engifineer

Previous owner of mine autocrossed it for I think 6+ years and even though he went STR eventually he still had the stock exhaust and cat. I believe the owner before him also autocrossed it. I bought it with 100,000 miles on it and kept autocrossing it and changed to a HFC (Berk) when I went with the Karcepts Emanage/Tune setup at about 125,000 miles. No issues on the cat and sold it to another guy who was putting his car back to stock. It did not look like the cat had ever been replaced, but am not 100% sure on if it had been. Autocross is not anywhere near as hard on a car as "Racing" which implies long times under heavy continuous load on a track.

As far as options for street class:

". If the vehicle has exceeded the warranty period, replacement catalytic converters must be OE-type as per Section 13.0."
per the rulebook

Live Fast

A friend of mine had this issue before with his 2001. We swapped the cat for a test pipe for a mountain drive and we noticed he was smoke screening a lot. We replaced the PCV valve, hoses, and it was much better. He did upgrade to a RSX PCV valve in a AP2v1 valve cover later though and didn't have issues on his next catalytic converter.

carpster006

I did run a Track Night in America on the second cat, so that probably explains the super short lifespan on that one. Its been a while since I've replaced the PCV valve, so I will do that too. Easy enough. But man, I looked up prices on cat's and they've shot through the roof since my last replacement! $1,800 for an OEM online!!!!

Maybe I'll just buy an aftermarket cat in and swap it out for once in a blue moon autocross that I run. Kind of annoying though, as my game plan has been to just run in random autocrosses when I have some free time. Having to do prep for it kind of defeats that purpose.

Jub

I had the waffle of my AP2's cat shake loose around 92,000 miles. I had 1.5 seasons autocross on the car in stock class on RE71R's. Shortly after replacement (used OEM), I realized that my motor mounts were in awful shape. I had a theory that bad motor mounts + launching/shifting fast caused or at least expedited my waffle shaking loose. I've watched plenty of cars launch with the exhaust shaking about violently. I did not hear that mine was doing that but my motor definitely had some movement on the mounts and I downshift pretty regularly on the streets too. I'm curious as to what your cat's mode of failure was. If your waffle shook loose and your mounts are shot, maybe we're onto something. I am simply guessing as to why mine shook loose.

carpster006

I doubt the shaking would be the root cause, just from what I've learned about how the waffle is held in place. The waffle is a cylinder wrapped in a compressible membrane (think of a beer can in a coozie) that creates an interference fit with the housing. From what I've read, our membrane deteriorates under high heat, which then allows the waffle to vibrate about inside the housing. When it first happened, I was thinking that I would just put some weld beads in there to prevent it from sliding for an aft (which I still might try), but you can't fasten it to the edge because it needs space to expand and contract (which is why the membrane is compressible). I think the weld beads might at least prevent the waffle from breaking the O2 sensor (which has now happened to mine), but it will probably still make that annoying rattle sound.

On a side note though, I definitely appreciate your comment about the engine mounts. My car has a lot of autocrosses under its belt, and its around 110,000 miles now, so I would guess mine are probably in rough shape too. Definitely going to look into that this winter.

Jub

Well, I recently went to STR class and put a high flow cat in my car. I had an exhaust rattle that I suspected was coming from the cat. The OEM cat that I replaced my previous one with had its waffle shake loose after about 10,000 miles. This involved another season of autocross and 3 track days. Hopefully the high flow cats hold up better to high heat.

HowlinFantods

Any tips for AP1 intake air temperature?

Even with the hood open between runs I saw temps hit 175 and power felt like it dropped off the line considerably. For the second heat I took an ice pack out of my cooler and rested it on top of the intake manifold between runs and it kept temps down to 150 and power seemed considerably better off the line but I figured somebody might have a better solution.

At what temp does the ECU start to cut timing? It feels like at 170+ it drastically cuts but I'd like to know what to aim for.

Rhop101

Any luck on figuring out a strategy to deal with that? Seems like your ice pack method is a good start.

I have an AP2 so I don’t have this particular issue.