Originally Posted By Supercuda
...As for the effects on what ever, there should be NO changes, that is the purpose of the ballast to maintain a constant primary current with variation in engine speed. That means a stable ignition with no variations related to engine speed...

Given the lack of explanation beyond this repated statement allow me to shed some light on this...just my amateur understanding of the principles and why lower primary TOTAL resistance appears to produce a better result.

Per the following reference material Ignition Coil High Voltage, it appears that following holds true at the time when the primary side of coil approaches it's peak, also called STEADY STATE, as governed by the following law (Ohm's law really):

I_steady_state = V_source/R_primary

where:

I - current
V - voltage
R - resistance

Please note the following statement:

"...The primary circuit is driven by closing a switch to ground, which allows current to flow from the power supply through the primary. When the switch is initially closed, the current in the coil remains zero, as the inductance of the primary does not allow the current to change instantaneously. The current in the primary then increases exponentially until it reaches its steady state value.

The steady state current is the maximum value the current will have. It is determined by the voltage of the power supply and the total series resistance of the primary circuit.

The steady state current in the primary is determined by:

I_steady_state = V_source/R_primary

Rprimary consists of the total resistance of the wire in the primary coil, as well as the resistance of the wires and other connections in the primary circuit..."


Therefore, per Ohm's law, as R_primary drops, given the same voltage it follows that the coil primary side current is higher.

Further on:

"...The energy stored in an inductor is a function of its inductance and the current flowing through it. The equation for the energy stored in an inductor is:

Energy= ½ * L * I^2..."


Therefore, given that coil primary impedance (L) stays the same AND that the steady state current rises it follows that TOTAL amount of energy stored in the primary side of the coil is greater.

Finally:

"...driving with a higher voltage allows the primary current to reach a given level of current in a shorter amount of time. Overdriving therefore increases the output power by allowing more pulses of the same energy to be released in a given amount of time (a higher drive frequency) compared to the case where a lower power supply voltage is used..."

seems to provide the explanation for why going to a lower resistor appears to result in an improved coil performance.

Cheers!