The aero mods begin (Now working on Diffuser) !!!

[ptjones]

This is one reason I started with weatherstripping...

I still am not sure what you are trying accomplish? Is this suppose improve aerodynamics? I taped up hood and head lights and didn't see any significant improvement in MPG's. It might improve cooling slightly, chin spoiler would do a lot more by creating low pressure under car.  Unfortunately with my CMAX out of commission for next couple of weeks or so I won't be able to tuff test. I am looking into video cameras. :)

 

Paul 

Edited November 20, 2013 by ptjones

[Recumpence]

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

Edited November 21, 2013 by Recumpence

[ptjones]

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

The camera I was thinking about was for high resolution video of tuffs to watch for changes in air flow with improvements on car.  As far as side view mirrors replacing temp sensor is a no problem. :) 

Paul

[mtb9153]

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

Matt what is that black material you are placing in the original grille openings?  I must say you are very creative and industrious with your mods.  I sort of like that stealthy look, but not too keen about mounting a bunch of screws and brackets to secure the grille blocks.  :thumbsup: Sorry I see in earlier posts you pretty much answered my questions.

Edited November 21, 2013 by mtb9153

[Recumpence]

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

Edited November 21, 2013 by Recumpence

[fbov]

I still am not sure what you are trying accomplish? ...

What Matt said, just without the plasma cutter... many small improvements needed to make a measureable difference, and best to keep expectations modest.

 

According to the EPA, 13-16% of fuel consumption is dissipated by aerodynmaic drag in higway driving. Make that 15-20% in a hybrid, perhaps. Assuming you're making 50MPG today (2 gal/100 mi), cut drag losses in half, and you cut consumption to 1.8 gal/100 mi, or 55.6 MPG.

 

Clearly, small imoprovements are not going to be verifiable in any but the strongest tests.  Thus, modest expectations and many little improvements should be our mantra.

 

Have fun,

Frank

Edited November 21, 2013 by fbov

[ptjones]

What Matt said, just without the plasma cutter... many small improvements needed to make a measureable difference, and best to keep expectations modest.

 

According to the EPA, 13-16% of fuel consumption is dissipated by aerodynmaic drag in higway driving. Make that 15-20% in a hybrid, perhaps. Assuming you're making 50MPG today (2 gal/100 mi), cut drag losses in half, and you cut consumption to 1.8 gal/100 mi, or 55.6 MPG.

 

Clearly, small imoprovements are not going to be verifiable in any but the strongest tests.  Thus, modest expectations and many little improvements should be our mantra.

 

Have fun,

Frank

From my experience on my trip any improvement is going tobe less than 1mpg and my solution of taping all the openings was as good as it gets aero wise. :)

 

Paul

[fbov]

As good as it gets... until you open the hood. Tape is fine for testing, but I wanted a longer-lasting solution, wiithout cutting metal.

 

Unlike Matt, I'm trying to stay as stock as possible; no screws into the plastic allowed. Removable adhesives and reversible additions are part of my assumption set. I may keep the car for decades, but it will always be within reach of stock. That's one reason I'm not doing the grill blocks, preferring to assume Ford's louvrers are working. I may add them later... even if I can't see a benefit when the louvres are closed

 

You see, my objective is knowledge, more than reduced fuel consumption. I'm learning aerodynamics the hard way, by testing as well as researching the work of others. Hucho's 4th ed. is on my Christmas list. While there's value in repeating the results of others, I've been looking for things no one's trying. Thus I'm testing AirTabs because I saw no value to another GasPod test thread, and sealing the upper hood area because two of you were sealing the lower two grills.

 

Not being contrary or critical, rather trying to fill empty niches, in a manner that would be appealing to someone who's concerned with resale value. Eventually, we should all end up agreeing on a suite of beneficial mods, albeit with many different implementations!

 

HAve fun,

Frnak

Edited November 21, 2013 by fbov

[Recumpence]

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

[Recumpence]

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

[viajero]

According to the EPA, 13-16% of fuel consumption is dissipated by aerodynmaic drag in higway driving. Make that 15-20% in a hybrid, perhaps. Assuming you're making 50MPG today (2 gal/100 mi), cut drag losses in half, and you cut consumption to 1.8 gal/100 mi, or 55.6 MPG.

