Engine shut-off switch

[MHT]

Anyone have a link or can give me directions on how to wire an alternator shut-off back to the exterior main shut-off switch. My shut-off switch currently won't kill the engine when its running.

Thanks, James

[Bryan Savage]

If you want to kill your engine, wire a switch to ECU Power, your ignition coils, or your fuel pump. I don't know your whole story, but why would you want an alternator cut-off switch? That will drain your battery and perhaps buy you a couple of extra horsepowers in the four-hundred meter, but it won't kill your engine.

[BlueVelocity]

Yes. Disconnect the primary output from the altenator that bolts on there. The copper looking jobby. Then run a big wire from that terminal post on the alternator to the battery directly. (good practive to put a breaker in there just for safty) Then from the battery, go to the cut off switch, and then the output of the cutoff switch back up to where you had disconnected the terminal from the alternator.

Or, you can go straight to the ECU fuse primary in the fuse box under the hood but the first method is much easier.
This will give you instant shutdown, which I know the techs you deal with are looking for. No battery, no alternator, no ecu, no fuel pump, no running car! My car goes dead before I have the switch fully over to off, works like a charm!

Erron S.

[BlueVelocity]

If you want to kill your engine, wire a switch to ECU Power, your ignition coils, or your fuel pump. I don't know your whole story, but why would you want an alternator cut-off switch? That will drain your battery and perhaps buy you a couple of extra horsepowers in the four-hundred meter, but it won't kill your engine.

I believe James is trying for the upper eschelon speeds at the salt flats. Right, James? (you're the man by the way for upping the anty on high speed DSM's)

What they are looking for is the same with any sanctioning body of racing, total shutdown. By doing it the before mentioned way, it allows a safty steward to entirely kill the car, then they only have to worry about gas leaks and hot areas. This is much safer to have it this way because it kills everything, no more DC voltage anywhere to ingnite fuel vapors, or short out giving off a toxic plastic burning fumes. By killing just one item, say the fuel pump, this is not accomplished. The car may not be running anymore, but if they are trying to get him out a "wadded" car, chances are there are wires crushed between panels and possibly the roll cage.

Erron S.

[MHT]

Thanks Erron,

What size wire is sufficient from the alt. terminal to the battery?
10ga. or something much larger like 2ga.?

James

[BlueVelocity]

Thanks Erron,

What size wire is sufficient from the alt. terminal to the battery?
10ga. or something much larger like 2ga.?

James

You want something in the 2ga area, if not larger, DC loves big wires. A good multistrand copper with a thick insulation is all you need.

Erron S.

[MHT]

Completed the alt. shut-off circuit yesterday. As Erron said, it shuts off the engine and everything else before the exterior switch goes to full off. Here's hoping I'll never need to use this mod during a run!

IMO/FWIW- When doing a trunk-mount battery conversion, it'd be a real time saver to install several extra cables(two 2ga. + three 10ga.) between the engine bay and trunk area so that you won't have to take apart and re-assemble the interior each time you add other components to the system.

[BlueVelocity]

Excellent! Glad to hear it James!

Erron S.