Titanium Valves in SS

[BBF67]

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.

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.