running a 4 ga ground strap

timewarped1972 · Feb 22, 2006

ok, stupid question...i got around to buying a 4 ga wire to add an extra ground strap being i have a 3g.

i found a place near the battery that already had some ground wires atatched to the inner fender, i ran it from there to a a/c compressor bracket.......but then i read in a post by jrichker the following

"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. "

k, so it should go from the block or a good grounded source to the block and go where exactly?? that "chasis ground where the battery pigtail connects" kinda threw me.......there's grounds all over the place which one is he refering too?

srothfuss · Feb 22, 2006

I can't answer the exact location but I can help to explain why you need to do it. The alternator is grounded through the engine and then on to the chasis. The existing metal strap ground and various other ground wires are all too small to process the higher current of the upgraded alternator. So by increasing the loading capacity of those grounds, you are allowing the alternator to work better.

jrichker · Feb 22, 2006

timewarped1972 said:
ok, stupid question...i got around to buying a 4 ga wire to add an extra ground strap being i have a 3g.

i found a place near the battery that already had some ground wires atatched to the inner fender, i ran it from there to a a/c compressor bracket.......but then i read in a post by jrichker the following

"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. "

k, so it should go from the block or a good grounded source to the block and go where exactly?? that "chasis ground where the battery pigtail connects" kinda threw me.......there's grounds all over the place which one is he refering too?

There is a ground for the battery pigtail to the chassis near the windshield washer filler on the driver's side. The computer power ground is supposed to go there. The computer power ground is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire. The wire goes into the harness at the starter solenoid. That is the best place for the extra 4 gauge ground wire.

Darkwriter77 · Feb 22, 2006

Hmmm ... I always thought you meant the braided stainless strap at the back of the motor that bolts to the firewall...?

Crap, now I gotta go buy ANOTHER 4 gauge cable...?

srothfuss · Feb 22, 2006

But, the more the better. You can never have too many grounds!

timewarped1972 · Feb 22, 2006

ok so i'm guessing that means by the windsheild washer where that other ground is bolted is the place to run it........

i had originally thought people were refering to that ground strap from the back of the engine to the firewall as well, but being it's there, and kinda a pita to get at, i left it alone and decided to put it elsewhere......then i read that post and thought ok, let me get this straight...........because there's little ground lugs all over the place and i figured if i'm going to do it i wanted to find the best spot.......

ok, back out to look at the car again............go figure

timewarped1972 · Feb 22, 2006

is this the area?? where the screw driver tip is pointing??

jrichker · Feb 22, 2006

timewarped1972 said:
is this the area?? where the screw driver tip is pointing??

You are correct. Just make sure the bare metal around the bolt hole is clean & shiny.

RYC CUKR · Feb 22, 2006

That is where I grounded my 3G to. I ran a 4 ga cable from the same place on the block that the negative battery cable lands to the spot that you have marked there.

timewarped1972 · Feb 22, 2006

great thanks.......

Darkwriter77 · Feb 23, 2006

So, the block needs TWO grounds, then...? I don't get it. Or would a 4-gauge on the back of the block to the firewall be sufficient? (Can't figure how it'd make a difference whether it's on the front or rear end.)

timewarped1972 · Feb 23, 2006

i think the general idea is because the 3g puts out more you wanna have a heavier ground......

example......your battery.....it has what ever gauge battery cable for a ground (usually 4 or 6 on most cars) it doesnt have like a 4 gauge positive and then some shoe string size ground......the ground should be proportionate to the power level....

in this case, while that one ground strap grounds the engine to chasis.......it's best to have a heavier gauge going from the block to where the battery cable grounds to the chasis........

that spot right there by the washer resivoir.....thats like a main ground area there, which is why he suggested to run it there......not just to any other part of the chasis.........i believe thats the point of it.......maybe one of the other electrical gods can chime in and explain it better.......

JimBowy · Feb 23, 2006

I know its for a battery relocation but it might give you an idea of the grounds....

Darkwriter77 · Feb 24, 2006

That chart's a bit ... odd. Running the 0/1 gauge back from the solenoid to the battery, sure, but ALSO running a 4-gauge from the alternator directly to the battery as well? ... and grounding the alternator, itself? Ugh. The simpler it seems it should be, the more complicated it gets.

Okay, disregard the relocated battery thing a sec, let's iron out the standard OEM location battery setup for a 3g swap. Now, the way I did mine, I upgraded the thin strap at the back of the motor to the firewall to a 4-gauge cable (I used that strap to ground the radiator, simply to help fight corrosion), ran a 4-gauge cable from the alternator over to the solenoid with a fuse bolted in-line, and I upgraded the stock battery cables to 2-gauge simply because they were old and beat-up. The battery, itself, currently is grounded against the frame near where the power steering pressure hose bracket bolts on. Everything else is OEM-spec; I left the two orange wires connected to the solenoid, as per most instructions, and I polished up all of the existing grounds (the solenoid, the firewall, the frame, and the little pigtail under the solenoid).

So, in addition to what's already listed above, you're saying it's recommended to run a second ground cable from the front end of the motor, such as around the old A/C bracket stuffs (deleted long ago), over to that same place where the little pigtail ground under the solenoid is at? ... and one from the alternator, itself, to the block AND chassis? Sorry if I sound dense for dwelling on this, it just seems a bit like overkill to add this many additional grounds to compensate for one 4-gauge positive cable coming off the alternator to the solenoid...

JimBowy · Feb 24, 2006

Ok, relocated battery disregarded it sounds like you have done just about everything correctly.

Your alternator grounds through the case, to your engine, to the front timing cover. Making a direct ground could make for a more direct path. But its not necessary, its optional. It certainly can't hurt to have extra grounds. Grounding problems suck, let me tell you....

timewarped1972 · Feb 24, 2006

the ground doesn't nessisarily have to go from the front of the engine to that pigtail thats just where i put mine for simplicity sake.......

basically i think what your doing is.....that pigtail or ground wires that bolts to the fender by the washer resivoir........i think thats a computer ground or something so it's basically an extra ground for that. the battery is already grounded to the engine, it's just an extra ground for that computer ground and for a block to chasis ground

maybe jrichker or someone else can elaborate on exactly what that new 4ga grounds and why it's nessesary after a 3g swap.........

HISSIN50 · Feb 24, 2006

timewarped1972 said:
someone else can elaborate on exactly what that new 4ga grounds and why it's nessesary after a 3g swap.........

The power ground pathway needs to have as much flux-capability as the power side. The ancillary ground ensures that the ground path is adequate. JR can tell you how much ground is the absolute minimum. I am not an EE so I go with overkill, esp since pathways degrade over time.

Even on a car (5N95) designed for the 3G, I found a hair better stability after adding an ancillary 4 AWG ground.

timewarped1972 · Feb 24, 2006

HISSIN50 said:
The power ground pathway needs to have as much flux-capability as the power side. The ancillary ground ensures that the ground path is adequate. JR can tell you how much ground is the absolute minimum. I am not an EE so I go with overkill, esp since pathways degrade over time.

Even on a car (5N95) designed for the 3G, I found a hair better stability after adding an ancillary 4 AWG ground.

holy crap.....you said flux capability......lol.......we'll have to come up with a special ground wire and call it the flux capacitor for real

HISSIN50 · Feb 24, 2006

Seems to me that in Gaussian terms, flux means 'flow', which was my reference. (Before all the EE's jump down my throat for using poor/wrong terminology, I am just a nobody).

timewarped1972 · Feb 24, 2006

your right, i've just watched back to the future too many times

running a 4 ga ground strap

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