View Full Version : Diffuser Project?

08-24-2010, 09:32 PM
I like the idea of increasing down force but don't like the idea of putting a wing on the car. Would anyone be interested in a diffuser if one were built? This is just an inquiry to see if there's anyone at all interested. For those of you who aren't familiar with what a diffuser is, they're common on the Mitsubishi Lancer Evo and some Ferraris.

After looking at my car there appears to be plenty of room for one. Any thoughts.


08-24-2010, 11:21 PM
Not an off the wall idea, but wouldn't it require a full underpan to do any good?

It wouldn't be that hard to fill in from the rear gfx, say up to the sway bar, but again, without going all the way to the front, it wouldn't be doing much I'd think...then you'd have to maintain the negative pressure zone (smooth pan, exaggerated side skirts, etc) underneath the engine all the way back to help suck the vehicle downwards - and with what these cars weigh, I'm fairly sure they're already d o w n :)

08-24-2010, 11:49 PM
How much faster are you looking at making these things to go?? I can hardly make it over a sidewalk now. :D

08-24-2010, 11:56 PM
how much faster are you looking at making these things to go?? I can hardly make it over a sidewalk now. :d

lmao thats classic

08-25-2010, 11:08 AM
You can probably tell I'm the guy stuck behind the car that's slammed and all tricked out that has to wait 1/2 an hour to go over railway tracks or turn into a parking lot or something. LOL
I still swear the sidewalk I backed into was higher than usual :o. Still have to fix that crack.

08-25-2010, 01:33 PM
Something tells me we really don't need something like that unless you are planning to run the car at 180mph+. My car at 140mph is very solid on the road and I can take bends with no feel of the back end coming out etc, or the front end becoming light.

Contrary to popular belief, Ford did one heck of a good job on these cars, and aerodynamics is one of them.


fast Ed
08-26-2010, 09:13 AM
I'd second that. With good tires and suspension, my 95 was fine at 150 mph.

The guy who runs his at Maxton at 180+ mph, does he have anything like that added?

Ed N.

08-26-2010, 10:33 AM
Well I think that if the time, money, and resources are available then this might be worth looking at as far as the overall aerodynamics are concerned.

I agree with Fraser that Ford did design a very aerodynamic car here but as always I believe there is room for improvement.

BUT, as with building your engine, one has to ask exactly what outcome they want. Is this just going to be for max down force, improved fuel efficiency, or a compromise of both? I think the third option is the best since most of our cars are mainly street driven and see some track time.

But the one thing that has to be remembered is that when you change aero on one end you can have negative effects on the other. In some cases it can act to balance it out but most you have to look at the overall vehicle and make sure the overall aerodynamics is addressed.

But this is just my opinion, I could be wrong.

09-03-2010, 08:03 PM
As far as the underbody is concerned, I was already thinking of trying to adapt a stock size rectangular carbon fiber plate to the bottom of the car to add rigidity and possibly smooth out the airflow. Both these projects are really only vague ideas.

I'm all about handling and with a stiffened suspension, anecdotal evidence of body cracking, and the redistribution of force into the body from a less compliant suspension, I'm interested in body stiffening. A full cage would of course be the best bet in that regard, but I want a stock interior as I actually haul the kids around in the back seat.

Who am I kidding; I want to have enough downforce that the car will suck a manhole cover right up into the air like they did at the Long Beach Grand Prix one year. After that they started welding the covers down for the race.

09-03-2010, 10:22 PM
You don't need to evacuate all the air under the car...just a small fraction.

Example of car that is 70" wide and 120" between headlights/taillights... one half of one psi reduction in under-floor pressure adds 4,200 lbs. downforce.

1 sq. ft vertical at 100 MPH exerts 100lbs. force. At an angle of 45 deg., you get 50lbs. etc.

You can evacuate under the car and use the entire body or you can bolt on a HAW and hope it doesn't cost too much HP to cut the air just for a few hundred pounds of downforce...

12-10-2010, 03:49 PM