The Mazda Renesis engine used on the RX-8 sport coupe is a 1.3-liter Wankel rotary engine that produces up to 247 horsepower in the High-Power trim of the vehicle. The engine is codenamed the 13B-MSP internally and features a dual-rotor design and side exhaust ports that improve the compression ratio and efficiency of the engine over the 13B rotary engine used in the RX-7.
The Mazda 13B-MSP rotary engine uses a rotating, rounded triangle as its primary engine component rather than traditional cylinders in an engine design that is unique to Mazda vehicles among major car manufacturers and unique to the RX-8 among Mazda production cars of its era. While the High-Power RX-8's engine was tuned to produce 247 horsepower, the engines of RX-8s sold with automatic transmissions produced 215 horsepower after 2006. The loss of power was due to the reduction of the maximum speed of the engine from 9,000 rpm to 7,500 rpm in these models, since no automatic transmission capable of dealing with the high speed of the full-power 13B-MSP was available at the time. The 13B-MSP was never offered with a factory turbocharging option, so the RX-8's engine was never offered in a form as powerful as the older RX-7's twin-turbocharged 13B-REW that produced up to 280 horsepower.