Our Renesis/RX-8 Lightened Rotor Assemblies are machined lightened using a CNC (computer numerically controlled) mill. These rotors are based on the stock RX-8 rotors and the initial weight of each rotor is approximately 9.2 pounds, and upon completion of the machining process the weight is reduced to approximately 9.0 pounds.
Jim Mederer, Racing Beat's co-founder and chief engineer, addresses the benefits of lightening the rotors in a high-performance or boosted engine application:
"Bearing loads in a rotary engine are primarily the result of two forces - centrifugal force and combustion gas loads. At low RPM, gas loads are the majority of the total load on the bearings. However, at high RPMs, centrifugal loads predominate since they increase proportional to the square of the RPM. Since it is desirable to continue to use most or all of the stock RPM range, the only way to decrease that bearing load is to reduce the mass (weight) of the rotors. Mazda has already lightened the rotors significantly on the Renesis engine, so we were not able to make further large reductions in rotor weight, but we did what we could in developing the RX8 Lightened Rotors. Since boosting (mechanical or turbo supercharger) always increases gas loads, anything you can do to reduce centrifugal loads is guaranteed to improve bearing life AND reduce flexing of the eccentric shaft - both helpful to reliability."
The Racing Beat machining process involves the installation of a snap ring between the rotor gear and the basic rotor to prevent the rotor gear from working away from the basic rotor at higher RPM. The ring gear is removed using a hydraulic press, and then an indexing groove is cut into both the rotor and the ring gear. A snap-ring is placed into the groove on the ring gear, and the assembly is placed into the rotor. Once the snap-ring expands into the groove on the rotor, the ring gear is permanently seated onto the rotor.
After completion of the machining process, we fully balance each pair of rotors with matching front and rear counterweights to provide an assembly capable of high RPM operation.
Each assembly includes two (2) lightened rotors, and one (1) front, and one (1) rear counterweight. Rotor housing shown in photo is not included.
|1974 - 1985||Mazda||RX-7||12A|