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KA swap battery in trunk and engine ground wires


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Needing some ideas/help on ground wires and battery in the trunk for a KA24 swap.  What did you do for ground wires to the engine and chassis.  I've got the stock wire running from the alternator to the chassis, one from the intake manifold to the strut bolts, and one from the head to the firewall.  What size wire are you running?

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Did some searching and I ran the negative wire from the battery to the bolt hole in the spare tire well.


For grounds, I have the stock 510 grounds, the stock KA24 grounds of the Alternator to the chassis, and the one going to the intake manifold and the head.  I added 8 gauge wires of the Intake manifold to the strut bolt, valve cover to the firewall, head bolt to a bolt on the motor mount on the engine bolt side and then one from that same bolt to the driver strut bolt. 

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Run the negative from a bolt in the trunk to the battery, run the positeve from the the starter to under your car and up into the trunk. there should be a hole along the way to put it through and there should be clips along the frame rail to hold it in place and not drag. i'd snap pics to show you but my cars at my buddys shop

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The biggest draw in current is going to be the starter. As current flow is the same in any part of a circuit both the positive and ground cables (and anything in between) must be able to handle it. If you have an 8 gauge positive wire to the starter you will need an 8 gauge wire from the block to the body if the neg terminal is grounded to it in the trunk. The ground in the trunk to the body must also be 8 gauge. Keep in mind that you can't just wrap the bare wire around the bolt with a washer.

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The wires from the batter to the starter and from the - battery to the bolt in the spare tire are bigger than 8 gauge, closer to a 2 gauge I think, (can't remember exact size) before I bolted the ground down I made sure the surface was clean metal to metal.  Removing all the paint from where the bolt would touch. 


All the 8 gauge ground wires are under the hood, plus the stock KA24 ground wire locations (intake manifold, chassis, alternator, head), I added from the intake manifold to the passenger strut bolt, head to engine mount bolt on the engine block side, and from that same bolt to the driver strut bolt. All surfaces were sanded to bare metal before everything was tightened down.

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Do a voltage drop test on both the positive battery terminal to the starter, and the negative battery terminal to the starter frame.

This is how.



The higher voltage your starter gets, with a minimal voltage loss in the cables, frame, connections, ETC, the better your car will crank.  A better connection to the starter, will actually cause the starter to spin faster, and that will drag the battery voltage down less when cranking, and you will actually have more voltage available to run the ignition system.


Conversely, a good connection will help your alternator charge the battery.  Your alternator actually has to put out more voltage than the ideal 13.5 to 14.5 volts needed AT THE BATTERY to charge it.  Unfortunately, the engine electronics, and car accessories are at the front of the car, getting the higher voltage.


If it was me, remotely locating a battery, I would use at least a 1/0 battery cable on both the positive and negative from the starter to the battery, with as few connections as possible.  I would connect the negative battery cable on one of the bolts holding the starter, or to the place on the KA engine the factory connected the negative battery cable.

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thats not needed, use a good heavy ground wire with a crimped ring terminal to the frame, you dont need 1/0 gauge eithier, it's just going to cost more and be a lot harder to run, we have used 2/0 gauge to run the batteries on these planes for decades, and the battery is in the tail it's more then adequate 

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