I started my car up today to back it out of the garage. I was wearing Bose noise cancelling headphones when I was doing this, so I did not hear anything weird. When I put the car back into the garage, I found this laying near where the tail pipe was. It looks to me like the honeycomb material inside of a catalytic converter. My car is on the stock twins with a haltech elite, HKS downpipe, bonez cat, and Racing Beat muffler. The airpump has been deleted.

I know the only way to know for sure, is to pull the midpipe, but what do you guys think, its that a cat?

 

After doing a quick google search (forgive me I should have started there) it does appear I have blown my cat. What do you think could have caused this? I recently switched to a high zinc motor oil and started using Idemitsu premix. I am open to suggestions for a new cat.

 

How many miles did you have on that cat?

 

9,500 miles

 

I also did the same thing with my FD on a bonez cat. Some people haven't had problems with the bonez cat but seeing your post makes me question that.

 

Broom stick highflow or open cell stainless core.

 

Wow. It looks like those pieces are melted on one end.

Out of curiosity- what's your power level?

 

That certainly looks like pieces of a blown out cat. Any big exhaust backfires recently?

 

I did that with my Pettit high flow cat a couple of years ago. I never found any of the substrate and the thing made big pretty flames from that point on. In that instance I was fairly certain that it was unburnt fuel entering the exhaust and igniting. I suppose it had had enough heat and pressure during its lifetime.

 

Arghx has posted most of this over the years, but.

a ceramic cat need to be at least 450c, to work, but then it also needs to be under 650c not to melt.
it also wants to see 14.7:1 afr as much as possible, the factory tune goes richer to keep temps under control.

a metallic cat, like the SARD, Knighsports, etc can run up to a higher temp, 1100C

and then the Rotary engine opens and closes the port so fast, that its lit hitting the cat with a hammer, so its days are numbered kind of no matter what

 

Its done... I see a new cat or muffled mid pipe in your future.

The question is Stank or No Stank?

Steve

 

Do you know anything about the Bonez Cat that Rx7.com sells? They advertise that it is more durable than your typical cat, suitable for rotary engines. I may invest in one of the JDM metallic cats, especially seeing how my first Bonez cat has not lasted that long.

 

So right now I have a dyno tune scheduled for the 18th. I do not think I can get a cat in time before then. Do you think I would be fine to not drive the car and then get it tuned on this fractured cat, and hope the back pressure is good enough or should I cancel? It is hard for me to get time off and my job is giving me the 18th off for Juneteenth.

 

Hate to say it, but I wouldn't invest in the tune/dyno time with the blown out cat - best case you'll just have to do it again, worst case the back pressure the blown cat has during the dyno/tune session will be very inconsistent & variable, and your tuner could end up blowing your motor if he's not careful. A good tuner will tell you to fix the cat first (new cat or resonated midpipe section) & reschedule.

 

In the US, there's only a few manufactures of catalytic converters (https://www.verifiedmarketreports.co...ic-converters/).
Then there are suppliers or fabricators of automotive catalytic converters such as Davico (https://davicomfg.com/), Eastern (https://apemissions.com/eastern-catalytic/), MagaFlow (https://www.magnaflow.com/) and Borla (https://www.borla.com/products/exhaust-systems). I think Eastern got bought out by AP Emissions. There might be a few other suppliers.
I've been using Bonez cats on my FC for the past 25 years. The last one that I bought was in 2019. Apparently, rx7.com buys cats from a common supplier and just resells them under the name Bonez. Before I bought my last cat in 2019, I did some online searching and came to the conclusion that rx7.com bought their cat from either Eastern or Davico and rebranded them as Bonex.

 

if i was my car, i would remove/hollow out the cat for the dyno.
its not my car, so ymmv

 

^This would solve the problem & risks of tuning with the blown cat as-is (i.e., inconsistent back pressure) that I mentioned a few posts back. But unless you want to live with the hollowed out cat, you'll still need a do-over session if/when you replace the hollowed out cat with a new one or a resonated mid-pipe.

 

Any update?

 

the 1990’s are like, so yesterday …

let me try one more time


https://hjs-motorsport.de/en/product...t/pe-catalysts



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Oh yeah I blew a chonky hole in it. Luckily another forum member had a knighsport metallic cat in good shape on hand and sold it to me. I got the car dynoed with it and have had no problems.

I cannot get a hold of rx7.com to order a new one or warrantee mine out. There is a whole thread about rx7.com being unresponsive, and may be out of business. Guess I will chuck this one up as a loss and sell it to a scrapper.