Experiment 20 (01/01/03)- Project RX7 - Computerised Instrumentation System

Engineer Xavier Borg - Blaze Labs Research

This page shows a few details of my final year university thesis project work which I had designed during 1993 at the completion of my Mechanical & Electrical Engineering courses. My thesis covered the part concerning the computerised instrumentation system. The rest of the mods in the engine compartment were done later on as a hobby. Not a research related project, but shows how engineering can be real fun.

The (at that time brand new) third generation rotary engine Mazda Efini RX7 seemed most suitable to carry out this project on, as it had a lot of useful and easily to be tapped into electronic sensors, readily built-in for use by its factory ECU (engine control unit). The aim of the project was to show that current display and electronic technology could be used to replace the old fashioned analogue and mostly mechanical instruments by a totally solid state, more functional system, which would be more visually pleasing, whilst capable of verbally and visually communicating malfunctions to its driver via voice synthesis. The LCD screen was manufactured OEM in Japan. All the project work was performed in my own electronics workshop.

High brightness and contrast VGA LCD display can be viewed in direct sunlight

The system is built into a modified RX7 cluster hood. I have got the hood shell from Japan in order to keep the original analogue hood intact. The new instrumentation display was than mounted on a piece of 2mm thick aluminium, leather coated and glued over this shell, giving a flawless factory looking instrumentation hood.

Window on central part of the screen operates in 5 modes

Functions covered by the system are:

  • Fuel level (left bargraph)
  • Battery voltage (left bargraph)
  • Oil pressure (left bargraph)
  • Indicator lamps
  • Engine revs (central bargraph)
  • G-force meter (central bargraph)
  • Speedometer (central digital)
  • Trip counter (central digital)
  • Odometer (central digital)
  • Gear position (central digital)
  • Date, time and ambient temperature (alphanumeric)
  • Turbo boost pressure (right analogue)
  • EGO sensor (right analogue)
  • Engine temperature (right analogue)
  • Catalytic converter overheating indicator
  • Alternator charge function indicator
  • Oil level indicator
  • ABS system function indicator
  • Radiator fluid level indicator
  • Rear window demister indicator
  • Headlamp indicator
  • Brake/ brake fluid level indicator

  • Six buttons provide access to all functions and modes

    Central window display can plot various functions in real time:

  • Mode 1: Plots Turbo boost pressure vs RPM
  • Mode 2: Plots BHP vs RPM
  • Mode 3: Sytem information
  • Mode 4: Plots Torque vs RPM
  • Mode 5: System self diagnostics mode

  • Apart from the visual indicators, 20 different malfunctions can be reported by a (female) synthesised voice messaging system. An optional voice recognition interface has been also designed, but actually I have never found any useful purpose for it other than to start the engine.

    Other mods done later (not part of the instrumentation project) to reliably achieve 300BHP using the stock ECU and stock rotary engine and turbos.

    All aluminium intercooler ducting for improved airflow

    Upgraded intercooler for reduced intake temperatures

    Cusco tower brace, extra ground and hyper voltage system

    Fan timer to eliminate baking hood components after power down

    The fan timer (next to the four fan realys) activates the low speed fan after the engine is turned off. The unit activates itself only if the underhood temperature exceeds 60 degrees celcius and times out after 10 minutes or when the temperature is brought down to 40 degrees, whichever comes first. Actually Mazda did try to add this timer function on later models, but it seems that it never got it to work properly, so I decided to make my own. Also shown is an engine torque damper, which reduces the torque stress of the engine over its mountings and over its transmission when driven hard. Brake cylinder support reduces brake spongy feeling, I think this is more effective than changing to steel braided brake lines.

    Slotted/ dimpled rotors for reliable braking

    These brakes help a lot when something happens while overspeeding at over 200km/hr!

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