Front chasis harness build - Advice apreciated.

Hello

Currently planning out my front chassis harness, for things like headlights, indicators etc. Only engine related wiring on it will be the Fan and wiring for an accusump.

Will be passed through an Deutsch Autosport AS18 coonector - leaning towards AS612-35PN. Ground will be a single M6 stud located on the front of the chassis.

I have attached the provisional plan, its not accurate for final version, connectors and wire sizes are wrong and I will be running the headlights low and high beams from a single channel each and then splitting with a splice before the connector. I will update fully once I have all the information need.

Hoping I can get some guidance on wire sizing.

Now my fan is a 16" spal, 21a continuous with a 40a inrush. I am running a PMU24 so I should be able to manage the inrush. I am still however planning to run 4mm² wire to limit voltage drop. Now 2.5mm² should suffice, is it still a good idea to run the 4mm²?

Next question relating to the fan is regarding the autsport bulkhead connector, should I run the 4mm wire split through 2 pins or should I use a secondary single pin connector alongside the AS18?

For the headlights I plan to use 2.5mm² wire, would I see any benefit to light brightness by increasing the diameter at all?

Planning to use Spec44, assuming its worth using this over TXL?

Will be going into this thing, wiring will be run along the top of upper chassis rail, below the wing and then along the front of that lower front panel, which will be hidden by the radiator diffuser panel. Will be using DR25 for protection.

What is the best way to install an earthing stud, and where is the best place to locate it?

Thanks for any help.

I keep getting recommendations to use 6mm² wire for the fan. Only reason not to is extra weight, larger size of total wiring and reduced flexibility.

What is the opinion on this?

Your choice of large wire sizes seems very conservative (although I agree with 12awg or 4mm^2 for the fan (probably 2 14awg/2mm^2)). I don't understand your desire to use a connector with such small terminals (rated at 3A each - designed for 22 awg - .325mm^2 wire sizes). So your 21A load would require 7 pins!

I would be looking for a connector with size #20 (7.5A ea) and #16 (20A ea) terminals. Something like: 14-94 (i.e. AS114-97PN or similar). Then you could two #16 terminals with a 14awg wire in each one for the fan, and have lots of margin.

Thanks for the reply. I appreciate it.

I have upped the wire size for a lot of them now.

The connector part number is actually wrong there, it was the AS16 AS020-16PN I was thinking of https://www.prowireusa.com/p-2009-16way-autosport-flanged-conn-kit-pin.html

Thanks for your suggestion, although now I am not sure that only 4 size 16 contacts will be enough.

The other wires are now slightly uprated, so most could use the size 16 pins and 2 pins for the fan I believe the size 16 connectors can take down to 20aeg wire so the wires for the accusump, indicators and sidelights will also be fine. Was going to change all of these to 1mm², simply to reduce the amount of different sized wires I need to order.

I don't see me needing more than 14 pins even with a couple spare thrown in for future so that should serve the purpose well.

So, the 4mm² for the fan should be adequate for the fan, no need to up to 6mm².

OK, that is a more suitable connector for heavy front power draws. Yes, I believe 4mm^2 should be OK for the fan.

Thanks

It seems that size 16 is still to small if I also want to run 12awg for the headlights, spot lights and horns.

So I guess i have the option to split, those 4 into 2 pins each or run another connector, but it seems they don't do the AS series with connectors larger than 16?

You can fit a 14awg wire into #16 pin. I would just use 14 awg for your headlights. But you could also just splice in a short section of 14awg or 16 awg to your 12awg wire at the connector.