones on the body. I may fabricate some.

reza

What is the bottom line?

Need or not the air pump connection to metallic catalytic converter?

Is the PFC base map stoich enough to not needing air pump?

alberto_mg

you do not need the airpump with a metal substrate cat.

check random technologies site for the facts on that.

M104-AMG

iTrader: (8)

Random Technology's facts are assuming you are running a DUAL closed-loop system that are not running rich.

As such, it is WRONG for rotaries.

Julien had it correct:
<SNIP>

Today's latest cars are using three-way converters without air injection by using the dual lambda feedback loops (o2 measurement upstream and down stream of cat's) with faster ECU processors to continually keep the engine running at a near lean mixture. These cats are the metal substrate cats that offer high flow rates, but it is the engine management system not the Cat itself that permits elimination of the air injection.

Guys, we want and NEED rich mixtures, thus for clean exhaust we Need air injection .. regardless of yesteryears Cat converter or 21st century Cat converter.

David Beale

No offense intended to anyone, but I'm not aware of any stock use of metal substrate cats. For example, the RX-8 uses a ceramic cat., even though it does have the dual O2 setup (one before and one after the cat). Ditto for my 2001 Pathfinder. Sooo, I'd say it's a guess whether you need the air pump or not. If you use the air pump, you may overheat the cat? If you do not use the airpump you may clog the cat?

My experience so far is the cat appears to build up deposits in open loop operation (as expected). In closed loop cruise control 120 km/hr driving, it appears to burn clean - and appears to clean itself out of previous buildup. Perhaps I need to install a wideband to see just what the exhaust looks like before the cat.

You don't NEED rich mixtures when running closed loop as you are not boosting (at least not above 0 PSI). You DO need rich mixtures in open loop.

What I AM sure of, is no one can say for sure one way or the other without more measurements and experience! I can also say for sure I'm happy with my 5" Random cat.

M104-AMG

iTrader: (8)

Porsche, Mercedes, and BMW use metallic cats in some of their production cars.

:-) neil

Julian

iTrader: (14)

plus at least the C5 C6 vettes and Ferrari

GoRacer

iTrader: (2)

I'm also in the process of making my own. I bought the mid pipe from rotary extreme and the cat from performance peddler, but it only shows 200cells. Damn, do I need the 500 cell version?
http://www.performancepeddler.com/im...etalcattxt.gif

neit_jnf

iTrader: (17)

more cells = more restrictive = cleaner exhaust

According to the guy at metallicsubsrate, a 200 cell core is 92% open area so the 4-inch core that I bought is supposed to flow the similar as a 3.68" diameter open pipe

reza

do we need richer mixture when using metallic cat with airpump?

GoRacer

iTrader: (2)

I could allways do two 200 cell cat's in a row instead of installing the Borla XR-1. Didn't someone reply that they talked to them and said we need the 500 cell version? ErRr?

alberto_mg

many of the metal cats being resold by major players such as random and dynatch are 300 cell

GoRacer

iTrader: (2)

I could allwys exchange it for one for my CRX or buy another three for my F150. I tried calling but they are east coast and it's after hours. If 200 cell is less dense, then ther may be a power advantage to do two in a row versus one 400 or 500 cell single even though it would cost twice as much.

GoRacer

iTrader: (2)

ok, just spoke with him: All their cat's are 4" OD core and the piping OD is what will vary in size. The one I have is a french company (according to him) ArvinMeritor. He also said all his cats are 300 cell, no matter what the retailer says. He only knows of one rotary specific retailer that uses his metalcat, which is rotary performance. What I may have to do is add the 300 cell in line and this would also put me in compliance with having a pre-cat. He doesn't think the 200 cell will be enough to pass smog. On RP's webiste they only list the Random Technologies main cat. I thought they carried a Bonez metal cat? Neither Random nor RP list the cat as metalic.

eyecandy

iTrader: (19)

Who did you speak with? Performance Peddler? I am looking for a good replacement cat that does not need the airpump. Do we know the cell count on the Stock cats, most importantly the main, but the precat would be cool to know as well.

I am sure since you would not be using the airpump you will need a higher cell count, I want to call a few places and see what I can find out. I will post my findings.

GoRacer

iTrader: (2)

^ no, I spoke with the metal substrate place. I also just spoke with the tech at random technologies. The bolt-on cat' they sell only comes in ceramic (w/air pump fitting). The do sell metalic race cats but universal only (part # 70300) for $239 and it's 9.5" long x 4" diameter core with 3" ID pipe (no air pump fitting). They are the metal substrate cats as far as I know and as stated above those are all 300 cell. I paid about $139 for the french 200 cell cat' from Performance peddler, so I may just do two of those instead of adding the random cat. I do have the air pump working but the pipe is blocked off. The air is going through the ACV (I beleive it's called) and through the exhaust ports only. That is one of the two ways it delivers air from the air pump. He also said the www.canzoomer.com might be making a bolt-on metalic cat for the RX7 in the future. I have no idea what the cell count for the pre and main OEM cats are but they are ceramic, so I don't think that would be a good comparison unless we know what an equivilant ratio would be.

David Beale

Here is a pic. of the setup Random did for me. It's in the hatch for size comparison. It fit perfectly. You can see the element pic that I inserted. To quote "cell numbers" with metallic cats is a little redundant, as they are made differently than ceramic ones. They impregnate a strip of stainless with rhodium and platinum, crimp it into a zig-zag, and wind it in a spiral. A cell quote would be just an estimate (though you could count them in my pic. if you like).

It's called a "super high flow cat". I didn't notice any difference when I replaced my mid-pipe with it, except perhaps a little more torque in the lower rev. range. I guess a little back pressure is good!

You can get this 5" metallic cat from Random through "Canzoomer".
E-mail maurice@harddata.com and he will quote you. It comes with an O2 bung for a wideband in case you want to tune. It also comes with the install kit. I forget what it costs, but it's not much over $300 US as I recall. The whole thing is stainless, including the flanges, and the supplied bolts and clamp are also stainless. I had a muffler shop install mine, and they welded it together instead of using the clamp, so I now have a super delux stainless 3" clamp.

From what others are saying, it seems if you want to add a resonator for less noise you may have to put it after the cat. section. My setup is a stainless downpipe, the stainless cat, and an HKS Superdragger cat back, also all stainless. The cat back has 4" pipe from the cat flange to the canister muffler, so adding a resonator would take a little engineering. For me, it's still a little loud (I had a mid-pipe and it was so loud it fatigued me on long trips), but I think I can live with it now.

GoRacer

iTrader: (2)

^ kit = mid pipe w/bunge + metal substrate cat for >$300ish? My mid pipe was about $179 (w/ship&tax) + $139 for cat = about $320ish but I have the 200 cell version or so it's labeled.