Wiring for flamethrower H4's

criv911 · 08-02-2009, 05:18 AM

I am rewiring for 130/100 bulbs, and using 10ga. wire. Do I need to rewire from the relays to the fuse block. I believe the current to the headlights goes through at least one of the pins in each relay to the headlight. Am I wrong?

kodioneill · kodioneill's Garage

I would rewire the relay power supply with a 30 amp inline fuse. Do you have the external relay kit installed?

criv911 · 08-02-2009, 06:30 AM

Yes I have the Sucro kit. Do you mean from the battery to the relay? What about from the relay to the fuse block?

kodioneill · kodioneill's Garage

Yes.

HarryD · 08-02-2009, 05:56 PM

Wow, 10 gauge wire. A glutton for punishment.

I say this for several reasons:

1-Finding headlamp connectors that will accept 10 gauge wires are hard to come by.

2-A single 130 watt lamp with an 11 volt supply draws about 12 amps (at higher voltages the amps draw drops). Per my ampacity tables (http://www.allaboutcircuits.com/vol_1/chpt_12/3.html), THHN wire at 90 C has the following amperage capacities (ampacity):

18 Gauge wire - 18 amps (198 watts) capacity
16 Gauge wire - 24 amps (264 watts) capacity
14 Gauge wire - 35 amps (385 watts) capacity
12 Gauge wire - 40 amps (440 watts) capacity
10 Gauge wire - 55 amps (605 watts) capacity

3-It is not prudent to supply all of your lamps power via a single wire. At a minimum, you should supply the high and low beam lamps separately. Since the high beams represent the highest load, your will need 286 watts of capacity (260 for the lamps plus maybe 10% safety margin) for the two high beams. As you can see from #2 above, if you you use THHN wire (commonly available and not to mention gasoline and oil resistant), you can safely use a 14 gauge wire for two lamps. Also, each lamp only needs wire rated for 143 amps, so the wires to each lamp from the relay need only be 18 gauge.

4-It is your car, and your choice. Do what you feel is right.

criv911 · 08-02-2009, 06:43 PM

Harry, Thanks for the insight. I am was going to use 10 ga. because I have it. Daniel Stern recommended 12 ga. So to get this straight I should run 2-14 ga hot wires and a single ground wire to each headlamp. What gauge ground wire.

HarryD · 08-02-2009, 08:44 PM

Quote:

Originally Posted by criv911

Harry, Thanks for the insight. I am was going to use 10 ga. because I have it. Daniel Stern recommended 12 ga. So to get this straight I should run 2-14 ga hot wires and a single ground wire to each headlamp. What gauge ground wire.

I will not second guess Daniel Stern. This IS his day job. If he says to use 12, then use 12. I suspect he is matching the wire size to the fuse size to be sure the fuse fails befor the wire melts.

The ground should be the same size as the power wires. Go to a good hardware store and buy THHN wire that is teflon coated (makes it easier to pull through holes) and rated for Oil and Gasoline. You should be able to buy it by the foot in various colors.

Bill Verburg · Bill Verburg's Garage

the required wire gauge is also a function of the length of the run, for the short runs used in a 911 headlight relay setup 12gauge is going to be fine. The fuses are selected to protect the wire

You can also use Marine wire, it is fully tinned and stranded so a smaller gauge is rated for a higher current draw. The sheaths on Marine grade wire are somewhat soft so spiral wrap is usually used when there is any chance of abrasion.

dtw · 08-03-2009, 06:41 AM

I bought all my electrical goodies from Daniel Stern when it came time to rebuild my '72. He also said 12 gauge, but that I could overkill w/10 gauge if I was really gonzo. Hey, overkill's good.

The only problem I had in wiring my setup was the ceramic H4 connectors he supplied - the wiring was too big to slide into the back of the connector. I cut down some of the ceramic connector and was back in business.

911st · 08-03-2009, 07:16 AM

Of the 130/100 bulbs, is the 130 high beam?

I have 100/100 bulbs. Wonder if trading up will add much.

+1 on ceramic conectors.

m110 · 08-03-2009, 07:33 PM

yes
ceramic connectors are a must for a retina burner setup
plastic bumpers ahead of you beware

criv911 · 08-16-2009, 09:28 AM

I have just finished wiring for the H4's and I did it with 10 Ga.[wasn't too bad]. I also got a set of amber LED's for the city lights. Should look cool! I am Just looking for new adjustment screws and I'm done. Any sources?

Canada Kev · 08-16-2009, 10:08 AM

Quote:

Originally Posted by criv911

I have just finished wiring for the H4's and I did it with 10 Ga.[wasn't too bad]. I also got a set of amber LED's for the city lights. Should look cool! I am Just looking for new adjustment screws and I'm done. Any sources?

The problem with LEDs for the city lights is that they will probably seem to be not as bright. All their light shines forward and not into the reflector. The incandescent bulb's light goes every direction, so is mostly reflected forward making the light seem bigger and brighter.

Or maybe I don't have a clue what I'm talking about. Let us know how it works and what the result is.

criv911 · 08-16-2009, 10:30 AM

You may be right but these have 9 LED's 1 that shines forward and 8 that shine off the 4 sides. It looks like a little tower. Now how about those adjustment screws?

RoninLB · 08-16-2009, 10:47 PM

I ran Narva 130/100w for years.

I'd burn one out every 5-10k night miles. It's a great bulb but carry spares.

believe it or not my current Osram 85/80w is just as good when compared with one side 130/100w and other 85/80w. Osram does a nice job so my 85/80w may not pertain to other makes. My testing is only eyeballing on a straight black road when stopped and covering one side at a time.

btw.. marine Ancor 12ga to lamps and 10ga from relay to battery and almost no voltage drop