Wikipedia
 

Fuel consumption and emissions

Just as the shape of the Wankel combustion chamber prevents preignition, it also leads to incomplete combustion of the air-fuel charge, with the remaining unburned hydrocarbons released into the exhaust. While manufacturers of piston-engine cars were turning to expensive catalytic converters to completely oxidize the unburned hydrocarbons, Mazda was able to avoid this cost by enriching the air/fuel mixture and increasing the amount of unburned hydrocarbons in the exhaust to actually support complete combustion in a 'thermal reactor' (an enlarged open chamber in the exhaust manifold) without the need for a catalytic converter, thereby producing a clean exhaust at the cost of some extra fuel consumption. World gasoline prices rose sharply at the time Mazda introduced their Wankel engine, making the cleaner exhaust/increased fuel consumption tradeoff an unwelcome one for consumers.[citation needed]

In Mazda's RX-8 with the Renesis engine, fuel consumption is now within normal limits while passing California State emissions requirements. The exhaust ports, which in earlier Mazda rotaries were located in the rotor housings, were moved to the sides of the combustion chamber.

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Bla bla bla. Does this mean the renesis runs rich? If so, can the mix be leaned out?

you havn't smelled the extra fuel just after starting it up? you can get it leaned out with a good tune....

Thanks Maniac,

To increase performance and gas mileage?

Would I need to kill the cat?

What hardware would I need to perform the tune? Can shops regularly do this?

best tuning option is the accessport bought from mazdamaniac. He offers free tuning services, you just have to wait in line till he can get to your specific tune which can take up to a month. With that, you'll also get a few other useful features and things thrown into the tune (such as turning the fans on earlier for better cooling, better oil flow etc).

If you get it leaned out, the cat will fail much quicker. You can either get a better cat or go catless. Another benefit of the AP from MM is that it can turn off the CEL caused by not having a cat.

Hope this helps.

i think i just cried a little. this solves like a good number of problems.