Ignition Coil Breakdown and Testing

Coil-on-Plug Breakdown

"As testing shows, we’ve designed our NAPA Echlin Ignition Coils for superior performance and durability under the harshest conditions."

Tomasz Michalik

Technical Director - NAPA Echlin Bialystok, Poland

Coil-on-Plug Testing

We performed an extensive engineering analysis of OE DG500 and DG508 to NAPA® Echlin®. The engineers measured winding resistance, inductance and output voltage, spark, energy, waveform peak voltage and ringing, as well as a complete physical and sectioned comparison to OE.


  Primary Secondary Output Voltage Spark Energy
  Resistance Inductance Resistance Inductance 50pf 60 Hz 60 Hz
Part no. (mohms) (mH) (kohms) (H) (Peak kV) (mV-S) (mJ)
NAPA® Echlin® IC386 492 1.53 5.36 9.59 25.2 3.70 29.6
NAPA® Echlin® IC369 489 1.49 5.28 9.47 25.2 3.74 29.9
Average NAPA® Echlin® 491 1.51 5.32 9.53 25.2 3.72 29.8
OE DG500 515 1.63 5.55 8.61 24.4 3.72 29.8
OE DG508 511 1.58 5.50 8.19 24.2 3.69 29.5
Average OE 513 1.61 5.53 8.40 24.3 3.71 29.7

The Findings

NAPA® Ignition Coils look, fit and perform like the original they replace with 100% end of the line production testing. The NAPA® coils also provide an improved secondary winding design (additional winding bays) that helps prevent internal arcing and high-voltage breakdown.

  • The NAPA® coils tested 3.7% higher than OE in output voltage.
  • The NAPA® coils were equal to OE in spark energy.
  • In waveform testing, NAPA® coils’ peak output voltage was about 1000 volts higher than OE.
  • The NAPA® coils had a longer spark duration than the OE, resulting in more energy supplied to the spark plugs.

The NAPA® coils match or exceed the OE coils in all categories and are an excellent replacement exceeding the OE performance.

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