21 replies to this topic

[Wil_h]

Well without an actual windtunnel test the levels of downforce will be unknown. I have seen that some diffusers in a mini can actually produce positive lift in certain circumstances.

What is important is smoothing out the underside of the car. I fitted a sheet of aluminium to my hillclimber and gained top speed and high speed stability.

[E-Tizzle]

and yeh the whole point is for extra down force while travelling fast.

then surely if it works then its gonna push the car down, but its on the back so its gonna push the back end down and in turn push the front end up! on a front wheel drive car its gonna give less traction and be worse than if it wasnt fitted at all.?

[AndyMiniMad.]

Last time im gonna say this but I dont beleive this device will provide ANY downforce on a mini. As I and Wil h say, its for cleaning the air from under the car NOT for pushing the back of the car down towards the road. If thats what the poster wants then as i have already said he should buy a spoiler. So pleeaase people read the thread before you talk about downforce.

[mini93]

If you want down force fit a spoiler!! I am not sure but i think diffusers clean the air turbulance as it leaves the back of the car therefore reducing drag allowing greater straight line stability. I might be wrong but I dont think it will help down force unless used in conjunction with side skirts in order to create a vacuume under the car. And im also pretty sure a mini design will not lend itsellf to this kind of aerodynamics.

oh thank feck someone knows what there talking about here!

although a diffuser will provide some downforce effect not alot when compaired to a wing air will speed up on exiting the underside and create a pressure change, it smoothens out air when used along side a flat floor any air that is allowed to escape from the side changes the aero(usualy have fences on the side of the flat floor), its not very easy to stop the air escaping out the side because the floor shape on the mini.

[Burnard]

From what i remember when they tested these things in wind tunnels, that diffuser wasn't worth the effort without fitting skirts, front dam and splitter, AND a flat floor. Without all that the diffuser does next to nothing for performance.

They dont provide down force, they are there to reduce lift, which means the car is closer to zero lift before the spoiler is fitted which is what creates the down force.

[Timify]

http://www.carbonwee...uk/testing.html

See the test results above ^

Personally I think minis are about as aerodynamic as a brick.

[Burnard]

Thats the thing i was looking for

The bit you need to know:

Diffusers help generate low pressure beneath the car, and our twin tunnel adjustable diffuser did produce rear-biased lift reduction with no drag penalty at 10 degrees. But its performance was hampered by the undulations in the minis floor. The gentle flow of smoke emerging from the diffuser showed the flow was lacking energy, pointing at unwanted disruption forward of the diffuser. Integrating it smoothly with a flat floor that connected to the splitter extension under the engine bay would produce much greater benefit.

And timify, dont be so harsh on the brick!

Edited by Burnard, 28 June 2010 - 03:09 PM.