Post by
DjPantsSpecR »
https://forums.nicoclub.com/djpantsspecr-u24575.html
Wed Nov 05, 2008 5:32 pm
I'm only going to post because Dave and Ian did....
But just back to the subject of "aerodynamic...."
The coefficient of drag is based on surface area exposed to the opposing wind resistance. So, to find the coefficient of drag (simplified, but not by much) you take the "flat" portion (the portion exposed to the opposing wind force) and multiply it to another term that i wont get into.
Drag force = D = A*Tau
The exposed surface area of a pop up headlight while it is closed is minor. It would be modeled as a rectangle that is probably around only 2 inches tall by about 8 inches wide. This is the MINIMUM possible surface area, and thus yields the smallest drag coefficient.
Unfortunately, when the light is popped up this area increases to the entire size of its headlight, PLUS its surrounding area. Now thats probably an area of about 8*8 inches, which is the MAXIMUM possible surface area.
The lights you have proposed not only contain the regular area of the pop up headlight itself, BUT they also contain the area of the two circles that represent the headlight. This surface area is greater than the area of just a closed pop up light.
THUS, when your lights are not in use, the coefficient of drag is HIGHER compared to stock with those lights. But when your lights are on, the CD is a little less than when the pop up is up.
Guess what, all of these effects are fairly negligible, mainly because when you model the front of the car it contains the entire front profile of the car.
So you wanted a useful post? I've made my own pop-up light replacements. The output was terrible. I had to make a new set, and the output was still not as good as stock. You have to pay to play (safe), and investing in headlights is not worth it.
especially because you plan on crashing the car apparently, and the only thing you're worried about is how much its gonna cost to replace the lights.
Bottom line, Silvia hood + GOOD DIY headlight set up is going to be the only viable solution. Its by far the most aerodynamic, it costs the least to replace (depending on the projectors/bulbs/etc), and it doesnt look like booty.
edit: i just read through the post, i accidentally write the drag force as the coefficient of drag almost the entire time, however it still all makes sense, and you probably dont care. I havent slept in 3 days, and i dont care either.