LOST JEEPS :: View topic - MPG & Ambient Temp.

With temps finally climbing up in NH, the CRD's gas mileage is improving. I'm wondering if anyone uses a radiator block in the colder months, and if it improves MPG. I've monitored the winter/summer fuel blends and can factor that out for my miles per tank. Still, I am getting a 2-3 mpg better average when temps are above 45 deg. Can this be corrected by putting a damper in front of the radiator when it's cold out?
Comments?

Charlie.

He said "winter fuel" not ulsd.

My bet is the seasonal fuel and operation of the viscous coolant heater are the biggest winter mpg robbers

Try driving at higher altitudes in the winter. The air is less dense and you still get decent gas mileage. That's because there is less air resistance.

later,
Nick

Gator4x wrote:

Try driving at higher altitudes in the winter. The air is less dense and you still get decent gas mileage. That's because there is less air resistance.

later,
Nick

Hahahaha, that is a good one, everyone move to the mountians in the winter. :lol:

I need to mention that the CRD does not use gas and thus has NO gas mileage, we use diesel fuel, have no spark plugs and get fuel mileage. :wink:

It should improve significantly on your way back down to sea level.

One of the large reasons for decrease in fuel mileage in all vehicles-but especilly boxy vehicles like ours is that cold air is more dense.

Denser air equates to more drag on a vehicle. As the ambient temps climb, the density of the air drops, and you have less wind resistance. This is a major factor for our vehicles, if not, THE biggest factor. So no, putting a peice of cardboard in front of your radiator won't help with that. It WILL help with your engine warming more quickly-thus acheiving peak effeciency from the combustion process. It will not increase your intake air temperature though-cold air means dense air means more fuel is needed to keep the A/F ratio at stoich.

Try driving at higher altitudes in the winter. The air is less dense and you still get decent gas mileage. That's because there is less air resistance.

later,
Nick

Author:	cgoodspeed [ Thu Apr 19, 2007 11:11 am ]
Post subject:	MPG & Ambient Temp.
With temps finally climbing up in NH, the CRD's gas mileage is improving. I'm wondering if anyone uses a radiator block in the colder months, and if it improves MPG. I've monitored the winter/summer fuel blends and can factor that out for my miles per tank. Still, I am getting a 2-3 mpg better average when temps are above 45 deg. Can this be corrected by putting a damper in front of the radiator when it's cold out? Comments? Charlie.

Author:	dgeist [ Thu Apr 19, 2007 11:48 am ]
Post subject:	Re: MPG & Ambient Temp.
cgoodspeed wrote: With temps finally climbing up in NH, the CRD's gas mileage is improving. I'm wondering if anyone uses a radiator block in the colder months, and if it improves MPG. I've monitored the winter/summer fuel blends and can factor that out for my miles per tank. Still, I am getting a 2-3 mpg better average when temps are above 45 deg. Can this be corrected by putting a damper in front of the radiator when it's cold out? Comments? Charlie. Would the goal be keeping the block warmer? I definitely notice a decrease in economy below about 40 degrees. It's still there when the engine warms up, though. I've had it happen even after my fuel supplier went back to the "summer blend". I wonder if it has more to do with the ambient temperature of the fuel...

Author:	crackercrd [ Thu Apr 19, 2007 5:22 pm ]
Post subject:
could it have something to do with the viscose heater activating below a certain outside temp? And would a grill block-off make any difference in the operation of that system?

Author:	vtdog [ Thu Apr 19, 2007 8:25 pm ]
Post subject:
I am also in NH. My mpg drops to around 22 in winter (lowest 20) and normally around 25 in warm weather. Three factors to winter fuel use: Cold temps mean greater heat loss (diesels work via heat/pressure) Cold temps mean longer warm up to normal-effecient use of fuel Winter blend fuels have less BTUs than summer blend

Author:	cgoodspeed [ Fri Apr 20, 2007 11:56 am ]
Post subject:
WInter fuel has more of the "wax" taken out of the diesel, thus lowering the temp at which it solidifies. The wax has lots of BTUs, therefore winter fuel produces lower MPG. Given. My thought on the radiator shroud question is whether the cold air intake is the place that effects MPG, or is it more the amount of energy needed to simply keep the engine hot - i.e., the cooling system. You would think the thermostat would regulate the coolant sufficiently to prevent a drop in MPG- but I dunno. Charlie

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Author:	onthehunt [ Fri Apr 20, 2007 9:16 pm ]
Post subject:
Actually usld has more "wax" in it than lsd. I'll try to find the link, suprised me too.

