Voltgage problem

[Bow Tie 67]

Just incase that throws anyone, earth = ground

What is interesting is the LS1 uses a one wire alternator. Although the factory system utilizes a main fuse / relay panel in the engine compartment, which helps reduce some of the long wire runs and therefore reduce voltage drop.

I have almost finished, fingers crossed, adapting a 4th gen body harness to fit in my 69 for this very reason. I'll post pics soon in the project update section.

[gmachinz]

No matter what your gauge reads, what is your actual volt reading taken directly off your alternator charge post with your fans on? The LS series motors as well as the Vortec families use a 1-wire from the alternator-it goes to the gauge. I believe the remote voltage sensing lead is further upstream from it in the wiring loom. I would advise going wih a good fan controller and using a HD relay as a backup instead. There's a wide variety of ways to incorporate a controller with (2) fans but I mainly have issues with the start up spike of fans when using relays....diodes and bridge rectifiers don't like high spikes. Over time, it's just a strain on the charging system that can easily be avoided.

[MonzaRacer]

Ok you use a resistor suppresed relay and you never have any problems with any type of spike.
If you use a diode suppresed relay you have to make sure you have the power on the proper side.
As for "spiking" an alternator I have ran SI and CSI alternators for years with electric fans.
The big thing to remember is to hook the heavy power wire straight to the battery with a fuse inline.
As for the "one wire" alternator. The term one wire means no wires to the regulator ,just the battery wire. These are using internally shorted regulators to "turn on" . A resistor allows it to not drain the battery.
CSI internal fan alternators are more sophisticated and can actually turn on and off with the rotation of the armature with out having a key on wire, you simply need a wire that goes to the charge light(still giving the regualtor something to activate by) see the regulator sends a 12 charge through the wire and the wire to the charge light gets 12 v key on,,,, the regulator/alternator fails to charge the light grounds.
If you draw heavy current from the battery or get a large brass power block from a stereo shop and hook a short 4 guage wire to the battery from it and draw power for accessories from that and the spikes and motor nise is usually absorbed by the battery(see batteries are large capacitors).
All you need to read system power on a volt meter is hook into battery power near battery (I prefer same connection as the feed wire from alternator.
Oh and most current fan motor designs do not create spikes upon starting, ripples as the drain is met by alternator, but not spikes.
Spikes are created when the electrical field colapses, but since you are opening the positive the spike is damped by the fan windings to ground.
As for controlers I just like to use the simple adjustable fan switch with a bourbon tube sensor slid into the core near the return hose from the engine. It grounds the relay the realy turns on the fan. NEVER run just the controler, after having a friend have his car burn up from doing that I take great precautions anymore.
BUT you need not worry on fans as I would stage them by having one fan come on at approx. 200 to 210 degrees and turn of in the 190/195 range. Use a 195 thermostat and dont worry as a typical engine runs more efficiently at those temps.
The second fan I would wire in two ways, One turn on would be wih the A/C (possibly even both fans at that time to make the condensor work more efficiently) and at a 210 to 230 temp.
The big tell is if your A/C system(if you run one) has a small high efficiency condensor then running both fans would make it more effiicient.
Cooling sytem setup isnt rocket science and I see so many smart people making simple blunders because they dont understand how electric fans and the cooling system should operate.
And I am not talking $600 radiators and $300 fan setups.
I spent $100 bucks on a 3 row copper/brass recore and a $20 junkyard single fan, a $15 controller and had a nearly 11 to 1 big block chevy running no higher than 200 degrees even when racing or driving in high heat.
I had a 350 chevy in an 86 Ranger with a 4 blade solid fan and the stock 2.0 4 cylinder no air radiator and that truck NEVER got over 200.
Cooling systems are not hard to setup and do not take lot of high dollar parts everytime.
I would only spend big money on parts that are needed.
But then thats me.
Lee