dumb aero question
03-18-2008, 03:31 PM
#31
It is not you, it is the car. I spoke about this very subject of D/E stock SC airflow optimization with Mark Hupfer at Road America last Fall. I am a big fan of his. He dreams up the slightest adjustments to make our cars go faster... he is all about drag reduction.
03-18-2008, 03:32 PM
#32
Lifetime Rennlist Member
They work by venting high pressure air inside the wheel well and reduce the lift from that section. Driving in the rain, I can tell you that in my car, anything over about 60mph and you can see the water blasting upwards from the louvers so they are doing the job from those speeds upwards.
03-18-2008, 03:32 PM
#33
Rennlist Member
Hey Jack, could we see your current underbody?
It's funny you mention ABS plastic as a less common mod on the wrx is to put on the underbody panels from the STI. This includes plastic panels running the length of the rockers and about a foot to a foot and a half in on each side as well as a small rear diffuser. Supposedly these factory Subaru bits were either tested or developed for the ring, they increase high speed stability, and even increase gas mileage by 1-1.5 mpg on the highway. Also, a subaru factory splitter claims a 30% reduction in lift and a .02 point reduction in the coefficient of drag. This stuff works, keep air out from under the car with a low front and keep the underbody smooth.
It's funny you mention ABS plastic as a less common mod on the wrx is to put on the underbody panels from the STI. This includes plastic panels running the length of the rockers and about a foot to a foot and a half in on each side as well as a small rear diffuser. Supposedly these factory Subaru bits were either tested or developed for the ring, they increase high speed stability, and even increase gas mileage by 1-1.5 mpg on the highway. Also, a subaru factory splitter claims a 30% reduction in lift and a .02 point reduction in the coefficient of drag. This stuff works, keep air out from under the car with a low front and keep the underbody smooth.
03-18-2008, 03:32 PM
#34
Drifting
03-19-2008, 11:56 AM
#36
Three Wheelin'
03-19-2008, 12:05 PM
#37
Three Wheelin'
I built a diffuser. I built a front wing. The front wing was especially dumb.
The other thing you can do for the air that does get down underneath is to make sure that the car's underside is generating as little turbulence as possible. Smoothing out the underbelly of my car with a sheet of ABS plastic made a noticeable difference in my laptimes.
The other thing you can do for the air that does get down underneath is to make sure that the car's underside is generating as little turbulence as possible. Smoothing out the underbelly of my car with a sheet of ABS plastic made a noticeable difference in my laptimes.
Jack -- I see you've built a diffuser. This is for a 911? I built one for my 914 track car, and am just in the process of testing it since late last year. How did you build your diffuser?
I also flat-bottomed my car, using aluminum sheet.
Scott
03-20-2008, 08:54 AM
#39
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I think that all undertrays on front ends are really to reduce drag and assumes that the air under the car is soooooo dirty (turbulent) that it won't affect lift much. The air gets very dirty from the car that went through it just before you got there (see flipping Porsche clip).
