Interior/Exterior Rear Diffuser?
Rear Diffuser?
Hey, guys i am new to this forum and have been hering alot about rear diffusers, and i decided to look for one that can be applied to the mini and i came up with this one, i dont know to much about aerodynamics but it looks pretty good to me
What site did you find that on? I believe there are several rear diffusers available for the Mini in Asia, but no vendors in the USA carry them yet.
If they aren't too expensive, give it a try!
If they aren't too expensive, give it a try!
6th Gear
Joined: Nov 2003
Posts: 2,349
Likes: 2
From: Concord, California
Trending Topics
6th Gear
Joined: Nov 2003
Posts: 2,349
Likes: 2
From: Concord, California
I would agree
A wing has air movement on both top and bottom
a spoiler has air movement on one side
These ARE also known as DIFFUSERS.
Diffuser (automotive)
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Bottom: Bottom-view. Top: Side-cut-view, the red circles mark the front and rear diffuser respectively
A diffuser, in an automotive context, is usually a shaped section of the car underbody which improves the car's aerodynamic properties by enhancing the transition between the high-velocity airflow underneath the car and the much slower freestream airflow of the ambient atmosphere. It works by providing a space for the underbody airflow to decelerate and expand so that the boundary between the car's airflow and "external" airflow is less turbulent, and it also provides a degree of "wake infill" (the wake being a turbulent area of low pressure that is caused by the passage of the vehicle through the air; this can cause pressure drag).
As the air enters towards the front of the car it accelerates and reduces pressure. There is a second suction peak at the transition of the flat bottom and diffuser. The diffuser then eases this "high velocity" air back to normal velocity and also helps fill in the area behind the race car making the whole underbody a more efficient downforce producing device by reducing drag on the car and increasing downforce.
The aft part of a car underbody can be a diffuser. It tries to connect the underbody to the back without producing turbulences so that Bernoulli's principle applies and the pressure increases while the velocity decreases. The side and the roof end in a sharp edge, so that their pressure does not increase. Because the pressure in the back tends to equilibrate, the pressure below the car is lower than on the side and the roof of the car.
Note that the front of the car slows down the air without a diffuser making this the ideal place for an inlet. But a diffuser reduces the pressure in front of the car and thereby the amount of air pressed below the car. Sometimes a diffuser is used to let the wheel-casing also pump down the pressure below the car. Many small engine-exhausts in the back also help pumping. The exhaust from the engine compartment in the underbody can blows the air outwards by means of convergent nozzles, which reduce the pressure from the high pressure in the compartment to the low pressure below the car (the nozzle is the inverse of the diffuser).
A wing has air movement on both top and bottom
a spoiler has air movement on one side
These ARE also known as DIFFUSERS.
Diffuser (automotive)
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Bottom: Bottom-view. Top: Side-cut-view, the red circles mark the front and rear diffuser respectively
A diffuser, in an automotive context, is usually a shaped section of the car underbody which improves the car's aerodynamic properties by enhancing the transition between the high-velocity airflow underneath the car and the much slower freestream airflow of the ambient atmosphere. It works by providing a space for the underbody airflow to decelerate and expand so that the boundary between the car's airflow and "external" airflow is less turbulent, and it also provides a degree of "wake infill" (the wake being a turbulent area of low pressure that is caused by the passage of the vehicle through the air; this can cause pressure drag).
As the air enters towards the front of the car it accelerates and reduces pressure. There is a second suction peak at the transition of the flat bottom and diffuser. The diffuser then eases this "high velocity" air back to normal velocity and also helps fill in the area behind the race car making the whole underbody a more efficient downforce producing device by reducing drag on the car and increasing downforce.
The aft part of a car underbody can be a diffuser. It tries to connect the underbody to the back without producing turbulences so that Bernoulli's principle applies and the pressure increases while the velocity decreases. The side and the roof end in a sharp edge, so that their pressure does not increase. Because the pressure in the back tends to equilibrate, the pressure below the car is lower than on the side and the roof of the car.
Note that the front of the car slows down the air without a diffuser making this the ideal place for an inlet. But a diffuser reduces the pressure in front of the car and thereby the amount of air pressed below the car. Sometimes a diffuser is used to let the wheel-casing also pump down the pressure below the car. Many small engine-exhausts in the back also help pumping. The exhaust from the engine compartment in the underbody can blows the air outwards by means of convergent nozzles, which reduce the pressure from the high pressure in the compartment to the low pressure below the car (the nozzle is the inverse of the diffuser).
