How to decide whether to remove rear spoiler to decrease drag, improve mileage

[Tango Charlie]

I mostly agree with Tim's reply.
#1 reminds me quite a bit of the Crisis Fighter Pinto's spoiler. It may be producing a virtual reduction in the rear window's angle, and be a benifit to reducing drag.

[MetroMPG]

I think the angle of the rear glass in #1 is too steep compared to the Pinto.

If the hatch angle is too great, and the separation point is the trailing edge of the roof, then the spoiler would be sitting in turbulent, detached flow:

[Piwoslaw]

So whether the spoiler helps or hurts depends on the car, since the rear window in a hatchback can be at a flatter angle than 45 degrees (5-door Opel Vectra) or almost vertical (Smart Fortwo, Daewoo Tico, most station wagons and SUVs).

So the safest spoiler is a top-mounted, slightly sloping roof extension.

[Daox]

The only spoiler which helps is one which helps to maintain a teardrop like shape to the profile of the vehicle.

[hamorhead]

so does anyone know hoe the civic eg(92-95) hatch spoilers are
i dont think it would hurt but dont know if it helps either

[dichotomous]

I have an adjustable wing on my civic SI (EP chassis) it has three angles. I can imagine the flattest is the best generally, but in the flattest the front of the wing sits much higher than the steepest and allows air to go under the wing which makes the wing now have a surface to air to smack into instead of flow over like at its steepest.

I'm having doubts as to flattening the wing out being the smoothest, thoughts?






I'll take some with the wing at steepest and flattest later today when I can, these are to show the general shape of the car and where the wing sits, I belive its shown as its steepest (rear is highest and front is lowest

[MetroMPG]

Hamorhead - the OEM hatch "spoiler" I've seen on those cars are pretty much roof line extensions. They probably help a small amount.

Hi dichotomous, a profile pic in the lowest position would really help.

[dichotomous]

Originally Posted by MetroMPG

Hamorhead - the OEM hatch "spoiler" I've seen on those cars are pretty much roof line extensions. They probably help a small amount.

Hi dichotomous, a profile pic in the lowest position would really help.

well, it wouldnt, cause the leading edge of the wing is below the sides, so you will only see sides and wing trailing edge ever. I'll have to take it from a bit above. its very smooth in the steepest setting.

::edit:: I just went out in the freezing weather to try to swap angles, and one of the front bolts that hold the wing on is stripped, but I did get to see that the wing would only flatten from the front, basically the rear pivot point (you can see it in the under photo) doesnt change much, but the front goes up a good inch. the front is currently at its lowest setting. I am thinking of "fabbing up" a couple thin 3 hole triangles or even just some 2 hole spacers to drop the rear of the wing for gas milage, since I really dont drive that fast MOST of the time, and it would be pretty easy to switch if I wanted the downforce again. or I might flip the wing over and see if that affects anything.

I'm pretty sure my low gearing and race piped (stock internal though) engine are hurting me more than my wing could ever give back though

[dichotomous]

well here is what I did, I spent $7 at the hardware store for two mending strips and a pair of matching nuts and bolts, the wing is lowerable now



previously it looked like this:


it can go a bit lower I think that where I have it, there are four adjustment holes on the wing, all next to each other in the back, and there are three above on the mount.

[guudasitgets]

There might be vortece's rolling off the sides, you could curl some aluminium and straighten them out. Like cutting a toilet paper roll in quarters and tape them on the side supports facing inward