Wire size for huge alternator

incynr8 · 07-29-2009, 07:45 PM

Ok I just got a deal on an alternator capable of welding amps. 160 at 7400 pulley rpm to be precise. Going on a big amc v8
does 8 gauge for charge wire sound right? I'm rolling 4gauge off my solenoid but I'm wondering if I should go 6gauge.

I have to ditch my ammeter to run this old school does touch that.

Next to fit this huge thing in. I think it will already require reclocking for one.

AngelChaser · 07-29-2009, 07:50 PM

8 gauge is more than big enough. Most newer vehicles come with 160 or larger alternators and run 10 gauge wiring from them.

incynr8 · 07-29-2009, 08:11 PM

thanks, I figured 8 would do.

John Satclaire · 07-29-2009, 08:12 PM

Ditto on the 8 gauge as really large enough. I put a CS130D (rebuilt to do 160 amps) into my Jag XJS, and the wire there (dual wire, to be fair) is 10 gauge, though I did run a separate 8 gauge to the bus bar to be safe.

The main issue is to be sure that you're sufficiently grounded. Clean all your grounds and make sure your grounding straps are both beefy and in good repair.

incynr8 · 07-29-2009, 08:18 PM

I'm running dedicated ground to both heads in 4ga, flat braid oldschool ground strap from engine to frame, and a series of separate ground leads from battery to firewall, dash and rear frame (for senders). Another 4 gauge runs ground directly to winch plate, with dedicated 4 guage on hot side to winch power.

And right now I'm running another ground (only 12ga) to a 4 wire old school motorola (which I suppose would be similar to a Lucas) for alternator ground.

John Satclaire · 07-29-2009, 08:22 PM

Sounds like you're good to go. Only thing that's Lucas on my car, though, are the gauges and the HEI ignition system . . . blasted inventor of darkness, that one.

ProX · 07-29-2009, 08:29 PM

Besides conductor gauge, a wire is rated on it's ability to handle and disperse heat. This is done through it's insulation.

8 gauge wire with a insulation rated at 90*C (ex. THHN or THHW) is good for 80amps in free air or 55 amps in conduit or another form of raceway.

If you step up to a higher temp rated insulation, like a 150*C rated wire, you'll be good for 106 amps or 124 for 200*C wire. (both specs are free air)

#6 is good for 75 in conduit, 80 in free air when using a 90*C insulation.

150*C insulated wire will handle 155amps in free air, and 200*C wire will handle 165 in free air.

Go to the welding supply store (farm stores too) and look for your desired gauge in welding cable. Outstanding insulation and a fine stranded conductor. MAKE SURE WHATEVER END YOU USE ARE PROPERLY SECURED!!! If using a crimp on end, buy or rent the proper crimper, not the typical auto parts store multi-tool junk. If you want more info on them, let me know. A good alernative is to solder and shrink wrap them.

I use welding cable for all my battery cables and as an added bonus, it's usually WAY cheaper than wire from the parts or hardware store.

incynr8 · 07-29-2009, 08:42 PM

Thanks, I do have an oldchool battery cable crimper, thing is a beast.
You're making me think I need 200C 8 or 150C 6 now though.

I was thinking of doing this:

ProX · 07-29-2009, 09:40 PM

Just take a field trip down to the local farm or welding supply store and get some #6. It's cheap and quite capable of handling your current needs and not all that much bigger than #8. It's called cheap insurance.

FYI, a lot of manufacturers are moving to #8 or #6 with their higher power alternators.

incynr8 · 07-30-2009, 06:55 AM

6 it is thanks, looks like I will get to reclock the alternator to 12 or 9 though, wire term and old school oil pressure sender might not play well.

07-29-2009, 07:45 PM	#1 (permalink)
incynr8 Purify with flame Join Date: Apr 2006 Location: On some dinky hill	Wire size for huge alternator Ok I just got a deal on an alternator capable of welding amps. 160 at 7400 pulley rpm to be precise. Going on a big amc v8 does 8 gauge for charge wire sound right? I'm rolling 4gauge off my solenoid but I'm wondering if I should go 6gauge. I have to ditch my ammeter to run this old school does touch that. Next to fit this huge thing in. I think it will already require reclocking for one. __________________

07-29-2009, 08:11 PM	#3 (permalink)
incynr8 Purify with flame Join Date: Apr 2006 Location: On some dinky hill	thanks, I figured 8 would do. __________________

07-29-2009, 08:18 PM	#5 (permalink)
incynr8 Purify with flame Join Date: Apr 2006 Location: On some dinky hill	I'm running dedicated ground to both heads in 4ga, flat braid oldschool ground strap from engine to frame, and a series of separate ground leads from battery to firewall, dash and rear frame (for senders). Another 4 gauge runs ground directly to winch plate, with dedicated 4 guage on hot side to winch power. And right now I'm running another ground (only 12ga) to a 4 wire old school motorola (which I suppose would be similar to a Lucas) for alternator ground. __________________

07-29-2009, 08:29 PM	#7 (permalink)
ProX Active Member Join Date: Feb 2009 Location: Iowa	Besides conductor gauge, a wire is rated on it's ability to handle and disperse heat. This is done through it's insulation. 8 gauge wire with a insulation rated at 90C (ex. THHN or THHW) is good for 80amps in free air or 55 amps in conduit or another form of raceway. If you step up to a higher temp rated insulation, like a 150C rated wire, you'll be good for 106 amps or 124 for 200C wire. (both specs are free air) #6 is good for 75 in conduit, 80 in free air when using a 90C insulation. 150C insulated wire will handle 155amps in free air, and 200C wire will handle 165 in free air. Go to the welding supply store (farm stores too) and look for your desired gauge in welding cable. Outstanding insulation and a fine stranded conductor. MAKE SURE WHATEVER END YOU USE ARE PROPERLY SECURED!!! If using a crimp on end, buy or rent the proper crimper, not the typical auto parts store multi-tool junk. If you want more info on them, let me know. A good alernative is to solder and shrink wrap them. I use welding cable for all my battery cables and as an added bonus, it's usually WAY cheaper than wire from the parts or hardware store. __________________ Proud owner of BZ 2596

07-29-2009, 08:42 PM	#8 (permalink)
incynr8 Purify with flame Join Date: Apr 2006 Location: On some dinky hill	Thanks, I do have an oldchool battery cable crimper, thing is a beast. You're making me think I need 200C 8 or 150C 6 now though. I was thinking of doing this: __________________

07-29-2009, 07:50 PM	#2 (permalink)
AngelChaser Active Member Join Date: Feb 2007	8 gauge is more than big enough. Most newer vehicles come with 160 or larger alternators and run 10 gauge wiring from them.

07-29-2009, 09:40 PM	#9 (permalink)
ProX Active Member Join Date: Feb 2009 Location: Iowa	Just take a field trip down to the local farm or welding supply store and get some #6. It's cheap and quite capable of handling your current needs and not all that much bigger than #8. It's called cheap insurance. FYI, a lot of manufacturers are moving to #8 or #6 with their higher power alternators. __________________ Proud owner of BZ 2596

07-30-2009, 06:55 AM	#10 (permalink)
incynr8 Purify with flame Join Date: Apr 2006 Location: On some dinky hill	6 it is thanks, looks like I will get to reclock the alternator to 12 or 9 though, wire term and old school oil pressure sender might not play well. __________________