13B-MSP Renesis
The Renesis engine – also 13B-MSP (Multi-Side Port) – which first appeared in production in the 2003 Mazda RX-8, is an evolution of the previous 13B. It was designed to reduce exhaust emission and improve fuel economy, which were two of the most recurrent drawbacks of rotary engines. It is naturally aspirated, unlike its predecessors from the 13B range, and therefore less powerful than Mazda RX-7's twin-turbocharged 13B-REW (280 hp).
The Renesis design features two major changes from its predecessors. First, the exhaust ports are not peripheral but are located on the side of the housing, which eliminates overlap and allows redesign of the intake port area. This produced noticeably more power thanks to an increased effective compression ratio. Secondly, the rotors are sealed differently through the use of redesigned side seals, low-height apex seals and the addition of a second cut-off ring.
These and other innovative technologies allow the Renesis to achieve 49% higher output and reduced fuel consumption and emissions (the RX-8 meets LEV-II). The Renesis won International Engine of the Year and Best New Engine awards 2003 and also holds the "2.5 to 3 liter" (note that the engine is designated as a 1.3 liter by Mazda) size award for 2003 and 2004, where it is considered a 2.6 L engine. Finally, it was on the Ward's 10 Best Engines list for 2004 and 2005.
The Renesis has also been adapted for a dual-fuel use, allowing it to run on gasoline or hydrogen.
All the Mazda rotary engines have been praised because of their light weight. The unmodified 13B-MSP Renesis Engine has a weight of 122 kg (247 lbs), including all standard attachments (except airbox), but without engine fluids (such as coolant, oil, etc.).
Read more about this topic: Mazda Wankel Engine