onepointone

ok, im in the final stages of my exhaust system, i have the header and muffler. my dad's friend said his son redid a rx7 and used a generic cat (which im planning such as catco) and it burned up. me and my dad think maybe he had a fuel problem or something. my question is.. is this normal? i really dont want to dump $300 on a mazda cat, and i cant afford the fine if im caught without one. could someone tell me if there is something special about a mazda cat. or if a catco or generic cat wont hold up to the heat? i think it should.. but i thought i would ask here

Suparslinc

what kind of header did you get?

onepointone

racing beat header, ractive muffler

MIKE-P-28

iTrader: (1)

The heat , the rotarys hot breathe will destroy must aftermarket cats

onepointone

have you or nyone else used this?

Suparslinc

with the racing beat header you also need the presilencer. It's $130 from www.racingbeat.com

You cannot bolt up a stock OR aftermarket converter to the RB header. In order to pass emmisions you will need to put a stock manifold and at least the replacement cat from RB on; I think the cheapest you can find an aftermarket cat is in the $270 range.

onepointone

i was trying to go without the presilencer. i was going to get a flange/collecter that bolts up to the header, then get the cat welded to the collecter. i dont have to worry about emissions because they dont do it here. as far as inspection, i have a friend with a 3rd gen who is a mechanic, and i think he will be able to pass me, if not im keeping the stock exhaust to bolt back up for inspection, then it comes back off.

doers anyone know actually exhaust temps it gets to by anychance?

Suparslinc

1200F

RacerX7fb

Rotary EGTs can run up around 1700 to 2000 at WOT...That's HOT! Volcanic lava is around 2200 for comparison. Mazda designed their cats to do the job for just that.
Many Spec RX-7s that I have seen use 'CARSOUND' brand ( posted this before , not a plug for them BTW )
I may have a muffler shop fabricate me one to bolt up to my header, costs around $120 so its not bad.
Are you in VA..I thought there were emissions testing there?

Keaponlaffen

I find that hard to believe, 'cause that would mean that the header would melt.... and steel melts at something like 3500 degrees if I'm not mistaken....

RacerX7fb

http://vulcan.wr.usgs.gov/Outreach/A...volcano.html.. that's why we're on the web.
which gives steel another 1300 degrees before it melts

Suparslinc

damn I just posted that off the top of my head, I don't really know for sure. I'm sticking by ~1200-1400F as a top limit, but I don't know for sure. I know you find it on the internet with a simple search.

PS your webpage won't come up for me.

PPS just because you have it on the web doesn't make it a fact. No offense racer

RacerX7fb

yeah damn site link not working..no offense taken, well its a USGS (United States Geological Survey) Government site, they do the official studies on that kind of stuff: Lava temps ranging from 1900 to 2200 degrees F.
I should've also made reference as to where I got the EGT info : How to Modify Your MAZDA RX-7 by Dave Emanuel with Jim Downing in the Exhaust chapter, At full throttle rotary exhaust temperatures are extremely high-possibly reaching 1600-1800F at WOT. Racing Beat catalog says 1700-2000F. so that puts us right up there with the volcanic stuff.
We can ask the turbo guys who have an EGT gauge what theirs read..anyone?

onepointone

so a catco cat which is stainless steal wont hold up? can anyone direct me to a cat that will thats at a reasonable price? i really appreciate this, i didnt even consider the cat wouldnt be able to hold up, i was just going to slap one on and be on my way. i would still like to use one, i just need to know if it will hold up.

MIKE-P-28

iTrader: (1)

I opted for no EGT, cause it would probally stayed pegged... The hot and cold and hot and cold cycles of the engine, are evil enough to crack the cast iron that enough for me...

Anyone ever use regular exhasut gaskets of the pipes further down the exhasut?

The burn quite nicely LOL