Winter gas blend is back

[RamGuy32]

I agree with you about the truck has more drag moving through colder and more humid air, but that does not necessarily make the engine less efficient.

One of the effects of using NOS is to cool the air going into the combustion chamber. This is also the concept of a CAI (Cold Air Intake)


"Essentially, the basic reason to inject nitrous oxide is to increase the amount of oxygen in the combustion chamber, allowing for more fuel. When the liquid nitrous is released from the canister and expands into a gas, it cools and thus becomes denser, and once in the combustion chamber, the oxygen splits from the nitrogen allowing for more fuel and preventing premature detonation. More air = burning more fuel = more power. This is basic engine mechanics."

Nitrous Oxide: What Is It And How Does It Work?

Should you add NOS to your car, and is nitrous for cars safe?

carbuzz.com

Yes, the engine wouldn't be less efficient, it would just work harder to move the vehicle through denser air of the cold winters, and thus use more fuel per mile.

 

[DEG]

That's exactly my point, winter blend isn't that much of a factor in why the mpg efficiency drops in colder temps.
1.7% is decrease in fuel efficiency of .31 for someone averaging 18mpg or about a drop to 17.7 mpg.

Yea, I don't know what % of MPG drop would result from a 1.7% drop in fuel efficiency (BTU).

I agree it might not be the biggest issue. I seem to get about 1.5 - 2 MPG less in the winter. The EPA study also indicated a 5.3% average decline in MPG just due to a drop in temperature from 77 - 20. I'm sure this is due to the added energy required to push a vehicle through the denser air.

For me personally, denser air and less efficient fuel blend will be the only two factors that are likely to apply to reduce my MPG. I tend to idle more in the summer than I do in the winter because I am less tolerant to heat than I am moderate winter temperatures in St Louis. I also tend to run higher tire pressure in the winter because the low pressure light really annoys me so I plan for 36 PSI on the coldest days which results in 40 psi on most days. I park in a garage so fluid temps don't get very cold.

 

[RAM Patriot]

The EPA Study below indicates winter fuel is 1.7% less efficient on average.

https://afdc.energy.gov/files/pdfs/2876.pdf

The EPA article that you linked states that the 1.7% decrease in MPG is for conventional gasoline, you have to deduct another 1.9% if your burning ethanol fuel in your winter blend.

 

[cerbo]

The EPA Study below indicates winter fuel is 1.7% less efficient on average.

https://afdc.energy.gov/files/pdfs/2876.pdf

Look on about page #4. There s why everyone's experience is different. I only have 1200 miles and averaging between 19-20 per tank. 17-20 per trip. I have a light foot and good driving conditions for MPGs. I run 1-3 psi tire pressures higher. All stock. I have a rear cover. Hoping for a little more after more miles and summer fuel.

 

[BowDown]

Yea, I don't know what % of MPG drop would result from a 1.7% drop in fuel efficiency (BTU).

I agree it might not be the biggest issue. I seem to get about 1.5 - 2 MPG less in the winter. The EPA study also indicated a 5.3% average decline in MPG just due to a drop in temperature from 77 - 20. I'm sure this is due to the added energy required to push a vehicle through the denser air.

For me personally, denser air and less efficient fuel blend will be the only two factors that are likely to apply to reduce my MPG. I tend to idle more in the summer than I do in the winter because I am less tolerant to heat than I am moderate winter temperatures in St Louis. I also tend to run higher tire pressure in the winter because the low pressure light really annoys me so I plan for 36 PSI on the coldest days which results in 40 psi on most days. I park in a garage so fluid temps don't get very cold.

I keep my tires around 38psi at all times and check when the temps drop. My mpg loss is about the same as yours when the temps drop below about 50°, I just don't know that the air density/resistance is enough to eat up those 1.5 to 2 mpg loss. I know on my Dallas to Houston trips, it takes a 10-15 mph headwind to cause the same drop in mpg which is why im suspect of pushing through cold air being the culprit.
Even in the winter months on the southbound leg when I'll have a good tailwind from the north, I can't get much more than 20 mpg @ 69-70mph

On a side note, I went to San Antonio last summer and we decided to drive out to Corpus Christi. There's QT gas station selling pure blood 89 (non ethanol, all gasoline) that I filled up with. I noticed absolutely no improvement in performance or mpg using that pure gasoline

