I pulled this out of the NHRA PDF Rulebook.
As outlined under Class Requirements, drivers in all classes,
including motorcycles, must wear a helmet meeting Snell or SFI
Specifications.
SFI Spec 31.1A = Snell SA, open-face helmet
SFI Spec 31.2A = Snell SA full-face helmet
SFI Spec 41.1A = Snell M, open-face helmet
SFI Spec 41.2A = Snell M full-face helmet
Full-face helmet mandatory on all cars 9.99 or quicker. See
individual Class Requirements for additional requirements. Shield
mandatory 7.49 and quicker.
Drivers of NHRA Lucas Oil Drag Racing Series and E.T. cars (13.99
or quicker) must use a helmet meeting Snell SA2000, M2000,
SA2005, M2005, M2010, or SFI 31.1A, 31.2A, 31.1/2005, 41.1A,
41.2A, or 41.1/2005 Specs. Drivers in supercharged, front-engine,
open-bodied cars and Funny Cars must wear a helmet meeting
Snell SA2000, SA2005 or SFI 31.1A, 31.2A, or 31.1/2005 Specs.
See Class Requirements.
Structural modifications to helmet/shield are prohibited. Cutting of
helmet or helmet shield prohibited. Helmet must remain as
manufactured, except for paint scheme/graphics and permitted nonstructural
driver modifications to helmet shield as set forth below.
Taping or similar modifications to the helmet shield made by the
driver that reduce the driver’s field of vision, and are deemed safe
by driver in the driver’s judgment, are permitted at this time so long
as the driver can demonstrate to technical inspectors that the
purpose of the modification is to reduce distraction in the driver’s
field of vision. By using such a modification to the helmet shield, the
driver acknowledges and agrees that the driver deems such
modification safe in the driver’s judgment consistent with the
driver’s obligations in Section 1, Participant Agreements and
Administrative and Procedural Rules, set forth above, and that the
modification does not impair or interfere with the safe operation of
the driver’s vehicle. See General Regulations 7:8.
NHRA Helmet Expiration Dates
Label Expires
Snell 2000 1/1/2012
Snell 2005 1/1/2017
Snell 2010 1/1/2022
SFI 31.1A 1/1/2014
SFI 31.2A 1/1/2014
Label Expires
SFI 41.1A 1/1/2014
SFI 41.2A 1/1/2014
SFI 31.1/2005 1/1/2017
SFI 41.1/2005 1/1/2017
SFI 24.1 (JDRL only) 1/1/2015
SFI 24.1/2005 1/1/2017