Electrical - "Is something burning?"

We all know what the wiring in old cars is like. You have old wiring looms that are held together by strips of gooey electrical tape and the copper (once bare) is impossible to solder. Yuck. Not only that but the Dazda had already had the engine bay wiring loom ripped to pieces during the previous rotary engine installation. What a mess! After we ripped out the heavy dashboard, heater, fan and vent controls, we were left with something that resembled a mainframe that had been dropped out of a 20 storey building. At that point we decided to rewire the entire car...

First to get fabricated was the ally dash. The gauges are positioned so that the co-driver can see them easily. The only gauge within easy view of the driver is the tachometer, which is mounted directly behind the steering wheel. In hindsight we should've tilted the dash and extended the top to provide some shade. Looking at the gauges on the skew meant readings had to be corrected for parallax error. A decent fuse box with circuit breakers would've also been a good idea; as searching around for a busted fuse during a race is a waste of precious time.

All gauges are VDO (Vision series) that we happened to pick up relatively cheaply from the paper. Note that all are backlit and we haven't had any problems with any of them.

My one complaint is that because of the angle of the dash (we obviously weren't thinking about this when we bent it up) the tacho is on rather an odd angle and a bit low. When you're cruising along at over 100kph on some gravel/sandy track the last thing you need to do is take your line-of-sight away from the road. For this reason we may (in the future) remount the tacho on top of the steering column, directly behind the wheel.

Whilst on the subject of tachos, you should also seriously think about installing a rev limiter, or at least a rev warning buzzer. For the sake of a couple of hundred bucks you can save a rather expensive engine.

Couple of things to note:

The switches are all metal toggle SPST, where up is ON. This is so that: 1. They don't get broken off during the rough and tumble of a race, and 2. In the event of a roll-over/crash it's very easy to turn everything off quickly.
The speedo is connected, however it required an adapter to convert from the Mazda gearbox drive to the Datsun cable (that screws into the rear of the gauge). The adapter also contains a small gearbox that provides the correct ratio for distance calibration with the existing diff and tyre combination. Only problem with this is the location of the adapter. It's right next to the gearbox and pointing downwards at a 45 degree angle. Seems to be a bit prone, however you can't move it to the top of the cable as the adapter drive does require some torque and you'd break the speedo cable. Good ol' catch 22 situation.

As an aside, the fire-extinguisher is required to be mounted with a metal bracket and easily reachable by both occupants of the car.

Older rotaries use dual coils (series 5 RX7's had four in two modules). One for the leading plugs on each rotor, and one for the trailing. We found a nice clean spot to mount these (using the stock bracket) behind the strut tower. To simplify the wiring these coils both have a built in ballast resistor (In hindsight this probably wasn't a smart idea. As the engine got 'dusted' it was harder and harder to start and the in-built ballast resistors couldn't be bypassed to produce a fatter spark).

You can see the series 3 RX7 electronic ignition module directly behind the coils. This drives the coils, which in turn drive the series 3 RX7 dizzy. Note that the RX7 module/dizzy combination is a direct swap for the original dual point dizzy.

We run NGK BE9V's whilst racing to keep the plug temperature down. These have platinum tipped electrodes and once the warm the engine will quite happily run on a set of these for the entire race (400-500k's). However, these plugs tend to foul quit easily at idle (due to the oversized float bowl inlet valve), but if the engine is running they'll clear out after a couple of hundred metres. If we're moving the car around, on and off trailers, etc, we put in a hotter plug (around a 6 or 7) which works just dandy.

Note that the coil leads are actually cable-tied to the strut brace; as we've had situations were they've fallen off due to the excessive motion of the car.

We've installed a series 4 RX7 starter motor as this item has an extra tooth in the pinion gear (as compared to an earlier item). Because of the extra tooth the offset of the starter motor is slightly different to the standard; however this is a problem with fire-wall clearance and not bolt location.

We've also acquired a series 4 RX7 alternator. This has a built in regulator and is rated at 60A (rather higher than the standard item). The alternator pulley has also been exchanged with a custom dual pulley. The crankshaft pulley has also been downsized to accommodate the higher rev range. This brings both the alternator and water pump back into their normal operating ranges. This is based on a normal engine's average RPM being around 4000, whilst this engine is constantly around 6500.

It is a MUST that you protect your lights in racing such as this. It is surprising just how much muck another car can kick up! We learnt the lesson the hard way and had 3 of the 4 lights at the front of the car smashed by flying dirt during a single lap of a short-course event.

These protectors are made out of standard Perspex (you can use polycarb if you want to spend the extra bucks). The single sheet is simply tekked to the existing spotlight cover clips and flexes whenever hit. Since installing these we haven't broken a single light. :)