Ok guys, I took the car to the track for the first time in a while the other day. Car dynoed 352/364 when tuned about 2 weeks or so ago. I was on street tires and didnt hook well at all, but I did manage to get just one pass where I didnt have to lift in second to keep the car from kissing the wall. This pass netted a 13.0x at 111 with a horrible ~2.29ish short time. Ran a low 8.6 in the 1/8 at 87.5 mph. Powershifted third and fourth, lifted for the 1-2 shift so as not to blow the tires off too much.
Traction issues not withstanding (well worn 275/40/17 Dunlops), I was concerned about the mph, which seems quite low for the power the car is making. Air temp was in the high 50s with around 30% humidity. Dont know the exact DA or berometer reading. However, there was a ~25 mph headwind blowing almost constantly right down the track all day. My hood struts are not working, and the wind was sufficient to hold the hood of the car up for 10 seconds or more at a time when the car was facing the same direction as the track while waiting in the staging lanes.
What I am wondering is whether a headwind like this is sufficient to eat up the 3 or 4 additional mph I think the car should have in it.

Car is an M6 with stock 3.42's, raceweight is around 3530 or so. Mods are bolt ons and xe cam, rockers, headers, stock heads.

Any experiences/thoughts/opinions on this? TIA...

 

Yes, a headwind will slow you down and a tailwind will make you go faster.

 

Yea, I knew that, just wondering by how much...

D.

 

Depends on the car's drag coefficient and how fast the headwind is blowing. It takes more HP to push through a headwind. Since the engine is using hp to push against the wind, it's not using it to accellerate at the same speed as if there was no wind. A loss of MPH is a loss of HP. Since the engine didn't change hp, the few MPH you lost were used to just push against the wind.

Since cars use gravity and have traction, you won't really see a huge loss. In an airplane, a headwind can be strong enough that all the engine's HP is enough to keep the plane in one spot with no forward progress. You could drive a car into a hurricane force head wind and still make progress. At least until the wheels left the ground.

Is there a formula to calculate HP loss against a headwind? Maybe, but anyone under 150 mph isn't going to need it.

 

Different cars will be effected different. IMO, in you case yes 25+ headwind will eat 3-4 mph. I don't pay too much attention to mph (bracket racer) but rather than ET. I usually run .030 to .040 slower with a 10-15 mph headwind. A 30mph headwind will cost me .2 The weather (DA) playes a bigger part of what you run. My car runs from 11.20 (good DA) to 11.70 (bad DA) and then you must adjust for the wind and track conditions.