Following up on the thread below, I wanted to give you guys an update on my custom Metal Substrate High Flow Cat.

https://www.rx7club.com/showthread.p...etal+substrate

The product:
I received the Random Technology (http://randomtechnology.com/) universal fit Metal Substrate Cat last week. I was kind of surprised how small and light it was compared to a stock cat. It is 4" in diameter and roughly 9" in length. The inside of it looks like a mesh filter. If you hold it up to sunlight you can see the light through the metal substrate mesh. The metal substrate looks like it is crimped in place. Looked pretty solid and well made. Nothing rattling around or anything.

The install:
I headed over to my local RX7 specialist (J&R Performance) to get it welded into the 3" midpipe that was already on the car on Saturday. Installing it was pretty straightforward since they had the right tools They measured it against the midpipe, marked it and cut using their electric cutter jimmy jammy tool. I would never ever want to try cutting through one of our midpipes by hand! Then they tacked it in place, pulled the midpipe off an welded it on.

The cat is supposedly designed to slip over the 3" midpipe up front and slip in the 3" midpipe out back. However, since rotary midpipes/exhausts use such thick walled steel it would only slip over the front of the midpipe. So they made a nice even bead along the mating surface in the rear. They had to be careful (read: warning for you guys) with the welding as the metal used for the external part of the cat is much thinner and will quickly get screwed up if you are a sloppy welder. They did an excellent job of installing welding it in place and got us out of their quickly. Much thanks to Joe and the boys!

Results so far:
The car is quieter compared to running a straight midpipe but not as quiet as the stock cat (no surprise there). The tone of the exaust (Racing Beat duals) sounded very similar just a few decibels quieter. It smells MUCH better. Midpipes and resonated midpipes are kinda cool, but smelling like exhaust sucks (unless it smells like the mid-90s F1 fuel) and the ladies hate it.

Next week, the car will be getting put on the dyno for some tuning so I'll probably have a sheet for you with this car. Week after, it's going to get emissions tested. Not really sure if it will pass, but worth a try.

I'll keep you informed about how it progresses.

Details of the car it went on are: street-ported motor, Jspec twins, Greddy FMIC, PowerFC, DP, RB cat-back and other goodies.

I know you're going to ask for pics, but I forget where I left the camera. Will get some up shortly.

 

Good to hear the info so far. I am really looking forward to the emissions test results. I'm about 99% sure I'm going to go this route.

 

Great!! Just wish we had a sound comparison against a stock or hi flow cat. I have a hi flow and would switch to this in a heartbeat if it wouldn't make it any louder.

 

i bought the dynatech last week and now waiting for it...

would you mind cutting and pasting your feedback on the thread that was started a few weeks ago on nopistons.com

http://www.nopistons.com/forums/inde...howtopic=48690

thanks a lot
martin

 

The inlet on the Random cat is 3" ID and the outlet is 3" OD -- that's why it fit over the midpipe (3"OD) on one side and not the other. I guess this is a common convention for "American" exhaust system parts, and it makes sense that it didn't slip over your midpipe in the back.

-Max

 

I updated your thread at nopistons.

It was actually pretty frickin cool heading over to J&R. Lots of nice toys there

Apparently Joe and the boys are working on a "black box" electronic OMP controller to work hand in hand with Haltech, Microtech and I think Autronic. The idea is to grab signal from the respective engine management system and activate the stock OMP to flow the proper amounts of oil to the rotors. This will eliminate the need for Premixing and other annoyances like that for those running those EMSes.

I could probably rattle on about other **** I saw there, but I got other things to do right now

 

Yep. Actually it was expected. I didn't think it would be a true slip fit, but I felt it was worthwhile mentioning to save the home mechanics some grief in case they actually thought it would slip over both sides

 

nice . got any pics?

 

I'd like to see more data on wether or not these cats still need air injection. I was talking to Dave @ KD Rotary about cats and the PFC, and he told me that, while the PFC does run all of the emmisions "stuff" on the car, it doesn't run it the same way that the factory ECU does, and thus essentially "kills" cats by not injecting as much air as often as it should. I ran a random high flo for several years, and passed a test after 1.5 years by a mile with a PFS piggy back computer. Bought a PFC about 6 months before the next test, BARELY passed, and the thing croaked about three months later. That's not scientific data by any means, but I basically bought a midpipe because I didn't feel like replacing expensive cats every year. If these metalic ones DON"T need air injection, i'll prolly jump on one. My car reeks.

 

Hey, does J&R have a website? I'm really interested in the OMP project they have going. PS - Great work on the metal cat!!...keep us up to date.

