Usefull Information for TFI Coils

[93gtmustang]

My car died last week and I tested a bunch of things along with my TFI Coil.
I thought my MSD TFI Blaster Coil was bad.
Read this before discarding your after market coil !!!!!
The Haynes Manual says to replace it if doesn't meet the following.


My Haynes Manual states the following for Ignition Coil Resistance.
Primary resistance................... 0.3 to 1.0 ohms
Secondary resistance..............8.0 to 11.5k ohms

MSD TFI Blaster Coil Resistance (from their web site)

Primary Resistance: 0.44 ohms
Secondary Resistance: 3.1K ohms
Maximum Voltage:
48,000 volts
Inductance: 7 mH
Turns Ratio: 85:1
Peak Current: 300 mA
Spark Duration: 250 Us

The MSD Coil doesn't meet the secondary resistance, but now I see that the lower resistance must be part of how it delivers higher voltage

 

[jrichker]

The turns ratio, peak current, and inductance are the key factors in how high the voltage output is on any given coil. All other things being equal, the higher the turns ratio, the higher the output voltage.