Front fender fences, silhouette style

[19bonestock88]

So I’m on the “fence” about adding front fender fences to my Saturn for drag reduction. They used to appear on race cars but is there really any measurable gain to be had at road car speeds? I mean it’s going to be participating in sporting events after the engine goes in but it will still be used for the occasional commute…

[aerohead]

Originally Posted by 19bonestock88

So I’m on the “fence” about adding front fender fences to my Saturn for drag reduction. They used to appear on race cars but is there really any measurable gain to be had at road car speeds? I mean it’s going to be participating in sporting events after the engine goes in but it will still be used for the occasional commute…

They're an aerodynamic safety device, not a drag reduction device.
Sliding sideways, a car acts as a crude airfoil, developing enough lift to vault the car into the air.
The fence creates so much turbulence that is 'spoils' the lift, keeping the race car safely on the track.
I don't think you'll ever find a citation from which it was ever claimed that these fences could reduce drag.

[19bonestock88]

The people that talked about them in grassroots motor sports mentioned a possibility of preventing air from spilling over the tops of the fenders, but I’m not sure how big a deal that is. Maybe worth experimenting with once the car is moving again

[freebeard]

More effective on the roof.

[aerohead]

Originally Posted by 19bonestock88

The people that talked about them in grassroots motor sports mentioned a possibility of preventing air from spilling over the tops of the fenders, but I’m not sure how big a deal that is. Maybe worth experimenting with once the car is moving again

A roll of yarn and Scotch tape would tell.
Even if they did, a fence cannot alter the velocity and pressure gradient for the local region of flow.
Transverse flow isn't an issue unless some horrific vorticity was created. I don't see that for Saturn. CAR and DRIVER aero tested all of them, and they represented some of the lowest drag for their market segment.
To reduce drag, flow must decelerate, and build pressure. That can only happen at the back of a car, allowing that you've cleaned up all possible rough areas along the way.
'The main contributions to the drag force originate from the rear part of the body.' Dr. Wolf Henrich Hucho

[19bonestock88]

Originally Posted by aerohead

A roll of yarn and Scotch tape would tell.
Even if they did, a fence cannot alter the velocity and pressure gradient for the local region of flow.
Transverse flow isn't an issue unless some horrific vorticity was created. I don't see that for Saturn. CAR and DRIVER aero tested all of them, and they represented some of the lowest drag for their market segment.
To reduce drag, flow must decelerate, and build pressure. That can only happen at the back of a car, allowing that you've cleaned up all possible rough areas along the way.
'The main contributions to the drag force originate from the rear part of the body.' Dr. Wolf Henrich Hucho

Makes sense and reinforces what I’ve learned so far, work on the back first and move toward the front. I’m tempted to try them anyway for style points if they don’t *hurt* drag