C-Max aero mod success questions.......

[Recumpence]

Yup, that is pretty much what the fog light area looks like.

I know what you mean about air leakage. A round parachute has a hole in the top to increase drag by allowing leakage.

There is air leakage through the fog light area into the engine compartment.

Matt

[drees]

Do you have any details on how you made your grill/fog block offs? They look awesome - very well done!

So you estimate about 10% improvement in FE from the mods? How fast is your typical driving?

[Recumpence]

The grilles are made from 1/8 inch thick G10 Garolite (Epoxiglass). I used the stock grille and fog light bezels as templates and cut it with a saber saw. I taped the material to prevent surface scratching). The fog light covers are thin carbon fiber I had lying around the shop.

I have done the following mods;

Grille blocks
Fog light covers
Smooth 1/4 inch thick Lexan wheel covers

Beyond that I run 51psi (factory maximum) pressure in my tires rather than the Ford recommended 38.

All of those mods, combined, have upped my FE about 10%. Bear in mind, however, that the car is broken in now. I think 1% or 2% of the FE improvement may have been from additional break in. Of course, I would prefer to take credit for the FE improvement myself.

Oh, I hate to throw this into the equation, but, Gas Pods (vortex generators) seem to make a difference on the C-Max. I know there is a huge controversy regarding them. But, I have run them and removed them and there apears to be a 1mpg improvement with them at highway speed. I have not done specific ABA testing of them specifically to verify the exact change (if any) they make. However, when I install them, I finish my day around 1mpg better than the previous day. This is a pretty consistent finding. I pulled them off the rear "Spoiler" however because I plan on making a modest Kammback.

The majority of my driving averages around 45mph. I do appliance repair with the car and drive town to town in northern Illinois. So, 50% of my driving is 35mph in town and 50% is 60mph on rural highways between towns.

Lastly, I carry 200 to 300 pounds of parts and equipment with me every day.

Matt

[drees]

Thanks Matt! How did you attach all the pieces to the car?

At freeway speeds you should see an even bigger improvement in FE - your driving speeds are rather modest...

Looking forward to what you have in mind for your kammback!

[kach22i]

Originally Posted by Recumpence

The grilles are made from 1/8 inch thick G10 Garolite (Epoxiglass).

Interesting material, I've never used it but have a Monopan sample with glass cloth infused into it.

Garolite
Garolite - Wikipedia, the free encyclopedia

Garolite is a glass fabric laminate with an epoxy resin binder, made by continuous weaving.[1] It is a material that looks like plastic but is a reinforced fiberglass on the top and epoxy at its core.[2] G-10 is frequently referred to as FR4.

Garolite was used majorly due to its low thermal conductivity (0.27 W/m K) and the efficiency to withstand high temperatures (168°C).[4]

Although there are various grades of garolite but Garolite G-9, G-10 and G-11 are high performance fiberglass composites. Many circuit boards are made of G-10 Garolite. G-9 has a melamine binder as opposed to phenolic, and may have higher impact resistance.[3]

About MonoPan
MonoPan :: About MonoPan®

MonoPan® is a sandwich panel made of a polypropylene honeycomb with a face sheet made of polypropylene with fibreglass reinforcement on both sides. An additional polypropylene layer on the outside gives a smooth surface.

The face sheet is fusion-bonded with the core being a world first for this remarkable new product.

another lazy Saturday and a piuece or Garolite.. - Telecaster Guitar Forum

Hey, the Garolite, AKA, Bakelite, AKA, Phenolic arrived Friday, soooo what the heck….

[Recumpence]

Bakelite and phenolic are much different.

[Otto]

One reason for reduced drag is the location of the foglights: Consider one of those color-coded pressure graphics showing air pressure along a car body, where red is the highest pressure, and blue the lowest. These correspond to the airflow velocity. So, the nose stagnation point is biright red, since the air flow slows and is compressed there, but as the air then accelerates rapidly around the fender and up over the leading edge of the nose, the map shows bright blue.

The air flowing past your lower nose section pretty much stops at the centerline stagnation point, then accelerates but stumbles as it goes past the fog light bay irregularities.

