Many different designs for rotary mechanisms have been attempted over the last 400 years, but what makes the NSU-Wankel engine, which Mazda adopted, stand out is its "rice ball-shaped" (triangular) rotor housing. Because of this design, three separate chambers are created between the rotor and the inner wall of the rotor housing. These chambers smoothly expand and contract in a constant cycle as the rotor spins. See the rotary engine in motion on the right.
The Rotary Engine of Mazda continues to evolve farther into the future. The new generation Rotary Engine "RENESIS" makes it superbly environmentally friendly with zero CO2 and almost zero NOx emissions. Mazda began commercial leasing in 2006, and currently many organizations and government bodies are enjoying the RX-8 Hydrogen RE.
New generation rotary engine "RENESIS" stands for "the RE(rotary engine)'s GENESIS". The RENESIS was given to the engine as exhibited in Tokyo Motor Show, 1999 of the RX-01, after which RENESIS was meticulously prepared for series production.
By capitalizing on the instrinsic benefits of the RENESIS rotary engine namely, low weight, compact size and high performance, Mazda was able to develop the RX-8, a wholly new concept, 4-door 4-seater Genuine sports car.
RENESIS is a 654cc x 2rotor engine that generates an outstanding 250 PS(184kW) maximum power at 8500rpm and 216 N.m (22.0 kg-m) maximum torque at 5500rpm.* RENESIS also shows a vast improvement in terms of fuel-efficiency and exhaust gas emissions.
*Figures are for the 6-port engine. Maximum power output is the specification for Japan and North America.
Side-Exhaust and Side-Intake Ports
A key innovation for the RENESIS is its side-exhaust and side-intake port configuration. Previous RE designs located the exhaust ports in the rotor housing (peripheral port, #1), whereas the latest version has its exhaust ports in the rotor housing #2, where the intake ports are also located.
The chief advantage of this side-exhaust / side-intake port layout is that it permits elimination of intake/exhaust port timing overlap, elimination the retention and carry-over of exhaust gas and encouraging more stable combustion. In addition, where the previous engine had one peripheral exhaust port per rotor chamber, RENESIS has two side ports, approximately doubling the port area. The new exhaust arrangement reduces exhaust gas flow-resistance, and while assuring ample exhaust port area, allows delay of the exhaust port opening for a longer expansion cycle, to raise thermal efficiency, power output and fuel economy.
Another major advantage of the side exhaust port is that it allows engineers more freedom to optimize port profiles. With RENESIS, both the 6-port engine and the 4-port engine have intake port cross-sectional area almost 30% greater than the previous engine.