Since the mid 1980's, Accel's U-Groove spark plugs have set the standard for high performance spark plugs. Accel engineers developed and patented the U-Groove technology which permitted the spark to develop a much larger, hotter and fuller flash front. That effectively gave a more complete burn of the air/fuel mixture in the combustion chamber. Over the past 25 years engine head design and fuel management technology has changed. As a result, Accel is moving away from the U-Groove construction to the familiar ''conventional'' style ground electrode. In addition, the upper insulator will now be white instead of yellow, and available in convenient 4-packs.Bottom line.This one-piece construction spark plug with conventional ground electrode provides exceptional performance and value by producing:
- Hotter Spark/Faster Burn Rate for more power at high rpms.
- Improved Throttle Response, Fuel Economy, and Reduced Fouling.
- Reduced Mis-fires.
- Purified Alumina Insulator to prevent arcing.
- Machine-rolled threads to protect heads.
Note: The higher the Part Number, the hotter the plug.
Example: 111-0111-4 is the coolest plug and 111-0116-4 is the hottest in that specific style spark plug.