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Starter Motor Trigger Cable Sizing

EFI Wiring Fundamentals

Discussion and questions related to the course EFI Wiring Fundamentals


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Evening HPA

Quick Question about choosing the correct Starter Motor Trigger Cable, I am in the process of Wiring a Life Racing PDU34A into a 1984 Porsche 928. I have worked out all my correct Amps which stock components will draw and the Starter motor is on a boarder line, test showed Inrush 0.07s max of 21 amps then consistent to 6 amps there after am I correct in using a single 16 AWG Spec 55 wire or to be on the safe side run 2 x 16 AWG outputs.

hope to hear from you soon

Regards Liam

After looking at a few charts and rules of thumb... a single 16 AWG should be fine.

Obviously you want a short path, and from dash to starter via a bulkhead should not be a big distance. Also, it's only in use for a few seconds, and Spec 55 should take a tiny bit more heat. And also, you can set your PDM to trip over 21 amps, so fairly safe.

Life's gear has some awesome inrush control/soft start strategies. In all honesty I'd be comfortable controlling, and do on my own vehicles, using 18AWG tefzel in those situations.

P.S. I don't recommend trying to limit inrush current yourself by way of setting a hard 21 amp target. Use the fancy software how its meant to be :)

Hello, Liam. I think the guys above have answered your question so I don't really have anything to offer. However, I am interested in you're project. I also have an 84' 928 that I'll be performing a motor swap into and am considering a chassis rewire using a pdm as well. Would you mind sharing your data on amperage draw from the circuits you plan on controlling? Or anything related? Feel free to shoot me an email. Maybe we could go back and forth a bit on some different subjects of these wonderful cars. Thanks and hope to hear from you! Dan@fsmoto.net