I'm looking at making a custom 3" downpipe for a turbo 4 cylinder. The car is not well supported because, well that's the sorta stuff my friends and I are into. I would like to keep the downstream O2 and not have a car that will be driven often smell like an all out racecar. I don't have OBD inspection or a sniffer test where I live, just trying to be more responsible about being irresponsible.
What do we know about "race cats" "200 cell cats" or the aftermarket universal catalysts? Is there a brand that is better than other or same factory different sticker kinda thing? I know the aftermarket cats aren't as good as OE but something has to be better than nothing right?
I know there was a thread not too long ago that was more towards replacing worn or stolen cats on unmodified cars.
Since the most important thing on the catalysts are precious metal, you really do get what you pay for.
If you don't want a light, stay away from any cheap catalyst. You can't sell Pt, Pd, and Rh cheaply.
Trent
PowerDork
8/2/22 3:20 p.m.
In reply to alfadriver :
If I remember correctly you once said that a cheap universal is better than nothing at all, right?
He says while eyeing the one on his workbench that he plans on installing in his now fuel injected 70's mini.
In reply to RacetruckRon :
I'll be the first to commend you for doing this.
In reply to Trent :
Better than nothing, sure. And I mis-read the lack of OBD- thought it was that it was part, lol.
Run it mostly stoich, and a catalyst will do some good work.
Mostly trying to gauge what's the cutoff for wasting money and see if anyone else has experience with aftermarket cats in an application like this. Is a $90 cat from Summit just going to be a $90 blob on my exhaust and I should have bought a specific $180 cat that actually does something? Kind of an open ended question because passing a sniffer doesn't really matter in my case but it would be cool to not have to tune the downstream O2 out.
There aren't that many aftermarket cat manufacturers. The difference between a universal and an application-specific cat is often down to the flanges. Once you make it application-specific, they're more expensive to manufacture and because volumes are lower, cost more per unit. That's assuming the universal has the same specs as the cat in the pipe.
The difference is in the cats that have an EO. They're equivalent to an OE unit in precious metal content, emissions control and, yes, cost.
In reply to RacetruckRon :
The one you linked to flow very well.
In reply to RacetruckRon :
Not including the start, what era of car emissions do you want to be? There's early up to the 80's, the small OBD I era, OBDII of the 90's, or early LEVII of the early 2000's? You can kind of select an era and find the cats with the EO that replace OEM's and then see if you can find the universal of that.
Given your control system, I'd not go much more than late 90's since you can't use a second cat fully.
In reply to alfadriver :
The car in question is early 2000's. I don't want it to smell like the uncatalyzed monster that is my V8 swapped minitruck or like a catless downpipe Subaru/Focus ST. The latter are all too common around here. So to answer your question probably 90's ish spec.
Peabody said:
In reply to RacetruckRon :
The one you linked to flow very well.
Have you used one in the past? What was the application if you don't mind me asking?
I installed one of these AP Exhaust "OBDII by design" cats on my Conquest, which was catless when I bought it, and it knocked out the stench big time.
608387 if you don't want an O2 sensor port: https://www.summitracing.com/parts/aph-608387
608397 if you do: https://www.summitracing.com/parts/aph-608397
Those are 3" pipe even though Summit doesn't list the dimensions. The body is 4" diameter and they're 10.5" end-to-end.
I prefer the OEM-style ceramic substrate cats to the spun metal high-flow cats. They are less sexy but they seem to be the most durable.
RacetruckRon said:
Peabody said:
In reply to RacetruckRon :
The one you linked to flow very well.
Have you used one in the past? What was the application if you don't mind me asking?
Yes, on a low hp 4 cylinder, but my buddy tested those on a 300hp 4 cyl turbo application. There was zero difference in tq and hp between it and no cat at all.
