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supercatxr7
05-22-2004, 11:35 AM
My battery is mounted in the trunk and I just picked up a Flaming River Battery cut off switch. What is the correct way to wire the switch to totally cut power on a 90 sc? I read an older post on the website, but of course there were 20 different ways of doing it and everybody was saying everybody else's way was wrong. Can someone tell me the correct wiring?

Brandon
05-22-2004, 01:20 PM
My battery is mounted in the trunk and I just picked up a Flaming River Battery cut off switch. What is the correct way to wire the switch to totally cut power on a 90 sc? I read an older post on the website, but of course there were 20 different ways of doing it and everybody was saying everybody else's way was wrong. Can someone tell me the correct wiring?

I think that was my post that you're referring too. I never did put my battery in the trunk because after that post I was more confused than when I posted it. I hope you figure out a way to do it. I'd like to know also. Good luck!

Darkside
05-22-2004, 01:33 PM
Here's how I did mine.

This is the battery position. Right Rear. It's a little cheezy right now. I'm planning a fabricating a stainless battery box soon. You don't have to enclose your battery but you can't use J-hooks for hold downs either.

Darkside
05-22-2004, 01:34 PM
Here's where I mounted my cut-off switch.

Darkside
05-22-2004, 01:36 PM
another one

Darkside
05-22-2004, 01:38 PM
I cut away the bottom right side of the license plate bracket and trunk lid and attached the on/off plate. Then when I race I just take off the license plate. It doesn't matter which post you hook up power and ground to on the cut off switch. Next I will weld a piece of sheet metal to close off the hole, paint it, and clean up the area so it looks clean.

racecougar
05-22-2004, 02:47 PM
Will you pass tech at the dragstrip using the style cut off switch that you have (as opposed to the "push off" switches)? Also, I thought you had to wire the switch to completely kill all power to the engine when turned "off", meaning you'd have to somehow cut the power from the alternator as well as the battery. I'm getting ready to install the trunk mounted battery in my 90 XR7, so I'm trying to get all the facts straight.

-Rod

Darkside
05-22-2004, 05:23 PM
As far as I know the rules are:
1. You must have rear mounted kill switch. Must label where the off position is.
2. You can't use j-bolts to hold the battery unless they are welded closed.
3. If your car has an open trunk you have to have a sealed battery box. Our cars don't so you don't need a sealed box although it is still a good idea.

I don't know about disabling the alternator but I don't think you need to.

I wouldn't pass tech because I have j-bolts holding down the battery right now. They let me race anyways on a one-time pass. Next time I must have 3/8 bolts holding the battery to the floor.

If anybody has any info on a alternator kill switch let me know.

BTW, anybody that plans on doing this; I wouldn't use anything less than 1 guage wire for the long stretch from the trunk to the engine compartment.

Randy N Connie
05-22-2004, 09:58 PM
Rod: here is a drawing of what you are talking about.You need the proper switch to cut off the battery and the alternator. www.moroso.com
Part #74102 for battery & alternator disconnect switch.
Part # 74105 T-handle push pull battery disconnect kit for switch.

Randy

Darkside
05-23-2004, 12:14 AM
This is off the NHRA website.


"I have a street car that I occasionally run at the strip. I've relocated the battery to the rear. What else do I need?"

"Any car with a relocated battery must be equipped with a master electrical cutoff, capable of stopping all electrical functions including ignition (must shut the engine off, as well as fuel pumps, etc.). The switch must be located on the rear of the vehicle, with the "off" position clearly marked. If the switch is of a "push / pull" type, then "push" must be the motion that shuts off the switch, and plastic or "keyed" typed switches are prohibited. Also, the battery must be completely sealed from the driver and/or driver compartment. This means a metal bulkhead must separate the trunk from the driver compartment, or the battery must be located in a sealed, metal box constructed of minimum .024 inch steel or .032 inch aluminum, or in an NHRA accepted plastic box. In cars with a conventional trunk, metal can simply be installed behind the rear seat and under the package tray to effectively seal the battery off from the driver. In a hatchback type vehicle the battery box is usually the easiest solution, since the alternative is to fabricate a bulkhead which seals to the hatch when closed. At present, Moroso is the only company which offers an NHRA accepted plastic battery box, part number 74050"

I'll probably get the right switch eventually. Righ now I can pass tech at my local strip so I'm OK for now. Sounds like a sealed battery box is the best way to go as well. I don't know how picky the tech inspectors are at your local tracks but it is better to be safe. They are not too strict at my track. If you have something done wrong they will usually let you run as long as you fix the problem before you come back next time and it isn't a huge potential hazzard, like a leaking oil pan or something.

None2Slow
05-23-2004, 04:00 AM
I know that NHRA wants the cutoff switch in the positive, but wouldn't be better and easier to cut power to the ground? You cut power to the ground and NOTHING works, including the engine. Just thinking out loud.

Darkside
05-23-2004, 08:47 AM
I know that NHRA wants the cutoff switch in the positive, but wouldn't be better and easier to cut power to the ground?

