Interior/Exterior Why not a functional rear diffuser?
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3rd Gear
Joined: Aug 2006
Posts: 164
Likes: 2
From: League City, TX
Why not a functional rear diffuser?
I admit I do like the design element of the black 'squished honeycomb' rear diffuser, but it seems like having actual holes in this honeycomb would be a real benefit. The bumper hangs down low enough that it looks like it traps quite a bit of air as a high pressure area under the car. Additionally, you've got the low pressure area behind the car. The combination of the two may be the reason relatively large pieces of road grime get thrown all the way up to the rear window.
I know there's a lot more to a properly designed diffuser than just holes in the bumper area, but that would be a cheap and fairly effective way to partially equalize some of these high/low pressure areas.
-JL
I know there's a lot more to a properly designed diffuser than just holes in the bumper area, but that would be a cheap and fairly effective way to partially equalize some of these high/low pressure areas.
-JL
6th Gear
Joined: Mar 2007
Posts: 7,578
Likes: 4
From: Paradise
It is hard to know whether such a change would be a good thing, or whether there are reasons BMW didn't do it. For example, the reason that the hood scoop isn't fully open is that it would increase air pressure under the hood and reduce airflow through the radiator.
It is hard to know whether such a change would be a good thing, or whether there are reasons BMW didn't do it. For example, the reason that the hood scoop isn't fully open is that it would increase air pressure under the hood and reduce airflow through the radiator.
Robin,
I realize this is an ollld post but searching for diffusers, I came across this. The idea of blocking off one hole to force more air into the other makes sense but because of the distance between the scoop and opening on the bumper, do you think it makes a difference?
It makes complete sense but I think that it's not if the front scoop was closed off, the air would travel around back to the opening in the bumper. Whatever air is being forced into the radiator opening is still being forced in to it, regardless if there is another opening 3 feet above it.
No?
Mark
6th Gear
Joined: Feb 2010
Posts: 2,836
Likes: 6
From: North Denver Colorado
Wow you dug up an OLD one.
Taping holes does reroute airflow to other openings (NASCAR uses duct tape all the time depending on track/atmospheric conditions). It works mainly in localised areas, and with the curve of the object making the high pressure area (bumpers/hoods/ect.)
As for opening the hood scoop flow through the radiator shouldnt be affected, the hood scoop is both higher and farther back than the grille. Closing off the grille area though in my therory might make more air enter the open hood scoop though.
The rear diffuser is there to reduse the drag by eliminating air pockets under the car. Taking out the plastic rear grilles will let air out and reduse drag, but a properly designed diffuser will do this job WAY better, and create a low pressure area under the rear of the car adding rear downforce and redusing drag.
Hope all of this helps.
Taping holes does reroute airflow to other openings (NASCAR uses duct tape all the time depending on track/atmospheric conditions). It works mainly in localised areas, and with the curve of the object making the high pressure area (bumpers/hoods/ect.)
As for opening the hood scoop flow through the radiator shouldnt be affected, the hood scoop is both higher and farther back than the grille. Closing off the grille area though in my therory might make more air enter the open hood scoop though.
The rear diffuser is there to reduse the drag by eliminating air pockets under the car. Taking out the plastic rear grilles will let air out and reduse drag, but a properly designed diffuser will do this job WAY better, and create a low pressure area under the rear of the car adding rear downforce and redusing drag.
Hope all of this helps.
Wow you dug up an OLD one.
Taping holes does reroute airflow to other openings (NASCAR uses duct tape all the time depending on track/atmospheric conditions). It works mainly in localised areas, and with the curve of the object making the high pressure area (bumpers/hoods/ect.)
As for opening the hood scoop flow through the radiator shouldnt be affected, the hood scoop is both higher and farther back than the grille. Closing off the grille area though in my therory might make more air enter the open hood scoop though.
The rear diffuser is there to reduse the drag by eliminating air pockets under the car. Taking out the plastic rear grilles will let air out and reduse drag, but a properly designed diffuser will do this job WAY better, and create a low pressure area under the rear of the car adding rear downforce and redusing drag.
Hope all of this helps.
Taping holes does reroute airflow to other openings (NASCAR uses duct tape all the time depending on track/atmospheric conditions). It works mainly in localised areas, and with the curve of the object making the high pressure area (bumpers/hoods/ect.)
As for opening the hood scoop flow through the radiator shouldnt be affected, the hood scoop is both higher and farther back than the grille. Closing off the grille area though in my therory might make more air enter the open hood scoop though.
The rear diffuser is there to reduse the drag by eliminating air pockets under the car. Taking out the plastic rear grilles will let air out and reduse drag, but a properly designed diffuser will do this job WAY better, and create a low pressure area under the rear of the car adding rear downforce and redusing drag.
Hope all of this helps.
Still digging though...
Mark
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