Electrical Engineers and Outhouse Engineers: Unwanted Opinions Needed
 

Background: Putting entire Subaru wiring network, column switches, instrument cluster and drivetrain into a '71 914.

Problem: Could adding terminal blocks and 4-6 feet of extra line mess with the signal strength of a 12v system enough to cause malfunctions? Most of the lines are under 18 ga wire and operating under 20 amps but 75% of the ones needing to be extended are running to the main ecu. Since the 914 is mid-engined and the Subaru had the engine up front, there are certain branches of the harness that need to be lengthened and run to to the back of the car.

Because some of the lines are probably carrying a very small load I'm concerned that extending them and adding the blocks might cause some slight dillution or disruption of signal strength (soldering all of the lines would take a ridiculous amount of time given my propensity to over-solder and I'd still need the extra wire but I am considering it).

There isn't really any other method to execute this idea but I am currently laying out the harness against the rear bulkhead to see if I can get away with only extending the headlight/turnsignal/cooling fans/horn harness and running the rest through the bulkhead to the engine without extensions. Only problem with this is that the instrument cluster and steering column harnesses might not fit but I haven't put them back in yet to verify.

Voltage Drop, Power, Battery Calculator

voltage drop calculator
plug in 18 ga, 6 feet, 10 amp, get 0.8 v drop
hmm, maybe enough to worry about, I don't know what the tolerance of the ECU is
but plug in 12 ga, get 0.2 v drop

so, to be safe, suppose you extend w/ 12 ga? I guess best to find out how much voltage variability the ECU can deal with, which may relate to if the subaru alternator regulates the voltage or if the subaru ecu does - someone must know - maybe ask over on the tech side or in a subaru forum

I would go elsewhere but ALL the smart people hang out here. I was considering using a larger gauge wire for the extensions . . . guess I should look at the signal strength for each branch first.

Are you talking about signal strength or voltage drop? Signals voltages are either amplified mVoltages or resistance measurement. You are dealing with lengths that if the proper gauge wire is used will cause you no problems in either. Make sure all your connections are good using the min. routing.

^^^ I agree with romad.

While we're on the subject, has anyone used the RayChem SolderGrip products??