2017 Toyota Corolla LLE aero mods
 

And just like that, Johnny Cash is no more and I have a new car. The transmission took a dump; 3rd issue with the gearbox in 5 years, so took the opportunity to wash my hands of it as this time it wasn't covered under warranty and the reality was long term this is the achilles heel of the Darts.

And viola, I'm the new owner of a 2017 Toyota Corolla. New car, new machinations...First thing I note, factory .cd is .29 (Dart was .285). So in the ballpark. Second thing I note, Corolla LE Eco's .cd is .28...the only difference I can tell; trunk trailing edge spoiler. And these can be had for cheap on eBay, like $40. So I might go ahead and get it, because even if that isn't the only aero difference (it's the only external topside difference I can see and so far I haven't found any underfloor shots), it's a contributor. Though a .01 reduction from the addition of a spoiler isn't unreasonable I shouldn't think.

Tomorrow I'm having a look at hood sealing to the engine bay. There are some gaps there that some weather striping would seal. So we're already off to the races.

If yours is an LE, the LE Eco also has different wheels--15 x 6.0 steel versus your 16 x 6.5. Congrats on the new car!

Yes, I was looking at that. However...would mean new rubber and the tires on it have lots of life left. Not something I could justify at the moment.

Thanks! The funny thing is, I realllly like the Dart. However, and this is the truth with me and always has been, my favorite car is always the car I'm currently driving. So while there's been some separation anxiety, I've already moved on. I realllly like the Corolla...now, just need to perform my flush wheel cover trick (this will be the 3rd car I've done this on and I only JUST finished the Dart's like 3 weeks ago...ugh).

Congrats on the new car! Got any pics? :) What color is it?

Couldn't you have used the aero caps from the Dart, or are the wheels different sizes?

Yes, I'll post up a pic probably tomorrow. She's white.

No, different lug pattern unfortunately.

Thar she blows....http://www.mulsannescorner.com/Ecomo...422_131137.jpg

Was looking over the car and spotted this aero device at the trailing edge of the rear fender:
http://www.mulsannescorner.com/Ecomo...422_131012.jpg

Any ideas what it does? Separates the flow so it reattaches and energises before the outboard sharp edge quarter panel/bumper trailing edge?

Also found this image of the underfloor of the LE Eco:
http://www.mulsannescorner.com/Ecomo...der_covers.jpg

From what I can tell, the LE (version I have) doesn't have the 5 panels in the center. At about $100 a pop I don't think I'll be buying them...

Close up of the trailing edge underfloor panel:

http://www.mulsannescorner.com/Ecomo...wheel_well.jpg

Has two interesting aero shapes of unknown function. Anyone enlightened/familiar with what they might do?

I first noticed these at an auto show a couple years ago and was curious about their function. Turns out it isn't an aerodynamic device at all, but is required to meet a FMVSS requirement that rear tires remain inboard of bodywork to 50 degrees past vertical. Some manufacturers use a small plastic add-on:

https://ecomodder.com/forum/member-v...mx-5-miata.jpg
2018 Mazda Miata

But at this year's Chicago show I noticed some of these are being molded into bumper covers now rather than added as a separate piece:

https://ecomodder.com/forum/member-v...uar-f-pace.jpg
2019 Jaguar F-Pace

https://ecomodder.com/forum/member-v...9-lexus-nx.jpg
2019 Lexus NX

Toyota includes those fins for stability on all their cars. Generally, airflow under a car spreads outward and these help straighten the flow at the back (unlike the faux "diffuser" vanes seen on a lot of rear bumper covers these days).

https://ecomodder.com/forum/member-v...yota-camry.jpg
2018 Toyota Camry

https://ecomodder.com/forum/member-v...ota-sienna.jpg
2018 Toyota Sienna

https://ecomodder.com/forum/member-v...ta-corolla.jpg
2020 Toyota Corolla Hybrid

Thanks for pointing out that those are regulations compliance features. I lanced it off the car at lunch time. Based on that it certainly wasn't helping aero. So off it went.

Do you have the documentation for that? Thank you in advance

My mistake--it's an EU regulation, not FMVSS (I had mis-remembered). It varies state by state in the US, with most states having a more aggressive regulation that requires coverage of tire tread to 75 degrees past vertical, like Washington: "Coverage of the tire tread circumference must be from at least fifteen degrees in front and to at least seventy-five degrees to the rear of the vertical centerline at each wheel measured from the center of the wheel rotation." I suspect this is mostly so they can crack down on lifted trucks and fender-less Jeeps.

The relevant EU statute is Commission Regulation (EU) No 1009/2010, Annex II, 2.1.1: "In the part formed by radial planes at an angle of 30° towards the front and 50° towards the rear of the centre of the wheels (see Figure 1), the overall width (q) of the wheel guard shall be at least sufficient to cover the total tyre width (b) taking into account the tyre envelope as well as the extremes of the tyre/wheel combination(s) as specified by the manufacturer."

This regulation is also referenced in this Car&Driver article, "How Regulations Dictate the Look of New Cars," which also explains why we still get those little plastic bits on cars in the US.

