aerodynamics

[schmeep]

forgive me again if i'm treading on previously debated issues,

but in another thread we were talking about grill blocks and aerodynamics in general,

besides making a car look all pimped, does anyone know if side skirts and front skirts and lowering a car would have any benefit or hindrance to fe?

i assume the aerofoils on most cars are simply cosmetic (and goofy to boot)

[Matt Timion]

Originally Posted by schmeep

forgive me again if i'm treading on previously debated issues,

but in another thread we were talking about grill blocks and aerodynamics in general,

besides making a car look all pimped, does anyone know if side skirts and front skirts and lowering a car would have any benefit or hindrance to fe?

i assume the aerofoils on most cars are simply cosmetic (and goofy to boot)

One guy I've talked to claims that certain body kits will help with aerodynamics.

In theory anything that lets less air under the car will air in aerodynamics as well.

Krousdb also lowered his car 2" and noticed a FE gain.

I can't give you any concrete numbers though. It might be better to just put a belly pan under your car instead of lowering it and adding body kits.

[SVOboy]

Dan also said that when he raised it back up he didn't notice a dramatic difference. The theory is there, but when I lowered (and will lower more) I'm more worried about handling and looks and saying "oh yeah, my frontal area is less" on a somewhat incidental note.

Darin (metrompg) has done some serious testing on the rear skirts, check out his thread/website for his results (cuz I forget where to find them).

[schmeep]

by rear skirts, do you mean a wing on the back?

[SVOboy]

I mean covering up the rear wheel wells!

[Ted Hart]

Aerodynamic drag is a function of speed ; If you want less drag, slow down! At 47ish MPH, drag starts to show up...slowing you down(more gas!).

[MetroMPG]

True enough.

But if you want less drag at highway speeds where it's not practical to slow down, improving the vehicle's Cd is a good idea.

[SVOboy]

Well, of course it pays off, as long as you don't factor in time,

[Ted Hart]

Time is money! Besides, the "clock ticketh"!

[MetroMPG]

Originally Posted by Ted Hart

At 47ish MPH, drag starts to show up...slowing you down(more gas!).

Just to clarify,

At approximately that speed, the contribution of aerodynamic drag is roughly half the sum of forces resisting a vehicle's motion (aero and rolling resistance).

Aero drag still exacts a fuel efficiency penalty at slower speeds, although proportionately less (in other words, it doesn't "suddenly" become a factor at 47 mph). Even at only 20 mph, it represents roughly 1/4 of the sum of aero+rolling resistance opposing vehicle motion.

Also, 47 mph is quite a high threshold (where aero forces start to exceed rolling resistance); That would represent a very aerodynamic vehicle - or a vehicle with very high rolling resistance. For most, I would say the 50/50 point is actually closer to 35-40 mph.