First Generation Mazda RX7
Throttle Body Injection, AND Turbo

The first generation Mazda rotary cars are fast becoming classics. The carburator on these cars was very complex, and prone to icing. The power from the 12a engine was nothing compaired to the 13b that followed. Here's one solution to these shortcomings.

The process involves installing the following:

• Remove the carburator and install the adapter plate and the throttle body
• A Volvo or Subaru turbo on a modified 1982 exhaust manifold, oil and coolant lines
• 4 sensors, including a 2 bar map sensor and a map sensor scaler module.
• EFI wiring harness, ignition and vss modules, and ECU with turbo tuned chip
• Knock sensor and indicator
• A 2nd heated oxygen sensor and a mixture meter.
• Boost gauge
• EFI fuel pump; and plumb the fuel system
• Intercooler, TBI turbo cover, and the turbo piping
• Blow-off valve, if not built in to the turbo, and manual boost controller
• Exhaust header pipe.

The turbo cover is cast alumnium and covers the entire top of the TBI including the fuel pressure regulator. This insures that the fuel pressure rises with the turbo boost.

A 2 bar map sensor is used with a scaler module to provide the ECU with a signal that varies from 0 to 5 volts over -14.7 to 7 psi (gauge). This way the engine can run closed loop under low boost situations.

The exhaust head pipe requires a flex joint or a flex pipe to help keep engine movement from over stressing the turbo. A ball in socket spring joint, such as front wheel drive vehicles use, works well.

This is also a good way to destroy the engine if care is not taken to avoid detonation. This system is designed for low boost. Higher boost can be used with internal engine modifications, more instrumentation and additional fuel delivery, but is much more prone to engine destruction, and should be considered only by wealthy racers.

The TBI injection can be used alone without turbocharging. The air flow rates are better than the stock carburator, and with porting and headers, the engine can do almost as well as the turbo setup.