Sonic Vortex Generator (think: Mitsubishi Lancer roof spikes)

[TheGreenDragon]

Figured I'd share a bit of research I did regarding vortex generators for the Sonic.

According to pop culture, vortex generators improve your MPG by reducing the amount of drag your car generates. They do this by causing mini vortecies (sp?) in the air where it separates from your car which cancel out the creation of a big vortex. Supposedly these have a bigger impact on hatchbacks than sedans.

If you want a more science-y document explaining what vortex generators do and why, here you go: Effect of Vortex generators on Aerodynamics of a Car: CFD Analysis | Mohan Jagadeesh Kumar - Academia.edu

Now, for the actual part: Honda Civic 4DR Sedan 2006 2009 Glossy Black ABS Roof Vortex Generator Spoiler | eBay

So now you're thinking, "Wait, that's a Honda part!" The dimensions of the Sonic Hatchback rear spoiler between the two edge 'humps' is 102mm wide by 12mm long at the edges, and 14.5mm long in the center. This part, although for a Honda Civic, fits nicely in that small gap.

Now, if this is something that interests you, here is what I recommend. Go to a junkyard and find a front-end-collision Sonic hatchback with an intact black spoiler. Clean it off, drill some pilot holes in the top, and then screw/bolt/rivet the vortex generator to the top. The instructions say it mounts with double-sided tape, however, they also have a disclaimer for several accounts of the part flying off at highway speed because 'the customer didn't put the tape on right'.

So yeah, my advice for those interested would be to get a spare spoiler and just bolt the dang thing on.

Happy modding!

 

[whitesmoke]

Been testing vortex gens for decades

You are the first guy ive seen that even knows what a vortex generator is, nice job. I have been testing vortex generators on cars and trucks for 100s of thousand miles and 30 yrs. My business is in aviation and i repair corporate jets, just about every aircraft on the planet has vortex gens. What they do is increase velocity of the air over the surface which in turn reduces pressure which is very usefull for creating lift and stabilizing control surfaces from fluttering. We have a 2001 gmc denali xl which originally got a best of 18 mpg and after 30k miles of moving them around and changing shape, size, and angle we ended up with 23 mpg. That vehicle was the best we ever found probably because of its size and the amount of air its pushing. We tried a few combinations on our sonic rs but got no results yet mainly because its very clean aerodynamicaly and small, but we are not done yet. Will keep you posted

 

[RMinNJ]

That may actually look good on my white sonic sedan. The top of the back window looks to be about 102cm wide.

You don't think it will just create extra drag up top ?

 

[TheGreenDragon]

You don't think it will just create extra drag up top ?

Not unless you fail to secure it properly, and it flaps upward like a deploying airbrake on a aeroplane...

 

[whitesmoke]

The rear half or the car is not where you want them

 

[cndctrdj]

I don't think it would do much for the hatch. But the sedan could gain something

 

[2014 Blue RS]

I'm at least curious about this. Hard to imagine feeling any difference even if a computer says it does something.

 

[carsNskis]

I'd like to see it in a wind tunnel, heck just the stock hb and sedan for comparo in a tunnel would be cool.

 

[TheGreenDragon]

The rear half or the car is not where you want them

Are you saying they work better on a leading edge than a trailing edge? For instance, installing a set on the forward edge of the roof or the underside of the front bumper?

Where did you place the ones on the Denali to see an improvement? And was that one big solid strip, or individual 'spikes'?

 

[whitesmoke]

They need to be at the furthermost front point of the car that actually has air going across the surface at a high pressure. On the denali it was at the top of the front curve coming up from the grille across the hood, 6 gens. 2 at the center opposing each other, 2 at the outside corners, and 2 in between those

 

[TheGreenDragon]

Do you think Canards would have a bigger impact on the Sonic's aerodynamics than vortex generators? From my limited knowledge on those, they are supposed to act similarly to the vortex generators by creating low pressure zones at the sides of the car.

Let's say that someone was a little crazy and decided to put Canards on the front bumper and vortex generators on the roof just after the windshield ended (probably more for looks). Would there be any gains or detrimental effects from this setup?

 

[carsNskis]

What effect are you looking for? Downforce? Front or rear?

Honestly if you're just doing it for cosmetics none of the previous questions matter.

If you care about the effects the only way to confirm all of our speculation is a wind tunnel

 

[cndctrdj]

A wind tunnel or a tuft test.

The biggest improvement for aero would be making the headlights flush

 

[KnucklestheRS]

I actually came from the lancer/evo community. This is the first I've heard about their use for better gas mileage. Mitsubishi designed them for the evo to increase the downforce on the rear spoiler.


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[ecohauler]

The biggest improvement for aero would be making the headlights flush

Flush headlights wouldn't do much. Best improvement I've seen is from adding the '12 bellypan, but I'm starting to look at some other things.

 

[carsNskis]

Flush headlights wouldn't do much. Best improvement I've seen is from adding the '12 bellypan, but I'm starting to look at some other things.

Right, because all aerodynamic cars have exposed headlights

 

[ecohauler]

Right, because all aerodynamic cars have exposed headlights

I think you'll find it difficult to define "exposed headlights" in a way that includes our vehicle but excludes any other modern vehicle. In the traditional sense, only every car built since the C6 Corvette came out in 2005.

To the point though, the less-than-smooth shape is not especially inefficient. The headlights do cause turbulence, but mostly because of the protruding corner markers. This is by design, as the detached flow goes right over the mirrors and keeps them quiet on the highway. This is a common modern design feature.

On another note, I tried to find a video to help explain my point, but all I ended up finding was a promo video for the Sonic that was somehow apparently made in 1985.
https://www.youtube.com/watch?v=u961-zW6w-o

 

[Llia]

I thought about adding VG's to the rear. I heard it not only reduce flow separation/drag but also made the low mounted rear spoiler on sedans/coupes more effective.

I've researched them in the 90's in High School, along with a dimpled underbelly for an electric car project to reduce drag. In the end most were voted off because we didn't have time to test or implement them.

 

[carsNskis]

I'm sorry the word "exposed" offended your sensibility. It's obviously NOT as aerodynamic as a fully enclosed headlight, as opposed to partially enclosed (ie: the Sonic).

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[2014 Blue RS]

Iwant that belly pan. Need to find it.