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Discussion Starter · #1 ·
I'm looking at installing a Taylor or Morosso battery relocation box in my supra, and it needs to abide by NHRA rules regarding the cut-off switch (see below). Basically the switch must be positive, it must be on the rear of the vehicle, (and the hard part:) it must kill all electrical functions when switched.

So obviously you have the positive terminal routed to the switch, but what else? Do you just cut the positive alternator lead and run each side of that cable to the switch? On Larry_A's site, he wired the starter too? :scratch: Should fuseable links be mounted at the battery, or in the engine compartment?

and my last question -- how safe is it to have a positive switch routed at the rear of the car? I mean NHRA doesn't exactly see a lot of rear-end accidents, but I've been hit once at a stoplight, and could theoretically see spinning on a track and backing into a wall. If such a crash happened, I wouldn't want my "safety" switch grounding out and causing sparks right over my fuel tank...

Thanks,
Jeff

PS, I asked this question in Drag Racing 2 or 3 days ago, but haven't actually recieved a reply since I learned the switch must be positive


8:1 Batteries
All batteries must be securely mounted. Batteries may not be
relocated into the driver or passenger compartments. Rear firewall
of .024-inch steel or .032-inch aluminum (including package tray)
required when battery is relocated in trunk. In lieu of rear firewall,
battery may be located in a sealed .024-inch-steel, .032-inchaluminum,
or NHRA-accepted poly box. If sealed box is used in
lieu of rear firewall, box may not be used to secure battery and
must be vented outside of body. Relocated battery(s) must be
fastened to frame or frame structure with a minimum of two
3/8-inch-diameter bolts. ("J" hooks prohibited or must have open
end welded shut.) Metal battery hold-down straps mandatory.
Strapping tape prohibited.

8:4 Master Cutoff
Mandatory when battery is relocated or on any vehicle running
9.99 or quicker. An electrical power cutoff switch (one only) must
be installed on the rearmost part of each vehicle and be easily
accessible from outside the car body. This cutoff switch must be
connected to the positive side of the electrical system and must
stop all electrical functions, including magneto ignition. The off
position must be clearly indicated with the word "OFF." If switch is
"push/pull" type, "push" must be the action for shutting off the
electrical system, "pull" to turn it on. Any rods or cables used to
activate the switch must be minimum 1/8-inch diameter. Plastic or
keyed switches prohibited.
 

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Discussion Starter · #2 ·
Also, can you mount two cables of difference gauges on the same switch? I say you're using a 1 gauge wire for the battery, but a 4 gauge wire for the alternator -- would you have to worry about the alternator's wire being overloaded?
 

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GOT BOOST?
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I have a switch mounted in the trunk but it is on the negative side... Most parts stores sell batery cut off switches with alternator protection.. Summit has one for sure. The switch is ~$30...

To run it just splice it in the battery cable coming off your positive battery terminal (in series). This way it will cut power to all electrical consumenrs.
Only problem is that it is the opposite acction of what they want. push turns it on and pull turns it off.
 

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Canada, Eh?
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i know some people mount the switch behind their license plate, so when your drag racing you just remove your plate and attach the switch handle.
 

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This is a difficult problem, because you will be running a pretty good amount of energy a fairly large distance... 4 gauge should be the minium run.

From what I understand in my limited range of knowledge is that, you should run the wire from the post on the alternator to the switch and then to the battery and then back to the car... its going to be a lot of wire. Make sure you use high quality wire and loom it anywhere it could snag. I really don't think that the starter is necessary to switch since it should not be working unless the key is in the start position. Unless the techs are total anal dicks you shouldn't have a problem.

Someone should jump in here because I have never done anything like this b4.
 

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another

I have a fuse in mine as you can see. I had it wired by mistake that when you turned off the switch is would still run :rolleyes: Now that I turn off it still runs with the timer on ;) :p

Duane
 

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Discussion Starter · #13 ·
Hey Duane, didnt want to call you for a simple question -- Do you have the facilities to make carbon fiber bars/pipes? For like a strut tower bar (maybe even the center section of a sway bar). And relevant to this thread -- a cf battery box?
 

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ma71supraturbo said:
Hey Duane, didnt want to call you for a simple question -- Do you have the facilities to make carbon fiber bars/pipes? For like a strut tower bar (maybe even the center section of a sway bar). And relevant to this thread -- a cf battery box?
No worries. The battery box... Hmmmmmmmm yet another idea! Thanks dude! I think I will look in to that! ;)

We have not made anything for strut bars but we can look in to that later on. I have waaaay to mnayprojects going on now.

headlight vent for passenger side is complete. I tried the prototype on the car tonight and need to make a few little changes to ensure a smooth installation.
Arm rest
Drivers side cover is being worked on now

I will make a post whe we want to start something new in a while.

We are making the MKIV carbon door panels. Any interest in this?

Duane
 

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Discussion Starter · #16 ·
Hmm, not from me. There is a company recently making fenders and targas for the MKIV. See their general section for details (they hope to have fenders by early december I believe) I personally don't think 2lbs of savings on the fenders is worth it, but you never know ;)


On a side note, did you run a wire to the alternator to your battery kill switch?
 

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Discussion Starter · #19 ·
lets_go_supra said:
IT would run on the alternator if the electric fuel pump wasnt shut off...........

You could wire the fuel pump positive to the switch, but the car would not turn off immediately per NHRA's liking. If you just disconnect the battery, the fuel pump will keep going...
 

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GOT BOOST?
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I think that what they are saying is that in case of an accident they can access that swich and disconnect the battery to prevent sparking. At all other times the battery is connected...
 
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