Evan Purple240zt Posted August 22, 2008 Share Posted August 22, 2008 I have read the specific instructions several times and have only one question. In order to make the engine stop running is there any reason I cannot tie relays into the fuel pump and ecu (2 different relays) to halt the engine vs. cutting alternator output? Of course, I understand I need a master on the +12v line. Eva n Quote Link to comment Share on other sites More sharing options...
johnc Posted August 22, 2008 Share Posted August 22, 2008 Until the engine shuts down the alternator will be providing power. The idea is to kill all power to prevent shorts and fire. What you're suggesting is a good idea but you still should kill the alternator output. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted August 22, 2008 Author Share Posted August 22, 2008 Until the engine shuts down the alternator will be providing power. The idea is to kill all power to prevent shorts and fire. What you're suggesting is a good idea but you still should kill the alternator output. Thanks John, I knew that the motor would run for a short period after cutting juice to the fuel pump but it would die instantly when the ECU power was cut. I guess its not that big of a deal to wire up a relay to kill the alternator too, I was just concerned about damage to the alternator itself. Evan Quote Link to comment Share on other sites More sharing options...
johnc Posted August 22, 2008 Share Posted August 22, 2008 The kill switch is an emergency shutoff so damaging the alternator shouldn't be a primary concern. You should have a regular ignition shutoff in the car and you should use that exclusively in non-emergency situations. There are kill switches that have internal circuits that keep the alternator from damaging itself. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted August 22, 2008 Share Posted August 22, 2008 What you propose will not pass NHRA tech, at least not a tracks that actually perform proper tech inspections. The power to the vehcile has to be killed, not just able to shut the engine, ALL positive power to the vehicle needs to die when the master cut off is switched off. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted August 22, 2008 Author Share Posted August 22, 2008 This question pertains to stopping the engine from running on its own with an alternator. Unless I am reading an incomplete rule, it does not specify if/how you are to kill power from the alternator. Shutting down the engine kills alternator output no? I fully understand that what I am talking about is used along side a master shut off switch! Thanks guys - Evan BTW, John. I have not been teched in before and didn't know if they would demand to see me shut the car off with the master in the rear. If they generally don't then no sweat! Quote Link to comment Share on other sites More sharing options...
johnc Posted August 22, 2008 Share Posted August 22, 2008 I don't know about NHRA tech procedures. For SCCA and NASA we do hit the kill switch if the car is running and it has to shut off immediately. We've also hooked up a meter and checked the cold side of the switch and made sure it went to zero when the switch was thrown, not when the engine finally died. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted August 22, 2008 Author Share Posted August 22, 2008 I don't know about NHRA tech procedures. For SCCA and NASA we do hit the kill switch if the car is running and it has to shut off immediately. We've also hooked up a meter and checked the cold side of the switch and made sure it went to zero when the switch was thrown, not when the engine finally died. I guess with the infrequency of the switch being used, its unlikely to cause damage. Thanks John, I appreciate the good information. Evan Quote Link to comment Share on other sites More sharing options...
JustinOlson Posted August 23, 2008 Share Posted August 23, 2008 I'm using a large 200A solenoid battery kill setup. Its nice because I don't have to run battery cable all the way to the back of the car. Here was I'm running: http://www.t1raceparts.com/product_p/t1bck.htm It uses a Cole Hersee 200A soleniod PN 24143. Regards, Justin Quote Link to comment Share on other sites More sharing options...
Warren Posted August 23, 2008 Share Posted August 23, 2008 FWIW, a Ford "Continuous Duty" starter solenoid would do the exact same thing as that $75 kit and it costs less than $30. Quote Link to comment Share on other sites More sharing options...
bjhines Posted August 23, 2008 Share Posted August 23, 2008 I went through this a while back. I can configure it to suit different requirements. Here is the thread. http://forums.hybridz.org/showthread.php?t=128736 ... Quote Link to comment Share on other sites More sharing options...
gregkring Posted August 23, 2008 Share Posted August 23, 2008 NHRA rule is that all power has to be cut when the switch is thrown. The switch should be as close to the battery as possible (which will also have to be in the rear of the car since that is where the switch has to be). You can not get power from the cold side of the switch once it is thrown. of course it will kill the motor, but the intent of the switch is to kill all power to the car, not just kill the motor. In reality all most tracks check is if the car dies when the switch is thrown. get a switch with provisions for an alternator. If you run the alternator wire on the engine side of the switch then the car can still run off the alternator when the switch is thrown. If you run the alternator wire on the battery side then the car will die, but the alternator wire will still be "hot". best bet is to get a relay that allows the power to be cut and the alternator power to be cut as well. Also for NHRA you have to have a cutoff anytime the battery is moved OR you run faster than 10.99. Greg Kring 71 240ZT Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted August 23, 2008 Author Share Posted August 23, 2008 Wow, Greg Kring... I haven't heard or seen anything of you for a long time. Thanks for being one of my inspirations back in the day. Ill do as you guys suggest. Thank you for the input. My real concern was alternator damage but it doesn't seem likely to be an issue done this way. Evan Quote Link to comment Share on other sites More sharing options...
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