CMAX Grill Cover Testing, 2-5 MPG Gain

[ptjones]

Can someone suggest where Grill Covers can be purchased?  Apparently, my Ford dealership isn't aware that they make a difference in mpg during colder temps so I suspect they're not available as a Ford product.

Any advice would be appreciated.

I came up with the idea for Grill Covers and believe I'm only place to get them. :)  Message me and I will give you the details. Also I have a few threads on this topic here.

 

Paul

[Jmonty]

I tried something different for closing the grill openings.

The cure all Duct Tape!

Half width fits between the grill members and black is hardly noticeable.

 

I have been driving this way for several days and am amazed that the duct tape strips are staying put!

I have seen my mpg go up, but since it has also warmed some here I cannot say exactly how much.

I left the top slot open but covered the rest including the lower all black grill.

Checking the water temperature it still is below 1/2 on the gauge often, so maybe I can do more, but am being cautious.

 

IMG_7007s.jpgIMG_7008s.jpg

 

 

very interesting..  i was wondering about duct tape but i was concerned about the residue when it comes off.  you know how sometimes it leaves like a tan colored adhesive gunk?

 

i'm about to head out on another trip to MI from CO and was thinking that'd save me a few MPGs, but i go 3-5 MPH over the speed limit so i only expect ~38 mpg at best.

[ptjones]

very interesting..  i was wondering about duct tape but i was concerned about the residue when it comes off.  you know how sometimes it leaves like a tan colored adhesive gunk?

 

i'm about to head out on another trip to MI from CO and was thinking that'd save me a few MPGs, but i go 3-5 MPH over the speed limit so i only expect ~38 mpg at best.

I have used clear packing tape and it can leave a little residue that is easily removed with lacquer thinner. Remember to monitor MyView temp gauge. We can get you covers when you are ready.

 

Paul

[Jmonty]

Thanks, man. I'll consider that.

 

I got some black tape on, not very neatly but it should hold.

 

After this trip I'll have roughly 18k miles total, with just ~6k on the interstate going cross country. So, it turns out that this car will have served me well because most of my driving is city where better MPGs are easier to obtain, stock.

[Jus-A-CMax]

Hey Paul, did you end up taking off your covers in the heat of AZ/TX? Can't remember if you reported on that or not...

[ptjones]

Hey Paul, did you end up taking off your covers in the heat of AZ/TX? Can't remember if you reported on that or not...

No, I left them on all year long. Now with the update it runs about 10degrees warmer than before because shutters don't open till 215degreesWT, before they started to open at  190degrees. Remember operating temp for ICE was 202-212degrees, but my last AZ trip I was interchanging about every 100mi. full cover for cut out cover with no obvious difference in MPG's. My take away from this is it is very important to get to 202degreesWT for max MPG's , but getting as high as 237degreesWT has little to no effect on MPG's  BTW it is still hard to reach 200degrees in the summer time and full covers with city driving. :) 

 

Paul

[Jus-A-CMax]

Bad news, I have similar covers with middle and lower. Tonight the overheat warning came on with the outside temps at 33F!!! This was during a 3 bar burn climbing Sherwin grade at 66 mph set on eco cruise. Maxine was fully, fully loaded and it came on after 5 minutes of this moderately hard burn. I was shocked it came on at that speed and especially at that temp.

Took me 30 secs to process this "wtf" moment and  I backed down to a 2 bar burn and the temp dropped back to middle. That was scarier than running out of gas.

I checked Maxine when I got to town and nothing appeared out of ordinary and the engine functioned fine.

So yeah, it is possible to push it over...even in freezing ambient temp!

 

ps I have climbed at those speed, load and temp, no issues back then. Scary.

Edited December 24, 2013 by Jus-A-CMax

[Adair]

Yikes Jus!!! Glad everything was ok! That's the very thing that scares me about the grill covers.

[Jus-A-CMax]

Yikes Jus!!! Glad everything was ok! That's the very thing that scares me about the grill covers.

I really do not need to use covers but since I was going to the snow ala MN temps I thought I would try them. It works pretty good@2bar burn going up most grades but Sherwin is special, its a steep and very long grade. Maxine has the energy for sure...but who knew this would happen. I'll leave the covers on for the trip and see.

