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Discussion Starter · #1 ·
Something I thought I’d share knowing the cooling problems we have during the summer especially those running front mounts. Just finished the final wiring on my fan and it pulls substantially harder than before, something like a small wind tunnel now. I never liked the factory wiring because of the long wiring runs, small wire, and obvious voltage drops, not to mention it drains other systems, so I improved it. Now awesome fan power is provided with less than 2 feet of 10ga wire, triggered by either the computer or manually, and looks factory.

Took two Bosch 20/30 amp relays and wired them in parallel because one relay would not allow the current I wanted. Used the factory fan high and low power wires from the relays plus my manual fan wire to trip the parallel relays, 85. Grounds goes to 86. Ran a 10ga wire from a positive terminal (fan power source) to the parallel relays, 30. Then ran a 10ga wire from the parallel relays, 87a, close to the factory fan connector. Took the high and low power wires and connected them to the 10ga wire on the engine side of the connector. On the fan side of the connector, connected the high and low power wires to 10ga wire and ran it directly to the positive fan terminal. Disconnected the resistor completely. The grounding was done like this, on the engine side of the factory fan connector cut the ground wire in half, ran the parallel relay ground wires and factory ground wire in one side of the butt connector and placed the other side of the factory ground wire and added a 10ga ground wire. This provides the best possible fan ground and helps out the wiring harness.

Caution: make sure the Bosch relays have the heavy-duty wire and not the thin stuff for the 30 and 87a connections. Connected the whole thing using butt connectors and shrink-wrap. Mostly 10ga butt connectors are needed and plan on spending a few hours. This is probably as clear as mud to some because I did not go into enough detail in some areas but if you are interested, draw it out on a sheet of paper before you begin cutting anything. Wish I’d done this years ago when I first thought about it.

Next wiring project, those mediocre headlights. Guess how I’m going to do it and why.
 

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Awesome sounding idea DarkForce. You think you could submit a detail instruction to the tech area of gnttype.org for your fan and headlight mods? I'm sure many could benefit from your innovations.
 

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DF, did you come off the battery for power. Reason I ask is the fan power all comes off the starter thru the fusible link thru mickey mouse wire as you say. I am going to rewire my dual fans and relay off the battery--

Kirban sells the headlight system to do the same but it is a bit pricy compared to what you can do it yourself for.

The other thing that I want to do is to move the fusible links to the inner fender. The one that feeds the ecm, FI, etc. has about six splices after it goes into the harness and this spliced area is often the reason that the ecm reads 12.5 when the battery says 13.5.

Finally, the wire from the alternator to the battery has a connector in it about a foot from the battery. If you grab this and it is hot, then it has probably gone high resistance and is soaking up some of the voltage going to the battery. Replacing this wire with something much heavier-such as number 4-can help as well.



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Steve Wood

Growing old is mandatory; growing up is optional.


86 GN bought new, 87 T-type-81 El Camino with GN drive train-basically stock 86, 94 Caprice 9C1, 69 SS396 Camaro Convertible
 

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NTE and others make 70A relays similar in style to the Bosch units. I was never a big fan of parallel relays.

Headlights are easy to convert to H4 lamps I use the factory wiring up to 80 watts low beams and new wiring and a relay for the bright lamp low beam and the high beam lamps at 120 watts each.


Doesn't look factory and I used a lot of very big wirenuts
but I didn't cut off or hack the Hella connectors from the lamps. Worked fine now for about 8 years.

Can't wait for the "econo" Xenon lamp kit to be developed.
 

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Discussion Starter · #6 ·
Steve, I ran 8ga wire with fusible link from the alternator to a terminal post. From there it gets complicated – don’t ask. The 10ga wire for the fan is run from this post to the parallel relays. I sat down and figured out what this fan upgrade cost me - not more than $5.00. Got the relays for a couple of bucks out of a junkyard, wire is cheap, and connectors / shrink-wrap are very cheap. Now the fan blows really hard.

