Catalytic Converter Question

Mazda RX7 and RX8 Suspension, Intakes, Headers, Exhaust, Shocks, Springs, Sway Bars, Brake Kits, Autocross and track mods.

Catalytic Converter Question

Postby raven32 » Wed May 12, 2010 8:02 am

Brian,

This is my first post on your forum, and I also want to say my friends and I in Florida love your site!! I recently bought a used RX8 with 24000 miles on it. I have always liked the rotary engine, and I have tooled around with them in the past (my friend and I had Gen 2 RX7s) I also have a friend with a 99 Miata, love whipping that car around BTW. Anyways, we both are looking to get into some SCCA racing again, and we are starting to do some minor mods to my car.

I see allot of different exhaust options, cat back, race pipes, and full set ups like OBX sports. Its clear to me that most exhaust companies including racing beat would just assume get rid of the Converter completely and replace it with some sort of resonator or test pipe. Neither of these have any brick filtering inside to lower the emissions and will ultimately leave the check engine light on.

I will admit, on our old RX7s we both ended up losing the Cat because they would burn out or clog to easy, and the car made a little more power without it, coupled with twin dynomax mufflers out the back. I’m sure the same is true for the renesis, as it is just a revised version of that old NA 13b engine in the RX7. However, all the rule books for SCCA and other events like redline time attack, require a Cat and from what I can interpret, no check engine light on.

So my question is, do you or anyone you might know have a solution to this? Maybe a race Cat of sorts? I’ve heard people say they don’t work.
Do the SCCA rules allow the welding in of a Race Cat (like from Random Technologies) or are we just stuck with the stock, Big, Heavy, restrictive Cat that will
eventually clog and have to be replaced?

Your thoughts?

Scott
raven32
 
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Re: Catalytic Converter Question

Postby Brian » Wed May 12, 2010 7:58 pm

Hi Scott,

Welcome. I wish that I had a good answer for you on the exhaust....but I don't. Moreover, even if a highflow exists for the exhaust catalyst, we are not seeing much gain in the RX8 from exhaust mods anyway (even removal of the cat). When Racing Beat says we only get a couple of horsepower from replacement of each of the exhaust sections, including the header, that has been our experience too. Thus, it is typical with the RX8 to add a highflow cat-back and then focus on performance of other parts of the package. We have found MUCH better bang for the buck in focusing our dollars on improvements to suspension, wheels, and tires with the RX8. The RX8 has such a wonderful chassis that getting more tire on the ground, and keeping it flat on the ground in the corners, will help your lap times FAR more than the few hp you get from playing with exhaust mods upstream of the muffler.
Brian Goodwin
Good-Win Racing
www.good-win-racing.com
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Re: Catalytic Converter Question

Postby raven32 » Thu May 13, 2010 6:19 am

Thanks for the reply, and that was what I was afraid of, but I guess it does not hurt to ask.

To me its not so much the HP gain as it is the weight, the stock monstrousity is like 40-50 lbs at least. I also know that if your driving heavy and putting additives like lubrication in fuel for engine longevity, plus with excess fuel and heat, its eventually going to clog up and have to be replaced.

Im going to look into this more and share with everyone what I come up with as far as a lighter (and less restrictive) set up, weigh in both setups before an after.

Also, looking to purchase some progress springs and tokico shocks in the very near future. Not quite ready to drop coilover money yet. I already have my silver Enkie NT03+M 18x9.5 +27 with 265-35/18 dunlop (switching to falkens next set) tires on my black car.
Once I tighten up the suspension Ill post some pics in the enkie wheel section so customers can see how they look with the springs and rear camber in a actual photo, like your blue car.
raven32
 
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Re: Catalytic Converter Question

Postby Brian » Thu May 13, 2010 9:36 am

I agree with the weight reduction. I really liked the prototype Racing Beat Race single that we tested for them. But for the production version they changed it to dump under the car. They did that to reduce sound levels behind the car....but it massively raises sound IN the car. Thus, many customers start with that Racing Beat single and have a local muffler shop continue the end out behind the car.
Brian Goodwin
Good-Win Racing
www.good-win-racing.com
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