dubulup

If you ordered P/N 903018 (FD direct fit) from Random Technology you will be in for a surprise. It has an air pipe. I talked to Clay out there this morning. I'm thinking about going up there and picking one up myself. He also told me this unit is the same dimension as the stocker. Clean air in the FD's exhaust is never a bad thing...especially when emission testing.

Also, the KS Metalit has an air pipe...well one of their versions.

Mahjik

iTrader: (1)

That also depends on which cat you pick from Random. They have 3 universal cats at 13", 10" and 8".

My only problem is that Random does not have a great reputation for cats in the 3rd gen past. Their older hi-flo's clogged easily and frequently. Maybe they'll have better luck with their metal substrate cats, but I'll be using the RPM Outlet one myself.

alberto_mg

I didn't find anything about that when I was researching. Had I found anything like that, I might have selected the RPM one. It is cheaper. I still can change actually. They all look so identical. I almost wonder if all of these places aren't just buying the core and rebranding them.

Mahjik

iTrader: (1)

Here's some info:

As far as these places selling rebadged cats, I'm sure they do. I doubt any of them actually manufacture their own cats (Random might). However, I doubt they are all selling the "same" cat.

alberto_mg

Thanks Mahjik. I had read that thread before. The only problem I have with it is that he used a ceramic based cat so it isn't as relevant of a comparison.

I just spoke with RPM who put me in contact with the cat's manufacturer - DynaTech Headers http://www.secureperformanceorder.co...e/powercat.cfm. It appears that they buy the substrate in bulk and manufacture the cylinders around the substrate. I suspect that is the standard for all of these catalytic companies. They certainly all look alike in the pictures. I don't think any of them have the resources to manufacture their own core substrate. I would venture that they all buy the substrate and encapsulate/package it for resale as a universal cat.

The rep I spoke with at Dynatech didn't have any flow numbers on the 3" unit. He was able to tell me that they use a 300 cells per inch substrate. He also mentioned that the recommend using 1 cat per 250HP. So if we were trying to achieve full emisions compliance with one of their cats, we would potentially need another cat run inline if running more than that number.

Unfortunately, the people at Dynatech really weren't able to comment on the cat's usage on a Rotary. Actually, the guy didn't even know what a Rotary was I felt a bit more comfortable that the people at Random had developed a metal substrate cat for use on the RX8 and seemed to be able to speak about the overall application in a rotary and turbo rotary environment. I don't like the fact that Random's costs an extra $60 compared to RPM's/Dynatech's.

dubulup - I didn't order the ceramic one. I order the metal substrate one here http://www.martelbrothers.com/custom...cat=550&page=4

Mahjik

iTrader: (1)

Hence why the comment was:

dubulup

I didn't read anywhere the direct fit was a ceramic?!

alberto_mg

Gotcha Mahjik. Thanks.

Dubulup - I'm not using a direct fit. That link is for a universal 3" inlet/outlet metal substrate which I'm going to have welded into the midpipe.

I just spoke with Dave at Random and the other specs are very similar to the DynaTech/RPM - 300 cells per inch 4" overall diameter yada yada. He confimed that they also did not manufacture the substrate like DynaTech. Dave is actually very knowledgable and was able to comment on their research with rotaries. Interesting conversation.

I'll start a thread with more info in the next couple of weeks. I think this will turn out well.

M104-AMG

iTrader: (8)

Mahjik: are you going to weld an air-pipe to the RPM Outlet cat ? Or do they have one already with an air-pipe ? I've kept my air-pump, hence the question.

:-) neil

Mahjik

iTrader: (1)

Sorry. I won't be using the airpump.

maxcooper

Here's a thread with some interesting data on cat flow rates, though all the tests with the test parameters listed seem to be for ceramic cats:
http://www.ls1.com/forums/showthread.php?t=524121

-Max

M104-AMG

iTrader: (8)

I called around and talked to Eastern, DEC, and Random Technology. All agreed that a rich mixture will need an air-pipe on the metallic cat, otherwise there will NOT be enough oxygen to do any "catalyzing."

Also, it seems that aftermarket/universal high-flow metallic cat substrates in the USA are all in the 400 cells per square inch (cpsi) range.

While anywhere between 50-400 cpsi substrates are available from the manufactuers like Ander Technologies, the substrate cost goes up exponentially due to the increased amounts of rare metals (e.g., platinum, rhodium, etc.).

As such, the market is VERY slim for anyone who will pay $200+ just for the metallic substrate.

http://www.andertechs.com/english/pr...s-03-01-02.htm
http://www.siemensvdo.com/default.aspx?menu=metalit
http://www.emitec.com/index.html?lang=en&tab=0&doc=01

So, does anyone have contacts to get like a 200 cpsi metallic substrate from Ander or Emitec/Siemens ?

:-) neil

alberto_mg

That is not what I heard from either Random or Dynatech. Read the technical specs of how the metallic substrate cats work and you will understand why an air pump feed is completely useless on a metallic substrate cat. Sounds like you might have gotten confusing info.

