Recumpence

So, it is illegal to warm up your car without you inside it? That is not the case here in Illinois........ Matt

I have gas pods, but they are not installed at this point because I am looking at making a Kammback. Turns out we went through town rather than on the interstate last night. Bummer. I really wanted those numbers. I need to do some A-B-A testing with and without all mods to get a very accurate number. I know my MPG is around 7mpg better now than last winter. What I don't know is how much of that is from the mods and how much is from the Ford software updates. Matt

The electronic system lines run nearly cold all the time. This subject has been covered at length. I understand your concern. There is still plenty of airflow to all systems. I can hold the cooling lines with my bare hands after a long EV run. No problem at all. Matt

http://fordcmaxhybridforum.com/topic/2074-the-aero-mods-begin-lexan-wheel-covers/ Smooth wheel covers All 3 grilles are blocked Fog lights covered Hood lowered to reduce air gaps Matt

Hello All, Today I decided to do some cruising MPG testing. Here is what I did; I found a stretch of road near my home that runs north/south with some rolling hills. That road is 2.4 miles long. It has a 50mph speed limit. I wanted to eliminate acceleration from the equation. So, I accelerated to 50mph and set the eco cruise. At that point, I reset my MPG gauge and cruised for the 2.4 miles to the end of the road. As soon as I broke cruise to slow down, I recorded the MPG and turned around to repeat the test in both directions. I did this round trip 6 times for a total of 12 trips. This back and forth eliminated any elevation change and wind from skewing the numbers. Oh the temperature was a frigid 21 degrees! After all of my testing, I averaged out the numbers and my average was 52.25mpg at 50mph in 21 degree weather! This was cruising on cruise control, no hyper miling or drafting. I must say, I am thrilled. Tonight we are doing a bunch of interstate driving and I plan on recording my 65 to 70mph MPG average too. :) I am totally thrilled with these aero mods. I would normally have seen a maximum of 45mpg under these conditions without the mods. Matt

I must be missing something. I have researched many tail box/boat tail mods and the average gain was 14%. So, by those numbers, if the EPA estimates are true, adding a tail completely eliminates all aero drag completely. The graphs I have seen typically look like the one posted above regarding the Tesla showing that roughly half of the drag at highway speed is from aero. I am not trying to be argumentative, I just have a hard time with a 15% to 20% number. Heck, my 7mpg increase would suggest that I have eliminated 40% of my overall drag so far and that is just not the case. Anyway, I am not trying to prove you wrong. I just do not understand how they got their numbers...... Also, I tend to be a bit doubting when I hear engineers saying things that seem unrealistic even though they have the math to prove it. I have manufactured RC helicopters in the past, as well and electric drive systems for bicycles. Every time I release a new product I have engineers giving me math equations to prove my design wont work. Once I prove them wrong by building it and showing them it works fine, they come back with the math showing me why it works. Cherry picking is done by the technical folks too. They tend to pick the math that proves their position right. Aerodynamics are so complicated, the best we can do is give generalities until a given design is thoroughly tested. Can you explain the 10% number and how it relates to chin spoiler height? Admittedly, that went over my he. Matt

My temp ranges from 170 to 197 degrees for most of my driving. :) Matt

One caution about the front air dam/chin spoiler; When you force more air over the hood, you increase downforce. Downforce is bad for FE. Ideally, you would part the air and send some to the left and some to the right of the car and some over the top. The chin of the C-Max has slight flares under and ahead of the fog lights. If you make an air dam that follows that contour, the air will be mostly forced over the top, generating downforce. If the dam is even with the chin of the car in the center, then passes under the corners of the car in a rounded shape, the air will naturally want to split left/right rather than mostly going over the top. This is preferable. Don't get my wrong, even passing the air over the top of the car should net a measurable gain. But, I believe, the gain will be much better of the dam was curved, encouraging air around the sides rather than over the top. :) Matt

To give you an idea of what kind of results I am seeing with the improvements I have made, today was 46 degrees and drizzling. My average for my day (140 miles) was 58.2mpg. Before the mods, the best I could ever expect with this type of weather would have been 52mpg and that is really a stretch. Most often weather in the high 40s to 50 degrees would have been right at 50mpg. I can actually feel the car coasting farther now than before the mods...... Much farther! Oh, as for the percent of drag on a car at highway speeds, it is WAY higher than 15% to 20%. There are guys doubling their mpg by adding full boat tails and other extreme mods. So, clearly, aero drag is HUGE at highway speeds. Anyway, Paul, taping openings is different than making good strong blocks. The tape will flex and flutter in the wind and it is not a smooth surface. The surface really needs to be free of odd shapes and as smooth (Flat) as possible. Taping an area is good for some basic test. But, you will always get better results by making something that is properly shaped. One of the next things for me is the Kammback. Lastly, as for being able to bring the car back to stock. I complete agree with you. I am taking a gamble drilling into things. But, the car will have huge miles on it very rapidly. So, the value is dropping anyway. Also, I personally prefer the look now versus stock. I also have no plans to ever sell the car. :) Matt

