Quoted from the IHRA website:
"Pure Stock entries may utilize OEM unleaded blends meeting the rulebook specifications."
From the IHRA rulebook:
B: New dielectric constant (D.C.) of the gasoline must not exceed +1 for the following
classes: Top Dragster, Top Sportsman, and Super Stock.
The dielectric constant (D.C.) of
gasoline for Stock will remain at +2.3.
Just curious...anyone know what the dielectric constant of 91 octane unleaded is ?