Yo,
Go back to a stock Motorcraft coil
#10 •
Oct 14, 2014
yo,
High Quality Motorcraft TFI Ignition Coil Attributes
Source: by SeattleFSB (Seattle FSB) @
http://www.fullsizebronco.com/forum/showthread.php?t=199185
Many Bronco owners shop for an ignition coil by looking for the highest voltage available. But I venture to say that there is much more to look for in achieving both a quality ignition system and saving money in the long run.
For clarification, it takes approximately 10-14,000 volts to initiate the spark across the OEM spark plug gap. After the initial arc, the voltage required to sustain the arc is much less and drops off significantly. So while you may have a 48,000v coil you can't actually get that across the plug. The extra power becomes reserve voltage which compensates for worn plugs, increasing resistance in wires and carbon fouling. This increased stress can require an additional 1-5000 volts.
Fact is a higher voltage coil does not work any better, it just lasts longer due to having a higher reserve reducing heat. You cannot push more than 20,000 volts across a spark plug without bad things happening. If you were to try you would see arcing down the side of the plug, across carbon buildups at the electrode end and out any weak points in the wire insulation and connections.
The bottom line is the ideal coil output required for normal applications is about 30,000 volts. So no, your coil does not need to be 48,000v for proper ignition. The benefit would be in having enough reserve to compensate for high resistance due to a worn or altered ignition system.
This is why the Sixlitre Tune recommends a 48,000v coil and larger spark plug wires – to compensate for a substantial increase in resistance from larger than specified spark plug gaps. You are adding resistance as the spark attempts to reach ground. This in turn causes the plug wires to break down and decreases the service life of the rotor, distributor cap, spark plugs and increases the chance of spark scatter within the Distributor Cap.
Think about it, you are setting your spark plugs at a maximum gap even before wear. The higher voltage coil does not reduce stress and wear on your ignition system; it only compensates within a larger margin and then ultimately becomes dependent upon the quality of construction for survival. When opening up your spark plug gap from factory specifications you must be prepared to check your secondary ignition system annually, as opposed to about 40,000 miles with a stock vehicle, or risk performance decreases down the road.
With that being said, IMHO the Motorcraft DG470 TFI Coil is one of the most dependable 48,000v TFI Coils on the market. This is largely due to the quality in design, testing and construction. I have personally had many dependability issues with other imported TFI Coils, such as MSD. Where a Motorcraft Coil has lasted 15 years, I have went through three MSD coils in five years. Your purchase of a TFI Coil should not be totally dependent upon the voltage, but strong consideration should also be made regarding the contruction attributes listed below:
Motorcraft TFI Ignition Coil Attributes
Insulation - Multiple coats on the primary and secondary windings to ensure no internal arcing
Radio-Frequency Interference (RFI) Suppression - Minimize electronic noise
Magnets - Hold strength for the coil to maintain proper energy output
Steel - Used in the lamination stack to ensure a consistent magnetic field needed to develop the required voltage
Coil Housing - Engineered to withstand extremes in temperature without cracking
Low Quality TFI Ignition Coil Potential Issues
Rough Running Engine or Misfires - Causing Check Engine Light
Fuel Economy and Power Decrease – Costs money and performance
Radio Frequency Interference – Affects radio, EEC, sensors, cell phone
Pre-Ignition and Detonation – Can cause engine damage
Weak Voltage Output – Can cause increase tailpipe emissions..."
