Questions on C-Max aero mods........

[Recumpence]

Hey Guys,

I think I am currently the only one on the board with a C-Max. I have 3,000 miles on it and I am completely satisfied! I am averaging about 48mpg without trying hard and 52mpg if I pay close attention to my driving......

Anyway, I am looking at making a full pan and wheel covers, as well as removable grille block panels. I have a small machineshop with plasma cutter, TIG welder, etc. So, making everything should be a breeze. What I want to know is, what can realistically be expected from these mods? The undercarriage looks vaguely like a gen1 Prius (there are some aero panels under there, but it is still quite "Dirty". Also, with a full pan, I am curious about water drainage (I assume a number of drainage hols would be good) and exhaust heat buildup. I plan on using 1/16" aluminum sheet, or thinner if possible. The pan will be in sections to make service and removal easier. Lastly, what about snow and salt? Do those of you with full pans have issues there?

Oh, also, should I powder-coat the pan or is aluminum sheet generally OK in the elements.

Thanks for any input you can give me. I am a phenominal fabricator, but I have never done these mods before and I need feedback on these issues I raised.

Matt

[arcosine]

For all the aeromods, I think the front wheel skirts had the most single effect. Heat is an issue with blocking the grill and a with a complete belly pan, the floor gets hot which makes the car warmer inside. Cant say about aluminum corroding, my belly pan is coroplast, but with had aluminium pieces near the exhaust and had no problems over the winters.

[AndrzejM]

That's a C-Max

[Recumpence]

Actually, that is an oversees model. The US model looks much different.

So, as for floor heat, I would assume an opening behind the engine could be made to evacuate the heat?

Matt

[MetroMPG]

You should enter your vehicle in the garage: Your Garage: [ Add new vehicle ]

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What I want to know is, what can realistically be expected from these mods?

It's impossible to say, since every vehicle design will respond differently to these mods. And the size of their impact will depend on your vehicle use: high speed drivers would notice a larger % change than predominantly city drivers would (who may see little difference).

I'd start with wheel covers, because they're easiest. Next, given the impending cold weather, do the grille block, because it has multiple advantages, with both aero improvement & engine warm-up / heat retention.

With all 3 mods in place, I'd guesstimate a conservative, reasonable estimate for improvement at moderate (55 mph) highway driving would be in the 4-5% range.

[3-Wheeler]

I would feel free to make a full underbody panel, as I have exactly that on the Insight.

Take a look at the link below. There is a lot of information there, so read through carefully and then report back with any questions.

The fuel mileage increase is about 5% or maybe a little higher.

Heat from the first catalytic converter was something I had to deal with by insulating it with fiberglass batting.

The smooth under side is an advantage in snow driving, as the car glides over deep areas easier, within reason.

http://ecomodder.com/forum/showthrea...els-10638.html

Jim.

[Recumpence]

Now that I look closer at the under side of the car, it looks like I can do this in stages (sections). First, the underside of the nose of the car has a nice area that can be covered with one pan, then behind that (leaving a small gap for air evacuation) I can mount a couple panels under the passenger cabin ending at the beginning of the rear suspension. Then the dirtiest part of the car is behind the rear suspension. It is huge and wide open back there. That area really needs to be closed up. If done in sections, I can spread this takes into a few smaller tasks. Also, if done in sections, various openings ca be left for air flow and water drainage.

Even the stock belly pan covers are not smooth. They are very odd shaped. Not good......

Also, I will make 3 grille block panels out of black plexiglass with a few small slits to allow a small amount if air inside. This car looks good from the front, but are very poor aerodynamically (or so it looks to me).

Matt

[Recumpence]

One more question for you;

The rear of the undercarriage at the muffler is completely open. You could climb up in there with all that space!

My question is this; is that area normally a very high gain area or not?

Oh, yet another question

The nose of the car is about 1.5 inches higher than the bottom of the pan under the engine. So, the car is actually setup to funnel air under the belly and accellerate it. Not good. So, I will be making a modest (maybe 2 inch) drop chin dam for the car coupled to a front aero pan.

Matt

[euromodder]

Originally Posted by Recumpence

The rear of the undercarriage at the muffler is completely open.
My question is this; is that area normally a very high gain area or not?

In order to make the belly pan work, you'll have to close off that area, as it tends to act as a parachute.

The nose of the car is about 1.5 inches higher than the bottom of the pan under the engine.

An air dam down to the level you need to clear the lowest hanging part of the car is good.
Don't go lower than necessary though, as that adds to the frontal area of the car - and thus to the total drag.

Suspension arms are usually covered by moveable sections.

[Recumpence]

Thanks for the advice!

Another question;

The rear doors do not allow a smooth transition from the body to rear wheel skirts. The skirts need to bulge outward to clear the wheels at the bottom 50%. However, the rear door corners end just in front of the wheel well. So, if I do skirts, I would either need to make them only partials (not a bad proposition), make them somewhat blunt in the front bottom corners, or make transition fillers on the door corners. That would be the best from an aero standpoint, but would take the most work. Plus, how much benefit would there be versus discs and just partial rear wheel skirts (not much I would think)?

Matt