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Shadoweb

First time Hybrid buyer

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Well Waldo, I get to pop your balloon here. Blocking off the grill does in fact increase the ICE running temps. When I had the BD, the major complaint I had was NO heat at highway speeds, the ICE WT would barely touch on 160*. After covering the upper and lower grills, the ICE WT jumped up to 180* and stayed there, and I had HEAT in the cabin. When driving the Hybrid at highway speeds of 55-60 (Rural Highway, not Interstates), and switching between EV and ICE, the cabin heater pulls so much heat from the ICE, that if you dont block the grill, the WT drops dramatically, I saw up to 40* swings on the Scan Gauge, so when ICE did kick back in, it had to warm itself all over again to become efficient. I would watch the WT drop to 120* or lower, and after making the cover, the temp dropped no more than 10* in EV. By blocking off the input of cold air into the engine compartment using foam or a plastic cover, it helps to trap that heat, so the ICE doesn't have to make up for heat loss as much as it has to without the covers.

 

Those of us who block the grill are not doing it for aerodynamic reasons, we are doing it to trap as much heat as we can in cold weather. It makes a marked improvement in MPG as well as comfort.

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Bottom line is I'm still convinced whether it's grill shutters, grill blocking or wrapping your front end with shrink wrap, the primary improvement in fuel economy is the aerodynamic effect, any incremental heat retained in the ICE is very minor in comparison. I'm also convinced that none of us could ever test this theory with the precision required unless we have access to a controlled wind tunnel.

With that explanation I now understand your earlier posts. I figured you were leading up to something and was waiting for you to make the connection. Now I understand where you were going.

 

I have not experimented with grill blocking and don't have any evidence one way or another regarding this debate. But, I assume the FFH's ICE has a thermostat like all conventional gas engines. When the thermostat is closed the engine coolant is circulating through the radiator at a significantly reduced rate or not at all. Given that it seems like reducing the air flow through the radiator will impact only the coolant that is trapped in the radiator because of the closed thermostat. Where am I going wrong here?

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The air doesn't just stop once it gets through the radiator, it keeps going and fills up the engine bay. Especially when the thermostat is closed, the air coming out the back of the radiator is still pretty cold, if the thermostat is open the air will be warm and this would all be a moot point. But when the thermostat is closed, the grill shutters should also be closed and my sources say that when they are closed they are blocking off about 75% of the airflow. So the argument is whether that extra 25% of airflow is really enough to make a difference.

I took a look under the hood of my FFH and this engine bay is not evenly remotely close to being an airtight compartment. There are large open areas in the back of the bay and the sides. Large amounts of air infilitration can come in around the headlight areas and the hood gaps. At highway speeds air will infilitrate from all directions. On a -20 degree Minnesota day it would be darn drafty and cold in the engine bay regardless of grill blocking. It would be very interesting if we could do a controlled test on warmup time with grill blocking vs no grill blocking.

 

acdii, you've certainly got more detailed data than I do (all I have is the temp gauge on the cluster), but I don't think it's fair to use data from your BD that was obviously not working optimally. My observations are that at highway speed the ICE temp quickly comes up and stays there, perhaps that's due to the programming changes that Ford made between your BD and my 2014. Maybe the shutters in your BD were staying open too much. Also how do you know that the MPG improvement you saw was because of the temperature of the ICE and not the aero effect? And I still say we're making an assumption that the ICE is more efficient running with WT at 180F than at 120F. Wouldn't a cooler running engine have less internal friction?

 

Was the thermostat on the BD ever tested? The lack of cabin heat in the winter time can be a symptom of a faulty thermostat. And I have always read/heard that an engine that does not reach full operating temperature is less efficent.

 

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Waldo, that is so true on the BD, however i saw no improvement in FE in that car with or without the grill blocking. It did help get some heat in the car though. I did see a marked improvement in my current car when the grill was completely blocked off and having all but the top row blocked off. That little bit of opening is enough to cause a faster cool down than with it entirely blocked off. I drove the car for a week or more with no blocking in 40 and below temps and did see that the MPG was lower then than it is with it completely blocked off. In any case, the biggest thing for me personally is that the cabin warms up faster with the grill blocking than with out it, by as much as 10 minutes faster.

 

On that "other" car, I questioned the t-stat several times and was assured it was working. Who the heck knows what was wrong with it and I am so glad to be rid of it. Other than a couple cosmetic things and the Titanium seats being not as comfy as the SE Luxury ones, I have had no complaints on my current one. My wife has been driving it now for all of February and has pretty much killed the gas mileage in it, last night I drove it briefly and it was at 38.7. Ouch. Best I got last night was 35, but it was a short drive to the train and back, so 35 is not bad considering it was frozen.

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It's not so much about fuel economy for me. It's about conserving as much of that precious engine heat as possible, without causing the engine to run for solely for the purpose of providing heat for my comfort! The way my commute is, the ICE heats up just enough to provide some warmth to the cabin, and then that heat dissipates so quickly when the ICE is not running. The first 15 minutes is usually a struggle, and I just hate to burn gas for comfort only (I know, it's not such a big deal, but this is fun)! Once the cabin reaches the desired temp (usually 70F), it's not so hard for the ICE heat to maintain temperature. The grill blocking seems help. I say seems, because I don't have the data. All I know is that I seem to be able to get heat quicker and keep it longer with the grill blocking in place. Slightly improved efficiency should theoretically also be a by-product.

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You may have not gotten to the right menu to reset the lifetime mileage. I see the car is a 2013 so it probably has 10's of thousands of miles on it. Unless the lifetime mileage ( called "Log Term Fuel Economy" in my 2010, a completely different car ) is reset periodically, it becomes set in stone. I reset mine at 10,000 mile oil changes and towards the end of that interval, it only changes tenths of mpgs even with a big driving change. That's the mathematical nature of averaging. It can change very rapidly at the beginning of the interval.

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