The wiring in my car may differ from most. The battery is in the trunk with a remote starter solenoid and heavy-duty type NHRA kill switch. If you have ever installed this stuff you know the wiring maze. I run a Speedpro/Felpro/FAST which has the long wiring harness to the trunk so the stock ECM is no longer in play.

I ran 8ga fine strand tuff wire throughout for heavy power loads; from the alternator to the primary positive terminal post, from the positive terminal post to the battery in the trunk, for all the kill switch wiring, from a secondary positive terminal to the stock wiring harness positive connectors that once connected to the starter. Funny thing you mentioned using the really heavy-duty wire (4ga) from the alternator. I’ll make a call to a friend who is a true wizard on this stuff and see what he says. Good thought.

Knowing how the headlights of the older cars respond to some simple wiring changes, I’ll bet you that it won’t take much rewiring at all. Mostly rerouting power from a positive terminal close to the headlights using a couple of relays and you’ve eliminated 15 feet of undersized power cable and power drops. Should not cost more that $5.00 for this either. Not knocking Kirban’s products which are top quality but I believe this would be a very simple problem to solve. I may try to knock it out next weekend if I can find the right relays. If this does not give me the desired result, I’ll be calling salvageV6 for some help.

Think about how much power you are eliminating going through the stock harness by rerouting the fan and lights not to mention increasing the performance of the accessories. Appears to be a win / win.

Can’t believe I typed all this…
 

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Discussion Starter · #8 ·
Ray, kicking myself right now for not doing the voltage check in the beginning. But now the fan pulls much harder with the engine off than it did before with the engine running if that tells you anything.
 

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Discussion Starter · #10 ·
Teking, I’ve been told our fans pull approximately 16 amps at 14.5 volts. You can run one Bosch 20/30 amp relay but you are dealing with an electric motor that creates much more heat at the relay than something like electric lights. Relays are usually rated for sources other than electric motors and what I’ve been told is you can knock about 10 amps off a relays rating when used with an electric motor. These relays are rated at 20 amps continuous and 30 amps intermittent, try the math see what you get. In this case, an electrical motor would definitely increase the probability of thermal run-away, which ultimately will cause the relay to fail. I think the marginal stock wiring may actually help the original relays live but when you run a 10ga wire as a power source, the draw is somewhat enhanced.

Reasons to run parallel relays for our electric fan motors: 1) allows more copper wire (relay) to carry the load from a 10ga wire to a 10ga wire, 2) eliminates the problem of thermal run–away, 3) builds in a redundancy factor like the use of twin magnetos in a Cessna. Reasons not to run parallel relays, none that I know of but that doesn’t mean anything.

So much for my two bits of know how. I am not a wiring guru but I do know some of the basics. If anyone wants to talk to someone who is truly knowledgeable about general automotive electrical systems, call Mark of MAD Enterprises at (559) 539-7128. He is one the most experienced and best natured people you will ever talk to. He provides many excellent parts (best battery relocation kit for the trunk I’ve ever seen!) and has a great quick reference book is called Tech Made Simple, I think, which is pretty neat. He’ll know the answer for sure, unlike me.

If I’ve missed something, let me know…thanks.
 

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Discussion Starter · #12 ·
All electrical equipment generates heat. Thermal run-away occurs when the equipment continues to generate heat faster than it can be dissipated. The temperature will continue to rise until the equipment fails or a fire breaks out.
 

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I'm not so sure "thermal runaway" is the problem. Electric motors are very hard to switch (like incandescent lighting). Making and breaking the circuit to an inductor (or a motor) is very tough on a relay. The motor will pull large amounts of current on the make cycle and will want to keep the circuit going and arc as the relay breaks. Therefore, with several make/break cycles, the relay contact will pit and resistance will build causing more problems.

Parallel relays are usually avoided. The reason is that even though it looks us us as though they are opening and closing at the same time, electrically there are always differences. So, one really will basically do all the work anyway.

Relays made for motors typically have a very wide area between the contacts.

Hope that helps.

Paul.
 

