3G Alternator....The Right Alternator for My 5.0?

You will be doubling your alternator output (on paper).

Where does your car idle? If at or above ~850 RPM, you shouldnt have issues with a 130 amper. If below that, O\D'ing the alt or raising the idle can help a full load burden at idle if you see a drop (idling with a full load at night with lights, elec fan and HVAC, etc running).

That said, I chose a 160 amp unit when buying a new one - why not go a little bigger - the additional cost is nominal.

Good luck.

Here's websites with pictures of the 3G installation...

See http://www.geocities.com/smithmonte/Auto/3G_130A_Alternator_Upgrade.htm - all the tech data you could ever want to know
OR
http://www.mustangcentral.net/tech/alternator.html - excellent pictures of installation

Use these sites for information on the right way to do the wiring. Some people will tell you that you can skip the wiring upgrade, but it will catch up with you sooner or later. A fire in the wiring harness is ugly and expensive.

Under no circumstances connect the two 10 gauge black/white wires to the 3G alternator. If the fuse blows in the 4 gauge wire, the two 10 gauge wires will be overloaded to the point of catching fire and burning up the wiring harness.

The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.

Electric fan = 3G alternator if you want long life & reliability from your car.
The electric fan saves some HP. The stock fan's parasitic drag runs from 7-12 HP depending on who you talk to. The electric fan uses about 1/2 HP of power from the electrical system.

Figure this:
Ignition system & computer = 12 amps
Fuel pump = 12 amps
Exterior lights = 15 amps
Fan (heater or A/C) = 15 amps (can run between 5-25 amps depending on setting)
Radio & instruments = 10 amps
Wipers = 10 amps

That's grand total of 74 amps from a 65 amp alternator. Talk about overdrawn at the bank!

See WWW.partsexpress.com for the fuse & fuse holder.
Fuse @ $3.90 each (need one) http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=071-952

Fuseholder @ $5.80 each (need one) http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=263-630

4 gauge black wire @ $1.25 a foot (use string to lay out routing & determine length) http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=100-196

4 gauge red wire @ $1.25 a foot (use string to lay out routing & determine length) http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=100-194

4 gauge ring crimp terminals (package of 5) $3.25. http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=095-584

3/4 “ Black heat shrink tubing, 4ft length, $3.39
http://www.partsexpress.com/pe/pshow...number=082-058

3/4 “ Red heat shrink tubing, 4ft length, $3.39
http://www.partsexpress.com/pe/pshow...number=082-064

Pre-fab 4 gauge cables with lugs already on the ends are available in most auto parts stores. Look for the starter switch to starter cables.

I am very careful to maintain backwards compatibility, so I did things a little different. The white/black stator wire gets the insulation stripped back about 1 1/2" in the middle of the wire & cut in the middle of the stripped area. Then a short length of white wire with a 1/4" slip on female spade connector gets spliced on to the white/black wire. Slide on enough 1/4" heat shrink tubing on the white wire to cover the solder splice you are going to make. Next all 3 wires get soldered together & the heat shrink tubing gets shrunk. When you finish, the white/black wire looks like a "Y" with 1 white arm and 1 white/black arm. I left the black/orange wires connected to the original plug and did not do anything to them. When you are done, the original plug still has all the wires connected to it and they are still functional. The extra white pigtail wire that you spliced, soldered in & covered with heat shrink tubing is just long enough to plug into the 3G without much left over.

I ran the 4 gauge wire under the front of the engine next to the 4 gauge wire for the starter power feed.
It came up the same path as the fuel injector supply lines, and gets bolted to the power output lug of the 3G alternator. The 125 amp fuse is mounted on a plastic panel bolted to the stock ignition coil mounts. One of side of the fuse has a 4 gauge wire connected to the battery side of the starter solenoid & the other to the 4 gauge power feed wire for the alternator.

I had some 1" silicone aircraft heat shield tubing that I fed the 4 gauge alternator power feed wire through and tie wrapped & clamped it in place with some aircraft cushion clamps. That provided the wire extra protection from road debris and rocks. Some heater hose could be used to do the same thing.

Apart from the grinding I did on the mount bracket, there wasn't much to it. Rather than just grind a notch, I ground the whole web back to the thick part of the bracket. It looks much more factory that way.

Yes,what jrichker said.I installed my 3G last year and then wondered why I hadn't done the swap ages ago.That was a VERY simple swap,and worth every minute you take to do it.

I choose to run the overdriven pulley on my 130Amp 3G but only because I wanted full charge @ idle with my underfrive pulleys, e-fan running and maybe all of the lights on? The needle (stock gauge) moves around a little if the fan needs to run at a higher rate but I am very happy with the swap as well. Heck who wouldn't want a car that puts out enough power to run the computer when you are sitting in traffic

IMO, do the 160, nix the ud pulleys, youll never miss em.

Joey5.0 said:

So should i run a 130 without underdrive pulleys, or 160 With?

Click to expand...

Search "progress thread" & threads started by user "srothfuss" Everything I did is in that thread. And yes you can keep your U/D pulleys with the 130Amp alternator. You don't have to, but if you are not getting a superchager tomorrow, I would say keep them. Here is how I thought of it:

Most alternators generate 1/3 of their power at idle. so 65A at full tilt equates to an amazing 21.45Volts! That is barely enough to run the computer and headlights! Now lets take 1/3 of the 130A alternator... That works out to 43.29Volts @ idle. So that is more than double the output. 130 is all you need IMO if you are not running a huge stereo, but having more never hurts.

My set up:

1995 Mustang 130Amp 3G
BBK steel U/D's
FFI overdriven alternator pulley
Still maintain A/C & Smog
NEW BELT lenght = 895

With all of that, my car still has plenty to power my DCC controlled Mark VIII fan.