5th Gear
Joined: Aug 2004
Posts: 1,079
Likes: 1
From: AZ
I disagree. A wing is a wing, a spoiler is a spoiler, a splitter is a splitter, and a diffuser is a diffuser. They all work together, but aerodynamically they serve different purposes.
http://www.mulsannescorner.com/diffuser.htm
http://insideracingtechnology.com/tech110underwing.htm
http://www.mulsannescorner.com/diffuser.htm
http://insideracingtechnology.com/tech110underwing.htm
5th Gear
Joined: Aug 2004
Posts: 1,079
Likes: 1
From: AZ
A diffuser, in an automotive context, is usually a shaped section of the car underbody which improves the car's aerodynamic properties by enhancing the transition between the high-velocity airflow underneath the car and the much slower freestream airflow of the ambient atmosphere. It works by providing a space for the underbody airflow to decelerate and expand so that the boundary between the car's airflow and "external" airflow is less turbulent, and it also provides a degree of "wake infill" (the wake being a turbulent area of low pressure that is caused by the passage of the vehicle through the air; this can cause pressure drag).
4th Gear
Joined: Jan 2006
Posts: 310
Likes: 0
From: Seattle
Cor Blmy's grills in the back would diffuse, the wing will provide a smidge of downforce at high speeds.
The Challenge cars kit has a nice duct and 3 functional grills which work to diffuse, also notice the shape of the two ducts that allows some air to escape near the exhaust, allowing the exhaust to assist with diffusion.
An amazingly functional kit.
The Challenge cars kit has a nice duct and 3 functional grills which work to diffuse, also notice the shape of the two ducts that allows some air to escape near the exhaust, allowing the exhaust to assist with diffusion.
An amazingly functional kit.
5th Gear
Joined: Aug 2004
Posts: 1,079
Likes: 1
From: AZ
The two tunnels on either side of the exhaust on the new JCW Mini Challenge car are technically the diffuser.
http://www.mulsannescorner.com/index.htm has some excellent examples if you click on some of the cars listed under Race Car Tech. Once you find a picture of a diffuser, you can click on the thumbnail and another page will open on most and give a little bit more information about it.
http://www.mulsannescorner.com/index.htm has some excellent examples if you click on some of the cars listed under Race Car Tech. Once you find a picture of a diffuser, you can click on the thumbnail and another page will open on most and give a little bit more information about it.
6th Gear
Joined: Nov 2003
Posts: 2,349
Likes: 2
From: Concord, California
It is from Ground Dynamics
>>>
I really don't get hung up on what you want to call it and wasnt after a samantics lesson.
02-06 Mini Cooper S H-Tech Rear Lip
[SIZE=2][/SIZE][SIZE=2]02-06 Mini Cooper S H-Tech Rear Lip[/SIZE] [SIZE=2][/SIZE][SIZE=2][/SIZE] [SIZE=2][/SIZE][SIZE=2]Product Code #015[/SIZE] [SIZE=2]Ref[/SIZE][SIZE=2]MINS02HIHMNRAD. [/SIZE] [SIZE=2]Regular Price[/SIZE][SIZE=2]$198.00 [/SIZE] [SIZE=2]Our Price[/SIZE][SIZE=2]$168.00[/SIZE]
>>>
I really don't get hung up on what you want to call it and wasnt after a samantics lesson.
02-06 Mini Cooper S H-Tech Rear Lip
[SIZE=2][/SIZE][SIZE=2]02-06 Mini Cooper S H-Tech Rear Lip[/SIZE] [SIZE=2][/SIZE][SIZE=2][/SIZE] [SIZE=2][/SIZE][SIZE=2]Product Code #015[/SIZE] [SIZE=2]Ref[/SIZE][SIZE=2]MINS02HIHMNRAD. [/SIZE] [SIZE=2]Regular Price[/SIZE][SIZE=2]$198.00 [/SIZE] [SIZE=2]Our Price[/SIZE][SIZE=2]$168.00[/SIZE]
Joined: Feb 2003
Posts: 1,825
Likes: 1
From: Silver Spring, MD
Thanks!. I've been wanting the M7 one from back in 2003/04 but they never made them. I don't think the demand for them was high at the time.
Last edited by golden_child; Sep 4, 2007 at 12:57 PM.
Former Vendor
Joined: Jan 2004
Posts: 8,337
Likes: 4
From: oh10
the M7 piece is more like the CF spoilers you see for sale in that it was a CF center piece with two endplates which allowed the center CF piece to be adjusted. The center piece of the M7 one was also much more contoured.
The one pictured looks much like the hamann which is one full piece and isn't adjustable. Erebuni also makes a replica of the hamann body parts as well.
You're right though...they kinda look similar and i believe they mounted in the same place.
The one pictured looks much like the hamann which is one full piece and isn't adjustable. Erebuni also makes a replica of the hamann body parts as well.
You're right though...they kinda look similar and i believe they mounted in the same place.
5th Gear
Joined: Mar 2007
Posts: 637
Likes: 0
From: Baltimore
Diffusers, Spoilers, Splitters and Wings are all different items that do totally different work.