It is black 1/8 inch thick G10 also called Garolite. It is basically cloth impregnated with resin (epoxiglass). It is very similar to Carbon Fiber, but 1/4 the cost and around 20% heavier as well as roughly 25% less rigid. The look is something I like, but some don't. Everyone tells me they love the blacked out look and some people love the look of the screws, while others do not like the look of the screws. As far as drilling and screwing into the car, I am in an interesting situation. This is my work car. It is full of equipment (the entire cargo area) about 90% of the time. It was bought with the sole purpose of being a "Work Truck". So, my wife doesn't care what I do to it. Also, it already has over 40,000 miles. I knew this car would not be new for long. Also, I am only screwing into the plastic facia. Worse case scinerio, I buy a new facia....... Good as new! Oh, I have been getting come good compliments on Ecomodder about the look. Have you seen the cars the guys there build? They are NASTY! Holy cow, I mean, come on, you do have to be seen in the thing. Some of the hideous add-ons I see there make me cringe...... Anyway, beauty is in the eye of the beholder. I normally feel odd when I bring the car in for updates or oil changes. I get "The look" from guys in the service department. :) Matt

The gaps around the headlights and other panels add up to a decent size opening. Sealing up these gaps nets very little in MPG gain (maybe one tenth of a mpg), however, all of these little things add up. The point is, if you do a dozen things that each give 1/10 mpg gain, together you will see 1.2mpg increase. It is kind of like drilling holes in brackets on a racecar or kit plane. A few holes does basically nothing. However, many thousands of holes add up to significant weight reduction. Same principal. It is painfully easy to seal up gaps. So, there is no reason not to. I have looked into cameras to eliminate the mirrors too. One problem is the outside temperature sensor is in the passenger side mirror. So, if you remove that mirror, you lose your temp sensor. I am, most likely, going with cameras at some point. But, there is other low hanging fruit I can grab first. The chin spoiler is one thing, a Kammback is another, wheel spats and partial wheelwell covers are others. I am guessing the chin spoiler would be good for 1/2 of a mpg. The Kamback is probably good for another 1/2 of a mpg. Partial wheel well covers (all four) with wheel spats are probably good for another 1/2mpg (all combined). So, I am assuming around 1.5mpg gain with those additions, conservatively. This is all pure guesswork, though. The Kammback may give me a couple mpg for all I know. This is just conjecture. My mindset is, I would rather have relatively low expectations, and be pleasantly surprised when the gains turn out to be higher than I thought. Matt

Here are a couple more pictures. I made a new lower grille. This new grille fits a lot better. Also, the intake is one rectangle opening with a 1/2 inch radiused edge. This edge radiuses into a 1 inch thick piece of Delrin just like a velocity stack. The upper grille is finished as well. You can see how close it comes to the hood edge. Oh, one thing I found; Once I got the upper grille mounted, I noticed the hood sits kind of high. I adjusted the rests to let the hood settle down 5/16 of an inch. This drastically reduced the gap above the headlights, at the grille, and all the way around. However, the latch was too high now. This made the hood sloppy in how it latches. So, I removed the latch assembly and used my plasma cutter to elongate the four holes (two screw holes and two alignment holes). Now, with the latch lowered, the hood shuts snug and sits at the proper level, thus closing off much of the gaps. The next thing to do is pick up some weather stripping to seal the gaps around the headlights. These gaps are quite large and constitute a relatively large opening in the nose if you consider all gaps together. Matt

I still have some work to do on the front end. But, I have considered buying a Ford emblem sticker to stick on the upper grille and some silver pin stripe to make the center grille look somewhat stock. But, honestly, with all 3 grilles somewhat matching, I really like the look. The upper grille looks really cool in person. The picture does not do it justice. Oh, wait till you see my new lower grille. :) Matt

That section is very open on the back side. If you open your hood and look at that area, there are large openings to the engine compartment at each end about the side of a tennis ball. I have done a bnuch of reading on warm air intake for FE. It runs out there is a slight FE improvement with warm air intake as opposed to cool air. Cool air increases power, but requires more fuel. Warm air intake increases FE. Matt