 

i think the 3"id and od is because you want the overlap a certain way on slip fitted piping. the pipe that is further away slips over the pipe that is closer to the engine. it makes sense so the 1-2mm lip doesnt cause much turbulance in the piping

 

You need to do back to back dyno runs with a MP and your new cat to compare.

 

these guys provide a metalic substrate cat for the FD

http://www.smb.net.au/fullsystemsmazdarx7.htm


[quote/]From our in-house flow bench testing, in a back to back test, the following results were gained, (note: our machine is not a certified machine), and is used to simply do back to back comparisons, therefore the CFM figures should not be taken as gospel. However the percentage change should be the same percentage difference on a certified calibrated machine, the converters shown below gave the following results.

Catco 3" in 3" out 299 CFM

Carsound 3" in 3" out 299 CFM

Metallic substrate 3" in 3" out 408 CFM = 36% increase if flow rate

Metallic substrate 4" in 4" out 437 CFM = 46% increase in flow rate

Pressure differential: Test carried out on Nissan 200 sx (silvia) the maximum pressure in the dump pipe using a carsound 3" converter was 4psi, with the 3" metallic substrate converter this dropped to 1.5psi, and thus increased the boost to the engine by a further 2 psi.
[quote]
info on converters here

http://www.smb.net.au/converters.htm

 

[QUOTE=ORX705]these guys provide a metalic substrate cat for the FD

http://www.smb.net.au/fullsystemsmazdarx7.htm


[quote/]From our in-house flow bench testing, in a back to back test, the following results were gained, (note: our machine is not a certified machine), and is used to simply do back to back comparisons, therefore the CFM figures should not be taken as gospel. However the percentage change should be the same percentage difference on a certified calibrated machine, the converters shown below gave the following results.

Catco 3" in 3" out 299 CFM

Carsound 3" in 3" out 299 CFM

Metallic substrate 3" in 3" out 408 CFM = 36% increase if flow rate

Metallic substrate 4" in 4" out 437 CFM = 46% increase in flow rate

Pressure differential: Test carried out on Nissan 200 sx (silvia) the maximum pressure in the dump pipe using a carsound 3" converter was 4psi, with the 3" metallic substrate converter this dropped to 1.5psi, and thus increased the boost to the engine by a further 2 psi.
Yep - I just ordered this cat two days ago .

 

Link is in my sig.

 

True, but I don't feel like spending the money to do buy another midpipe and pay the time for back to back dyno runs.

Now if you guys are interested enough and want to donate funds/parts toward that end, I am willing to give it a try.

 

so actually do u need to pump air to this cat ??
my airpump is out of the car already and it smells like gas + oil ...
if i keep driving like that daily i m gonna die soon

 

you dont need an air pump,

and im sure someone in the forum would be glad to let you borrow their midpipe for now

 

will it pass emisions with the cat and no airpump.

What's the deal of you have a single turbo with this piece of work?
Not suggesting you know but what would be the difference regarding emissions between twins and a single, decently tuned and running a cat.

 

Nice work Alberto.

I had similar custom work done, exept that I had the shop weld they're 3" exhaust pipe and flanges (instead of a MP) to fit as stock with a 3" Borla Turbo Muffler from summitracing.com in the middle.

The Borla piece I got you can see right through though, there's no restriction of any kind, the muffler has some insulation looking thing inside that I guess muffles the sound pretty much, with a DP, borla center setup and N1 Dual the exhaust is't realy loud, yet nice and deap and it smells a bit to.

 

well i got a muffler in the mid pipe section so it's "better" than the straight pipe
but i need to re-arrange the order or something i guess ....

how well do u think the cat will work if i put it in the downpipe section

 

the substrate will probably melt if its too close to the engine

 

Please let us know how the Austriallian cat works out.

Also pictures of the substrate would be great.

Thanks,
:-) neil

 

I should be getting it in around two weeks, but it wont go on my car for probably another two months. I'll post pics when I get it, though .

 

I don't think so. The substrate was rated to something like 2000 degrees F iirc. That is the benefit to using the metal substrate.

Things that will cook the substrate is no matter if its metal or ceramic is:
- tuning: running way rich continuously
- tuning: massive off-throttle flames melting the core
- oil/coolant in the exhaust
- super high heat

So it seems like the biggest factor on a well running car is going to be tuning - running so rich that you'll clog any cat and the huge flames that you no longer see when you put a cat in the midpipe.

I have some other info that learned while researching this that I'll post when I have more time. Grad school is kicking my ***.