 

I found this graph on power consumption vs. speed.  I'm assuming it's for a Model S, since that's what car they're talking about in the text.  C-Max would have an even greater percentage of power going into aero drag because it's lighter and less streamlined.

 

http://www.teslamotors.com/goelectric/efficiency

[ptjones]

Recumpence  what coolant temps were you running?  When I get my car back in couple of weeks I hope, I'm going to do some Tuff testing of the front end and adding chin spoiler.  :)

 

Paul

[ptjones]

As good as it gets... until you open the hood. Tape is fine for testing, but I wanted a longer-lasting solution, wiithout cutting metal.

 

Unlike Matt, I'm trying to stay as stock as possible; no screws into the plastic allowed. Removable adhesives and reversible additions are part of my assumption set. I may keep the car for decades, but it will always be within reach of stock. That's one reason I'm not doing the grill blocks, preferring to assume Ford's louvrers are working. I may add them later... even if I can't see a benefit when the louvres are closed

 

You see, my objective is knowledge, more than reduced fuel consumption. I'm learning aerodynamics the hard way, by testing as well as researching the work of others. Hucho's 4th ed. is on my Christmas list. While there's value in repeating the results of others, I've been looking for things no one's trying. Thus I'm testing AirTabs because I saw no value to another GasPod test thread, and sealing the upper hood area because two of you were sealing the lower two grills.

 

Not being contrary or critical, rather trying to fill empty niches, in a manner that would be appealing to someone who's concerned with resale value. Eventually, we should all end up agreeing on a suite of beneficial mods, albeit with many different implementations!

 

HAve fun,

Frnak

My Grill Covers don't seal, they still allow some air through and they don't damage the car being attached with velcro. I'm still surprised that living in such a cold place you wouldn't have made your own to heat up the car faster. Everyone loves a warm car in the winter. :)

 

Paul

[Recumpence]

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

 

Matt

[fbov]

Matt, two things:

 

if you want to dispute anything I say, please do so with backup. Many disagreements can be eliminated if the disagreeing party does the research and finds out, before sticking foot in mouth, that they're the one in error. My numbers for drag are aleady adjusted from EPA estimates to account for hybrid drivetrain, and the guys who are halving their fuel consumption are doing a whole lot more than aero mods. Get your facts straight; I was agreeing with you.

 

It would also be helpful if you organized your data when you think you have a point to make. What you're doing is known as "cherry picking" in data analysis. It's a common practice among non-techncial people (and lawyers) as it allows one to prove anything one wants, which also makes the results meaningless. Take a look at Paul's write-up on his grill blocks for an example of a well-documented improvement.  

 

Paul,

Stop telling me to block off my front grills, you've graduated into obnoxious. This feels like about the fifth time you've quoted my posts to do so, and this time, it appears you didn't read a word I said. Can you not understand English? How much more plainly must I say it? Is rudeness a requirement for getting through to you? Courtesy isn't working...

 

BTW, I had downloaded your write-up weeks before you forwarded it to me; it's nice work. What modifications I choose, especially in an experimental setting, says nothing about my regard for your work.  

 

For my part, I'll be posting my expressway results with the AirTab VGs on the tuft test thread; I want to keep things together. Suffice it to say, I don't see anything moving my expressway mileage, just one big trend line in several parts; no change with the PCM update, increased tire pressures or VGs. It'll be Spring before I get to test VGs on back roads, where the other two showed a difference, because... 

 

This weekend marks the end of aero testing for a while, as the temps are dropping, turning on the lake effect snow machine. Snow tires go on tomorrow morning, which will be a test of it's own, but with a negative impact...

 

Have fun,

Frank

[fbov]

One caution about the front air dam/chin spoiler

Have you all seen this?

http://www.grandmarq.net/blaze/Blaze_Pics/AE%20507%20lect%207%20Aero%20Drag%20of%20Autos.pdf

 

Pages 14-19 cover front end effects.

- The key metric for front end shape optimization is pressure along the vehicle axis, page 14.

- Extending the air dam can increase drag due to elevation of the stagnation point, page 15

- the subtleties of nose contour, pages 16-17

- air dams, pages 18-19.

 

One of my next tests will be a pressure contour from windshield to air dam (page 14). I've got the parts, just need the time and the motivation... here's the equipment/methodology. The trick is to place the tubing perpendicular to the air flow, so there's no direct pressure into the tube, just what results from the air flow across the mouth of the tubing.

