i just had a high flow cat and muffler put on my Rx-7 to go with my racing beat headers . I took it for its first test drive last night and when I opened it up for the first time a TON of sparks flew out of the exhaust. I turned around and got out to look at them as they were still glowing red hot in the road. They seem to be some sort of glassy grey rock. Anyone know what could be up? I'll grabbed a couple of the rocks and I'll post a picture when I get home today.

 

Sounds like the cat gave up the ghost.

 

what does this mean? did the cat blow out? I think the exhaust is a little deeper of a tone but I'm not too sure.

 

Sounds like your high flow cat couldn't handle your rotary or your rotary tune.

A stock FD cat is high flow and metal substrate. See if you can pick one up. Otherwise you need a $durable cat$ and maybe a more cat friendly tune.

My TII did the same thing when I put mufflers on it except it would should molten bits of SS muffler packing out on the road to glow behind me...

Guess that is why the 100lb Mazda Competition muffler used whole lava rocks (not wool) for muffler packing.

 

So what's the deal with the cats now? Are they practically punched out now? I didn't even want them in the first place, when I picked up my car from getting the muffler put on they had just thrown the cat on without tell me (and charged me for it too).

 

Yup. You could probably drop a tennis ball right through them lol

Rotary flow ALWAYS finds a way...

 

Could be blown out if you are lucky.

Could be a melted mass of slag clogging up your exhaust if you are unlucky.

Hard to say without looking.

 

You probably melted the cat. Hopefully it hollowed out rather than clogging. But yes, you are pretty much running without a cat now I would imagine. This is why I just bought the racing beat presilencer so It would be a bolt in affair and I could do it in my driveway.

 

theres a pic of the stuff that came out. These were the biggest chunks and they were glowing red hot when it happened.

 

Welcome to the world of hot rotary exhaust!

 

I'm guessing muffler seeing this. I'd go back to the shop that installed the exhaust.

 

Glass-pack mufflers have a life expectancy of minutes on a rotary.

 

Or one WOT run in this case

 

The only glass pack that seems to hold up to rotary heat is the cherry bomb. Everything else I have seen has been burned out after the first couple of flames.

 

However, a hollowed out glass pack will still cause some minor muffling.

 

Rotary Engineering glasspacks last for about a year on a rotary.