Some answers:
T-top cars are considered full body cars. 11.49 and quicker need a roll bar, 10.99 or faster than 135 MPH needs a full roll cage.
All vehicles running 7.49 and quicker must utilize an NHRA accepted lower engine oil retention device. NHRA License and chassis certification required for racecars quicker than 10.00.
Hope that clarifies some things! Any other questions....just let me know.
Little more specified from the 2009 NHRA Rule book:
roll bar is required in any convertible running 13.49 seconds or quicker in the quarter mile, and in other cars beginning at 11.49. The roll bar is accepted in vehicles running as quick as 10.00 second e.t., provided the stock firewall and floorboard is intact, other than for installation of wheel tubs. The rollbar must be constructed of minimum 1 ¾ inch o.d. x .118 inch wall mild steel tubing, or 1 ¾ x .083 chrome moly tubing,
If the floor and/or firewall has been modified, then a full roll cage is required beginning at a 10.99 e.t. A full roll cage is required in any vehicle running 9.99 seconds or quicker, and any vehicle running 135 mph or faster (regardless of e.t.). The roll cage must be constructed of minimum 1 5/8 o.d.x .118 mild steel tubing, or 1 5/8 x .083 chrome moly tubing.
T-top cars are considered full body cars. 11.49 and quicker need a roll bar, 10.99 or faster than 135 MPH needs a full roll cage.
All vehicles running 7.49 and quicker must utilize an NHRA accepted lower engine oil retention device. NHRA License and chassis certification required for racecars quicker than 10.00.
Hope that clarifies some things! Any other questions....just let me know.
Little more specified from the 2009 NHRA Rule book:
roll bar is required in any convertible running 13.49 seconds or quicker in the quarter mile, and in other cars beginning at 11.49. The roll bar is accepted in vehicles running as quick as 10.00 second e.t., provided the stock firewall and floorboard is intact, other than for installation of wheel tubs. The rollbar must be constructed of minimum 1 ¾ inch o.d. x .118 inch wall mild steel tubing, or 1 ¾ x .083 chrome moly tubing,
If the floor and/or firewall has been modified, then a full roll cage is required beginning at a 10.99 e.t. A full roll cage is required in any vehicle running 9.99 seconds or quicker, and any vehicle running 135 mph or faster (regardless of e.t.). The roll cage must be constructed of minimum 1 5/8 o.d.x .118 mild steel tubing, or 1 5/8 x .083 chrome moly tubing.