So i've decided that with a new alternator (180A) and a new amp (orion 1200d), i should probably upgrade the big three. What i was wondering is, i'm planning on using 4ga wire to do that, with a 250A fuse for the amp to battery wire. Should that be big enough, or should i go with 0ga?

Also, all of my connecters use set screws (instead of soldering), should i use thread lock on them, or should they be fine?

they should be fine and 250 amps is way too big. I have the 2500d at .5 ohm and a power 750 x and I have a 300 amp fuse in mine with no popping of it. I would say 100-150 at the biggest.

I mis-wrote myself. I have a 150 amp fuse for the amp to battery (fused dist. block). What i meant to say was that i have a 250 apm fuse from the alternator to the battery, not amp to battery.

Damnit we need an edit button!!!

n8ball: Did you have to do anything special to run 1/2 ohm? I've got two RE HC 12''s that are 4ohm DVC, so i have the choice of 2 or 1/2 ohm at the amp. I'd love to run 1/2 and get the full 1200 watts, but i was just wondering if there's anything i should do to make sure i don't fry the amp.

bro that will give you either 8,4 or 1 ohm. if you have dual 2s you can get 4,2 or .5 the 1200d will run .5 no problem. straight out of the box. It is gonna require some juice though. I have two optima yellows and a 260 amp alt and i stil dont feel that its enough. by comparison it seems to pull more current than the 4 1000bds that I replaced it with.

Doh, you're right. I have actually have dual 2 ohms (i forgot what they were for a bit, but used my multimeter just now to make sure that i'm not going insane). Well that's good to know that it can handle .5 ohms. I'll have to see how it does, the amp should be here tomorrow, and the install stuff (wires, terminals, fuses etc) will be here friday.

It's a good thing it's not here today, because i am NOT on the ball today!

4 awg would be fine...your fuse is there to protect the wire. 125 amp fuse would be plenty big enough


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Good stuff, i must've done good research this time.

On to the next question though. Since all of my connectors are the kind with set screws instead of crimps, do i need locktite on them? Or will they be fine if i just tighten them down?

they will be just fine once and a while just check on them but i have yet to have any problem with mine that hasn't been touched in a year

Woah, justin! I just looked at your Registry and realized you're in holt. I graduated from holt ('00). If you ever go up to the gut we'll have to compare RE speakers. I have 2 HC 12's (older model) that i'll be running 1200 watts to. We'll have to see how the two different systems compare.

Guys read a little closer...

180 amp alternator is going to melt the hell out of 4 gauge wire. True along with the stock wiring you will have some current go through there, but the point of the big 3 is to open up the floodgates and have no resistance. I would go with 2 gauge for the big three if not 1/0 gauge/

It's very difficult, especially on a Twin Cam, to use 0awg on the big 3.

I had a hard enough time with 4 gauge. If you're going to use Set Screw Ring Terminals, you're in for a big surprise once you get to the alternator. There's not alot of room to work with as the intake manifold is in the way, so make sure you take some measurements beforehand and get some Set Screw ring terminals of the appropriate size.

Also keep in mind that the wiring of the Twin Cam does NOT go straight from the Alternator to the battery, The stock alternator wire goes from the alternator to the starter and then another wire on the same post on the starter goes to the battery. The stud on the alternator AND the starter was not big enough to accomodate for both the stock wiring and my ring terminals, so I had to remove the stock wiring.

Just a heads up before you dive in and realize it when it's too late.










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From what i understand (reading other forums etc.) when upgrading the big three it is unnecessary to go from the alternator to the starter. That makes a lot of sense too. The only place you need bigger wire is where there is a larger current draw. Since i haven't upgraded my starter, it isn't going to try to draw any more current, so the wire going to it doens't need to be any bigger.

We'll see about melting the wire. The fuse holder i have takes 4 ga wire and holds fuses up to 300A. I'm assuming something that can take 4 ga wire isn't going to allow you to put a fuse in it that will melt 4 ga, but maybe that's wrong?

Chris wrote:From what i understand (reading other forums etc.) when upgrading the big three it is unnecessary to go from the alternator to the starter. That makes a lot of sense too. The only place you need bigger wire is where there is a larger current draw. Since i haven't upgraded my starter, it isn't going to try to draw any more current, so the wire going to it doens't need to be any bigger.

We'll see about melting the wire. The fuse holder i have takes 4 ga wire and holds fuses up to 300A. I'm assuming something that can take 4 ga wire isn't going to allow you to put a fuse in it that will melt 4 ga, but maybe that's wrong?

ok..let's get you straight here.

You can run your 4awg all day without a fuse and not melt. the fuse is there to protect you from a fire if the wire shorts out.

If the fuse is too big..and the wire shorts. the fuse won't blow and you'll go up in flames. 300amp fuse is WAY too large fora 4awg wire. the biggest fuse you should have on that 4awg is 125amp.


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Chris wrote:Woah, justin! I just looked at your Registry and realized you're in holt. I graduated from holt ('00). If you ever go up to the gut we'll have to compare RE speakers. I have 2 HC 12's (older model) that i'll be running 1200 watts to. We'll have to see how the two different systems compare.

yeah i still go to the gut once and a great while i would like to meet up some time to compare once i get every thing put in

Ok, thanks for the info. I'll have to get another 0ga fuse holder. It does seem kind of odd to me that companies market fuse holders that accept (at the largest) 4ga wire with a statement that says "holds up to 300A fuses!".

Cause there is minimal differance between a 60 amp maxi fuse and a 300 amp maxi fuse size wise. What changes is there ability to withstand more current, i.e. thicker bridge, differant metal. So all maxi fuse holders, can hold all maxi fuses, anl can hold all anl.

Oh yeah, i understand that. Prudence would say that you should only advertise a product up to the largest fuse size that should be used in the fuse holder though. A company could possibly get its self in legal trouble otherwise. Oh well, i've got it figured out now. Thanks to everyone for their help!

well they cant really do that, the company is rating the power of the fuses, not the wire, and the amount of amps a wire can hold will vary depending on the length of the wire, the company has no idea if your running a 6" power wire or a 60' power wire.


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