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.

[DaX]

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

[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: http://www.racingworks.com/images/str_diffuser.jpg

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

[Compaq888]

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]

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.

[Compaq888]

Checked under my car and a thick piece of plastic can just go under the spare tire compartment. Not only will there be less wind resistance but it will block all the small pockets where air can get held up.

My spare compartment actually hangs lower than the bumper, so do you think I should still go through this???

[SVOboy]

Go for it, just make sure everything's smooth and not in a way to obstruct airflow.

[kickflipjr]

I have been thinking about cutting holes in my bumper also. But i am too chicken.

[mjo]

Why not just remove the bumper, people?
;)

[Matt Timion]

Why not just remove the bumper, people?
;)

LOL. If it was only that easy. Stupid safety laws.

[kickflipjr]

I saw a truck today with no front or rear bumper on it. Of coure this was in the country.

[Matt Timion]

Something I didn't think about before. If the majority of driving is city driving there is little need to adjust for aerodynamic drag. Aerodynamic drag is only a factor at highway speeds.

So unless you're on the freeway/interstate on a regular basis, I would recommend not spending the time/money on it.

But then again, I'm the one spending crazy amounts of money trying to squeeze every mpg out of my car, so don't listen to me.