When I look at the Grand Am GT class manufacturers, and I think about which of these would more than likely spit flames out it’s exhaust pipe like a dragon, Mazda and their RX8R is not what comes to mind. I think of Chevy and their big V8 engines in their Corvettes and Camaros. I also think of BMW and their V8 in the M3. Porsche, not so much, I think of them as too refined to have fire. Mazda, hah, no way!! They use a 3 rotary engine (2 in the street going RX8) and they scream like a crotch rocket on steroids. Certainly not what comes to mind when you think of a fire breathing dragon!! A dragon roars, not screams, but nonetheless, the Mazda is the one car in the entire field that puts on a fireworks show.
After searching for a bit, I was able to find an explanation as to why this happens. The boys at grand-am.com forums were able to enlighten the public, so I am going to give you their explanation in my own words:
When it comes to rotary engines, it is essential to lubricate the apex seals, or you will completely demolish your engine. In the road going RX8s there is a small motor that injects the lubricant into the engine. In racing spec cars, this motor can be a point of failure, and absolutely disastrous to the entire block if this fails, so teams commonly put the lubricant right into the fuel tank. When you lift your foot off the throttle at 8000 rpms, very little fuel (and thusly the oil) is getting to the cylinders and still cause excessive wear on the block. So what the engineers have done to counteract this is to adder a larger idle fuel jet to the carburetor. (There is also something comparable to guys using FI.) In the end, what ends up happening is, there is more fuel than necessary and gets sent out the exhaust, igniting once it reaches the oxygen of the outside world. Since race cars use straight pipes, the excess fuel doesn’t get picked up in the catalytic converter. For people wanting to try this on their own car, be forewarned that this will eat mufflers for lunch.
For more information, visit the actual thread: grand-am.com