No. That wouldn't kill the alternator.

Slysc
05-23-2004, 02:07 PM
It's a little bit unorthodox but I have mine so that the cutoff switch disconnects the battery ground. The way I make that work with the alternator is by having a constant on 80-120 amp selenoid that cuts off the alternator. Then the ground to from the selenoid (16 guage) goes back to the cutoff switch also. So when I flip the cutoff switch, it disconnects the battery ground, and the ground of the selenoid at the alternator so it disconnects the alternator also.

I just can't do things the normal way. It's a curse.

racecougar
05-27-2004, 05:42 PM
Rod: here is a drawing of what you are talking about.You need the proper switch to cut off the battery and the alternator. www.moroso.com
Part #74102 for battery & alternator disconnect switch.
Part # 74105 T-handle push pull battery disconnect kit for switch.

Randy

Randy,

Shouldn't I use something larger than 10 gauge wire from the alternator to the switch? I would think that wire would need to carry quite a bit more than 20 amps from the alternator to the switch.

What I'm planning on doing is running 1/0 gauge from the battery to the switch, and 1/0 gauge from the switch to the distribution block under the hood. The starter solenoid will be connected to the disribution block by 1/0 gauge wire. Then I will connect the alternator output to the switch with 2 or 4 gauge. Does this sound ok?

Thanks,
Rod

supercatxr7
05-27-2004, 11:34 PM
I agree on running larger wire from the alternator. I ended up using 1/0 gauge from the battery to the cut off switch and then to the starter relay on the drivers fender. I then ran 2 gauge from the alternator back to the battery. Works good so far. I am also putting in a 175 amp fuse between the alternator and battery.

Slysc
05-28-2004, 07:34 AM
You would definately want to run some heavy wire from the alternator back to the switch. That's why I decided to use the selenoid up by the alternator and just shutoff the ground side. That way I'm just running 14-16 guage wire from the alternator switch to the battery shutoff.

I was told that if you really knew what your doing, you could check out the wire diagram of all the wires in the plug that goes to the alternator and find one that would shut down the alternator. Ideally you could just run that wire back to the shutoff and avoid using a selenoid or running the main power cable all the way back to the shut off switch and forward again to the alternator.

racecougar
05-28-2004, 12:46 PM
I was told that if you really knew what your doing, you could check out the wire diagram of all the wires in the plug that goes to the alternator and find one that would shut down the alternator. Ideally you could just run that wire back to the shutoff and avoid using a selenoid or running the main power cable all the way back to the shut off switch and forward again to the alternator.


I was really thinking about doing that. After making my own wiring harnesses for the past couple cars that I've put together, I don't think it would be too difficult to figure this out.

Thanks,
Rod

J57ltr
05-28-2004, 02:15 PM
Instead of using a big *** relay to cut the alternator use a small ISO relay to cut power to the coil pack +. It's a whole lot easier and if your large solenoid goes they are harder to get on the road. You can buy an ISO relay anywhere.

Jeff

Randy N Connie
05-28-2004, 03:25 PM
I posted what the manufacture recomended minimum wire size that
should be used with there switch.So you would use this size or larger.
I would go larger on the alternator,& 1 on the rest.

I would think that the manufactures minimun wire size is right.
And just that the minimun!

RANDY

J57ltr
05-28-2004, 03:32 PM
If you use the second pole on the cutoff switch and cut the power for the coil then you don't have to worry about running large gauge wire for the alternator, and have less wiring to deal with anyway. Don't make it so hard. this should have been a 4 post thread.

Jeff

racecougar
05-28-2004, 03:43 PM
That sounds like a good idea, though it wouldn't kill the fuel pump. I may go this route though, and just have it kill power to the coil packs (this is on a 4.6L DOHC).

-Rod

J57ltr
05-28-2004, 04:00 PM
On the 4.6 you have dual coil packs with 2 coils per side. You only need to cut the + wire as the other 2 wires are switched by the DIS module and are ground. There may be a common + wire spliting to each coil pack. You can also use another relay for the fuel pump, or a multi pole relay.

Jeff

racecougar
05-28-2004, 04:43 PM
Jeff,

That's exactly what I'm thinking about doing.

-Rod

racecougar
06-20-2004, 12:16 AM
A couple new questions:

1) To those who have the Flaming River kill switch, what is the shape of the rod coming out of the switch? I'm talking about the small rod that actually sticks out of the switch that the knob (or 18" push/pull handle) is attached to. It will probably either be square or round with two edges shaved off.

2) Does anyone know if NHRA has any stipulation against mounting the switch through the trunklid itself? It's just a thought at the moment.

Thanks,
Rod

J57ltr
06-25-2004, 10:17 AM
Come to think of it you really have to have the ignition wired (to cutoff). If you were just to do the fuel pump the engine will run for several seconds after the switch is cut off. If you kill the main power and the ignition then there is no way for the pump to run. No alternator (since the engine can not run), no run on. If it doesn't kill the car instantly then it won't pass tech.

Jeff

Don't know the answers to the other questions.