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Discussion Starter #1
Vehicle is a 04 GT, Spent the past three hours trolling the switch topics and really can't find a definitive answer on basic configurations. I've seen remote solenoids, switches, and fuses galore. What I have is the battery in the trunk, grounded right there, 4 gauge to moroso kill switch, opposite side of switch has jumper to fuel pump, and onto the front of the car where it junctions in a basic battery isolation switch. One goes to the main fuse and one goes to the starter. Without reinventing the wheel, my first question is: is this too simple to work? It works and kills everything as it should, but maybe not fused/safe? Second question is I am wanting to mount this on the trunk, reusing the moroso switch, has anybody went about this with a hole saw to mount it next to where the license plate is? Sorry if this sounds newb, but I figured in following The basic nhra rules, the switch SHOULD does its job in killing all power on the + side and shutting down the vehicle, but I drive it very little, and when it's parked, it's plugged into a trickle charger with the kill switch off to the rest of the system. Thanks for all input.
 

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The NHRA is not real clear or safe in their descriptions, but let's assume we want three things. We want to not burn the car down because of safety equipment, we want to kill power to all wiring, and we want to shut the engine down.

If you have an alternator up front, it will not kill the engine by the switch. The alternator will power the car with the switch flipped.

If you run the alternator back to the battery, the alternator high current lead would be hot in a wreck with the switch off. That is a fire hazard and against rules.

What I finally decided to do was use a double pole switch. The heavy pole runs the main battery power up from on a heavy cable. The small pole kills my fuel pump and alternator regulator field control voltage.

I have a 350A CCS, 450A surge fuse link on the battery negative.

Battery Wiring
 

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If you have an alternator up front, it will not kill the engine by the switch. The alternator will power the car with the switch flipped.
I may be misunderstanding you but every late model car with an alternator and an ECM is powered from the battery. The alternators only function is to keep the battery charged.
The drawing I posted works, is safe and has passed tech every time.
 

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Discussion Starter #5
In a sense, that's how my kill switch is wired, but the split off is up by the front Fenderwell, I wondered that when I wired mine, even if I kill the battery, the alt should still power the car. Very nice install, I have debated the push pull switch because of the smaller diameter hole and ease of mounting. When cutting it out, is it just fiberglass ribbed onto sheet metal?
 

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In a sense, that's how my kill switch is wired, but the split off is up by the front Fenderwell, I wondered that when I wired mine, even if I kill the battery, the alt should still power the car. Very nice install, I have debated the push pull switch because of the smaller diameter hole and ease of mounting. When cutting it out, is it just fiberglass ribbed onto sheet metal?
I used a large hole saw to cut through the inner panel and a correct sized drill bit to go through the outer fiberglass.
 

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Discussion Starter #7
Last question, because I saw how uneven the inner fiberglass is, how hard is it to keep the hole saw from walking! I lined mine up last night in the flattest location and it looked like a nightmare, any tips? I thought at first a dremel, but everyone said hole saw. Thanks for all the help!
 

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Last question, because I saw how uneven the inner fiberglass is, how hard is it to keep the hole saw from walking! I lined mine up last night in the flattest location and it looked like a nightmare, any tips? I thought at first a dremel, but everyone said hole saw. Thanks for all the help!
I should have mentioned this but I had to get a long bit for the holesaw. After drilling a small pilot hole in the right spot the longer bit held the holesaw in place.
 

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If you have an alternator up front, it will not kill the engine by the switch. The alternator will power the car with the switch flipped.
I may be misunderstanding you but every late model car with an alternator and an ECM is powered from the battery. The alternators only function is to keep the battery charged.
The drawing I posted works, is safe and has passed tech every time.
Passing a local track tech is one thing. My car can pass without any switch in circuit and no fuses. My buddy's car passed for years and the electrical was a death trap. I finally insisted he fix it.

If the alternator goes to the common point power feed for electrical up front, killing the battery will not stop the car. Things will run off the alternator without the battery in line. This is also terrible for electrical parts.

