Cheap AF MODE Catted DP - Should You Buy One?

[Brenden]

I just fail to see a cheap cat as causing any issue. I had a factory one literally turn sideways in it's housing. Car didn't make much power and that's it. Didn't endanger the car, nothing exploded, those turbos went on to live happy high psi tuned lives for years.
My understanding of a cat is a substrate coated with a reagent to some exhaust gasses. If it fails then your gasses stay gasses. If the cat "clogs up" somehow then your converters get smaller. Which I would argue perhaps a 200 cel converter clogging up would still flow more than a 400 cel converter.
Essentially my argument is, if a cheap converter goes bad, it performs slightly less efficiently in terms of gas flow, likely still flows better than oem. At worst, the substrate could turn sideways in the converter and create a lot more backpressure that reduces your ability to spool but likely not in a way that would damage the engine. In my view, the converter works or it doesn't and if it doesn't..meh

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[BMWAF]

search google

Super helpful. Thank-you so much for your insights.

 

[GRMan]

I just fail to see a cheap cat as causing any issue. I had a factory one literally turn sideways in it's housing. Car didn't make much power and that's it. Didn't endanger the car, nothing exploded, those turbos went on to live happy high psi tuned lives for years.
My understanding of a cat is a substrate coated with a reagent to some exhaust gasses. If it fails then your gasses stay gasses. If the cat "clogs up" somehow then your converters get smaller. Which I would argue perhaps a 200 cel converter clogging up would still flow more than a 400 cel converter.
Essentially my argument is, if a cheap converter goes bad, it performs slightly less efficiently in terms of gas flow, likely still flows better than oem. At worst, the substrate could turn sideways in the converter and create a lot more backpressure that reduces your ability to spool but likely not in a way that would damage the engine. In my view, the converter works or it doesn't and if it doesn't..meh

You are making many incorrect assumptions here.

1. One of your car had a faulty cat and didn't cause any engine issues and you think it' going to be hunky-dory again on the B58? Was the cat on your old car located right beside the engine manifold like the B58? With a melted or clogged up cat, the excessive heat build up in the manifold and the engine will affect the longevity of the B58 and the turbo. Especially if tuned. It does not mean a clogged cat has to cause a catastrophic engine failure for it to be a nuisance and I won't even rule out an engine failure from overheated valve heads.

2. How does a clogged up 200 cells cat flows better than a working 400 cells cat? What is the science behind it? The standard cat on the Supra has around 600 cells btw.

 

[Brenden]

You are making many incorrect assumptions here.

1. One of your car had a faulty cat and didn't cause any engine issues and you think it' going to be hunky-dory again on the B58? Was the cat on your old car located right beside the engine manifold like the B58? With a melted or clogged up cat, the excessive heat cumulated in the manifold will affect the longevity of the B58 cylinder head and the valves inside.

2. How does a clogged up 200 cells cat flows better than a working 400 cells cat? What is the science behind it? The standard cat on the Supra has around 600 cells btw.

1. Quite right, the cat on the 2jz is from memory a little further downstream. It's been a long time since I had a factory exhaust on mine.

2. The main point is that I've never heard of or experienced a clogged up cat that was relatively new. Something that has done 100s of thousands of kms sure, everything has it's life span. I wonder how a cheap cel could clog up. In theory it's possible, you only need to search Tofu Dreg construction in China to be amazed at what some people will do. My scientific reasoning was based on fluid dynamics and the only mechanism I could imagine a near new converter with only a few thousand kms could get "clogged up" which would be for the cell walls to react with something or get coated in black exhaust gasses, thickening the cell walls. This would reduce the diameter of the opening. If a 200 cel cat occupies the same space as a 400 cel cat, then in theory the air passages could be considered close to double the size of the 400 cel openings. Even if reduced in size by 25%, there is likely still more flow volume than two unobstructed openings in a 400 cel cat. I am basing these summaries on the calculated flow differences I have looked at when changing exhaust and other pipe sizes. A most recent example would be two 100mm water pipes flow less than a single 150cm pipe.
That was the extent of my logic. Happy for you to provide many examples of near new cheap converters clogging or melting by other means. I'm not saying it can't happen, I'm just saying it doesn't make a bunch of sense by the mechanisms I understand. I could be wrong and would change my opinion based on the supplied evidence

 

[GRMan]

1. Quite right, the cat on the 2jz is from memory a little further downstream. It's been a long time since I had a factory exhaust on mine.

2. The main point is that I've never heard of or experienced a clogged up cat that was relatively new. Something that has done 100s of thousands of kms sure, everything has it's life span. I wonder how a cheap cel could clog up. In theory it's possible, you only need to search Tofu Dreg construction in China to be amazed at what some people will do. My scientific reasoning was based on fluid dynamics and the only mechanism I could imagine a near new converter with only a few thousand kms could get "clogged up" which would be for the cell walls to react with something or get coated in black exhaust gasses, thickening the cell walls. This would reduce the diameter of the opening. If a 200 cel cat occupies the same space as a 400 cel cat, then in theory the air passages could be considered close to double the size of the 400 cel openings. Even if reduced in size by 25%, there is likely still more flow volume than two unobstructed openings in a 400 cel cat. I am basing these summaries on the calculated flow differences I have looked at when changing exhaust and other pipe sizes. A most recent example would be two 100mm water pipes flow less than a single 150cm pipe.
That was the extent of my logic. Happy for you to provide many examples of near new cheap converters clogging or melting by other means. I'm not saying it can't happen, I'm just saying it doesn't make a bunch of sense by the mechanisms I understand. I could be wrong and would change my opinion based on the supplied evidence

Simple, the core honeycomb structure crumbles and blocked off the pathway. Doesn't matter it's 200 cells or 600 cells. The quality of the substrates is what we are talking here. In addition, the less cells there are, the weaker the core.

The tuning world has changed from say 20+ years ago when the emphasis was mostly on quality and parts were engineered and made locally. These days seems to be more about selling products at the cheapest possible price, rebranding replicas from China.

 

[swrdply400mrelay]

curious if you're going to dyno, wondering how much power the dp adds with the jb plus

 

[BMWAF]

curious if you're going to dyno, wondering how much power the dp adds with the jb plus

I don't plan to at the moment but I'll probably get her dyno'd once I'm running the MHD OTS tune.

 

[ColonelAdama]

All the faulty cat stuff is silly lol. I've had a cheap 200 cell catted DP in my GTI running well over stock power for 80k+ miles. No issues. You'll be fine.

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