The thing about IDIs, they don't need very much power once running. The only thing keeping the engine running is the fuel cutoff valve being open with power feeding a solenoid.
If you have a C6 or stick, the transmission uses no electricity at all. E4OD uses some, but probably not a ton.
The biggest draw when driving would be the headlights, if turned on. If you have an electric fuel pump, you can add that to the list.
So, a 120A alternator is pretty generous for an IDI already.
If you have a C6 or stick, the transmission uses no electricity at all. E4OD uses some, but probably not a ton.
The biggest draw when driving would be the headlights, if turned on. If you have an electric fuel pump, you can add that to the list.
So, a 120A alternator is pretty generous for an IDI already.