Working on a custom metallic substrate cat for the FD
 

I just got the parts for my metallic substrate cat I will be working on. Hopefully by tomorrow I will be updating this thread with pics of the finished project. Shortly thereafter I will be dyno testing it, to compare the hp variance between my custom FD cat and a non-resonated midpipe.

Having owned an FD with a midpipe I can say I appreciated the additional hp gain up top, but I did find the exhaust fumes to be very bothersome. I have high hopes that this setup will significantly reduce emission levels while offering hp gains similar to a bare midpipe.


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would the air pump still be needed to run this cat efficiently?

It will be nice to see some dyno results.

My experience running a ceramic HF cat is that it takes care of the smell quite well without an air pump, but I suspect that it would need the air pump to pass an emissions test, at least in CA.

-Max

Is that the one that Jegs sells? My homie ccarlisi runs that w/out the airpump. I am planning on getting one as well. Supposed to flow like a m/p but without the smell.

w/ airpump, better emissions, w/o worse emissions and chance of melted cat. hp loos for having it? negligeable. purpose for removing it: cleaner engine bay and fitment issues. i say you keep the airpump.

The stock air pump doesn't fit with many single turbo setups. The ACV doesn't fit with aftermarket secondary fuel rails. The generic metallic cats don't have a port for the air connection. One or more of these facts precludes the use of an air pump for many of us (including me). I want a cat mainly so the car doesn't smell; the environmental benefits are just a nice bonus. :)

The air pump makes the cat run hotter, so removing it won't cause the cat to melt. However, not having one could lead to build-up on the substrate if it doesn't run hot enough, or so the theory goes. I have personally run a high flow cat without an air pump with no problems. Some people kill cats even with the air pump. I think the story about damaging the cat by running without an air pump is largely false.

-Max

I just dropped it off to the welder; he's going to tig weld it and have it ready by Monday for me.

sux without pix of drop off.

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The custom metallic substrate cat weighs about 10lbs, compared to about 35lbs for the stock unit.

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I am talking with Jesuscookies about arranging to have this cat dyno tested. He is currently running a resonated mipipe on his single turbo, so we'll see if there is a minimal hp loss running this cat.

Maybe if I get my metallic-cat-and-muffler midpipe together in time, we can dyno that, too.

-Max

That would be a tremendous service to the RX7 community; I'm sure there are a lot of owners watching these developments. I think Max Cooper plans to dyno his new setup, too.

what are the chances of an airpump option?

RX7.com's RX8 midpipe uses a similar type of cat an w/o airpump hookup and it supposedly can pass smog.

http://rx7.com/store/rx8/rx8supercat.html

I don't think anyone in this thread is talking about producing these for sale. But you could get one and have a pipe added in front of the cat for the air hook-up.

-Max

random cat offers a drop in cat using for the RX8 the metal substrate also. the difference between the one Random used for the RX8 and ours is that it is 5" in diameter with a 3" in/outlet. They tested it on their emissions rig and dyno and found that the 5" worked better and had better temps than the 4" one. I was tempted to use the 5" one but it was more expensive and the flow ratings for the 4" was sufficient for my needs.

will this unit bring down the noise level alittle? As well as getting rid (mostly) of the gsa fumes?

will get rid of exhaust smell

will bring exhaust levels down, but only very slightly. if anything it seemed to transfer the noise to the back of the car (tail pipe) leaving the cabin quieter but overall exhaust note similar if not just a bit quieter.

if you are looking for more quieting, you might also want to place a resonator/silencer/muffler in the midpipe while you are at it like Max described.

sorry i jumped, im still reeling from the headlight kit.

so how well will this unit hold up to the heat and stuff without an airpump. Will it last as long as the stock cat?
alberto_mg do you think the mp is long enough to place this unit along with a muffler? I am just looking to take out maybe 50% of the gas smell and maybe 20% of the exhaust noise. Basically dont want to hurt hp and take off the edge or the "extremeness" of the exhaust. I currently have a dp,mp,apexi N1 dual. Its loud and I can take it....but if I could bring it down just one notch in noise and the gas fumes, then I am willing to pay.

My understanding from my previous research is that it will hold up much better than any ceramic based cat due to the fact that the metal substrate core stands up to higher heat levels than ceramic based cores. You can refer back to my thread on this subject for the exact temps. https://www.rx7club.com/3rd-generation-specific-1993-2002-16/my-custom-metal-substrate-high-flow-cat-project-414054/

i do think that the mp is long enough to accomodate both the cat and an appropriately sized silencer/muffler. You will have to measure both and compare to the space available before and after that bend in the midpipe to find the optimal placement. I would lean toward putting the cat up front and the midpipe after.

You might have to mount the cat closer to the front of the midpipe before the bend and then the muffler/silencer after that bend. The cat itself is about 9-9.5" long, but you can easily cut 1" off each end when mounting it. The front side of the cat actually slid over the outside of the midpipe so i was able to move it back and forth a bit before final welds were made.

My impresssions sitting inside the car after it was installed is that it sounds quieter *in the cabin*. It sounds as if the exhaust sound and loudness now comes from the tailpipe rather than being all around you. I had a similar experience when I wrapped my downpipe in header wrap where is quieted the noise from the front and allowed you to better hear the noise coming from the tailpipe.

Adding the cat alone, did not change my exhaust note but it did seem to decrease how loud it was slightly. Volume on 9 instead of 10.

More importantly, it killed the damn fumes which made me happy and stopped my woman from complaining :)

I do plan on offering this cat for sale in the future. If a reputable member on this board is interested in buying it off me, let me know. I'll offer it at a reduced price if you can post your findings (fitment, noise, perceived power gains, etc) on this board.

This thread is mainly for informational purposes, but I am looking for someone to test this product out as I sold my FD about a month ago.

Eastondle on this forum should be picking up this cat tomorrow, so he will be able to provide info on this hi-flow cat once he installs it.

Adding an airpump tube shouldn't be too difficult to do; however, I've been told by the manufacturer that these new metal substrate cats can run without an airpump hookup.