SpecE30

Where is the best place to source power?

e.g cool suit, pusher fan, etc.

The easiest place for me was right on the passenger side on the firewall. There is power and good ground spots right there. Use a relay and tap into switched power on some wire inside the car. Just poke around with a test light until you find one that is switched, or run it right off the ignition cylinder area wire bundle.

Or just run all the wires right to that junction and use a toggle switch. Just make sure to use a toggle that can support the amperage. We don't need any E30's burning to the ground.

While you may get away with grabbing power off existing circuits, if the new loads draw appreciable power blown fuses and/or fried wires can result. The best way to add accessories is to pick unswitched power off the power junction point on the right side of the engine bay. Feed that to a fuse block and to a relay whose coil is powered by a switched circuit (the coil positive is handy) and feed the output of the relay (30A or larger) to your fuse block. That will give you switched and unswitched circuits at the fuse block. You can get a DIN six position fuse holder (and relays, wire switches, etc) from www.wiringproducts.com/

I mount the DIN fuse holder near the power point in the engine bay on the "battery shelf". It is easy to get to there and there are openings in the firewall (where the A/C hoses ran) to get wires into the cabin. I always power an electric fan with a 30A relay and control the relay via a switch in the cabin and an 82C thermo switch in the radiator. The thermo switch is a safety in case I forget to flip on the fan in the paddock or during a cool down lap.

A couple years ago I put an aux fuse box near the DME. This allowed me to use one wire to get switched power out of the engine bay fuse box, and set up individual fuses for each component.
Gauge power
Camera power
A/F meter & wide band O2 sensor power
Coolshirt cooler
Helmet air
Radiator fan

I used the rear defrost wire (and switch) for my coolshirt pump. Just had to pull the wire off of the window and splice it in. I called Coolshirt and the pump is super low amperage.

There is also a little fuse box directly forward of the main box with one switched and one constant 12V fuse. Works well for transponder and other little stuff.

Matt