Originally posted by 99fordsvt:
1. The alternator only draws as much as the regulator tells it to
If the battery is fully charged, the alternator will NOT draw a load (or take HP to turn).
2. based on the state of charge of the battery.
3. Seems this is a nice machined part - but don't buy it thinking it will help performance.


1. The regulator regulates the voltage. (I.E. Voltage Regulator) Not the amperage draw!

2. The car most certainly DOES run off the alternator.

Only in times of peak load where the alternator can not support the amperage demand does the battery supply it's reserve power to the car.
The battery has 2 functions: It's main function is to start the engine & it's secondary function is as backup reserve for when demand levels exceed alternator output.

Common times where this can occur is at idle with accessories & lights running and definitely if one has a high wattage sound system.

For Reference - The alternator is rated at roughly 4000-5000 rpm (engine speed)
It is not a linear curve either. It starts out at about half rating at 1000rpm and arcs up to it max rpm (normally tested to the equivalent of 6000-7000 rpm engine speed)

For instance our alternator. (a rough example but close enough for a reference)
1000rpm = 60 amps
2000rpm = 75 amps
3000rpm = 95 amps
4000rpm = 125 amps
5000rpm = 135 amps
6000rpm = 140 amps
7000rpm = 145 amps

Now figure any underdriving would directly lower the max amperage output at each rpm point by the % amount compared against the curve slope.

3. Since the alternator is rpm dependant slowing it down will create less drag on the FEAD system. Are we talking bunches of HP/TQ. Heck no.
Probably not even an amount big enough to ever be verified.

However you have to think about the fact it is slowing the alternator down as rpm passes 5k, 6k, 7k.

This will aid in longevity of the alternator for those people that drive their car like it was designed to be driven. The fact it may free up a little parasitic drag is just a bonus.

As I have said before I think this is definitely a good mod for anyone running a stock sized battery, no electric waterpump, or no major sound system. (personally I've not any problem with it & my dyna-batt though)

2000 SVT #674 13.47 @ 102 - All Motor! It was not broke; Yet I fixed it anyway.