This is a terrible place for any flow disrupters to be, as the airflow there tries to be very fast. Doubling the speed of the flow means 8X the drag, so you want to avoid any shape irregularities in such drag-prone locations. When you covered your foglights, you pretty much fixed the OEM bad shape there. It's a pity the factory designers don't "get it." They should never have botched this shape in the first place.

This reminds me of a conversation I had with a NASA aerodynamicist: He pointed out that on airliners, flashing light fixtures were often put just above the cockpit windscreen, right where the curved shape blends into the tubular fuselage. He said that is the worst place to put a bump for the flashing light, because just there the airflow exceeds the forward speed of the plane. In other words, if the plane is flying at 450 knots, the airflow accerating past the nose if going significantly faster than 450 knots at that particular location, and since drag increases exponentially (2X speed = 8X drag), the drag penalty is very high. Better to put the strobe lights someplace else, such as at the very tip of the nose at the stagnation point.

Not to hijack your thread, but I posted another thread about optimum nose shapes, Hucho's latest findings, etc. This because I'd like to do a nose on my Porsche that (like your modded vehicle) has nice optimally smooth shape, i.e., no fog light holes in the wrong places, etc. Your mods reinforce my hunch that nose shape is very important not just to reduce drag at the nose, but also to smoothe the airflow for as non-tubulent and optimum flow along the body as possible. So, thanks for sharing.

PS: One cheap and easy way to fill these holes would be to put aluminum foil into the nooks and crannies, held in place with tape. Smooth the foil to the body, then fill the foil-lined cavities with Great Stuff expanding foam, let it rise and cure, then sand to match the body contour, then spray with PlastiDip or paint to match the vehicle. With the aluminum foil prophilactic barrier, the foam will not stick to the car, so you can pull it off without a trace.

[Otto]

PPS: Your aero mod shows that the vehicle did not need nearly so large a cooling intake as the factory evidently thought. After all, you covered >~2/3 of the nose intake area without overheating the vehicle, even in summer, right? We may infer from this that you're smarter than the factory guys.

Add a few more low-hanging fruit mods (plastic garden edging air dam, Prius-like wheel fairings, etc.) as are common on this website, and I'd bet you exceed factory fuel economy specs by 20-25%.

[kach22i]

Originally Posted by Otto

This is a terrible place for any flow disrupters to be, as the airflow there tries to be very fast. Doubling the speed of the flow means 8X the drag, so you want to avoid any shape irregularities in such drag-prone locations. When you covered your foglights, you pretty much fixed the OEM bad shape there. It's a pity the factory designers don't "get it." They should never have botched this shape in the first place.

This is good information, thank you for posting it.
Doubling the speed of the flow means 8X the drag

I think we can blame every designer on the planet attempting to emulate the upper end Porsche 911's with their twin outboard corners radiators. Everyone except Honda seemes intend on marking those front corners with some type of garnish. Most of it is non-functional.

Porsche 911 Turbo history, photos on Better Parts LTD

[Otto]

Methinks centerline radiators (and everything else that needs airflow through it) at the stagnation point would be better: More pressure to push cooling air through, less drag since the airflow essentially stops at stag. pt. anyway, so you can have a smaller inlet hole, smaller radiator will do the job, better fairing of the outward and upward flow which then goes on over and past the car.

Some say, it's the tail shape that counts, not to worry about the nose. I disagree--apparently Mother Nature does too, which is why a tuna or trout does not have a nose shaped like a brick. If it did have a nose shaped like a brick, the flow downstream would be so buggered that the poor fish would get no traction, and get no breakfast, either. (It would be breakfast.)

Speaking of fast fishes, study their inlet/outlet geometry of mouth and gill. Mother Nature spent the past several hundred million years perfecting that, so we may as well copy the concept for vehicle inlets and outlets, as well as nose shapes. I'm working on that idea for the intercooler cooling air outlet on my Porsche 944 Turbo. Also may redo the whole face of the car, which (I regret to say) too much resembles a brick. Anybody here do Photoshop? If so, can you paste a Porsche Carrera GT face onto a 944 Turbo?