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Flat Floor Needed for Functional Diffuser (Article Inside)

Old 01-11-2019, 04:01 PM
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Default Flat Floor Needed for Functional Diffuser (Article Inside)

Found it neat to read through.. discuss?

https://www.verus-engineering.com/si...ffuser-to-Work
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Old 01-11-2019, 11:44 PM
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Thats really surprising.
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Old 01-13-2019, 05:32 PM
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Interesting.

Unless I missed it, its a pity they didn't describe the diffuser a bit more, AOA, height off the ground fron and back, length etc...

Was it a very aggressive diffuser or a very mild one like the pictures appear to indicate...
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Old 01-14-2019, 06:48 AM
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I think the article misses a trick to not be disregarded by keyboard warriors as it says its "100% untrue".
"We" have never stated a diffuser needs a flat floor simply that for it to reach its full potential i needs to be part of the floor package.
Instead of comparing something shouty folks argue about they could have given the representative changes their explanation showing that careful package creation gives better results not just slapping parts on.
They at least admit the smooth+diffuser result is likely caused by the model and would easily be better if slightly tweaked.

Just seems to try to be inflammatory with numbers than trying to show the benefits of better design.
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Old 01-14-2019, 11:51 AM
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Would a front splitter reduce the effectiveness of a rear diffuser/dirty floor because of less airflow? In other words, is the flat floor necessary for the rear diffuser to work if you have proper aero in the front?
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Old 01-14-2019, 12:25 PM
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Curious, but I wonder how much that more modern looking floor pan (flatter) compares to something designed in the late 80's (I.E. NA/NB Miata). Given the majority of their products are for more modern cars, I would suspect diffusers will work more efficiently than the NA/NB Miata. I think most of the arguments I've seen for the NA/NB application is that they work marginally, but not worth the effort/weight penalty.
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Old 01-14-2019, 12:51 PM
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That's blog post attempts to disguise itself as a white paper but it is marketing material. The company that published it is in the business of selling a diffusers for production cars without flat floors.

The repeated diatribe that you pointed out is the red flag. Marketing agenda much?

I don't agree with the methodology in the post so their conclusions are suspect in my view.


With the number of genuine, scientific method based white papers available on the web it's now common for various entities to publish their own heavily biased documents in that style. White papers are not peer-reviewed so it's sort of a gray area. Bottom line is, always take any white paper document with a grain of salt. We have talked to some of the guys at that company. Interesting bunch of gear heads like us.
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Old 01-14-2019, 01:16 PM
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Originally Posted by HoustonNW View Post
Would a front splitter reduce the effectiveness of a rear diffuser/dirty floor because of less airflow? In other words, is the flat floor necessary for the rear diffuser to work if you have proper aero in the front?
The low pressure created under the splitter will feed the floor and diffuser. So a flat floor will control the airflow more letting the diffuser be more efficient. Once again the floor is not required you are just creating a situation that doesn't work well.

Originally Posted by Midtenn View Post
Curious, but I wonder how much that more modern looking floor pan (flatter) compares to something designed in the late 80's (I.E. NA/NB Miata).
Given the majority of their products are for more modern cars, I would suspect diffusers will work more efficiently than the NA/NB Miata.
I think most of the arguments I've seen for the NA/NB application is that they work marginally, but not worth the effort/weight penalty.
All of the arguments I've seen are about the gain because aerodynamics is a package deal.
Of these things work they amount they work is governed by the amount you work on the entire package.
On our rather lumpy underfloor a diffuser on its own is likely of negliable benefit without do more to control airflow to feed it up front like with a floor.
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Old 01-14-2019, 02:04 PM
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Old 01-14-2019, 03:32 PM
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Originally Posted by emilio700 View Post
That's blog post attempts to disguise itself as a white paper but it is marketing material. The company that published it is in the business of selling a diffusers for production cars without flat floors.

The repeated diatribe that you pointed out is the red flag. Marketing agenda much?

I don't agree with the methodology in the post so their conclusions are suspect in my view.

With the number of genuine, scientific method based white papers available on the web it's now common for various entities to publish their own heavily biased documents in that style. White papers are not peer-reviewed so it's sort of a gray area. Bottom line is, always take any white paper document with a grain of salt. We have talked to some of the guys at that company. Interesting bunch of gear heads like us.
I'm not going to argue your white paper points at all. I've just seen the question posed enough times that article (with assumptions made, right or wrong) seemed relevant.

At the end of the day, we are a bunch of data driven folks here. What data means the most? Probably lap times. I've yet to see a real world comparison showing that a dirty fed diffuser is more effective than without. I'd also be curious to know impacts of a barge board setup ONLY vs barge board AND diffuser. Not seeing published results on this matter has led me to believe the diffuser isn't worth my time investment yet. By comparison, there is a ton of feedback with various spoilers or airfoil elements, splitters, and air dams making a notable lap time difference.
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Old 01-14-2019, 04:59 PM
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Having a diffuser on a car is not a goal.
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Old 01-15-2019, 07:10 AM
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I have their diffuser installed in my car, compared before and after lap times without much improvement. Looks **** af tho

Cameron at Dsport had a positive experience.
https://www.dsportmag.com/the-cars/n...ata-part-four/
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Old 01-15-2019, 07:21 AM
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Originally Posted by concealer404 View Post
And big shock they have a splitter, flat floor and diffuser. Marketing tat without good data comparison
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Old 01-15-2019, 10:25 AM
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With regard to most people here we've got much bigger fish to fry than a rear diffuser. And if we are adding one we are probably trying to incorporate some flat underbody at the same time. So I don't see much Point unless you're trying to sell diffusers.
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Old 01-17-2019, 04:10 PM
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If I'm reading this correctly, the smooth floor alone was better than either diffuser option.

Setup | Drag | Lift
Dirty Floor | 285.7 | 143.4
Dirty Floor w/ Diffuser | 259.5 | 133.2
Smooth Floor Only | 225.7 | 92.2
Smooth Floor w/ Diffuser | 223.6 | 101.9

On the dirty floor, the diffuser reduced drag by 10%, and reduced lift by 7%.
By comparison, the flat floor alone reduced drag by 21% and reduced lift by 36%.
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Old 01-17-2019, 06:21 PM
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Didn't read article...but based on your numbers, the diffuser only improved drag and solely by ~1% from having a flat floor and yet added ~10% in lift. Smooth floor only looks like the ticket.
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Old Yesterday, 11:28 AM
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Originally Posted by Blackbird View Post
Having a diffuser on a car is not a goal.
If there was a proven performance benefit to it, I'd say it would be a goal to have.

Haven't found any overwhelming evidence that says there's a benefit though. My car won't have one unless I find that proof, or I get really really bored and want to build one to test myself.
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Old Yesterday, 02:09 PM
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No part is ever a goal.
The performance benefit is the goal.
Just like no one's goal is having a turbo for example, the goal is to have the power and powerband desired, which is why there's more than one way to skin the cat.
No one's goal is having a diffuser (save for looks, but I'm not commenting on that), it's the performance benefit that you should be after.
Can the performance benefit be justified for the diffuser in question?
Not in my book.
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