Repair And Fix it

First released in 1978 and spanning three generations, Mazdas rotary-powered RX-7 grew to become one of the most easily recognizable and sought-after sports cars to come from Japan. Now out of production, the RX-7 is not only enjoyed by enthusiasts, but is also competitive in several classes of racing. With its single-minded philosophy and emphasis on performance, the 13B-REW (the motor designation of the last production model) is able to crank out 255 horsepower, all from a minuscule 1.3-liter twin-rotor Wankel engine bolstered by sequential twin-turbos. The drawback of this design -- and power output -- is the extreme heat and stress to which engine components are subjected, in some cases requiring expensive rebuilds after just 60,000 miles. The engine can be quite finicky to troubleshoot.

Instructions

1

Attach an engine code reader to the Mazdas diagnostic port to quickly identify any faulty components.

2

Tune up the vehicle by installing new filters (oil, air, fuel) and replacing vital engine fluids. Pay special attention to the engine coolant -- which should have no traces of dirt or oil. If you are experiencing any sort of hesitation, rough idle, or inconsistent power delivery, thoroughly inspect and replace any worn ignition components such as the ignition coil, igniter module and spark plugs/wires. This can cure a myriad of symptoms and prevent new ones from developing.

3

Install a new set of silicone vacuum lines (silicone withstands heat better and stays more flexible). The stock lines will often become cracked or brittle due to prolonged exposure to heat, causing erratic boost levels and idle surge.

4

Connect a data-logger unit to your vehicle in order to further investigate engine conditions. The data-logger is able to read values directly from the engine control unit, and displays a list of vital parameters in real time. This will help identify pre-ignition (knock) events, as well as display the various timing and fuel maps under varying engine loads.

5

Attach a multimeter to your battery and alternator to test for correct voltages. Low readings (under 12 volts) indicate a weak system, potentially making the vehicle difficult to start, or even causing a backfire through the exhaust.

The Mazda 20B rotary engine belongs to a very rare classification of engines known as Wankel rotary engines. Wankel rotary engines do not have traditional cylinder-and-piston designs. Instead, they operate with a rotating reaction chamber. The Wankel rotary engine has roots that go all the way back to early propeller-driven aviation, and it combines high engine power with a great deal of space reduction, making it a good choice for a sports car motor.

General Wankel Engine Specifications

A Wankel rotary engine operates using a triangular prism-shaped internal rotating combustion structure. Each face of the prism performs the same function as the cylinder head in a typical engine. Rather than having a simple up-and-down piston movement, the Wankel rotary engines entire internal structure moves around within the engine block enclosure. Because of the greater mass of the internal moving parts, Wankel engines need to be more securely mounted to the vehicle frame than conventional cylinder/piston engines in order to avoid damage from vibrations.

20B Engine Specifications

The Mazda 20B engines central triangular reaction surfaces can be removed from the camshaft, a notable change from early types of Wankel engine where the two pieces were fused. This makes for simpler repairs and engine rebuilding. The entire engine block of the Mazda 20B engine can be disassembled into 11 smaller replaceable components, which to some extent addresses mechanic complaints about other manufactures Wankel engines in terms of finding replacement parts. The modular design makes replacement parts easier to stockpile and simpler to custom-fabricate should the need arise. The 20B engine has a compact design, and retains a high horsepower output at 250 HP stock without enhancements.

20B Engine Successors

Motor Trends Magazines 2009 article "Mazda RX-7 Dilemma" pointed out the notable absence of a next-generation Mazda rotary-engine sports car. It did, however, showcase a new hybrid minivan powered by a hydrogen-compatible rotary engine. This translates into a possible future for the technology derived from creating and supporting the 20B engine. It also signals a possible future trend in mainstream, family rotary-engine vehicles. Previously, the rotary engine has been reserved for high-performance sports cars, motorcycles and aircraft.