How to Properly Ground a Race Car

[Ed Wright]

Originally Posted by Jeff Niceswanger

Don't go directly to battery on the positive side if your running 16 volt battery's . You will have to connect to kill switch, so you are not charging your ECU and MSD during charging . They charge at 20 volts ,and I found out the hard way it will pretty much damage everything in your car ......

I learned this one the expensive way as well.

[Jeff Niceswanger]

Originally Posted by Ed Wright

I learned this one the expensive way as well.

Me 2 .. And 2 seasons ... Burnt up the BS box 3 times( Points Drivers ) .. The Digital 7 box twice ... I had Andy Kronenbitter ( PK Racecars) re-wire the whole car, switch panel, shutoff switch...everything . In the process ,he found the problem ... Its probably fine as long as your on 12 volt system ..But he came up with a point.. " that is not legal" ... You would have hot wiring going up through car at all times ... No way to shut it off...

[Ed Wright]

The battery cut-off switch kills my engine too. Shuts off everything but the battery charger plugs Eastexas Racecars put in my rear fender. Everything else wired to the cut-off switch. Killed two FAST XFI ECUs and two MSD boxes before I pulled my head out.

[buzzinhalfdozen]

Originally Posted by Jeff Niceswanger

Don't go directly to battery on the positive side if your running 16 volt battery's . You will have to connect to kill switch, so you are not charging your ECU and MSD during charging . They charge at 20 volts ,and I found out the hard way it will pretty much damage everything in your car ......

Jeff, yes didn't clarify this as you stated. My ECU is hooked directly to the battery disconnect, which as you said prevents over voltage to the module. Should have reread my post before hitting submit.

[Bobby Fazio]

Just wanted to revive this thread to see if anyone was willing to share a race car wiring schematic or know where I can find a good one. I am still fighting RF noise and possibly some grounding issues with my o2 sensors. The tach signal is still very erratic on the graph.

[SSDiv6]

Originally Posted by Bobby Fazio

Just wanted to revive this thread to see if anyone was willing to share a race car wiring schematic or know where I can find a good one. I am still fighting RF noise and possibly some grounding issues with my o2 sensors. The tach signal is still very erratic on the graph.

Bobby, contact Rich Concato. He is a Div 1 racer.

http://www.concatoracing.com/

[Rob Wright]

Do yourself a favor & set the system up with a floating ground.

The only things that should be connected to a chassis are 4-link bars & shocks, not wires.

[Ed Wright]

Originally Posted by Jeff Niceswanger

Don't go directly to battery on the positive side if your running 16 volt battery's . You will have to connect to kill switch, so you are not charging your ECU and MSD during charging . They charge at 20 volts ,and I found out the hard way it will pretty much damage everything in your car ......

I learned the same expensive lesson. Both of my 16 volt chargers also put out over 20 AC volts. Had to replace the ECU & MSD. Not going to say who did it (not me this time) but me charging plugs in the fender were originally also shut off by the battery shut off. Had to change that so I could plug in & charge my batteries with it shut off. Sure don't want to charge them with that switch "on".
Instead of running the ECU, fuel pump, and fans through the toggle switch on the dash, I power them from GM fuel pump relays, turned on & off by the toggle on the dash. ECU has it's own roofer relay. I was seeing some voltage drop running all that thru the toggle switch. Power for the relays are double 10 ga wires directly from the batteries. May be over kill.
Everything, including to the batteries ground to a stud on the back of a cylinder head.