Don Terrill’s Speed-Talk

Hello,

I'm building ground-up wiring for a street car, 4 cylinder to run fully sequential, high impedance injectors normally aspirated at about 100BHP/liter max output. Tips on how to wire power to the injectors? Same for COP igniters? The relays for these feeds will be nearby both battery and engine.

Thanks
Steve

High impedance Injectors, 0.5mm or 24 awg from OEM's. 22awg is very common when making a custom harness from scratch.

COP, 0.8mm or 20 awg on B+ and B- and 0.5mm or 24 awg on the trigger from OEM's. 18 awg common in custom harnesses, 22 awg on the trigger.

"Custom" harness assumes Tefzel wire or equivalent, OEM assumes pvc/vinyl jacket.

Thanks kindly for your advice @dannobee! I am thinking it OK to take something like a 12 or 14awg feed off the relays, run up into the vicinity on engine and there splice the lighter wires under well sealed crimp. Injectors are to be high impedance. The COP coils are something I need to study a bit further in order to understand what wiring requirements apply, as I've seen connectors with 3 or 4 wires. Thinking Denso found on recent Toyota's might be good, seems they have integral igniters.

Two terminal COP's are "dumb coils," 3 or 4 terminal COP's are "smart coils" with ignitors built in. the 4th terminal is a feedback circuit to the PCM. You won't need it for an aftermarket PCM.

Go 18 awg to the injector splice if you're worried. Plenty big, and bigger than what the OEM's use.

Thanks for that!

To wrap this up with one final question what gauges to feed LS type CNP units? Same installation, alternative to the COP.
Cheers

GM LS CNP (~2004 or so) is 0.8mm, ~20 gauge, so more commonly available 18 gauge, with a single 15A fuse at the fuse block, shared with 4 of the injectors. On the ground side, 0.8mm to the spice, then 1.0mm from the splice to ground. But like anything under the hood, use something rated for temp, just in case the S hits the fan. So "Spec 55" (200 C rating) or "Spec 44" (150 C rating). In the big scheme of things, the money spent on high quality wiring is cheap and might save you from an electrical fire. The big money is in the crimp tooling and little things like DR-25 shrink tubing, splices, SCL shrink tubing, etc that all seem to add up.

Resolved to go with CNP layout using AC Delco part # 12713668 coils, as fitted to many vehicles post 2014. These are the flat, square-ish shaped ones with 5 pin connector. Attached screenshot is from a Haltech web page pertaining to IGN 1A coils, also 5 pin which leads me to conclude same wiring applies to my garden variety coils. Connection to pins A and E seem clear enough, but what would be the best way to deal with the B through D ground pins? Basic aftermarket ECU in use, wiring up the car from scratch.

Thanks
Steve

That's in fact a GM part #. Somehow unable to search up a connector pin out diagram.

Well confession time, seems I somehow got the eronneous idea that my coils are 5 pin when they are, in fact 4 pin. Duh. No great challenge getting the connector wiring figured now that I'm straight on this fact.