Quote:
Originally Posted by Alan Roehrich
When they refactored the aluminum head combination to 411 a few years back (that's 16HP over the iron head combination, which is a natural SS/D car), they allowed the aluminum head combination to move to SS/C, from SS/D.
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From the 2018 NHRA rulebook====NHRA-accepted aftermarket cylinder-heads carry a horsepower penalty that is calculated to the weight of the vehicle and does
not change the class of the vehicle.