My spoiler showed up, $37, though I haven't mounted it yet:

http://www.mulsannescorner.com/Ecomo...428_202010.jpg

http://www.mulsannescorner.com/Ecomo...428_202019.jpg

I've tweaked the trailing edge, sharpened it up a bit by translating the two surfaces to their coincidence. Still have some finish work (will give the edge a slight radius just to break it) and plan to paint:
http://www.mulsannescorner.com/Ecomo...425_181705.jpg

Still plugging away, added a few things that I'll detail later, but been wondering if anyone knows Toyota's philosophy behind their front wheel spats? With the open, but framed, inboard section? I'm close to completing a couple of small front underfloor panels that will substantially smooth out the airflow lead-in heading to that inboard open section and wondering what the consequences might be!

http://www.mulsannescorner.com/Ecomo...428_202245.jpg

You trashed the tyre thingies as they weren't helping aero, then add a spoiler that's very unlike to help aero either ?

Weird :rolleyes:

Reading is fundamental in this day and age...

I've asked a question about the design intent of the tire spats. They help reduce drag and are quite effective in their simplicity vs. productivity and I have no intent on removing them, nor have I stated as much. I've have asked aloud what the inboard opening's function is on the spat as I'm about to add a panel ahead of them that flattens out the section ahead of the spat and in my mind will provide better airflow to the spat, and I said as much.

The spoiler, if you read further up, is part of the lower drag aero package for the Corolla LE Eco. My car is the plain ole LE. So I'm adding the bits I can afford off the aero package of the LE Eco to my LE (total package is spoiler, front underfloor add-on panel, and center underfloor add-on panels x 4). It provides for a drag reduction from .29 to .28, as published by Toyota. So instead of grasping in the dark, where I can afford it, and it is cost effective (the 4 center underfloor panels are not at around $430 for the set when all said and done), I'm going with known drag reductions for this car. The spoiler is part of that package. The spoiler is of the flat variety with effectively no angle of attack at the trailing edge. I've sharpened the trailing edge on the spoiler to hopefully further increase the turbulent kinetic energy in attempt to enhance the wake energy into the base area. Furthermore, for $37, if it doesn't function as I like I have a carrier for improvements that bolts onto the car without having to create such out of thin air. $37 well spent IMHO.

So, in summation, you've not read the thread and then made a fundamental judgement on what you think I'm doing.

Weird. :rolleyes:

inboard open section
 

Could the opening simply be for adequate brake cooling during a panic stop?

Perhaps? One Aero here at work indicated that might be the case; brake cooling. The region ahead of the spat is a concavity and I've templated a small plate that covers over it providing a much smoother path to that spat. Probably will do nothing, but it bugged me on principle. Furthermore, I spent $47 and purchased the LE Eco front underfloor "splash panel" that smooths out the front center underfloor section (I'll post images later on), so these outboard panels ahead of the spat simply complement those.

I've really wondered about this, especially as I've looked at my own car, which used an identical design. Brake cooling--maybe? Perhaps the shallow duct and hole in the deflector straighten the flow there to reduce the yaw and send it around the wheel?

Only one car I know of still uses this design, the Chrysler Pacifica. Everyone else has moved on to solid wheel strakes that curve inboard.

But then, why bother extending it further inboard with a framed "window" ?

Or they had designed a solid spoiler, and only later found out brake cooling could become an issue in some otherworldly scenario, kept the general design and its mounts, but made a hole in it ...


Which then can't explain how the same design ends up on 2 different cars :-/

So some updates. The front underfloor on the Corolla LE looked like this:
http://www.mulsannescorner.com/Ecomo...428_202358.jpg


Two things, I removed the center tow hook which can just be seen and I purchased the front underfloor off of the LE Eco, which simply bolts over what you see here.http://www.mulsannescorner.com/Ecomo...424_201334.jpg

This is what the LE Eco front underfloor. For $29 I couldn't resist. However, the other LE Eco underfloor panels are much more expensive and I don't think I'll be purchasing them:
http://www.mulsannescorner.com/Ecomo...709_090901.jpg

The area ahead of the front wheel spats is a ugly concavity:
http://www.mulsannescorner.com/Ecomo...721_105925.jpg

So I've created a panel to cover it:
http://www.mulsannescorner.com/Ecomo...721_120547.jpg

Frankly I don't expect any noticable gains from these panels to be honest. But maybe they'll surprise me. I'll give them a squirt of paint and fill any gaps with Drip-Chek. Also noticed a gap along the flange for the spats that I'll fill as well.

I also created a panel aft of the rear wheel to close up the gap between the parachute rear fender and the exhaust. I did it more to create a mounting panel for an eventual pontoon fender to clean up the aero aft of the rear wheels. For some reason I don't have a photo of that but I'll grab one later.

