Steve, thanks for doing the legwork on this. Great find from manufacturer. This seems to match Ed's comments.
Stevehose said:For your 6 cylinder engine we recommend Bosch red coil 0 221 119 030 without ballast resistor. The blue coil is better for 4 cylinder cars. We are working on a new website....
The ballast resistor is used to keep the coil from overheating, the condensor protects the points, yes?
I drove with the ballast resistor bypassed over the weekend. Amps from the coil went from 2.8 to 3.6.
I am curious how much the impedance is potentially skewing these resistance based formulas. I only say that because these numbers do not necessarily match the Bosch coil resistances (that I've read people having measured in other forum posts - specifically MB and 2002). But the math and principles are solid!!! Thank you for posting.So the coil alone must have resistance of 12 v / 3.6 a = 3.3 Ω. The coil + ballast resistor must have a combined resistance of 12 v / 2.8 a = 4.3 Ω. Therefore, the ballast resistor alone would have resistance of 4.3 Ω - 3.3 Ω = 1.0 Ω
I am curious how much the impedance is potentially skewing these resistance based formulas. I only say that because these numbers do not necessarily match the Bosch coil resistances (that I've read people having measured in other forum posts - specifically MB and 2002).
the voltage is more like 12.8 at idle would that change things or is that just a constant?
Hi Jay. I agree that there is a dynamic factor within the induction component that adds some variability with the formula. But I suspect the general increase is about what you are coming up with at 1.67 increase. It is great to see these formulaic calculations applied to our ignition system.Again, the fact that the coil is an inductor probably explains this.