Here is an upper grille block I made today. I have about 45 minutes in it so far. I have it mounted with a few screws for testing purposes. I will finish mounting it tomorrow. I used a piece of 3/4 inch 6061 aluminum box tube bent to the shape of the nose of the hood as a support behind the grille to hold the proper shape since there is nothing at the top edge to mount the grille to. Otherwise it would try to flex flat. The nose finally has that nose fully rounded look to it. I will post FE numbers when I have them. Matt

The chin spoiler is something I am very interested in as well. Problem is, I would like to make a new totally flat belly pan from the new chin spoiler rearward. However, I do not want the dealer freaking out when I bring it in for oil changes. That being said, the solution seems to be to make the new pan easily removeable with the stock pan still above it. That way I can remove my simple flat pan when the car goes in for an oil change. I have considered many designes for chin spoilers ranging from a simple flat panel running straight down to a nicely radiused edge like the stock spoiler has. As a general rule, to maximize drag, the leading edge of a moving object should be rounded (radiused) and the trailing edge should be sharp. Matt

When someone dies and leaves me a wad of cash. :) He bought his before any of the fires. I am not adicted to the thought of owning a Tesla. Actually, I would much rather have a roadster than a Model S. But, I can say they are very good cars. Nothing is perfect. Matt

Uh, huh......... You are still wrong, plain and simple. The high end car is under $100,000. Just admit it, you are over exadurating to make a point (in incorrect point at that). Also, he did not buy the base model, he bought the mid size battery. Tesla dealers will work with you. They do not automatically overcharge people. Matt

OK, here is what I would like to do (aside from the upper grille and other grille revisions) is to go with the modest Kamm-Back as I said before. This will reduce the size of the wake. I also am planning to make some simple vanes on the sides of the car below the tail lights above the bumper. These will be simple 1/16 inch thick black fiberglass or G10 panels just double side taped to the car extending rearward. The point of these extensions is to give the air a sharp end to detach from the body. The only problem I see with the side vanes is the leading edge will not be flush with the body. The panels are 1/16" and the tape is 1/16". So, there will be an 1/8 inch leading edge there. I will do my best to bevel it and I can use some black tape as a transition (obviously just for testing purposes). If you feel like doing more tuft testing, this would be a super easy thing to test. Oh, also, I had already decided on making partial wheel well covers as well. Your testing has confirmed the value in doing that. Plus, rear wheel well covers would smooth the airflow going toward the side vanes I will be making. What are your thoughts? Matt

A friend of mine bought a new Model S for $72,000 out the door. My facts ARE straight........ Matt

Frank, I have been looking at a couple things to try on my car and I wanted to ask you a couple questions; #1 I was planning on making a subtle Kamm-Back out of Lexan that would run around 8 inches rearward of the stock "Spoiler" and flanking the rear glass. It would be heat bent at the corners and follow the contour of the car. However, if we have good separation there already, the only benefit would be slightly reduced area for the air to detach from. Is this correct? What I mean is, there would not be any measurable turbulence reduction, but, rather, slightly reduced rear area for the air to detach from, thus minimizing the improvement there? #2 I have long known the rear curves behind the rear wheel wells are far too gradual to promote clean separation and I have considered adding subtle side vanes that would attach just behind the wheel well from the bumper edge up to the bottom of the tail light giving the air a clean edge to separate from. This feature is clearly visible on the Volt and late model Prius, for example. What are your thoughts on these two ideas? The side vanes would be very easy to make and install with simple foam double sided tape. They would also be very easy to remove. Matt

Gotcha. I just find it odd that every web site that mentions a Tesla fire has someone saying the same darn thing; "I would never pay $100+K for a fire trap" and it just absolutely gets under my skin. Only the highest priced, tricked out Tesla is $100K (and not even quite that high), not $120K. Just like when a customer of mine complains that they "Took the day off of work to meet me." When, truth be told, they told their boss they would come in an hour late to meet me there at 8AM. I just want people to use correct data when they are trying to make a point especially a negative one....... Matt

Sheesh, read my post. I am talking price facts........ Matt

I am so tired of people overstating the price of a Model S. The average price paid for an S is $70,000. You can get them far cheaper than that with the base battery and options. You cannot even spec one as high as $120,000........ Let's get our facts straight. Matt

It was 44 degrees today and I averaged 55.9mpg. I would say these aero mods are definately helping with all driving, including cold weather. I am planning on doing the upper grille and remaking the lower grille this Saturday. Also, I have done some research, and it looks like I will be making a very simple Kamm-Back from Lexan. The roofline is such that it looks like I can do it with minimal effort and minimal impact on the look of the car. It would only be around 8 to 10 inches long. Not a big deal. But, they normally make quite a difference in FE. Beyond that, wheel spats, a lowered chin spoiler, and possibly small wheel well deflectors, to reduce turbulence around the tire/wheel well gap, may be in order Matt