Wiring for an Engine Run Stand with DJet Options

[doug_b_928]

I'm building an engine stand that will serve multiple purposes (transport, storage, installation/removal, and testing/break-in). The one part I have very little clue about how to do is the wiring. I've searched the forum and have seen others express an interest in having wiring info for a test stand, but it doesn't seem to be documented anywhere. So, hopefully this thread will help not only me, but also anyone else in the future who is looking to do the same.

I'm going to have the djet 'computer', manifold pressure sensor (MPS), decel valve, fuel pump, and regulator plate/relay board mounted to the stand. The ground that normally connects the battery/engine to the chassis will be grounded to the stand. The wiring for the MPS will be connected to it and the wiring for the fuel injectors, alternator, and 12 pin connector will all be connected to the regulator plate. In other words, it is as if the engine were in the car with the exception of the wiring connections at the 14 pin connector on the regulator plate.

On the stand's 'dash board' I think (please correct me if I'm wrong) I need an ignition toggle switch, a momentary starter switch, an oil pressure 'idiot' light (I'm getting a cheap LED light on sale tomorrow), a tachometer (I have a cheap, generic one from FLAPS), and lever with a cable for controlling the throttle.

So the question is, what is the correct way to wire these items? I have the figures from Jeff Bowlsby's webpage and the wiring diagrams. What I'm missing is the theory of what I need to do wiring-wise to make the engine run and get the feedback to the tachometer and idiot light. I'm hoping others who appear to have done this can chime in with their thoughts (paging @StratPlayer @VaccaRabite @michelko @mb911 @barefoot ) and wiring gurus (like @JeffBowlsby ). I assume I run wires from the battery to the two power pins on the 14 pin connector, so that the regulator plate has power. After that, although I think it should be pretty simple, I'm not 100% on how to wire the ignition, starter, tach and idiot light to the 14 pin connector. Please advise.

[doug_b_928]

Thanks again for the SUPER CLEAR and straightforward instructions. Despite that, being me, I still have some questions for clarification:
1. Out of curiosity, what does the acronym VCC stand for?
2. For the heavy cable that goes directly from the battery + to starter, from battery + to VCC switch, and from battery - to engine and engine stand, should that be 4 gauge cable?
3. Re fusing, so should there be an in-line fuse for each electric powered by VCC?
4. What gauge of wiring is recommended for going from VCC to the electrics?
5. For the Gen light you specify an incandescent light. I'm guessing that's purposeful. My FLAPS has LED ones that I thought I'd use (I don't see incandescent versions on their website). Will these work (here's a link: https://www.princessauto.com/en/detail/gree...ght/A-p8172736e )?
6. For grounding the fuel pump, on my car it was grounded to the chassis. Is it better to connect it to the battery - or the engine stand, or no difference either way?

[Spoke]

Thanks again for the SUPER CLEAR and straightforward instructions. Despite that, being me, I still have some questions for clarification:
1. Out of curiosity, what does the acronym VCC stand for?

I believe it comes from transistor circuits where the positive voltage supply is named because an NPN transistor's collector pin goes to the positive voltage. Likewise, a negative voltage is sometimes called VEE since the NPN transistor's emitter pin goes towards the negative voltage source. In general, it could be called anything. My first thought was to call it VSPOKE. (IMG:style_emoticons/default/piratenanner.gif)

2. For the heavy cable that goes directly from the battery + to starter, from battery + to VCC switch, and from battery - to engine and engine stand, should that be 4 gauge cable?

Yes, 4 gauge is fine. You can pick this up at your FLAPS. Get cables with the battery clamp attached. The positive one should have an extra small wire coming off the clamp to run the electrics. It is very important that the battery cables be bolted onto the battery and starter and engine case. If spring clamps are used like jumper cables, it is possible for the clamps to come loose or make a bad connection and possibly damage the alternator when running.

3. Re fusing, so should there be an in-line fuse for each electric powered by VCC?

You could do that although one fuse would be there just in case something gets shorted. The battery power in the 914 to pins 12 and 14 have no fuses between them and the battery. The fuse would be the wires themselves or the relay board.

4. What gauge of wiring is recommended for going from VCC to the electrics?

The same size as on the car. Looks like 10-14 gauge or so.

5. For the Gen light you specify an incandescent light. I'm guessing that's purposeful. My FLAPS has LED ones that I thought I'd use (I don't see incandescent versions on their website). Will these work (here's a link: https://www.princessauto.com/en/detail/gree...ght/A-p8172736e )?

This one must be incandescent and should be the same wattage as specified for the 914 GEN light. The current through this light could go one way or the other and needs to have a pure resistive characteristic. LEDs do not do that. They sometimes need several volts across them to turn on and light up. Also if the wattage isn't high enough, the alternator may not bootstrap itself into operation.

6. For grounding the fuel pump, on my car it was grounded to the chassis. Is it better to connect it to the battery - or the engine stand, or no difference either way?

The battery negative terminal or the engine case will be your chassis ground.