if your racing when do you need a helmet?

Yes all the time.

14.00 Seconds & Slower 1/4 mile (8.60 1/8 mile) » Pants, Sleeved T-shirt and shoes.  » Auto trans reverse lockout  » Neutral Safety Switch  » Liquid Overflow  » Working Tailights  » Seatbelts  » Master Electrical Shutoff (If battery has been moved from OEM-position.    13.99 Seconds & Quicker 1/4 mile (8.59 1/8 mile) - Previous rules apply including but not limited to the following: » Drive Line Hoop with slicks  » Helmet Certified to SNELL 2010 or 2015 standards, or certified to SFI Specs 31.1/2010, 31.1/2015, 41.1/2010 or 41.1/2015 required  » SFI 3.2A/1 approved jacket for vehicles with a non-OEM installed turbocharger  » Master Electrical Shutoff (If battery has been moved from OEM-position.

At all times!!

Only if you run under a 7 i believe