I'm getting pretty tired of smelling like exhaust every time I step out of my FD. Are any single turbo FD owners running a cat; if so what brand are you using? I'm looking for something that (obviously) flows well and lasts without an airpump.

Thanks

 

Metallic substrate is what you want. They flow the best but they are not as good at passing emissions tests compared to the more common ceramic substrate converters. See this post https://www.rx7club.com/showpost.php...6&postcount=34 from part 2 of my "Why is this engine so damn complicated?" series of articles.

 

Lol. That's funny because I have a cat already on my fd(s), and I'm tired of smelling like exhaust. I was wondering how much worse it would be if I just removed them all together.

When I first start the car is when it smells the worst. After its warmed up the smell becomes more bearable. If I was catless would it smell like the startup all the time?

 

Thanks arghx, great write-up as usual . My last single turbo FD had an SMB metallic cat - it only lasted about 1k miles. That was during an engine break-in period, however, and I was running crazy rich. That FD also had an N-Tech ceramic cat prior to the single turbo (~300 rwhp on seq twins) and that held up nicely w/o an airpump and controlled the exhaust enough to keep me from smelling.

While I'm not too concerned about losing some HP (car put down 504rwhp at 18 psi and >450 at 15-16 psi), I want a cat that is as large as possible (to flow good) and withstand the temps/heat from a high HP FD. Any specific brands that you can recommend (metallic or ceramic)?

 

I had a randomtec 3" cat on my big single FC, it worked well for sometime but once started getting aggressive with my tune and egt's got up there, it started to fail. It did however last about 10k miles and wasn't useless when i took it out, was just starting to melt in on its self

-Jacob

 

I had have the smb sub met cat witht the muffler on it, my car was dyno and tune this year and it mad 391 at 16 psi, and 343 at 7 psi. About years ago I had the Bonez hi-flow cat and the car made 343 hp at 15 psi, I know it has allot to do with the tuner but my air pump and a.c still works on my car.
Khris

 

i had the re-amemiya SD converter on my fd. while i would never pass the emissions due to the absence of the airpump + the huge primaries it didnt smell bad.

 

yes it would

i doubt there is a cat out there that can survive a close to 500WHP rotary environment, the met substrate cats flow well but even they will fail under situations like that.

 

I can't speak for your previous SMB cat. A lot of things can affect cat life. I'll admit I don't have firsthand experience with metallic cats on FD's, only turbo Subarus. Those engines love the metallic cats. They don't smell at idle at all, but when you get into rich mixtures from boost you will smell the exhaust. In that article I cited, know they discuss "larger frontal open area" on the metal cats. But that may have to do more with the internal design of the converter, not necessarily the nominal dimensions. I'm not convinced that just because a cat looks or measures bigger it will flow better, all other things held equal. I would think that it's actually the opposite... the more catalyst material to pass through, the more restriction (not to mention expense).

I wonder how this Vibrant Performance 3" cat will hold up? Vibrant makes good stuff from my experience, and this supposedly has a 50,000 mile warranty. If they would actually honor that it would be sweet. At $125 the price is right certainly, but it would have to be welded in.



http://vibrantperformance.com/catalo...cb108f6055b222

 

generally the opposite is true, unless the larger core cats have tighter mesh pattern or thicker honeycomb design. metallic substrate cats have a thinner weave material versus the ceramics so they flow better naturally but are less efficient.

 

vibrant sells good stuff but you cant buy directly from them!

 

from Vibrant's website:
"300 cell per Sq. Inch catalyst flows at 578 CFM, up to 40% better than a typical ceramic core converter."
From long ago, I think I recall calculating you need to flow over 800 cfm on a single turbo setup. That's why you get so much more HP running a mid-pipe, and why cats don't last on a single turbo. JMO.

 

there is no ideal airflow max with a turbo car, because airflow increases with RPMs and boost levels. 600cfm may be ok for a 375WHP application but it will turn into a bottleneck for anything above that, the harder you push it the faster it will fail even with a well tuned car.

 

Thanks for all the info guys - I don't mind losing some HP here, and I agree that this will be a bottleneck. That being said, I may try something like the vibrant cat (the price is certainly right) but I would prefer a bolt on cat. Does anyone have one on their FD?

R-R-RX7, I looked up the RE-A converter and it's way out of my budget, but looks very nice .

 

If you are willing to go with a universal part it expands your options. If you've got a trusted local muffler shop they can weld up flanges to make the Vibrant one bolt-on.

 

i'm almost curious now to test a 3" met substrate cat versus a 4" one side by side to see the differences.

 

I've spent some time and money on this. I had a Bonez high flow cat; the metallic cat came out and seemed superior, so I got one from Random and there was little/no difference in HP. Then, I tried a mid-pipe, and HP went from 320ish to 400ish. So, I thought to myself "self, these cats are too much of a restriction, lets y-pipe the 3" to two 2 1/2" and run 2 Magnaflow cats (y-piped back to 3" before the muffler)". Well, that sorta worked, in that I then had 360ish HP. My car is white, and even with 2 cats, I still get an oily black coating on my rear bumper. Im thinking about hooking up the airpump again....

 

So after searching around and talking to a few people I think I've narrowed it down to either Random Technologies, Vibrant, knight sports metalit or SMB (despite my experience). The knight sports and SMN are both direct bolt, but the KS is pretty expensive unless I can find it used. The RT and Vibrant are not - I like the vibrant alot because it’s cheap, I just haven't read about any rotary experiences...

 

Summit sell metal substrate cats made for 7.8L Ford Trucks for $110!

Magnaflow 99409. Someone give it a go! It 15.5" long 7" wide. Thats gotta take the smell out! I would try and put it a fair way downstream tho. Possibly even towards the back.

 

I don't care about emission testing but the smell I hate on the streets...I've been thinking about going with a Magaflow metal cat with V-band connections on the street and to swap out for straight pipe at the track... Any body think about installing these in the Cat-Back pipe right after the subframe bend?? Might just be enough clearance for the 4" cat body, easy to access and less chance of killing the damn thing. Only draw back I see is that it might take a couple minutes for it to heat and work...

Here's the one I found http://www.magnaflow.com/02catalytic...niversal=59959 or http://www.magnaflow.com/02catalytic...niversal=59929

 

Anybody try a 100 cell per inch^2 metallic substrate cat.? Obviously they are not for passing emissions but more for cleaning up the rotary smell with minimal restriction since they are touted as offroad race cats. Most all you see are 300cpi met. substrates, but one would guess the 100cpi to be a little more heat/oil burning tolerant just by looking at the x-section between the two substrate cores.

 

Its not a bad idea, Im not too sure that it would fit though; it probably depends on the cat-back too.

For what it's worth, I just emailed RT to see what the dimensions and flow rates are for their FD converter (PN 903018). I'll post them when I get them.

 

this is actually the most ideal answer for people who want to retain the cats, splitting the exhaust is really the only best way to keep the cats semi cool and flow better. but cats will always rob power, there is no getting around that.

 

My small port single turbo does not have a cat except for emissions passing time.
It has a full time working stock air pump. With my tune the exhaust is only stinky when accelerating.

If yours stinks at idle, maybe your tune is the problem!

 

Their Fd specific part is probably a ceramic one. They had a 5" OD 3" in/out metal cat for the RX8 iirc. I used the generic 3" in/out 4" OD metal cat on my car for a while as I mentioned in my PM. The engineers there were very nice to speak with at the time I was doing this and very helpful overall.