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I thought Todd or someone else had measured current draw in the past and found that the higher amperage was found at kick on but it dropped significantly after the first couple of seconds. The 16 amps was more like for a second or two. I may be totally wrong as I am not sure who, where, or when, or how much. LOL

This has been an interesting thread and has made me rethink the way I was going to rewire some of the things as I was going to feed everything off a terminal box off the positive battery post. I think I will use two boxes now-one off the battery and one off the alternator.
 

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Dark Force:

Great stuff in your posts. You mentioned an NHRA kill switch. I want to install something that will prevent someone from ripping my car off until I have enough $$ for a formal alarm system ( spousal unit not pleased with my recent GN purchase) Can you recommend a source for this kill switch? Are they hard to install? Either a starter kill and/or a fuel pump switch would be great!! I have a Walbro fuel pump and a .380 Baretta automatic if that helps


Thanks

Roger
 

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Ditto, on the good thread, but all this talk of electrical current has made my eyes glaze over. I need a diagragm.


Hey Jolly Rodger.....I installed the 30 amp relay for my fuel pump hot wire in my trunk and also a switch to kill the power to the relay. As long as you don't mind opening the trunk to kill the power to the fuel pump, it's one way to go.

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John DiCarlo
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Email me at
mailto:[email protected][email protected]</A>
 

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Discussion Starter · #17 ·
Jolly Roger 1, (great handle) an NHRA type kill switch is designed to kill the engine in case of an emergency, usually a crash. Mine is located behind the license plate which stays in the down position at the track. This is not what you want for security and if not wired correctly, it could fry your electrical system when switched off. First, dump the .380 Beretta auto and get a 45 ACP (use hp or semi-wad cutters), second tons of switches are available at auto or electrical stores. Now you need to determine what to kill. Fuel pump / cam sensor / ecu power (but makes the ecu dumb) / injector harness / starter solenoid are some of the usual kill switches that work very good, just splice into a circuit and install a switch. But there is one particular wire I found behind the dash that kills EVERYTHING but I can’t remember the color and it’s difficult to reach. Best of luck.

Bama GN, you are 100% right about motors being tough on relays and heavy-duty relays having wide spade contact points. I wish I had first hand knowledge on the amps being pulled through the fan but that may for all practical reasons be a moot point. With one relay you are almost stuck running the fan at the factory levels due to current restrictions. Two relays almost doubles the throughput. I am not normally an advocate of parallel relays either but in this situation it works and works well. I’d bet this system would work a minimum of 5 to 8 years with no problems. Then just pop the top of the relays off and put some $2 boneyard relays on and go another 5 to 8 years. I’ll be the test bed for this project for couple of years and let everyone know how its working. How’s everything in LA (lower Alabama) these days Paul, could really use some rain here?

I worked up a wiring diagram for using parallel fan relays using Visio, the only weakness may be using the stock ground wire rather than 10ga or 12ga wire. My original thinking was that a voltage drop would occur across the motor and the stock ground wiring would be sufficient plus I wanted to keep things looking stock. I’m going to test this tonight and see if I get more improvement.
 

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>My original thinking was that a voltage drop would occur across the motor and the stock ground wiring would be sufficient plus I wanted to keep things looking stock

Yes there will be a voltage drop across a load; in fact that's where almost all of it will occur, otherwise it's no load :)

The ground side is just as important as the power side- in fact in the physical electron flow sense the ground wire IS the power wire :)

The voltage drop (loss) you see on the cabling is proportional to the current flow, the length and the wire gauge. If the wire is short there should only be a small drop.

You've hot wired the fan basically, which should be a good thing for maximizing its performance, just like hot wiring the fuel pump.

TurboTR
 

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Discussion Starter · #20 ·
Yea, what Teking said, haha.

Just got back from the boneyard saw several of the good low profile Fiero fans. This is what I use and is identical to the stock GN fans. Also picked up a double handful 20/30 Bosch relays with the heavy wires, should be enough for the headlight, brake and internal power distribution projects.
 
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