This SAE Recommended Practice describes the equipment and procedures used in obtaining preignition ratings of spark plugs.
The spark plug preignition ratings obtained with the equipment and procedure specified herein are useful for comparative purposes and are not to be considered as absolute values since different numerical values may be obtained in different laboratories.
Information updated to reflect current industry practice related to the heat range testing of spark plugs. Key changes are noted below:
Deleted references to obsolete U.S Government publications related to lubricating oil and oil for fuel and added applicable SAE document references.
Updated section on operating conditions to include engine warm-up procedure.