Five Worst Engines | Overhyped and Underengineered
DSPORT Five Worst Engines

5) Mazda 13B-MSP Renesis

Renesis Spells Exodus for the Rotary / Rotary without Turbo

Mazda has been the only manufacturer to champion the cause of the Rotary powerplant. A turbocharged rotary engine had proudly served Mazda in 5 a variety of platforms since 1965 with the twin turbocharged 13B- REW representing the pinnacle of rotary street performance. When the RX7 was discontinued for US sale in 1995, rotary fans waited anxiously for nine years before a new RX platform would be brought back to America. Unfortunately, the capable RX-8 platform took a step backwards with its naturally-aspirated 13B-MSP (Multi Side Port) Renesis engine. To its credit, this engine offered improved fuel efficiency and reduced emissions but at the sacrifice of power production. In fact, too much power was sacrificed, as the optimistic factory horsepower rating of the RX-8 caused uproar among owners and prompted a corporate buy-back program to satisfy disgruntled consumers. Positioned to compete with Nissan’s 350Z platform, some aftermarket tuners produced forced induction solutions to improve the Renesis power output. However, these costly upgrades could only bring the rotary’s performance on par with unmodified 350Z levels. Of the available solutions, many faced challenges because of limited tuning options and an uncooperative factory engine management system that seemed to negate any power gains shortly after installation. This discouraged the aftermarket from seriously pursuing power with this mill and subsequently stalled any RX-8 owner seeking respectable power from their ride. Mazda ceased production of the RX-8 with the 2011 model year. Had our government allowed a turbocharged version of the 13B- MSP, this engine may have easily made the list as one of the Ten Best. 13B-MSP OPINION WHAT’S HOT: • Lightweight • 1st production rotary engine with side port exhaust • Highest factory-rated naturally-aspirated 13B engine • High specific output • One of the most fuel-efficient rotaries WHAT’S NOT: • Engine overrated from the factory forcing corporate buy back program • Does not take well to modifications – difficult to produce horsepower due to uncooperative ECU • Lacks factory turbocharger(s) • Emissions systems cripple this rotary • Limited aftermarket support • Lacks torque because of limited displacement

SPEC SHEET

ENGINE
Manufacturer: Mazda
Years In Production: 2004-2011
Engine Code: 13B-MSP (Renesis)
Displacement (cc): 1,308cc
Peak Horsepower (@ RPM): 232-238 hp @ 8,500 RPM
Peak Torque (@ RPM): 159 lb-ft @ 5,500 RPM
Pistons/Compression Ratio: 10.0:1
Rotor Material: Aluminum
Rotor Housing Material: Aluminum
Intake Manifold / Throttle Body: Single, 3-stage Variable Induction System
Fuel Injectors: 550 cc/min (Primary), 850 cc/min (Secondary)
Ignition System: Coil-on-plug
Applications: 2004-2011 Mazda RX-8 (SE3P)
13B-MSP

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