So I'm looking to blank off some radiator inlet area. Going to first concentrate on the middle slot, the one below the Toyota emblem.
http://www.mulsannescorner.com/Ecomo...725_192620.jpg

The lead-in ducting for the radiator is non-existent. The radiator is plopped so many inches behind the intake. And it almost seems as though they've intentionally designed the airflow to partially blow around the radiator, for whatever reason, in certain conditions? Peering into the inlet and you can peer "around" the radiator and effectively see the engine. It's to me, an odd arrangement:
http://www.mulsannescorner.com/Ecomo...725_122848.jpg

So I've been contemplating designing a rad blanking panel combined with a partial lead-in duct. I've made a template:

http://www.mulsannescorner.com/Ecomo...725_192811.jpg

http://www.mulsannescorner.com/Ecomo...725_193626.jpg

http://www.mulsannescorner.com/Ecomo...25_192836b.jpg

Obviously this lead-in duct will mitigate the possibility of air flowing around the side of the radiator by creating the barrier. However, note I haven't extended it the full height of the radiator inlet; air flowing into the slot inlet at the very top can go around, and air flowing into the large inlet at the bottom can do the same. I've only segregated the flow coming from the middle inlet below the Toyota emblem. That is, assuming it was partial design-intent to allow air to go around? That might not be right at all of course! Thoughts?

later found
 

That's exactly the thing an automaker can discover,once the prototype is constructed.Hucho has mentioned that features this small are hard to model in CFD and require wind tunnel verification,at full-scale.
They may have had the 'solid' taco fairing initially,only to find later, that they'd shot themselves in the foot,brake-cooling wise.Changing a small,thermo-formed piece of ABS plastic and it's tooling wouldn't be the sort of thing that would blow their budget.

blow around the radiator
 

There might be an igniter on the wheel-well or some other electronic device,which needs some airflow over its heat-sink.You don't want to overheat a battery either.

Just a touch base. Back in November of last year I was rear ended. Car was damaged and subsequently repaired by January 2020 and all was well with the world. And then Covid happened. That put many things on backburner though I've continually been mulling what I'd do next, and more so recently. I've gone ahead and implemented some more grill blockage and I'm realizing I never documented my previous grill blockage piece. I'm further contemplating underfloor-age, as always, and I'm very intrigued with air curtains. Anyhow, lots of ideas, some decent tools (CAD and 3-D printer, composites, etc.), just a matter of finding time and executing! A shame it's cold now!

I hadn't seen your thread before but all that you are doing looks great.

I don't know why they have done that. No definitive answer at all.

Air guide for brakes ...

Some general catch up from about a year ago:

So in the rad inlet just below the Toyota badge I noticed it was blanked, but only half blanked:

http://www.mulsannescorner.com/Ecomo...820_174506.jpg

Which bugged me, so I envisioned creating a blocker panel that integrated into the design of the car and had some fun with it. Shaped sheet insulation foam:

http://www.mulsannescorner.com/Ecomo...814_091725.jpg

And then covered it with fiberglass and epoxy, using acetone to eat out the foam form from the backside (I call it the lost-form process) leaving me with this, which I then had to tickle here and there for fit:

http://www.mulsannescorner.com/Ecomo...820_174443.jpg

Final bit. Covered it in black vinyl:

http://www.mulsannescorner.com/Ecomo...210_130845.jpg

Also added symmetrical grill blockers on the outboard ends of the middle inlet. Went simple route and they're made out of conveyor belt with holes drilled into them and then zip tied into place:

http://www.mulsannescorner.com/Ecomo...210_130857.jpg

Created this little panel just at the end of the front undertray. It's where the tow hook used to reside and there was another awkward concavity:

http://www.mulsannescorner.com/Ecomo...807_180057.jpg

Hehe ... it looks like you're playing on another level.
My first panel was made of fiberglass, 10 years ago.

While I'm at work and don't have access to pictures...I've been contemplating a small modification to my spoiler which I'll try to describe without pictures. So trailing edge sharpness is an obsession for me, maybe it's important, maybe not so much. But aero details on road cars are detuned to avoid pedestrian issues (and manufacturing practicalities I'm sure). I've been wanting to add a trailing edge extension to my spoiler (the old spoiler didn't survive the rear ending, see pictures further up in thread, and they replaced it with a proper factory spoiler) that essentially redoes that work, but also angles down slightly. So it would be an extension, not merely a sharpening of the existing trailing edge, perhaps 60 mm in length, angled down approximately 10 degrees from the trailing edge of the base spoiler. Curious thoughts on this? The idea is all about base area infill of course, and it would have a sharpened trailing edge to boot increasing turbulent kinetic energy as the airflow snaps off that edge. Or should I just concentrate on giving the existing spoiler a shaper edge (it's rather rounded)? Nothing pedestrian-slicing of course, the end part would be FDM 3-D printed.

A few points:


- Trailing edges don't have to be sharp sharp to work, so I wouldn't obsess over that.

- If you "increase turbulent kinetic energy as the airflow snaps off that edge" you will likely make things worse, as I would think that the trailing vortices will be more intense. (That's not how separation edges work.)

- I think the notion of "base area infill" is a bit deceptive, as I don't think you can easily do that. What you can do is reduce wake size - not quite the same thing.

- An angled downwards rear extension probably will reduce wake size and reduce drag, but you'd find out only through testing whether it was worth doing. Test first with a mock-up of plastic sheet!