 

No promises when, mind you. The tuft test was an abberation in some ways...

 

In terms of expectations, Barnard's data on stagnation point, above, indicates you want it below 10% of body depth. Here's an idea where the 10% point is on a C-Max:

 

Most of the discussion regarding effectiveness of grill blocks has focused on mechanisms using lateral flow perpendicular to the vehicle axis. Perhaps there's a component due to a lowering of the stagnation point...

 

 

HAve fun,

Frank

Edited November 22, 2013 by fbov

[fbov]

http://ecomodder.com/forum/showthread.php/dam-works-air-dam-smart-fortwo-3-4-a-26046.html

 

Just saw this on Ecomodder...

[ptjones]

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

 

Matt

You must not be going very fast or far to have that low of a temperature. Those are around town  temps. :)

 

Paul

[Recumpence]

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

Edited November 23, 2013 by Recumpence

[Recumpence]

Today I removed my center grille and shimmed it forward flush with the fascia. It looks much better. That also gets rid of the ridge there to smooth airflow better in that area. I doubt any gain found there would be measurable. But, I wanted the look to be consistant with the rest of the nose of the car. Also, any gain (.05mpg?) is better than no gain especially when it is free.   :)

 

I have many very tiny things like that I plan on doing. All together they do add up. Of course, our wonderful little C-Max is already quite aerodynamic in many ways. There are a few areas Ford dropped the ball, however. Those are the "Low hanging fruit" items that I really want to tackle.

 

Matt

[ptjones]

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

 

Matt

It would nice to tie to shutters so when they open, the Grill Cover would open too. Only down side would be that shutters open when you stop the car and let the heat out. The operating temp was 202-212degrees so you are running cold of that you might try blocking one of the holes in cover. Dec. 9th the body shop starts to work on the front of the car and hopefully I can take some pics of how things go together. I'm looking at  the intake system to see if I can get hot air off exhaust and cool ram air when ICE warms up. :)

 

Paul

[Recumpence]

It is far easier to heat the air without drawing it into a ram system. My under hood temp averages 30 degrees above ambient by sealing things up as I have. I Have also found removing the snorkel from the intake increases temp another 20 Degrees with the nose sealed up.

 

Matt

[ptjones]

It is far easier to heat the air without drawing it into a ram system. My under hood temp averages 30 degrees above ambient by sealing things up as I have. I Have also found removing the snorkel from the intake increases temp another 20 Degrees with the nose sealed up.

 

Matt

Actually I was thinking having a door that would block off Ram Air until the ICE warmed up then block Hot air like what was done in the 60's-70's. We loose to many MPG's  warming up the ICE and heating inside the car. :)

 

Paul

[Recumpence]

Here are pictures of my new air dam.

 

This was made from a 3/4 inch box aluminum tube (14 gauge) bent into the shape shown. Once bent, I rivetted lawn edging along the aluminum every 3 inches or so. It is screwed to the car with four screws untilizing stock holes that would normally attach the plastic belly pan to the fiber pan around 12 inches in from the nose.

 

It took about 2 hours to complete. This was amazing time considering it was 6 degrees F when I started and I did all the work outside. I had to stop repeatedly to warm my hands and warm the lawn edging at my heater.

 

The whole dam weighs very little. If I had to guess, I would say it is about 3 pounds or less.

 

I have not done any ABA testing. However, here is what I did for the few minutes of time I had;

 

I took my average mileage from yesterday (a full day of driving without the air dam), and compared it to a drive today around my area with the dam installed. Yesterday was 18 degrees and I averaged 47.1mpg. In 10 miles of driving today (after I warmed the car up), I averaged 49.3mpg. Now, bear in mind, yesterday's mileage was total mileage including the terrible MPG encountered with warm up. While todays mileage was recorded after the car was warmed up. Yesterday I drove 120 miles. So, the warm up MPG would have averaged in pretty well over those long miles. However, I would assume that I could have had maybe .5 to 1mpg better if I had warmed the car up yesterday before I reset the mileage trip odometer. So, realistically, the dam is probably giving me 1 to 1.5mpg increase (conservatively). This is right in line with what most people get on Ecomodder when they install an air dam (actually most report around 2mpg or more).

 

I will do some ABA testing sometime soon and report back.   :)

 

Matt

[Recumpence]

Here are the pictures.  :)