Whilst the engine was sitting in the garage waiting to go back in the car, I couldn't resist tackling the nasty wiring loom. As I'd raced through the last part of the build to get the car to meet the rolling road deadline, I'd cut corners and the wnd result looked terrible. Granted it worked, but it let the car down. Having the engine out of the car was the perfect excuse to redo it.
Initially I thought I'd just redo the engine loom but it's reasonably interlinked with the dash loom so I decided in for a penny, in for a pound....
I got some approximate figures to outsource the engine loom to professional motorsport loom-makers but the costs were hovering around the £1,000 mark which I could ill afford and that it seemed silly to pay when it wasn't something I couldn't do myself. Granted I might not make such a good job at it, but I reckoned the end results would be reflected in how much time I took over it and by applying some care and thought. I also invested in some decent connectors and tools.
I bought a ratchet-crimp frame with interchangable heads so that I can properly crimp just about any connections. I also invested in a Dremel Multi-Tip gas soldering iron/heat gun and a Dremel multi-vice.
I decided to replace everything in the loom which meant all new connectors, terminals and cable. I sourced almost everything from either Polevolt or Simtek, both of which provide excellent service. I've used quality adhesive-lined 6mm heatshrink with a 3:1 shrink ratio and thinwall cable throughout. There are a few points in the loom where I need to join several wires together, particularly the earth circuits. I did a bit of research on a nice neat way of doing this, looking at some aircraft wiring sites. Soldering is okay for a couple of wires but I know from my experience what a big blob you can be left with and soldering too many together makes things worse. In the end I came across Durite solder-lined heatshrink butt connectors. THese seem to be just the ticket and are able to hold together five, 1mm thinwall cables so I'm giving them a try.
The Multi Function Relay Unit (basically 4 relays in a box, and used to power the Injector/Coil/Fuel Pump/Lambda/Starter/Fan circuits is being moved from the engine bay to behind the dashboard. This cuts down the number of cables needing to pass through the bulkhead.
I've got 2 main multi-connectors in the new loom;
The first is a bulkhead connector which passes power and signals between the front of the car and the dashboard. This includes such things as:
headlights, indicators, wheelspeed, fan power, ecu power, horn power, starter solenoid power, etc, etc
I've used a Neptune plug for this which is a mil-spec connector handling twelve 30 amp power feeds and nineteeen signal feeds
The second connector is an engine loom connector that carries power and signal for;
Injectors, Throttle Position, Air Temperature, Oil Temperature
I've used a 10-pin mini-sureseal connector for this which means the engine can be disconnected and removed simply by unplugging it.
Everything else is wired via mini-sureseal connectors directly to the ECU or Neptune plug as appropriate.
I'm using more sureseal connectors to replace the front light and fan connection blocks.
I've found the best way to construct the mini-sureseals is to lightly coat the pins/sockets with vaseline, heat the rubber connector with a hot air gun until hot, then slide the pins/sockets in with a jewellers screwdriver.
Wiring loom