[Adair]

So it was the 3 bars AND the grade that caused it? What is Sherwin? 7% ? I know you've said but I don't remember.

[bemyax]

I'll have to see if this stays on in the car wash. It's the snap-around pipe wrap you can get for a couple dollars at Wal-Mart. Since it was still dark and -18F when I did this, a nicer day might yield better looking results. I had to clip angled notches for the vertically oriented members. It might not show in the pic, but the lower grill openings are full of snow and it's way too cold to lie on the ground. 

 

From everything I've read here, tiny changes can make statistically significant changes in the vehicle performance. So I'm thinking these "covers" will also alter the aerodynamic shape along with the better temperature curve I'm after. No data collection expertise or capabilities here. I'm going to crudely follow your lead. 

 

David 

[Adair]

Thanks for posting that David! This is something I've considered. Someone  (fotomoto?) mentioned that this had been done by Prius owners with great results. Do you have 2 different diameter wraps?

[bemyax]

The 3/4" diameter was the only size at my store. I had to try to jam the two tube sides into the same in-between grill slot with my frozen fingers. A garage would have been nice. 

 

For three dollars (US) it couldn't hurt to try. The seven-day forecast for northeast Iowa doesn't show us getting slammed with frigid temps soon, maybe just a little below zero a couple of times. It's really a band aid type solution, so if they get blown off in the car wash, I'll just replace them. (Add: I hit the highway a 65mph and I couldn't see where they moved around, but a longer trip would produce better evidence of them working loose.) 

[ptjones]

Bad news, I have similar covers with middle and lower. Tonight the overheat warning came on with the outside temps at 33F!!! This was during a 3 bar burn climbing Sherwin grade at 66 mph set on eco cruise. Maxine was fully, fully loaded and it came on after 5 minutes of this moderately hard burn. I was shocked it came on at that speed and especially at that temp.

 

Took me 30 secs to process this "wtf" moment and  I backed down to a 2 bar burn and the temp dropped back to middle. That was scarier than running out of gas.

 

I checked Maxine when I got to town and nothing appeared out of ordinary and the engine functioned fine.

 

So yeah, it is possible to push it over...even in freezing ambient temp!

 

ps I have climbed at those speed, load and temp, no issues back then. Scary.

I think it is important to figure out what happened. Jus doesn't use my Grill Covers; not all covers work the same.

 

1.  Jus what temp did you get too? MyTouch temp gauge and ScanGauge?

2. What type of gas? Reg,Premium or Pure Gas

3. How tight does your grill cover fit?

4. What temp were you running before you started climbing?

5. Were you using the heater? You can adjust ICE WT with heater.

 

I think this event is important because the ICE computer notified you that there was a problem, so the system worked the way it was supposed to. The Handbook explains what happens as ICE temps reach unsafe levels and computer takes actions to protect the ICE. Jus activated the first step, which no one has reported before. If the computer works like it is supposed to Jus could have kept going and the worst that could have happen is the ICE would shut down. After cooling down it would restart and go until it heated up again. No harm no foul.

 

Paul

[Jus-A-CMax]

These are not ptjones grills, jus want to make that clear. I built these myself, they are tight and removable, and unless Paul had vent holes in his grills, they are essentially similar. I have no use for grill covers in Los Angeles since temps are mild almost 365 days, but I made these to play with for the trips up north.

Adair...yeah, if I kept the burn at 2 bars and not gun it (I decided to try Mcgyvers trick), I think I would have been OK.

 

The engine had been running about 2.5 hrs since Mojave, pulse & glide and ambient temp was low, myview gauge showed middle bars. That was OK. Everyone knows I use premium. Cabin temp was 70 for me and the wifey had 75 on hers. 3 bar acceleration from the bottom of Sherwin. It was climbing nicely at 66mph at 3 bars, it was kinda sweet to drive... then OOOPS.

 

Here's the deal, I now strongly believe the grill covers are too much for the load & grade and speed. Not even below 30f could sustain the heat at those loads. This is easily repeatable if anyone wants to try.