If the alternator output goes back to the battery, it is unsafe and not NHRA legal. It is unsafe and non-compliant because the heavy alternator wire will remain hot even with the switch off, and that is a fire hazard. Everything has to cut off according to rules.

The only way to kill an alternator car compliant with rules is to kill fuel, ignition, and/or alternator with one pole of a switch while the second pole kills the main heavy feed to front.

There is no other way to do it. It has to have a second pole.

I would never run a heavy alternator feed back to the battery in my car. I back feed the heavy main cable to the start relay/solenoid. I do the engine kill primarily by cutting fuel pump voltage, although I cut other things, and the large pole opens the heavy start cable that goes to the front common power point.
 

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If you have an alternator up front, it will not kill the engine by the switch. The alternator will power the car with the switch flipped.

Passing a local track tech is one thing. My car can pass without any switch in circuit and no fuses. My buddy's car passed for years and the electrical was a death trap. I finally insisted he fix it.

If the alternator goes to the common point power feed for electrical up front, killing the battery will not stop the car. Things will run off the alternator without the battery in line. This is also terrible for electrical parts.

If the alternator output goes back to the battery, it is unsafe and not NHRA legal. It is unsafe and non-compliant because the heavy alternator wire will remain hot even with the switch off, and that is a fire hazard. Everything has to cut off according to rules.

The only way to kill an alternator car compliant with rules is to kill fuel, ignition, and/or alternator with one pole of a switch while the second pole kills the main heavy feed to front.

There is no other way to do it. It has to have a second pole.

I would never run a heavy alternator feed back to the battery in my car. I back feed the heavy main cable to the start relay/solenoid. I do the engine kill primarily by cutting fuel pump voltage, although I cut other things, and the large pole opens the heavy start cable that goes to the front common power point.
If you notice in the drawing I posted the alternator is only connected to the positive battery terminal in the trunk of the car. The Pos lead goes through the switch at the rear of the car. When the switch is open, no power (alternator or battery) is being delivered to the front of the car. That kills the ECM, fuel pump, and the ignition therefore killing the engine. It works, is safe and passes NHRA, NMCA and NMRA tech, not just local tech.
This method has been argued on more that one message board in the past. The bottom line is that when the safety switch is opened there is NO POWER to any component of the car. Engine is killed and no electrical hazard is present. It is as safe as your method
 

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If you notice in the drawing I posted the alternator is only connected to the positive battery terminal in the trunk of the car. The Pos lead goes through the switch at the rear of the car. When the switch is open, no power (alternator or battery) is being delivered to the front of the car. That kills the ECM, fuel pump, and the ignition therefore killing the engine. It works, is safe and passes NHRA, NMCA and NMRA tech, not just local tech.
This method has been argued on more that one message board in the past. The bottom line is that when the safety switch is opened there is NO POWER to any component of the car. Engine is killed and no electrical hazard is present. It is as safe as your method
you are correct in your drawing that the switch will shut the car off, however there still is an electrical hazard potential there. The heavy alternator wire is still "hot" the whole length of the car even with the switch off. at minimum, there should be a high amp fuse in the alternator circuit .....as close to the battery as possible, just in case that cble gets pinched, cut or wears through to "ground".
 

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you are correct in your drawing that the switch will shut the car off, however there still is an electrical hazard potential there. The heavy alternator wire is still "hot" the whole length of the car even with the switch off. at minimum, there should be a high amp fuse in the alternator circuit .....as close to the battery as possible, just in case that cble gets pinched, cut or wears through to "ground".
I stand corrected. You and Tom are correct about the Alt wire. It should be fused (mine is but not shown on the drawing) and ran through a switch as well. Although myself and I think most people don't see that as a great risk but you guys are correct.
 

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Hate to dig this back up, but what are you guys using to fuse the alt circuit? Mega fuse? What size is sufficient?
I use a wire fuse link. They are more reliable.
 
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