Megasquirt ECU – Rover V8 4.6Ltr

Locost Rover V8 Megasquirt

My Megasquirt ECU project is getting close to the point of turning the key. During the Christmas break, a couple of key parts have been delayed, so I allowed my attentions to be diverted.

Megasquirt Wiring Loom

With a couple days to wait I decided to tidy up the panel on which the Megasquirt ECU is mounted. The intention was to enclose all the wiring for several reasons:

  • Shield the ECU and related components from the weather
  • Control the heat around the ECU
  • Create an RF shielded enclosure
  • Make the area look tidier
  • Create a flat area for the battery to sit on

Megasquirt ECU Weather protection

My Megasquirt Printed Circuit Board (PCB) has not been hermetically sealed. Any moisture from road spray or from humidity would cause the ECU to shut down or malfunction. In a effort to keep the wiring loom as compact and as small as possible, I’d mounted the ECU under the windscreen scuttle.

The box has to be close to water-tight whilst also being RF shielded. At the same time I needed to be able to take it apart. Without any bodywork in place, it is possible to remove in multiple pieces. Once bodywork has been started, the loom will probably have to be removed with the box as an assembly.

Where the cables pass into the new box, there will be bulkhead grommets.

Locost V8 Megasquirt

Megasquirt ECU Heat Dissipation

Although placing the ECU in a metal enclosure will slow the build up of heat around the ECU, eventually the box would reach the same temperature as the whole engine bay. Ideally the ECU would be kept somewhere at a constant temperature such as the interior, but having read numerous articles with people struggling with RF noise, I kept my loom as short as possible.

Therefore my intention is to use cold air drawn in by the heater fan to pass over or through the heater box. This air will need to be channelled and kept away from engine and particularly exhaust heat.

Megasquirt ECU Radio Frequency (RF) Shielding

The Megasquirt ECU has processors inside that are sensitive to high frequency electrical noise or Electro Magnetic Interference (EMI). Unfortunately an engine bay has several sources of High Voltage / High Frequency noise. Anything that can be done to prevent this noise from entering the ECU are always welcome and could end up in smoother running.

For an RF/EMI enclosure to be effective, all surfaces have to be well grounded, to each other and the chassis. Between any gaps I will be using Chomerics 82-121-74019-G8708 conductive EMI gasket. I’ve tried to keep the edges as flat and square as possible. Any minor metalwork discrepancies will be taken will be taken up in the EMI shielding gasket.

Tidying ECU Wiring

Lets face it, no matter how hard you try, wiring looms aren’t pretty. I wanted to hide mine.

Inside the boxed enclosure would be some fuses and relays that no doubt one day I’ll curse hiding, but I went for it regardless. It wouldn’t be the end of the world to get to them, but if it was raining…. well…

I’ve made the enclosure out of some 20awg steel. To strengthen the top, I’ve used my homemade bead roller to add some ribs. On top will be the battery and the washer bottle.

Locost V8 Megasquirt

Hopefully in the next couple of weeks, I’ll have all the parts needed to get the engine running.

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