Based on SAMTech.edu NHRA Factory Stock Showdown performance numbers from the first two races of the 2019 season, the NHRA Technical Department is reducing the supercharger overdrive of the 2019 COPO 350 combination by (5.4) percent from (142.9) percent to (137.5) percent.
Additionally, the supercharger overdrive for the 2019 Cobra Jet 327 combination will be reduced by (15.3) percent from (128.6) percent to (113.3) percent.
To accomplish the supercharger overdrive reduction on the 2019 COPO 350, the upper supercharger pulley will be changed from (3.500) inches to (3.580) inches. To accomplish the supercharger overdrive reduction for the 2019 Cobra Jet 327, the upper supercharger pulley will be changed from (3.500) inches to (3.750) inches.
As a reminder no other changes may be made to all approved superchargers, including, but not limited to: (upper or lower pulley sizes, gear ratios, cases, rotors, etc.). All other permitted combinations in the SAMTech.edu NHRA Factory Stock Showdown will remain unchanged.
This rule change will go into effect immediately. NHRA reserves the right in the future to make additional rule changes to control performance and maintain parity in the category.