Normal voltage drop on boost ?

[Butters]

Reviewing the logs on my car after a few pulls and notice the voltage steadily drops on full noise. 

Now I assume this is normal as the injectors, pump(s),  and other items are all drawing more. 

Does 13.8 to 12.8 then back to 13.8 in a gear change sound normal ?

Also is the ecu good at measuring voltage or is it giving false numbers due to its own demand ?

 

 

Extra info:

Car runs staged pumps, volt drop increases slightly as second pump comes on but really its steady angle down. 

The alternator is aftermarket 120amp jap brand.

[Dose Pipe Sutututu]

Shouldn't drop, if it is there are signs of current demand overwhelming supply.

FWIW, I run 1x DW200 lift, 2x Walbro 450Ls (via PWM) and voltage is flat across the RPM range at full tilt as per logs.

All this is on a Circuit Sports 90amp alternator. Most of the power wiring is factory bar an additional engine to chassis earth strap and a new battery to chassis earth using 4GA audio cable because that's what I had lying around.

[Guilt-Toy]

what alternator are you using bud ?

[TurboTapin]

Also wanted to chime in that this is not normal. ECU is reliable to read voltage but there's roughly a .4-.5v difference from battery voltage and ecu voltage.

[Guilt-Toy]

stock earth wires?  where are the pumps wired to on power side?  whats the earths like on the pump?