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Let's Talk Aero

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ChrisM

Mostly harmless.
1,180
1,419
Exp. Type
HPDE
Exp. Level
3-5 Years
South Carolina
Interesting. So is this one of those cases where one or the other is okay, but the two working in tandem has a greater effect than the sum of it's parts? I may have to invest in some vortex generators to supplement my spoiler...
 

Grant 302

basic and well known psychic
Interesting. So is this one of those cases where one or the other is okay, but the two working in tandem has a greater effect than the sum of it's parts? I may have to invest in some vortex generators to supplement my spoiler...

Yes, I think so. But the key is working in tandem and not just in straight-on flow. I think that gets ignored a lot on front end aero. I don't have any pictures of it, but flow patterns change drastically with yaw from turning and I only have one place that's good for testing that. Unfortunately, it's really close to the house so I don't like to make repeated runs.

I've been meaning to make some of my own VGs, but I like that the ones I bought are made of plastic and I wouldn't want aluminum ones turning into shuriken if they come off on the freeway or track.
 

ChrisM

Mostly harmless.
1,180
1,419
Exp. Type
HPDE
Exp. Level
3-5 Years
South Carolina
What aerodynamic effect does boxing the radiator have? Combined with properly placed hood venting I know this generates downforce. Does it have any effect on the air in front of the car?
 

Grant 302

basic and well known psychic
What aerodynamic effect does boxing the radiator have?
Depends on the shape and details of the installation. Drawing from lower and venting higher would help create downforce. The red Vorshlag car is a good example. It only drew air from the lower valence opening and the grille opening was blocked off. Boxing in general should reduce drag from all the turbulent airflow from all the separation over all the sharp angles behind the bumper and openings, etc. Design details will determine how much so.

Work of art and engineering:
_DSC0145-X3.jpg

Does it have any effect on the air in front of the car?
Sure does in the example above. Lowers the front stagnation point and therefore the effective AoA of the entire car. But in any installation, there's going to be *some* change from reduction in drag and redirection of flow based on the design of the box.
 
369
146
Exp. Type
HPDE
Exp. Level
5-10 Years
Waco, TX
What aerodynamic effect does boxing the radiator have? Combined with properly placed hood venting I know this generates downforce. Does it have any effect on the air in front of the car?

The reason i boxed my radiator is to force air through the radiator to keep as much cooling as possible. I also put my oil cooler in there as well. Combined with a tiger hood cooling hasn't been an issue. When at the track this past summer ambient temps were in the high 90's and oil temps and cooling all remained steady.

Hope that helps.
 

Grant 302

basic and well known psychic
Suggested reading for aero enthusiasts:
Competition Car Aerodynamics by Simon McBeath
Race Car Aerodynamics: Designing for Speed by Joseph Katz

The first has better graphics and CFD info with much of it in color. The second reminds me a bit more of an engineering textbook somewhat dated and just b/w. They cover a lot of the same material and I don't think anyone needs to own both.

Somewhat related, this book goes through a simplified model of a car and you *have to* go through it from beginning to end to follow along and make the numbers relevant. Not really much on just aero, but does incorporate aero into the theoretical model. Good for a broader knowledge base. Rather dated since first published in '92:
Chassis Engineering: Chassis Design, Building & Tuning for High Performance Handling

Look at the previews before buying.
 

ChrisM

Mostly harmless.
1,180
1,419
Exp. Type
HPDE
Exp. Level
3-5 Years
South Carolina
Oh I knew about the primary reason for boxing the radiator, was just curious about the aero effects too.

I will definitely be checking those out, I need some new reading material.
 
501
550
Exp. Type
W2W Racing
Exp. Level
20+ Years
Snowy North
Suggested reading for aero enthusiasts:
Competition Car Aerodynamics by Simon McBeath
Race Car Aerodynamics: Designing for Speed by Joseph Katz
The first has better graphics and CFD info with much of it in color. The second reminds me a bit more of an engineering textbook somewhat dated and just b/w. They cover a lot of the same material and I don't think anyone needs to own both.

Somewhat related, this book goes through a simplified model of a car and you *have to* go through it from beginning to end to follow along and make the numbers relevant. Not really much on just aero, but does incorporate aero into the theoretical model. Good for a broader knowledge base. Rather dated since first published in '92:
Chassis Engineering: Chassis Design, Building & Tuning for High Performance Handling

Look at the previews before buying.

The book by McBeath is a solid investment. He has a unique talent for making black magic seem simple.
 

Grant 302

basic and well known psychic
Found some old screenshots of Ford wind tunnel testing.

Compare this to the 302S video and see how this flow line is more 'stepped' than the 302S with the Tiger Racing vented hood. Venting does appear to make the stream 'dirty' somewhat.
13098721825_76c07ca6f0.jpg
boss-302s-wind-tunnel.jpg



And this shot shows how a splitter doesn't actually/literally 'split' the air. Lowers the stagnation point also accelerates and *increases* the air going under the car for lower under body pressure.
13098850433_9bc2c89b33.jpg
 
I would like to reduce "lift" generated from high speed operation. Which application, tiger racing hood or an LS style splitter, would be more effective? I am sure there are many variables at play, just trying to keep it simple in a complicated environment.
 
501
550
Exp. Type
W2W Racing
Exp. Level
20+ Years
Snowy North
Grant's posts 107, 113 and 117 are a really good read. Basically, a lowered, properly raked (flat bottom - lol) chassis with a suitably sized splitter can increase downforce by lowering undercar pressure...lots of "voodoo" in this area...(waiting for a quip from @VoodooBoss).

My money would go first, however, to reducing overcar lift by blocking/ducting the rad and ventilating the hood effectively. This can significantly re-profile the bulk of the airflow and thereby, reduce how much the thing flies the nose. Lots of (cost effective) ways to block/duct the rad...construction foam, sheet metal...but no cheap solution for a ventilated hood. Tiger and Kohr offer race-proven (worth the money) options.

In terms of realizing a significant reduction in front-end lift via a splitter... many folks/internet articles suggest buying a bigger splitter first...but that advice can be commercially-based vs proven empirically to reduce lift as much as a decent blocking/ducting/ventilating option. At the end of the day, it's just kinda hard to extract big gains from a splitter without having access to empirical data for sweet ride height/rake ranges and splitter sizing for your application.

Having a buddy with a wind tunnel would be a big bonus......:rolleyes:
 

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