CONCORD, NC- Please note the following clarification and/or changes to rule 618.6: 618.6 PRESSURE / VACUUM TESTING
Testing may be performed to insure extra air is not being pulled into the engine for a performance gain. Any means to bypass the intent of the class rules is illegal. Both pressure and vacuum tests may be performed -- engine must hold 5 psi for 60 seconds and/or 5 HG of vacuum for 60 seconds.