HELP: electric/fuse - for V8 radiators Options

[jimkelly]

I test ran my engine after running a bunch of wiring and fuse blocks for my horn, wipers, and radiators.

the blocks are rated for 6 fuses, all can be 20 amp circuits.

I had one 20 amp fuse (in my dash fuse block) feeding my front trunk fuse block, which had two 15 amp fuse for each radiator, and a 10 amp fuse for my horn.

when the engine got to temp, the 20 amp fuse in my cabin blew.

I can only keep it from blowing if I run only one radiator by leaving one 15 amp fuse out of my front trunk fuse block.

looks like I have no choice but to run another (10 guage 12v) hot from battery to radiator area, to a fuse block that can handle at least two 30 amp fuses, one for each fan.

thanks guys!

[Mike Bellis]

I have fuse panels in the front trunk, rear trunk and under the dash. I agree you need at least a 10ga wire from the battery. You will need to fuse this wire within 18" of the battery as well.

[andys]

Yeah, you need to run a dedicated power wire for your fuse block. I ran an 8ga wire to mine, which powers two radiator fans (20A each), fuel pump (20A), and OBD II power (10A). The 8ga wire runs through a 50A circuit breaker.

Andys

[jimkelly]

so I guess I will use the one remaining bussmann fuse block I have to power my radiators. it has six 20 amp circuits. I will use two to power my two radiators with a 20 amp fuse to each.

what fuse do I put within 18" of battery? 50 amp?

[Spoke]

what fuse do I put within 18" of battery? 50 amp?

Correct. This one is to prevent your main cable from the battery from being a fuse itself.

In all the wiring you're doing, have you drawn up a schematic? I'm having trouble following your description of the wiring.

[Chris914n6]

Fans are rated constant. There is a surge on startup that you will need to account for with the fuse rating. I'd say double constant, or whatever the factory used. Mine are 30 each, I'd have to look in the brochure what constant was for the Spal 11" HP.

Porsche didn't use any fuses at the battery, but new cars do, so it's up to you if you feel the need.

[jimkelly]

here is all I can come up with at the moment.

I ran a 10 guage wire to my first fuse box but then ran it to subsequent boxes from a 10 amp fused spade from previous block ... BUT I think I should have ran my 10 guage wire to fuse block studs only, not thru fuses at each block. I will add a 50 amp fuse near battery.

[jimkelly]

new wiring - will put a 50 (or 100) amp inline fuse near battery today.

I currently have..
a 10 amp fuse to horn switch - will put a 5 amp fuse
a 10 amp fuse to wiper switch - will put a 5 amp fuse
a 10 amp fuse to horn relay
a 10 amp fuse to horn relay
a 20 amp fuse to radiator relay pass side
a 20 amp fuse to radiator relay drivers side

it seems 10 guage wire can handle up to 100 amps in a 10' run, which is about what I have. (a 10' run, not 100 amps of auxillary stuff)

for the moment, I installed a 100 amp circuit breaker between battery and circuit. I also put switches on a panel for easier access to them.

just ran it, got to 190 degrees, fans (2) came on and brought temp back down to about 165 or so. tested wipers while fans ran, all good, so far.

time to hit the road. need to get registered and inspection, though I still think I have crap in my gas tank, after numerous replaced filters and partial gas drains, and fuel pump flushes. current fuel tank far better than removed tank BUT not perfect.