Wind diffuser

[Compaq888]

What do you think about them??? Would they work if you placed them under the car where the spare??

Would it hurt mpg?

[SVOboy]

If it cuts down on resistance it should help.

[Compaq888]

I think it might hurt my mpg is because my car is really high off the ground.

[Compaq888]

Ok after some careful research I have come to a few conclusions.

*The air has to have a good transition from one part to another, there can't be big gaps in between the parts.

*There has to be a good flow which means the surface should be smooth.

*Don't get the air trapped in the rear bumper, at 5mph it doesn't matter but at 65mph the rear bumper works like a parachute for the incoming air. The less wind resistence under the car the faster the car will go and the less force you need to push it.

I'm thinking If i put a wind diffuser under my car where the spare is I'll gain 1mpg for sure. Every little thing counts in the mpg war.

[GasSavers_DaX]

The Civic VX has a rear bumper wind diffuser on it already. (just a little trivia)

[GasSavers_davens]

"*Don't get the air trapped in the rear bumper, at 5mph it doesn't matter but at 65mph the rear bumper works like a parachute for the incoming air. The less wind resistence under the car the faster the car will go and the less force you need to push it."

I have been intrigued one of the tricks some of the drag racers have been using...holes in the rear bumper to allow that air to flow out.
Here's a premade version:

...but I'd need concrete, measureable results before I cut two big hole in my bumper.

[Compaq888]

Originally Posted by DaX

The Civic VX has a rear bumper wind diffuser on it already. (just a little trivia)

Yes but I don't have a civic, I have a 3000lb behemeth that has a 150hp 4 cylender motor.

I was mainly looking at the new civic coupe. On the honda website you can click the 360 3D view and see the underside of it and the wind diffuser under the car.

[Compaq888]

I'm not going to cut holes in my bumper, there are other methods.

[Matt Timion]

Originally Posted by Compaq888

I'm not going to cut holes in my bumper, there are other methods.

I'm actually thinking of cutting holes in my bumper eventually and covering it with some black metal screen material. Maybe in the spring I'll get a donor bumper and do it myself.

If you guys have any good links to websites that talk about diffusers I'd love to read them. I think it would be a way cool mod to do.

[Compaq888]

check the 360 3D view of the new civic coupe on the honda.com website. You'll see exactly what i'm talking about.