 

I am posting this as a cautionary note to those who drive with grill covers or anyone who tries to block the middle & lower grills...there IS A LIMIT.

Edited December 25, 2013 by Jus-A-CMax

[ptjones]

I wish we knew what temp this happened at on both gauges to educate Grill Cover users. Jus were you using inside or outside air? BTW Jus Grill Covers are worth about 2mpg at 70mph, well worth any potential problems IMO when all you need to do is slow down to two bars. I also supply a summer cover that solves this problem in about 15 sec.

 

Paul

[Recumpence]

I call tell you I have all three grille openings covered with my own covers. The center and upper grilles are completely air tight sealed and the lower grille is open with a 1.5inch by 3 inch opening. I have no issues what-so-ever in winter. In summer I open up the center grille with an opening about the size of half my palm.

 

Matt

[bemyax]

Because you folks have monitored temperatures with varying configurations and climates, I figure watching the user gauge will be sufficient. My only concern in hot weather is if we are corrupting some kind of highly tweaked airflow dynamics under the hood. I can't provide a link; my recollection from my 2000 Focus was that we could create unintended hot spots in the engine. 

[BobJustBob]

I'll have to see if this stays on in the car wash. It's the snap-around pipe wrap you can get for a couple dollars at Wal-Mart.

 

 

Hi David,

 

I also am giving grill covers made of foam pipe insulation a try.  I bought 1/2 inch diameter black foam pipe insulation at Lowe's.  It comes in 5-foot sections, which cost 99 cents each.  I used 2 1/4 sections and sealed all openings in my lower and middle grills.  Unlike you, I cut the insulation in roughly 4 inch lengths to fit the area between the vertical support members.  (I tried to take a photograph of my covers, but am having difficulty with my digital camera.)  I made sure to make each length about 2 or 3 mm longer than the section I was trying to fill, to make for a really tight fit.  Due the flexible nature of the foam, it would "flow" over the vertical support post and almost merge with the edge of the foam in the adjoining section, thus creating a tight seam.

 

Because the foam is black, it is hardly noticeable when one steps back from the automobile. 

 

I installed mine on December 24th, so it is too early to tell how successful the covers will be in increasing my cold weather gas mileage.  I was getting desperate--last winter was fairly mild, but this year we have already had two brutal Arctic air blasts come roaring through, and my gas mileage was plummeting.

[bemyax]

Bob @BobJustBob, 

 

That sounds like a definite improvement in materials. The larger size hasn't moved around in the car wash or the highway maybe because they are a tight squeeze. Since Matt @Recompence covered his top grill, I'll try that, too. While taking a long (100 mile) highway drive yesterday, the gauge went to center, and stayed put. But the air temperature was right around freezing. I'll repeat that drive when we go subzero again, to see if I can observe the thermostat opening and closing. Before the cover, when I would run into the convenience store for coffee in sub-zero, it was just like starting all over. :facepalm: 

 

I think our original topic was miles per gallon related to operating temperature. Since I've been tinkering with using E10, pushing up the tire pressure, and working harder at manipulating the CVT into lower ratios there's no way I can even get a seat-of-the-pants sense of how my MPGs are affected by this. Will have to leave that to the scientists.  

 

David 

Edited December 28, 2013 by bemyax

[marshtex2]

I covered the middle and lower grill on my 2013 C-Max Hybrid last July in El Paso, TX, 70 to over 90 degrees F ambient, following discussions with Paul Jones.  I found a cheap and quick way of doing this with a layer of thin film sold to cover and protect carpets in work areas and this very much sealed off the grill. 

 

Through Ford tech reps Jones found that the thermostat is fully open at 202 degrees, so normally the coolant should be approximately 202-212 degrees.  He pointed out that the coolant reservoir cap has 21 psi stamped on the top and that a 50/50 mixture of water/coolant at 21 psi boils at approximately  285 degrees F.  

 

With my sealed off grill, engine operating temperature was not troubled, it got up to thermostat opening a little quicker, perhaps, but it stayed within acceptable operating range for the pressure tight system, most I ever saw was 215 deg. 