Dave at Random did mention that the 2 main things that kill cats are overly rich Air/Fuel ratios and the presence of other things in the exhaust (such as coolant). A turbo rotary running 11.1:1 A/F ratios under boost is a bit rich for most cats. However, we shouldn't be tuning A/F ratios that rich under cruise or idle. Even running 11.1:1 is enough to "catalyze" the exhaust gases.

The people at both Random and Dynatech said that a 300 cell is standard. Less than that and the cat needs to be longer to have enough surface area to filter as much. Again, sounds like you got some confusing info.

maxcooper

Though I still have some suspicions that the Dynatech and Random metallic cats have the same substrate (and should thus have very similar flow rates, if I understand that correctly), I decided to order a Random cat from Martel Brothers yesterday. Besides the possibility that the Random cat supports more flow, it is also shorter in length, which is attractive since I want to run both a cat and a muffler in my midpipe. I still need to figure out how large of a muffler I can fit in there, but the short and relatively small diameter metallic cats (particularly the Random one) should allow me to run a relatively large muffler compared to what would be possible with the typically larger bodies (length and girth) of the ceramic-subtrate cats.

-Max

dubulup

so, does the site say something about the direct fit being ceramic? Did I miss something? Metal sub cats can use air, the KS Metalit cat has an air tube.

maxcooper

I am pretty sure the Random direct fit is ceramic.

As for the air, it seems like the metallic substrates that the Random and Dynatech cats use are 1-piece cylinders and thus have no place for air to be inserted. I'm not certain of that, but that's what it looks like to me from the pics. Even so, I suppose you could pump the air in before the substrate. The HF cats with air ports typically have one brick, then a space where the air is pumped in, and then another brick. For anyone who has seen one, how does the KS appear to be constructed, and where is the air port relative to the catalyst brick(s)?

-Max

7racer

Max,

this is the orginal thread when we were purchasing the KS cat.

https://www.rx7club.com/forum/showth...nightsport+cat

it looks like the pipe is plumbed in before the substrate by the pic

moehler

iTrader: (12)

Interesting... I got this from the Milltek website (they claim only 100-200 cpsi):

"Your original catalytic converter will typically have 400 or 600 cells per square inch (cpsi), these original cats are restrictive in their flow, typically allowing an open area of around 55-65%. A Milltek Sport Hi-flow Sports Cat which will be fully integrated into a large bore downpipe, has only 100-200 cpsi depending on application. These cats have an open area of between 75-85%, thus reducing back pressure substantially and increasing flow rates, all very desirable for extracting more performance, especially on turbocharged engines. Emission levels are maintained at legal limits by careful selection of the volume of the metallic substrate. Lamda probe positions remain unchanged from the original equipment.

Milltek Sport Hi-flow Sports Cats work exceptionally well on re-mapped (chip tuned) engines. Click here for an example of the power and torque gains that can be achieved.

Milltek Sport Hi-flow Sports Cats are made from a special stainless steel containing aluminium (called ‘Fecralloy’). This material was developed in England in the 1970’s specifically to provide resistance to oxidation at very high temperatures.

The material is used as a very thin strip (2 thousandths of an inch) and is coiled together to make a honeycomb structure. Because the metal strip is so thin, the honeycomb has a very low flow-obstruction. To reduce the flow-obstruction even further, the honeycomb is made with 100 or 200 ‘cells’ (i.e. channels) per square inch compared with 400 or 600 per square inch for a standard catalyst.

The result is that about 85% of the total cross-section is open. The honeycomb is held together by using a special nickel-based brazing material which is applied in a vacuum. The finished honeycomb is then coated with Aluminum Oxide, some rare earth metals and Platinum and Rhodium. The Platinum and Rhodium are applied at a rate of 25 grams per cubic foot, which compares with between 5 and 10 grams per cubic foot for typical US aftermarket items.

It is normal practice in Europe to use much higher quantities of precious metals on catalysts, because European gasoline has more impurities in it which gradually poison catalysts. If catalysts with such high levels of precious metals are used with US fuels, the post-catalyst emissions are extremely low and the durability of the catalysts is very good indeed. "

alberto_mg

I had come across that as well

Couple of points:
- they refer to original catalytic converter i.e. probably a stock ceramic type
- I like the idea of a less cells (100-200) when using the cat as a "pre-cat" near the downpipe that way you maintain higher flow rates coming out of the turbo.

FWIW I found a lot of good info Googling around for metal substate cats. What was especially interesting was the industry white papers and research on the topic. I based my research more on that than the content I found on "tuner" sites as I thought it was more impartial.

moehler

iTrader: (12)

Yeah I just found this . Interesting, although they are testing higher density cats.

http://www.emitec.com/pdf/sae_2002_01_0347.pdf

Herblenny

iTrader: (13)

Very Interesting thread..

I thought you don't need the air pump for the knightsport metallit cats.. I have a brand new one sitting in my garage. I just found out a month ago that starting april, I have to pass emission..

AgentSpeed

I've been thinking of going back to a cat myself. This looks like it might be the ticket. Keep the info coming guys!