NBS Big 3 upgrade

[01 Suburban LS]

What amperage fuse or circuit breaker would be needed? The max rating of the alternator?

[Macedawg]

Originally Posted by ScottMH

Bypassing or negating a fuse or fuseable link is a pretty bad idea. the fuseable link serves as a saftey measure. if your alt overloads and blows a ton of volatge into the system it can fry computers, blow fuses it can even heat wires up to the point of catching fire. thats why there is a fuseable link. the fuseable link blows before anything else. your not protecting the alt from the car or the car from the bat. your protecting the car from the alt. adding a large gauge wire from the alt to the bat is a bypass. if the alt overloads the fuseable link may blow but you created a huge highway for the surge to pass through. from there havoc is created. i will never understand why people disable saftey features. they are there to protect your ride and ultimatly you. the only responsible thing to do is to put a circuit breaker or fuse inline of the larger gauge wire.

i have a 100A circuit breaker i never installed from a previous system would that be acceptable to use when i do the big 3 on my NBS silverado?

[Slammed94]

Can I run just normal 4awg for them all?

[Slammed94]

Ok any of you guys with a pre 95 block can you tell me where the ground on the block is located? All I see is the top part which goes to the battery which I did.

[2500ak]

I've been working on running my own dedicated grounding lines on my 01 2500HD.

From the battery (-) lines to the frame, to the firewall, and to the block. With a line from the block to the firewall. All are 2 gauge.

Basically



My question is how is the starter grounded (through the block, from the wiring harness)? And how would one go about supplementing that ground?

[2500ak]

I just drove about 400mi, no mileage improvements with just grounds so that must lie in the extra power pumped out via the bigger charging wire. I'm thinking about replacing that little 8 gauge charging line with a fuse and some 2 gauge.

Bringing this back to the top to see if anyone knows how the starter on nbs trucks are wired. I'd like to add a big negative cable back to the battery to help with winter startups, I theorize that it may help.

[cichlid_baby]

On our OBS tahoes.. there isn't any kind of fuse on the charge wire to + battery terminal. It's just a straight shot directly from the alternator charge stud to the battery positive. That's how it came from the factory.

So much for a fusable link in terms of safety precaution as some of you have argued about.

I don't think is needed as long as there isn't any chance of mechanical failure of the wire connection while alt is on or engine is running.

[2500ak]

I'm pretty sure the fuseable link is the wire itself. I know on the nbs trucks its a little 8 gauge wire that says fuseable link in little white letters on the side. If its replaced supposedly the next weakest link is the 6 gauge that goes to the battery and the distribution box.

[cichlid_baby]

Originally Posted by 2500ak

I'm pretty sure the fuseable link is the wire itself. I know on the nbs trucks its a little 8 gauge wire that says fuseable link in little white letters on the side. If its replaced supposedly the next weakest link is the 6 gauge that goes to the battery and the distribution box.

I don't know but..... How can the wire itself be the fuseable link? In order for it to break the connection in a hazardous situation, it would have to burn and melt completely to disconnect the circuit.. wouldn't it? Meaning that "buring" would not be in a contained environment.. much different from say... a fuse would have been.

I don't understand but is this some kind of special wire of some sort?

Either way.. I don't think a fuse is really needed here if you are planning on doing the Big 3 wiring upgrade.

[01 Suburban LS]

Originally Posted by cichlid_baby

I don't understand but is this some kind of special wire of some sort?

Yes. Its designed to instantly melt in the case of a currrent overload from the alternator. Saving your battery, wiring and other electronics from going up in flames. Its a quick, easy and cheap way of accomplishing what a fuse would do.

[cichlid_baby]

Originally Posted by 01 Suburban LS

Yes. Its designed to instantly melt in the case of a currrent overload from the alternator. Saving your battery, wiring and other electronics from going up in flames. Its a quick, easy and cheap way of accomplishing what a fuse would do.

