Mazda 13B-MSP Renesis

The Mazda 13B-MSP, known by the name Renesis, is a twin-rotor Wankel engine that Mazda introduced in production with the 2004 model-year RX-8. It evolves the earlier 13B family and takes its MSP label from its multi-side-port layout, in which the exhaust ports sit in the side housing instead of around the rotor housing. That change removes the overlap between intake and exhaust timing and was aimed at cutting emissions and fuel use, two long-standing weaknesses of rotary engines. Mazda also redesigned the rotor seals, using new side seals, low-height apex seals and a second cut-off ring, and added a water jacket passage to the side housing to stop carbon building up at the exhaust port. Unlike the turbocharged 13B-REW of the RX-7 it is naturally aspirated. It displaces 654 cc per rotor chamber and is rated as a 1.3 litre engine by Mazda, and the unmodified engine is described as weighing 112 kg. The Renesis won the International Engine of the Year and Best New Engine awards in 2003 and appeared on the Ward's 10 Best Engines list for 2004 and 2005.