Living with the Random Technology High Flow Catalytic Convertor

[loc182]

I have been planning to replace the aging stock exhaust on my 1989 Turbo with a BIC DDP with recirculation, the Random Technology high flow metal substrate catalytic convertor (Model #141-30033) and the HKS Turbo Exhaust (LET-T16).

I was about to purchase the cat and cat back exhaust when a co-worker warned me of the failings of high flow models. He stated that the smell of gas, especially in the garage, is a problem and that high flow cats have to get extremely hot before they become effective, making the car a worse source of pollution over all.


So I was just curious as to how people with the Random Technology models have found life with these cats?
(Are there smell of fuel/gas issues? Do you fail emissions with an otherwise smooth running car?, Is reliability a concern?, Do you recommend another brand?, etc.)


Also, please no arguing about test pipes versus cats. I will have one on my car as I don't wish to be a further burden on those behind me or the environment.

Apologies for yet another cat related thread, but after reading everything I could find here and elsewhere I couldn't find all the information I was looking for.

Thanks in advance for all comments and insight!

 

[vCo2v]

I don't know what model high flow cat I have, but I passed emissions perfectly fine in washington state. I have an ebay recirculated divorced downpipe with a custom greddy EVO exhaust. I do smell a bit of extra gas, but shit it beats running a test pipe or open downpipe any day.

 

[jetjock]

Your friend has NFI what he's talking about.

 

[loc182]

He is known to embellish, that is why I came to the source of all Supra knowledge : )

Honestly, the gas smell is my biggest concern, as my garage is not very large : (

 

[3p141592654]

Evap issues are going to be on the intake side of the engine. If the smell of gas is your primary concern then make sure the charcoal canister, plumbing, tank, gas cap and such are all in good condition and functional.

The RT converter must meet at a minimum the U.S. EPA aftermarket converter program requirements by testing over the EPA Federal Test Procedure (FTP-75) with a chassis dynamometer to 25,000 miles. California is more stringent, requiring California aftermarket converters to meet the emissions limit that the vehicle was certified to after full useful life aging of 50,000 equivalent miles.

The primary issue you will face with aftermarket cats is durability. The famous "one-pass cat" that quickly deteriorates was such an issue that California and now NY and pretty soon the EPA have worked to get rid of them. The attached plot shows emissions versus miles and you can see the EPA cats age poorly compared to the ARB (California approved) cats. This is going to be the real issue you face by going to the RT cat.

 

[supraguy@aol]

Just bought a 2 element cat, to replace the 3" test pipe on mine.
Im emissions exempt, but dont want the smell of the exhaust anymore.

 

[Nick M]

If you put a two cat pipe in place of a factory 4 cat pipe (which will not be 50 state legal), then you would have problems. He could be thinking of those things.

 

[loc182]

Just bought a 2 element cat, to replace the 3" test pipe on mine.
Im emissions exempt, but dont want the smell of the exhaust anymore.

Started reading through your build thread looking for the cat, but got very distracted with the sweet pics of your kitchen remodel. Love the backsplash!

But back on topic, what brand cat did you get?

 

[loc182]

Thanks to all for the info, especially the detailed post by Pi.

From reading various posts I had come to believe that the RT models were CARB/ARB certified, but it sounds like I was wrong. (Their website claims better than EPA required performance, but they never mention CARB or ARB.)

Looks like I have some more searching to do!

 

[supraguy@aol]

Well, the build thread in my signature is "project get'r done". In that one i use a metal substrate cat.
In my second build, "project get'r driving", i used a two pass cat. Its made by thunderbolt. No pics of it, though.

 

[3p141592654]

"Two-pass" cat. I think that qualifies as a Freudian Slip! Slightly better than a "One-Pass" cat maybe.

 

[Nick M]

Nobody in the USA is exempt from emission. Living in an area that doesn't have a high population density and pollution and as such no emission test doesn't mean it is lawful to remove the catalyst from the vehicle.

Just FYI.

 

[loc182]

Agreed Nick, emissions are important to keep under control.

My original thought is that 25 years of technology advances would mean a 3 inch high flow cat would exist that met or exceeded the capabilities and longevity of the stock cats the Supra originally came with.

Am I crazy for thinking this? Or is there something out there that fits the bill?

I haven't found anything yet, but I am notorious for being too specific in my searches :$
(I have found many testimonies confirming pi's data, not that it was ever in question.)

 

[Nick M]

The 450mv switching feedback/cat system does work, but the A/F sensor system works better because the fueling system is better.