NGK spark plugs can be cross referenced with Champion spark plugs at SparkPlugCrossReference.co.uk and ProGreenGrass.com, as of 2015. SparkPlugCrossReference.co.uk has a cross reference search tool that displays Champion and other brands of spark plugs that cross references with NGK. ProGreenGrass.com displays a cross reference chart.
The cross reference tool on is displayed on the home page of SparkPlugCrossReference.co.uk. Visitors select NGK in the "Select Manufacturer" blank, enter the model number and click Search. A list of compatible Champion and other brand spark plugs is displayed.
The cross reference chart on ProGreenGrass.com is found by clicking Spark Plug Cross Reference Chart near the bottom of the home page. A chart with Champion, NGK and other brands is displayed.