Aerodynamics of Toyota offered Spoilers

[fnkngrv]

So does anybody have any hard evidence or solid conjecture on which of the Toyota offered spoilers out there for the Yaris sedan which would be the most aerodynamic and not totally form over function?

[CrankyOldMan]

I would have to put them all into the cosmetic category. The whole idea of a rear spoiler is to create downforce on the rear-end proportional to the speed of the vehicle. For RWD/AWD vehicles, this generates more traction on the drive wheels, allowing higher speeds through corners. For FWD vehicles, this would at best reduce oversteer--something that only happens if you have your setup tweaked just right. The other concern--aerodynamics--is usually defeated (spoiled?) by a spoiler, unless it's able to generate a turbulence pattern that reduces drag below the trunk lid. If someone has access to a relatively accurate 3D CAD model of a sedan with and without, I could run some fluid analysis on it.

[fnkngrv]

Might actually remove mine for this upcoming weekend then or else during the week and see what/if any effects are noticed.

[Kaotic Lazagna]

Yeah, almost all spoilers on non performance oriented cars are purely cosmetic and has no or minimal affect on aerodynamics.

[cali yaris]

Any spoiler or wing placed behind the rear wheel, if it produces downforce at all, will produce LIFT at the front of the car - you don't want that.

Focus instead on getting the air underneath the car to speed up.

I see some canards in your future.

[tooter]

Originally Posted by CrankyOldMan

I would have to put them all into the cosmetic category.

I agree...
Legitimate competition cars go fast enough to make them functional, but most all road vehicles don't... especially the pokey little Yaris.

[xnamerxx]

hatchback spoilers are mainly used for drag reduction rather than downforce. When we were testing the PP cars we removed the giant rear diffuser(not a spoiler but looks similar) to reduce drag on the vehicle and the effect was the venturi's below the car would stall and the car would stop producing downforce.

What you want to do is add a diffuser below the rear wheels and a splitter in front of the front wheels which in turn should create a low pressure zone below the car increasing downforce and reducing aerodynamic drag. Thats why you see lots of diffusers and even mini diffusers on econoboxs and minivans because it can if designed correctly increase fuel economy by reducing drag.

Any car can benefit from reduction in drag and most can benefit from a increase in downforce as long as it reduces lift. Thats why you see lots of the fsae cars with giant wings and diffusers even though they don't reach speeds where there effective.

I've been quite curios about the drag reduction properties of the toyota spoiler as well but I'm willing to bet dollars to doughnuts that they don't do a damn thing and were designed to be tuned out of the airflow.

[fnkngrv]

Originally Posted by tooter

especially the pokey little Yaris.

This perception may be misconceived. Only time will tell. There is nothing pokey about my Yaris

[Kaotic Lazagna]

namer, are you talking about the technical differences between a spoiler and a wing? I think most people just call wings spoilers. lol

[xnamerxx]

hahaha maybe.

[tooter]

Originally Posted by fnkngrv

This perception may be misconceived. Only time will tell. There is nothing pokey about my Yaris

Your Yaris earned it's wing.

[b20vteg]

Originally Posted by Kaotic Lazagna

Yeah, almost all spoilers on non performance oriented cars are purely cosmetic and has no or minimal affect on aerodynamics.

if anything, I would say it actually has a negative impact on performance being that there it's now useless added weight...

[fnkngrv]

guess we will find out this upcoming weekend in my case.

[malibuguy]

New camry hybrid comes with a factory rear diffuser...

[xnamerxx]

Originally Posted by malibuguy

New camry hybrid comes with a factory rear diffuser...

My point exactly its all for reducing drag to get better mpg.

[Kaotic Lazagna]

Originally Posted by xnamerxx

hahaha maybe.

[Jason@SportsCar]

Originally Posted by cali yaris

Any spoiler or wing placed behind the rear wheel, if it produces downforce at all, will produce LIFT at the front of the car - you don't want that.

Focus instead on getting the air underneath the car to speed up.

I see some canards in your future.

Like these ones collecting dust on my desk:

[fnkngrv]

Originally Posted by Kaotic Lazagna

namer, are you talking about the technical differences between a spoiler and a wing? I think most people just call wings spoilers. lol

That is a common association and misconception. AFAIK when you go to look at valuation of a vehicle it is listed a spoiler as well as when you do the "build your owner" on a manufacturer's site. This is how they are officially listed by the Land Speed staff here which has attempted to bring their rules in alignment with the SCTA and ECTA:

Spoiler
A device on the upper portion of the body for the purpose of spoiling lift.

as opposed to a wing:

Wing:
A special class of aerodynamic effect device intended to provide down force.

I am not an aerodynamic engineer therefore I can't argue or debate the nuances between the two devices. I only know that Toyota calls it a Spoiler as well as NADA, etc when you look it up. I would need to get general direction from Toyota themselves on whether the spoiler that is OEM is specifically and officially merely cosmetic or whether or not their definition is truly as a Spoiler or Wing. The main driving factor for this is that according to an engineering site that I was researching on had this to say about the differences:

Basically, what Bernoulli's principle says, for a physics refresher, is that fluid moving at higher rates of speed create less pressure than fluids moving at slower speeds, and if you have to move an equal amount of air around each side, you can make the distance longer on one side to impart a force. In the case of an airplane, a wing has the longer side of the air foil on top, to create low pressure on top of the wing and high pressure underneath it, which gives the plane enough lift above certain speeds to fly. On a car, you can use a wing the exact same way for the opposite effect. Flip the wing over so that the longer section is on the bottom, then you create a low pressure section on the bottom side of the wing, and a high pressure area on top. This will create downforce on the rear of the car, pushing the rear of the car into the ground. This is more complicated, but ultimately more effective as a wing creates less drag than a spoiler. Basically, all things being equal, if you put a spoiler and a wing on 2 identical cars, set for the same amount of downforce, the wing would have less drag, which results in quicker acceleration and a higher eventual top speed, however minor these numbers might be (as little as .2mph, or as much as 10mph, depending on how aggressive the wing/spoiler are.)

This being said then the lip spoiler that is sold elsewhere in the world would be just that, a spoiler as opposed to what they offer with the S kit and the Thai Vios equivalent which in turn would actually be a wing per Bernoulli's principle since the underside of the device is shorter that the top. This would mean that Toyota's official designation of a "Spoiler" would be wrong by technical definition. This all may be a moot point dependant upon what they would allow me for devices since the car came from production with a Spoiler/Wing.

This is making my head hurt.