3G just installed....

5.0CRAZY · Feb 4, 2008

I just bolted in a 3g alt and didn't notice much change over the 2G. At idle the headlights still dim very slightly with every increase in the heater blower fan speed. It measured about 12.5v at idle with headlights on/full heat/rear def on. Anything above 1000rpm brings it well above 14v however. I don' t need the 3g at the moment but I put it on because I plan on bolting in an electric fan in the next month or so.

Anyways no serious issue here just curious if thats normal for a 3G? So far not much of an improvment of the 2G.

bloopbloob · Feb 4, 2008

well i noticed a HUGE difference with mine. almost no drop when i run accessories. headlights don't dim at all. i only see a a slight drop in voltage when i turn on rear defrost, headlights and fan. Before the swap, i couldn't even shut my car off after a fairly lengthy drive with all of them running, or it wouldn't start back up if i shut it off. Headlights would dim by nearly half if i ran my fan at the same time, needle would drop and bounce in the very low range depending on rpms.....

LiquidGT · Feb 5, 2008

If you got it from a parts store take it back. When I did my 3g I got a bad one out of the box and I didnt notice a difference, (around 12V like you) then I got another one and it went bad. So I sprung and got a new one intstead of a reman, havent had a problem since.

I recently upgraded the power and grounds with 4G speaker wire, just because I can get it dirt cheap at work. Now the elec system is BULLETPROOF, I can run headlights, defrost, radio, cooling fan, with underdrive pullies and it charges strong.

HISSIN50 · Feb 5, 2008

I agree with needing to know the idle speed and pulley configuration.

I've noted that with a full load (including E-fan), I need about 800 engine RPM for the alt to not allow dimming. Just in case that relates at all.

Good luck.

jrichker · Feb 5, 2008

Did you upgrade both the power and ground wiring? The stock wiring is too small and poses a fire hazard.

The Stangnet 3G install sticky has all the wiring upgrade info - see http://forums.stangnet.com/showthread.php?t=646825

5.0CRAZY · Feb 5, 2008

Id say it idles around 700-800rpm. I did install it with 4 gauge cable, but I still have to add the 4 guage ground strap and add a fuse off the power cable. (The fuse I bought was too high amperage-200amp). Pulley configuration is underdrives but left the stock alt pulley on. I doubt its the grounding strap causing the issue as mine seems to be in ok shape...I will add a 4g strap though.

Is it normal for the 3g to only put out 12.5v at idle with all accesories? Once I add an e-fan I figure it will drop quite a bit more whenever it kicks on.

HISSIN50 · Feb 5, 2008

5.0CRAZY said:
Is it normal for the 3g to only put out 12.5v at idle with all accesories? Once I add an e-fan I figure it will drop quite a bit more whenever it kicks on.

At 800 RPM, it's not normal IMHO.

5.0 Nostalgia · Feb 5, 2008

Edit: Nevermind, I didn't see that you already responded to what I was going to say.

5.0CRAZY · Feb 5, 2008

HISSIN50 said:
At 800 RPM, it's not normal IMHO.

So is this just a weak alt or could it be the regulator? I just checked my idle and its more like 800-850rpm so that should be more than enough to get the alt putting out decent power

fastford91 · Feb 5, 2008

I'm thinking its a bad one to! when i did my 3G install my volt meter went from way down low i mean not registering to way up and not moving at all when stereo and everything was on ! so id say bad one or bad install! you need the 4G ground also!if you haven't done it already! James

cenok is family · Feb 5, 2008

i noticed a difference. amps stay more steady and constant than with the stock alternator.

shewitt · Feb 5, 2008

Just finished mine last night its like night and day if you cant see a diff there is a problem. Also I didn't put the ground wire on yet and i can run everything"lights ac Lincoln fan" and the gauge just barely moves down.

Mustang5L5 · Feb 5, 2008

Did you install it with the huge 3" pulley that comes on it?

Do you have underdrives??

If you have stock pulleys on, take the 3" pulley off and put your stock 2G pulley on it. You may need a washer behind the pulley. It's a 5/8" shaft.

If you have underdrive pulleys...you need this then.
http://store.summitracing.com/partd...=ASP-540120&N=700+4294843151+115&autoview=sku

I have U/D's with that pulley, a 3G alt and an electric fan and get 13 volts at idle.

5.0CRAZY · Feb 5, 2008

I have u/d's but not on the alt. The pulley that came on the 3g alt looks to be the exact same size as the one that came stock on the 2g. I haven't measured the size but it definitely doesn't look like a 3" pulley.

Seems weird that the alt would be no better than a 2g.... just my luck though

Mustang5L5 · Feb 5, 2008

It should be better, but like any alt, it needs RPM to make power, so it shouldn't be any surprise that it's not at full capacity at idle with U/D pulleys.

You might want to look into the OVERDRIVE alt pulley in the link above.

I also beleive the 6G also has better low RPM charging capabilities than the 3G. I do not have evidence at this time however. But recently i've been trying to get people over on the 6G bandwagon as it's a more compact upgraded alt with the same hookup as the 3G

88mouse · Feb 5, 2008

Mustang5L5 said:
Did you install it with the huge 3" pulley that comes on it?

Do you have underdrives??

If you have stock pulleys on, take the 3" pulley off and put your stock 2G pulley on it. You may need a washer behind the pulley. It's a 5/8" shaft.

If you have underdrive pulleys...you need this then.
http://store.summitracing.com/partd...=ASP-540120&N=700+4294843151+115&autoview=sku

I have U/D's with that pulley, a 3G alt and an electric fan and get 13 volts at idle.

+1 just done mine a few weeks ago checked it sunday and it was at 13.5 at idle. My battery was a little low tho.

5spd GT · Feb 5, 2008

My PaPerformance alternator did not have a 3" pulley. I want to say it was on the lower side of 2", but I could be mistaken.

I did not notice much improvement either when I did mine a few years ago. I am sure I did something wrong. I just followed the PaPerformance instructions to a "T", but I may have been missing something.

myslo50 · Feb 5, 2008

i have the same problem....i did mine last summer and my voltmeter still reads the same as before i did the swap. my altrernator is a reman from a 95 gt, ran 4 guage wire fore the power wire with a inline fuse, and a 4 guage ground strap from the block to the chassis. and at night time my lights dim and is in the red zone? explain.......ohh and i got the info from the thread index on the 3g conversion?

HISSIN50 · Feb 6, 2008

AFAIK, the 6G's have improved heat rejection capabilities for the diode-pack (a weak point on early 3G's) and better bearings. The actual output is the same (not on paper but in what I've seen in actuality).

gregsmy · Feb 6, 2008

So what vehicle uses the 6G? Is it still a easy swap?

3G just installed....

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