Sport Compact Car has 2 really good tech articles on automotive aerodynamics. Article 2 is a lot more in depth and breaks down the different components. Both are well worth reading and will help solve a lot of confusion around here. Plus there are some great photo illustrations of a Super GT Skyline GT-R for those to lazy to read.
http://www.sportcompactcarweb.com/te...t_2/index.html
From page 3 of the article:
"A rear diffuser helps drive the under-car flow by exposing it to the turbulent low-pressure wake region behind the car, using this low pressure to suck the flow out. In addition, the diffuser slows the air emerging from the underbody region by expanding it through a larger-area opening. They are effective in generating large amounts of downforce by increasing air speed underneath, thereby reducing pressure. Since this low-pressure region acts on a large surface area, plenty of downforce can be generated. Even if pressure below the diffuser is only half a psi lower than outside, over a 3x6-foot area, that equates to over 1000 pounds of downforce.
Vertical fences are installed within the diffuser channel to ensure that flow remains attached to the diffuser. Since the diffuser ceiling slopes upwards, airflow there is slowing down, resulting in increased pressure. Aerodynamicists call this type of region an adverse or unfavorable pressure gradient, since maintaining attached flow almost always requires that the flow speed increase throughout the region where it moves over a surface. Flow separation - and the resultant loss of flow velocity - would reduce downforce significantly if nothing were done to prevent it. The fences act as vortex generators to assist in energizing the flow through the diffuser, which help maintains attached flow and allows the air to fill in the wake."
So basically, a true diffuser provides increased under car surface area while acting as a reverse venturi. Cool stuff.
On a MINI a true diffuser would look something like the back of the Cup Car. Everything else is a lower rear wing.
It looks as though the kit pictured at the top of the thread may be close to a true diffuser. But without install pics it's hard to tell.
Hope this doesn't start a flame war…
Sport Compact Car has 2 really good tech articles on automotive aerodynamics. Article 2 is a lot more in depth and breaks down the different components. Both are well worth reading and will help solve a lot of confusion around here. Plus there are some great photo illustrations of a Super GT Skyline GT-R for those to lazy to read.
http://www.sportcompactcarweb.com/te...t_2/index.html
From page 3 of the article:
"A rear diffuser helps drive the under-car flow by exposing it to the turbulent low-pressure wake region behind the car, using this low pressure to suck the flow out. In addition, the diffuser slows the air emerging from the underbody region by expanding it through a larger-area opening. They are effective in generating large amounts of downforce by increasing air speed underneath, thereby reducing pressure. Since this low-pressure region acts on a large surface area, plenty of downforce can be generated. Even if pressure below the diffuser is only half a psi lower than outside, over a 3x6-foot area, that equates to over 1000 pounds of downforce.
Vertical fences are installed within the diffuser channel to ensure that flow remains attached to the diffuser. Since the diffuser ceiling slopes upwards, airflow there is slowing down, resulting in increased pressure. Aerodynamicists call this type of region an adverse or unfavorable pressure gradient, since maintaining attached flow almost always requires that the flow speed increase throughout the region where it moves over a surface. Flow separation - and the resultant loss of flow velocity - would reduce downforce significantly if nothing were done to prevent it. The fences act as vortex generators to assist in energizing the flow through the diffuser, which help maintains attached flow and allows the air to fill in the wake."
So basically, a true diffuser provides increased under car surface area while acting as a reverse venturi. Cool stuff.
On a MINI a true diffuser would look something like the back of the Cup Car. Everything else is a lower rear wing.
It looks as though the kit pictured at the top of the thread may be close to a true diffuser. But without install pics it's hard to tell.
Hope this doesn't start a flame war…
the M7 piece is more like the CF spoilers you see for sale in that it was a CF center piece with two endplates which allowed the center CF piece to be adjusted. The center piece of the M7 one was also much more contoured.
The one pictured looks much like the hamann which is one full piece and isn't adjustable. Erebuni also makes a replica of the hamann body parts as well.
You're right though...they kinda look similar and i believe they mounted in the same place.
The one pictured looks much like the hamann which is one full piece and isn't adjustable. Erebuni also makes a replica of the hamann body parts as well.
You're right though...they kinda look similar and i believe they mounted in the same place.
Former Vendor
Joined: Jan 2004
Posts: 8,337
Likes: 4
From: oh10
You're mistaken......as i said, the M7 one was 3 separate pieces. It was a CF center piece and then two endplates that allowed adjustment.
M7 diffuser
Now the hamann (erebuni also)...follow the line the center piece makes. You will notice that hamann's slopes up like a smile and the m7 one slopes down like a frown. The M7's endplates (since they are separate pieces) over extend past the center piece....the hamann is all one piece with no overlap.
best photo from the side i could find...its dopamines custom CF diffuser...but its based off the hamann ones
Former Vendor
Joined: Jan 2004
Posts: 8,337
Likes: 4
From: oh10
For all diffuser ideas....you should really check out this thread.....they have everything from the M7 and hamann.....to true track pieces
http://www.motoringunderground.com/f...=rear+diffuser
http://www.motoringunderground.com/f...=rear+diffuser
