Explode64

I have bought a JDM RX8 to convert into a race car. The car came with a Metalit Cat and 60mm OD stainless steel mid pipe.

I have not been able to find much info on this forum or the net on this cat.

The class the car is being built for used stock engine but allows a free exhaust from the headers back.

Would a 60mm mid pipe with Metalit Cat be an acceptable exhaust for a race car or would it restrict power compared with a 75mm cat less exhaust.

Myself or my friends don’t have any experience with the MSP engine so any advice would be appreciated

xexok

You are much better off without the cat since you wont have to worry about it failing.

alnielsen

iTrader: (4)

The temperatures found in the rotary engine exhaust are almost double what you would find in a conventional piston engine. The only catalytic converter known to be able to survive the heat produced by the rotary engine exhaust is made by HJS. HJS North America, LLC: Catalytic Converters
It is expensive, but it will last. This is used in European classes where the car is required to retain the converter.

HiFlite999

iTrader: (2)

My $100 metallic-substrate Magnaflow #59959 is still fine after nearly 20k miles. While it's done many "1/4 miles" and one AutoX, it's not been on the track yet. I hope to fix that problem this summer.

RIWWP

iTrader: (2)

HiFlite, I've been forgetting to add your cat info on the modding thread. My apologies. I've just corrected that, if you could take a look for accuracy.

I don't have your original information set, so I grabbed your comment here. I will adjust whatever you recommend.

HiFlite999

iTrader: (2)

^ Your entry is good enough for now. Besides a track day or two, I'd like to have a 'sniffer' test done on it (not required in my location). I suspect it will fail, though be much better for the environment and the gf's nose than running catless. If the required emissions test is only one of pulling codes, it will pass though; no codes have yet come up on me.

You might mention a couple other things in the thread for noobs and/or, mods. If you have a functioning OEM cat, keep it - there might be no way to pass an emissions test without swapping it back in. If you want to gut it, help a California member out by swapping for his non-functional one first. To buy an OEM from a Mazda dealer, you must have a core to trade in. For "49-state" street-only use Magnaflow sells an OEM bolt in replacement for about $350 (I have no experience with it).

Also, you (I think) never mention that a catless rotary exhaust STINKS. The high combustion temps form NOx and SOx which not only smell, they are poisonous. (Very wife un-friendly, too.)

RIWWP

iTrader: (2)

'Stink' is subjective. Some like it, others hate it, others don't even smell it. But agreed, wives hate smelly sox...

I'll note it.

HiFlite999

iTrader: (2)

Seems quite objective to me:

Girl no likey --> me get no nooky --> that STINKS!

HiFlite999

iTrader: (2)

Explode64: Concensus is that exhaust resonance effects play little role in the Renesis since there is no intake/exhaust overlap. Given that, the lower the backpressure, the better. So yes, the larger diameter tubing is a plus, as well as removing the cat (if allowed).

We had an active member who campaigned 2-rotor RX-8s on road racing circuits. Go to "Search - Advanced" and search for posts by "Eric Meyer". There is all sorts of detailed information in his posts. Much of it will save you a small fortune.

TeamRX8

iTrader: (25)

The Metalit cats are made by Emitec. Since you're in NZ it's likely to be from Knightsport and this is likely what it looks like (or did when new) and its 300 cpi so you will be better off without it for max racing performance.

Explode64

Cheers TeamRX8. Thats exactly what it looks like.
May flick it and make my own 3" system

Spin9k

Are you speaking of this cat working & not dying on a properly tuned track car? I didn't think anything could survive 2000+ F deg rotary exhaust very long during 30min-60min periods of full bore track operation and so required cat delete. Which of HJS's cats have you used or seen used successfully?

HiFlite999

iTrader: (2)

If I'm not mistaken, it's used by TeamRX8 with success.

TeamRX8

iTrader: (25)

generally speaking a Renesis isn't likely spitting out 2000 degF exhaust temps, or at least not for long, but they are rated for 1070 degC max I believe. There are many other factors on why a cat may last or not, like excessive oil in the exhaust stream, etc.

The GT1407 is best flowing (and most expensive) one they sell, rated for 400 HP per cat; 3" in/out and and 5.7" OD with a 100 cpi rating. There are smaller ones that will work I just wanted to make sure there was an absolutely minimum flow restriction, in this case likely insignificant - none. I know of one that is supposedly not catalyzing any more, but otherwise have never heard of any that plugged or failed structurally.

the infamous Team cocktail shaker