Race Kill Switch problem

Joe Bob · Joe Bob's Garage

I switched from a four cylinder to a 2.0/6 in my 914. The POs red flag style kill switch mounted above the engine bay is wired into the POSITIVE circuit.

When swapping out the electricals and such I hooked it up as the PO did and did a test over the weekend.....revved it to 2500 rpms per the tech rule book and turned the emergency cutoff key to OFF. It dipped a bit in RPMs and then returned to running. Obviously a fail.

I'm thinking that the the three wire alternator needs to be hooked thru the switch as well? Either the D+ or the more likely the main?

Anyone have a wiring circuit diagram for it?

Stock Porsche CDI box, 2.0/6 "S" motor....

I had a "similar" issue with the dash ignition on an another car that needed a diode on the D+ to get it to stop when the ignition was killed...don't think this is the same.

TIA

304065 · 05-02-2005, 08:04 AM

Mike,

Search here. Hopefully you didn't destroy your alternator in the process.

The six pole switch has the following contacts

1 fat pair, for the battery positive lead
1 small pair, normally closed, for the ignition circuit
1 small pair, normally open, for the alternator dump resistor.

When you throw the switch the battery gets cut off, but the alternator still provides power, which is why your engine didn't stop running. Except that when the electrical load (the battery) is removed the alternator voltage and amperage spikes OFF THE CHART. This is why the wiring diagrams say "Operation of engine with battery removed results in immediate destruction of alternator."

With the six pole switch, when you throw the switch, the battery and ignition are cut and the alt poles are CLOSED. One of those poles is connected to the positive battery terminal on the same side as the alternator. The other one is connected to one terminal of a 10 ohm, 100 watt resistor, and the other to ground. When you throw the switch, the current from the alternator gets shorted to ground through the resistor, which is providing the load.

Be careful, don't burn the car down! Good luck!

donporfi · 05-02-2005, 08:11 AM

Where do they sell the 6 pole safety switch?

The two pole safety switches do not work? I noticed that they are conneted between the battery negative and ground, but the effect is the same, if actuated the engine does not stop.

Thanks for your help

Joe Bob · Joe Bob's Garage

Great....is it immediate? I switched it back on after about 3 seconds....

Guess I will have to get the multi meter out.

914/6 · 05-02-2005, 10:54 AM

painless wireing sells a relay kit to do the same thing as the multi pole cutoff switch. look in jegs or summit or painless wireing.

Joe Bob · Joe Bob's Garage

Well I didn't kill the alternator.....checks out as charging....so the dual post kill switches won't work or are illegal or just junk?

304065 · 05-02-2005, 01:17 PM

Just junk. They are useful in dirt-track cars that don't run an alternator.

Joe Bob · Joe Bob's Garage

Well no harm no foul....who makes a good one?

304065 · 05-02-2005, 01:27 PM

Sparco.

greglepore · 05-02-2005, 01:31 PM

Mike-smart racing has one of the 6 pole #'s for 44 bucks, or you could do the relay- the kit is 40 bucks, but if you're creative with parts I think you could put it together for half that.

rattlsnak · rattlsnak's Garage

No need to run the Alt resistor. Just connect the battery cutoff through the positive side, as you described, and on the other contact run a wire (in series) to the ignition (dme relay or such) and you're done. What you're doing is causing the engine to shut off when you flip the switch, by A. shutting the battery off, and B., shutting off the Ign. And that way, the alt cant keep the car running.

Joe Bob · Joe Bob's Garage

So run the big wire from the alt thru the switch like the paostive battery terminal?

greglepore · 05-02-2005, 01:50 PM

What they suggested on 914 club was to do that-run a seperate wire from the alt to the battery side of the switch, so that when you hit the cutoff the alt still sees the battery as a load and doesn't spike. That should work, but if your cutoff is on the front cowl that's a fair amt of wire-at least in my case, where my batt is located in the former gas tank space and the cuttoff is near the driver's a pillar. Where does the alt output go now, to a starter pole?

You'd also need to make sure that the only way that the ign sees voltage is thru the cable on the cutoff out side.

Joe Bob · Joe Bob's Garage

It's on top of the engine bay, above where the battery used to be....

304065 · 05-02-2005, 03:08 PM

The resistor is $1 from Radio Shack. I would not recommend running a separate unfused wire through the many nooks and crannies of the car. Remember that one of the purposes of a kill switch is to isolate the electrical system from the car to prevent sparks in the event of a crash. You back it into the wall, you have fuel leaking all over the place, the corner worker runs up and isolates the electrical system from the whole car with the exception of a 12" run from the battery.

Joe Bob · Joe Bob's Garage

Battery is in the passenger seat area. The run is no more than 2 feet.

Matter of fact....wouldn't it make sense to kill power to the coil?

Been looking on line for a schematic...no luck.

greglepore · 03:33 PM

Mike-look at smartracing's instruction page-it gives you a good idea of what the six pole does. What you might want to do, given the proximity of everything is run the alt lead to the "in" side of the cutoff, along with the lead coming from the battery-currently it isn't isolated in this fashion-while I don't know how your car is currently wired (why I asked above where the alt lead runs to now) it likely runs to a point common with the main lead from the bat to the starter, which is why cutting off the battery only isolates the battery-the alt is on the "out" side of the switch, along with the ign and the starter primary-if you isolate it to the "in" side of the switch, the batt provides a load to the starter and the alt is removed from the ign as well. Capice?

Still haven't mounted those darn Deltas I bought your bike to get...

Joe Bob · Joe Bob's Garage

THAT'S WHAT I WAS LOOKING FOR....the stoopid book.

Thanks.

BTW....it says to hook the coil into the cicuit and have a resistor to ground....nothing about the alternator.

greglepore · 05-02-2005, 03:48 PM

Yah-if you have a six pole switch to begin with....
If you wanna utilize the 2 pole you have, you need a relay to dump the alt when you open the switch, or you need to isolate the alt feed to the "in" side of the switch.

Joe Bob · Joe Bob's Garage

Gonna take a closer look at the switch I have...the four "other" poles seem pretty small and easy to overlook.