 

[RAM Patriot]

I keep my tires around 38psi at all times and check when the temps drop. My mpg loss is about the same as yours when the temps drop below about 50°, I just don't know that the air density/resistance is enough to eat up those 1.5 to 2 mpg loss. I know on my Dallas to Houston trips, it takes a 10-15 mph headwind to cause the same drop in mpg which is why im suspect of pushing through cold air being the culprit.
Even in the winter months on the southbound leg when I'll have a good tailwind from the north, I can't get much more than 20 mpg @ 69-70mph

On a side note, I went to San Antonio last summer and we decided to drive out to Corpus Christi. There's QT gas station selling pure blood 89 (non ethanol, all gasoline) that I filled up with. I noticed absolutely no improvement in performance or mpg using that pure gasoline

When I have switched from ethanol to non-ethanol it usually takes 2-3 tanks before I have noticed a difference.

Probably because it takes a while for all of the ethanol to work out of the tank since you don't wait until the tank is empty before the next fill and therefore has residual ethanol fuel still in the tank.

Another reason is due to the truck PCM takes awhile to detect and adjust the timing map.

 

[BowDown]

When I have switched from ethanol to non-ethanol it usually takes 2-3 tanks before I have noticed a difference.

Probably because it takes a while for all of the ethanol to work out of the tank since you don't wait until the tank is empty before the next fill and therefore has residual ethanol fuel still in the tank.

Another reason is due to the truck PCM takes awhile to detect and adjust the timing map.

I fueled up on less than an 1/8th tank, there may have been a gallon left and it would have been run out in 20 miles or so much less 300 mile round trip. These trucks aren't flex fuel so there's no ethanol content detection and no time needed for the PCM to figure out that it's got gasoline vs E10, it's just knock detection then retard timing based on load and IAT.

Now, thinking back on what I said and my past experience, I now realize that my previous post wasn't accurate.
I normally use 93 octane E10 or pump 93, the non-ethanol fuel was 89 octane. I got the same MPG from 89 octane non-ethanol gasoline as I do E10 93; I have previously found that I consistently get 1-2 mpg less on E10 89 octane vs E10 93 so in this situation, the gasoline 89 performed the same 93 E10 (pump gas).

I use 93 because of the loss in mpg using 89 and that costco only sales 87 and 93 and their 93 is the same price as everyone else's 89.

 

[HSKR R/T]

I fueled up on less than an 1/8th tank, there may have been a gallon left and it would have been run out in 20 miles or so much less 300 mile round trip. These trucks aren't flex fuel so there's no ethanol content detection and no time needed for the PCM to figure out that it's got gasoline vs E10, it's just knock detection then retard timing based on load and IAT.

Now, thinking back on what I said and my past experience, I now realize that my previous post wasn't accurate.
I normally use 93 octane E10 or pump 93, the non-ethanol fuel was 89 octane. I got the same MPG from 89 octane non-ethanol gasoline as I do E10 93; I have previously found that I consistently get 1-2 mpg less on E10 89 octane vs E10 93 so in this situation, the gasoline 89 performed the same 93 E10 (pump gas).

I use 93 because of the loss in mpg using 89 and that costco only sales 87 and 93 and their 93 is the same price as everyone else's 89.

The fuel gauge would have to be on E and range at 0 for several miles to only have one gallon left in the tank. Even if I wait until range hits zero and needle is on E, Im lucky to get 24 gallons into a 26 gallon tank. If I filled up closer to 1/8 tank, there would be at least 4-5 gallons left in the tank.

 

[Willwork4truck]

2 pages of technical info (you guys are quite knowledgeable) and nobody has thrown out random gear ratio comments yet. Amazing! (ha ha)

 

[TSR6]

The fuel gauge would have to be on E and range at 0 for several miles to only have one gallon left in the tank. Even if I wait until range hits zero and needle is on E, Im lucky to get 24 gallons into a 26 gallon tank. If I filled up closer to 1/8 tank, there would be at least 4-5 gallons left in the tank.

RAM is very conservative on the fuel gauges.

My F150, I would routinely fill the tank to the number of gallons the tank was advertised as holding, or within a gallon of it.

With my last 2 Ram trucks, I've had the 32gal tank, and typically only fill it to 26-28 gallons max, and thats even running it down to "Low Fuel"