Hmmm... so there's a special wire on the NBS trucks.. what about our OBS trucks. When I took the factory alt wire off. It was just regular stranded 8 gauge.

[01 Suburban LS]

Originally Posted by cichlid_baby

Hmmm... so there's a special wire on the NBS trucks.. what about our OBS trucks. When I took the factory alt wire off. It was just regular stranded 8 gauge.

I know other GM makes didnt get fusable links until the eairly to mid 90's. I remember back in 1992 I had to take my 1991 Saturn in for a recall because there was a regular wire going from the alternator to the starter then the battery cable from the starter to the battery. A few cars caught fire because of this and the wire was replaced with a fusable link.

[thumpintruckred]

I have:
Alt to bat (+)
Bat to firewall (-)

Should i change the neg to something else IN ADDITION to the battery to frame (-) im going to do next? Like motor to firewall like the first post?

[2500ak]

Originally Posted by thumpintruckred

I have:
Alt to bat (+)
Bat to firewall (-)

Should i change the neg to something else IN ADDITION to the battery to frame (-) im going to do next? Like motor to firewall like the first post?

In stock form there is no batt to firewall. That's a mistake imo because when the block to firewall fails it toasts the cluster and 4wd system, as I have found.

The true Big 3 just follows the stock wiring of - batt -> block and then block -> firewall.

Now if I remember correctly, to arrest electrical problems a lot of military trucks used to be ordered with independent grounds. Which is what I attempted to do in my setup.

Basically a common grounding post wherein the firewall, block, frame, and starter grounded. Then a large gauge cable was run from the post to the - battery.

Is that overkill? Maybe, but its reliable and insures low resistance.

You really can't have enough grounds.

So running a ground to the firewall is good because now you have a separate ground to the firewall, block, and frame.

The one to the frame is pretty small though. Might want to add some large gauge to that.

[csx7006]

So i need to do the negative terminal to the ground?

[2500ak]

Originally Posted by csx7006

So i need to do the negative terminal to the ground?

Any wire coming off the negative terminal is a ground.

[csx7006]

well on my 92 burban,i have 1 wire going from the neg to the engine block, and the other neg wire is going to the right fender. I still have the stock neg btry cable for it.

[thumpintruckred]

If I do the battery to frame (-), do I still need to do a block to frame (-) or a block to firewall (-) ???

Edit: So basically I'm looking at a possible of 4-5 ground wires?

(1) battery to frame
(2) battery to firewall
(3) block to frame
(4) block to firewall
(5) block to battery

Which can I NOT do, and / or which SHOULD I do???

[2500ak]

Originally Posted by thumpintruckred

If I do the battery to frame (-), do I still need to do a block to frame (-) or a block to firewall (-) ???

Edit: So basically I'm looking at a possible of 4-5 ground wires?

(1) battery to frame
(2) battery to firewall
(3) block to frame
(4) block to firewall
(5) block to battery

Which can I NOT do, and / or which SHOULD I do???

You can do any of the above, in any combination as long as the block, the firewall, and the frame have a ground.

In an ideal world every single component would have a ground of 0 Ohms back to the - terminal of the battery.


Instead, to save a lot of money on wire manufacturers attach cable in this configuration:

- battery ----> block
- battery ----> frame
block ----> firewall


Then everything gets grounded to one of those. So lets say your the blower motor for your HVAC wants to operate.

Well in a DC system the energy flows in a circuit so that energy has to leave the battery preform its operation, then fight its way back through the firewall, through the ground strap to the engine block, through the 6 gauge wire back to the negative terminal.

That's a fair amount of resistance.


Your fuel pump grounds to the rear frame rail, it has to fight its way back through the frame, through a tiny little 8 gauge lead back into the battery.


I'm not saying the stock setup is bad, just that a lot a people have had a lot of success making the system more efficient by increasing the grounds.

[csx7006]

well i guess i need to add more ground studs