alternator wire

[Tinker]

On my 71 I upgraded to a 135 amp alternator because of the spal fans. Is it a must to run a bigger wire to the alternator and if so how?

 

[Bob Chadwick]

The Powermaster site recommends upgrading the wire or you can actually lose power. It has the recommended sizes on their website. I'm not sure where it goes to. The battery or the starter.

 

[pws69]

The Powermaster site recommends upgrading the wire or you can actually lose power. It has the recommended sizes on their website. I'm not sure where it goes to. The battery or the starter.

If the gauge of the wire is the same as or smaller than the wire from the battery to the starter, then it can go to the starter. I plan to run mine to the starter via a junction block to which I will also wire the Spal Fans.

 

[photovette]

I used a 4 gage wire from the alternator to the starter/battery connection. I used a circuit breaker and got rid of the fusable link.

 

[pws69]

I used a 4 gage wire from the alternator to the starter/battery connection. I used a circuit breaker and got rid of the fusable link.

Nice! Where did you buy the CB?

 

[photovette]

I bought it here: http://www.wiringproducts.com/

They have everything you need to bring your 'vette's wiring and electrical system up to aviation standards...


I also installed a high current relay and a vacuum switch--when at WOT, the relay opens and totally unloads the alternator except for the feed to the distributor. This does two things, it increases available horsepower by dropping out the alternator--about 5hp+ I estimate--and increases voltage to the distributor (no load condition) thus increasing spark energy.

 

[Tinker]

Do I need to run the wire from the starter to the horn relay, then to the alternator, or straight to the alternator

 

[pws69]

Do I need to run the wire from the starter to the horn relay, then to the alternator, or straight to the alternator

I'd run it direct - alternator to starter.

 

[mrvette]

I bought it here: http://www.wiringproducts.com/

They have everything you need to bring your 'vette's wiring and electrical system up to aviation standards...


I also installed a high current relay and a vacuum switch--when at WOT, the relay opens and totally unloads the alternator except for the feed to the distributor. This does two things, it increases available horsepower by dropping out the alternator--about 5hp+ I estimate--and increases voltage to the distributor (no load condition) thus increasing spark energy.

Sorry man, don't see where you get 5 hp outta that.....750 watts/hp roughly...times 5 equals 3750, divided by 12 equals....312 amps, roughly....

so even dropping a hundred amps of load, it's NOT, hardly EVER, but 100 amps would be 1.5 hp or so.....at best....Now the only thing that has much chance to pull that much current, is the dual fans.....BUT if the car is going faster than ~30 mph, the fan load is greatly reduced, and so is the current drain, from forward car motion/air throug the radiator...no sucking air load, no current drain...fan may actally act as a generator at high speeds....

I found the way to wire the fans is to take the ground and main load heavy wires directly to the alternator frame and output stud, leave the rest of the wiring alone if you wish....unless maybe you got a HPower amp of some sort, then from the main horn relay/terminal block....

GENE

 

[photovette]

The way I figured it was my max alternator output 165amps * 14.2 volts * energy conversion ineffiencies.

Probably closer to 2hp max--you're right--I did a bit of checking and determined the energy conversion loses were less than I had thought.

Though I'm unsure how the alternator behaves in a rapid transient nearing max RPM's, i.e. WOT.

Basically, by using a relay, I drop out the electrical loads and also drop out the a/c compressor.

For a modest cost, a modest gain in horsepower during WOT--but a true one.

When I had electric fans, I wired them exactly they way you did. I have my 65 amp headlight system wired that way now--we gotta lot of deer running around here...

 

[Jack]

V-belts & pulleys consume hp ... regardless if alt is loaded ... and in addition to the alt, the V-drive consumes more & more hp as the load increases.
JACK:gap