Current draw calculation on injectors

Im using 8 Siemens Deka 2300cc low impendance injectors for my 4 cylinder engine harness and I would like to calculate the max current they will use to properly size the power wires for them.

This depends entirely on your ECU. Usually they have setting for Peak Current, Peak Time and Hold Current. Typically might be 2.5 - 4A peak for 1-2ms, then 0.5 - 1A for the remaining time the injector is open.

Or you can just use the typical 20-22 ga wire and you will be fine. With those large injectors, I bet your duty cycle won't be that large anyway.

In this case its a Haltech Elite 2500. What wire gauge do you reccommend? The distance from ecu to the injectors is at 6.5 feet.

I woudn't think twice about using 22 awg wire for each injector.

As your question was basically answered, just wanted to add on that save for coils and the actual throttle power wires if running DBW, you can be entirely confident using 20 awg and with a bit more planning a mix of 20 up to 24. Keep in mind, 24 is tricky to work with just due to size and I tend to stick with 22 or 20 for the bulk of wiring on the engine.