Drag car versus wind resistance

[pmhmustangs]

Are there any expirienced drag racers out there who can answer a question for me? I have a 90 GT that made 540HP and 543 ft. lbs. on the chassis dyno, and weighs 3380 lbs. with me in it. Last time I raced it, it went 11.50@127 mph into about a 15 mph headwind, and on the next pass I sheared the input shaft at the line. Can anyone give me an idea of what MPH it should run on a calm day? Thank you