Alternator unable to keep up voltage

[hemi8]

I Powerlogged 45min of driving yesterday making a few WOT blasts to see how all the systems and sensors are working. The voltage stayed between 13.0 to 13.5v during all conditions except WOT, it dropped to 12.5 to 12.7. I have been reading about voltage boosters this morning and that does not look like something I want to use because of the alky injection system I use. Is this low voltage an indication my alternator is unable to keep up under the demands of WOT?
Mike

 

[Dabigguy]

You've got a high amperage fuel pump plus the alky pump running at full throttle. What amperage alternator do you have? If you are running headlights and AC at the same time too, you are probably exceeding the alternator's output. You need at least 120 amps, preferably 140-200.

 

[hemi8]

It is a 120 AC Delco. I see others are running the Impala SS direct bolt-in 140 amp but I did not know there was a 200 amp available. Is it a direct fit and are there any negative effects from running such an alternator? Part #?
Thank you for you help,
Mike

 

[mikestertwo]

That voltage you are reading is not battery voltage, it is ignition voltage. The voltage drops because the ignition system is drawing more current as the rpms rise. The voltage drop is in the wiring. If you put a volt meter across the battery while at WOT you will see the voltage is not dropping.

 

[hemi8]

Turbobuicks.com 240 amp alternator, 0 gage wire from battery to alternator and all is up to par, 13.0V on PL under WOT.
Mike