 

The air conditioner seemed to work OK, however, when I would switch it on to Max AC it would start blowing hard and cold but the chill went away in a very few minutes.  Before I dare take the C-Max in with an AC complaint with the grill covered, I peeled the cover off.  Then giving the Max AC a test, I found that it worked just fine; lots of cold air blew and blew.  So my style of grill cover did interfere with the function of the AC system.

 

I did not detect a noticeable difference in mpg in my mostly suburban area driving.

[hybridbear]

The 3/4" diameter was the only size at my store. I had to try to jam the two tube sides into the same in-between grill slot with my frozen fingers. A garage would have been nice. 

 

For three dollars (US) it couldn't hurt to try. The seven-day forecast for northeast Iowa doesn't show us getting slammed with frigid temps soon, maybe just a little below zero a couple of times. It's really a band aid type solution, so if they get blown off in the car wash, I'll just replace them. (Add: I hit the highway a 65mph and I couldn't see where they moved around, but a longer trip would produce better evidence of them working loose.) 

1/2 insulation fits between the grille slats. See pics of on our FFH and on my parents' C-Max Energi

 

Squeezed between the slats the foam will not move. Since it also hooks around the slats with the slits I cut in it to match them it is quite solid. I've driven 70 MPH on the interstate and washed the car numerous times with no movement of the foam. I've observed that the change in peak coolant temp is pretty small, maybe 10 degrees F. The big improvement is in how quickly the ICE gets warm. Less than 3 miles at 60-65 MPH will get the coolant temp from 20-30C up to 80+C. Engineering Test Mode is really useful for monitoring coolant temps as it allows you to see the exact temp in Celsius instead of just the vague temp gauge on MyView. I use ET Mode every time I start the car until the ICE warms up. Once the ICE is warm then I turn it off so I can see the Empower, etc screens again.

 

These are not ptjones grills, jus want to make that clear. I built these myself, they are tight and removable, and unless Paul had vent holes in his grills, they are essentially similar. I have no use for grill covers in Los Angeles since temps are mild almost 365 days, but I made these to play with for the trips up north.

Adair...yeah, if I kept the burn at 2 bars and not gun it (I decided to try Mcgyvers trick), I think I would have been OK.

 

The engine had been running about 2.5 hrs since Mojave, pulse & glide and ambient temp was low, myview gauge showed middle bars. That was OK. Everyone knows I use premium. Cabin temp was 70 for me and the wifey had 75 on hers. 3 bar acceleration from the bottom of Sherwin. It was climbing nicely at 66mph at 3 bars, it was kinda sweet to drive... then OOOPS.

 

Here's the deal, I now strongly believe the grill covers are too much for the load & grade and speed. Not even below 30f could sustain the heat at those loads. This is easily repeatable if anyone wants to try.

 

I am posting this as a cautionary note to those who drive with grill covers or anyone who tries to block the middle & lower grills...there IS A LIMIT.

That kind of grade would cause overheating in many cars in summer. A grille cover restricting airflow is just too much. I'm glad the car warned you Jus. How long had you been doing the 3 bar burn when the ICE got hot? We don't have much in the way of hills in MN but there is one freeway stretch where I'll climb with a 2 bar burn for a couple minutes at 60-ish MPH and that will get the coolant up over 90C. Usually it settles in around 80-84C with full grille blocking and MN temps of <20F. Once I finish that climb and go back to alternating EV mode with ICE charging the coolant temp quickly drops back to 80-84C. In the city I've seen it hit 90C with outside temps 25F and 20+ miles of city driving. However, mostly in the city the coolant temp struggles to reach 80C and maintain 80C even with full grille blocking in MN. The time it hit 90+ C was a rare occurrence where I was driving in an area with a ton of stop signs so there was minimal EV run time. During the stretch where the coolant increased in temp so much my SOC also went from being <20% to >55% because of how much the ICE was running.

 

The Prius does much better than the Fords at getting hot and maintaining heat in the winter. The Prius will quickly reach 193-195F coolant temp even with ambient temps of -10F. In the city the Prius will maintain 175-190F coolant temp with the heat running and outside temps <20F. Ford should learn from Toyota's design and improve the FFH and C-Max for the next gen so that they work better in cold climates.

 

Here's a pic of the Prius grille blocking

 

Sorry for the mix of Celsius and Fahrenheit... Since I monitor coolant temps in the Fords with ET Mode I use Celsius there because that's the display in ET Mode. I've gotten pretty good at converting Celsius from ET Mode to Fahrenheit in my head by doubling the C temp, subtracting 10% and then adding 32. The Prius temps are monitored with the ScanGauge so there I talk temps in Fahrenheit.

 

Hi David,

 

I also am giving grill covers made of foam pipe insulation a try.  I bought 1/2 inch diameter black foam pipe insulation at Lowe's.  It comes in 5-foot sections, which cost 99 cents each.  I used 2 1/4 sections and sealed all openings in my lower and middle grills.  Unlike you, I cut the insulation in roughly 4 inch lengths to fit the area between the vertical support members.  (I tried to take a photograph of my covers, but am having difficulty with my digital camera.)  I made sure to make each length about 2 or 3 mm longer than the section I was trying to fill, to make for a really tight fit.  Due the flexible nature of the foam, it would "flow" over the vertical support post and almost merge with the edge of the foam in the adjoining section, thus creating a tight seam.

 

Because the foam is black, it is hardly noticeable when one steps back from the automobile. 

 

I installed mine on December 24th, so it is too early to tell how successful the covers will be in increasing my cold weather gas mileage.  I was getting desperate--last winter was fairly mild, but this year we have already had two brutal Arctic air blasts come roaring through, and my gas mileage was plummeting.

Putting it between the vertical supports might allow your pieces to come out from air pressure at high speeds or from water pressure at the car wash. Notching the foam to hook around the vertical support bars will keep the foam securely in place. Dark colored foam that runs in one piece all the way across is also less visible that many pieces. See my pics above. The Prius was the first car that I blocked. Thus, it looks the worst because I didn't know what I was doing back in October as well as I do now. At some point I will redo the Prius grille so that it looks better and isn't in so many separate pieces.

[marshtex2]

Has anybody with a Scanguage noticed what the water temp it shows when the overheat warning light has come on?  I have never seen anyone report a Scanguage water temp that would seem to be getting into a danger zone.

[ptjones]

It is important to know that the radiator doesn't do anything until the thermostat starts to open at 182degrees and I'm guessing fully open at 202degrees given that is the operating range. The only cooling that is being done is by the ICE radiating heat and air flow pulling it away down under the car. Unlike foam my Grill Covers allow some air flow which gives it a larger OT range. When temps get to hot you just install Summer Cover in about a minute.  

 

Has anybody with a Scanguage noticed what the water temp it shows when the overheat warning light has come on?  I have never seen anyone report a Scanguage water temp that would seem to be getting into a danger zone.

Jus is the only member that has been able to get hot enough to make this happen and he doesn't know the temp. I have been able to get to 237degrees during the summer in AZ and not get that message. If anyone has this happen all they have to do is slow down to 2Bars and problem temperately solved and then remove cover and install summer cover. BTW Grill Covers improve MPG's  by better aerodynamics by about 2mpg's at HWY speeds. :)

 

Paul 

Edited January 19, 2014 by ptjones

[plus 3 golfer]

Has anybody with a Scanguage noticed what the water temp it shows when the overheat warning light has come on?  I have never seen anyone report a Scanguage water temp that would seem to be getting into a danger zone.

You need to know the algoritm used in setting alarms / DTC and then maybe one can figure out what the threshold temperature is for triggering. It's likely not one instantaneous value. Usually, there is a sampling rate and a time constant used to compute a weighted average value. When the weighted average value exceeds the threshold, an alarm or DTC is initiated. IIRC, the threshold for the PCM to limit fueling on over temperature is 270F (I read that in either the service manual or perhaps the OBDII operations manual). So my guess is that the over temperature warning threshold temperature would be between say 240-260F.

 

I have seen instantaneous temperatures climb into the mid 230F with covers and ambient temp near 70F at 67 mph going up grades and then fall back to low 220F once over the crest of the hill.