Author:	CATCRD [ Fri Apr 20, 2007 10:26 pm ]
Post subject:
He said "winter fuel" not ulsd. My bet is the seasonal fuel and operation of the viscous coolant heater are the biggest winter mpg robbers.

Author:	onthehunt [ Fri Apr 20, 2007 11:38 pm ]
Post subject:
Quote: He said "winter fuel" not ulsd. My bet is the seasonal fuel and operation of the viscous coolant heater are the biggest winter mpg robbers My apologies. My bet is winter fuel and ambient air temps as the biggest mpg robbers.

Author:	RFCRD [ Sat Apr 21, 2007 8:42 am ]
Post subject:	Re: MPG & Ambient Temp.
cgoodspeed wrote: With temps finally climbing up in NH, the CRD's gas mileage is improving. I'm wondering if anyone uses a radiator block in the colder months, and if it improves MPG. I've monitored the winter/summer fuel blends and can factor that out for my miles per tank. Still, I am getting a 2-3 mpg better average when temps are above 45 deg. Can this be corrected by putting a damper in front of the radiator when it's cold out? Comments? Charlie. I used a series of blocker plates behind the grill part of last winter which made a noticable difference in warm-up time and maintaining engine & cabin temps in the extreme cold. I was seeing mileage jump into the low 20's (from the high teens). You have this pegged @ 45 deg which I believe is correct and the temp when I removed the plates (when I traded this Jeep for something that works). My experience with other diesels tells me DCX has this engine configured to run way too cold to deliver good fuel economy in air temps below freezing. I have also seen where it is possible to over-chill charged air in cold weather causing very dense charged air and too cold to maintain fuel efficient engine temps (which is why OTR buses have clutched fans & shutters over their CAC).

Author:	Gator4x [ Fri Apr 27, 2007 5:39 pm ]
Post subject:
One of the large reasons for decrease in fuel mileage in all vehicles-but especilly boxy vehicles like ours is that cold air is more dense. Denser air equates to more drag on a vehicle. As the ambient temps climb, the density of the air drops, and you have less wind resistance. This is a major factor for our vehicles, if not, THE biggest factor. So no, putting a peice of cardboard in front of your radiator won't help with that. It WILL help with your engine warming more quickly-thus acheiving peak effeciency from the combustion process. It will not increase your intake air temperature though-cold air means dense air means more fuel is needed to keep the A/F ratio at stoich. Try driving at higher altitudes in the winter. The air is less dense and you still get decent gas mileage. That's because there is less air resistance. later, Nick

Author:	oldnavy [ Fri Apr 27, 2007 8:10 pm ]
Post subject:
Gator4x wrote: Try driving at higher altitudes in the winter. The air is less dense and you still get decent gas mileage. That's because there is less air resistance. later, Nick Hahahaha, that is a good one, everyone move to the mountians in the winter. I need to mention that the CRD does not use gas and thus has NO gas mileage, we use diesel fuel, have no spark plugs and get fuel mileage.

Author:	BVCRD [ Sat Apr 28, 2007 7:22 am ]
Post subject:
oldnavy wrote: Gator4x wrote: Try driving at higher altitudes in the winter. The air is less dense and you still get decent gas mileage. That's because there is less air resistance. later, Nick Hahahaha, that is a good one, everyone move to the mountians in the winter. I need to mention that the CRD does not use gas and thus has NO gas mileage, we use diesel fuel, have no spark plugs and get fuel mileage. I'm already up here fellers. No improveent for me over what I have heard others say.

Author:	fatweasel [ Sat Apr 28, 2007 7:55 am ]
Post subject:
It should improve significantly on your way back down to sea level.

Author:	oldnavy [ Sat Apr 28, 2007 10:29 am ]
Post subject:
fatweasel wrote: It should improve significantly on your way back down to sea level. Nothing like the Georgia overdrive.

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Author:	CATCRD [ Sat Apr 28, 2007 2:34 pm ]
Post subject:
Gator4x wrote: One of the large reasons for decrease in fuel mileage in all vehicles-but especilly boxy vehicles like ours is that cold air is more dense. Denser air equates to more drag on a vehicle. As the ambient temps climb, the density of the air drops, and you have less wind resistance. This is a major factor for our vehicles, if not, THE biggest factor. So no, putting a peice of cardboard in front of your radiator won't help with that. It WILL help with your engine warming more quickly-thus acheiving peak effeciency from the combustion process. It will not increase your intake air temperature though-cold air means dense air means more fuel is needed to keep the A/F ratio at stoich. Try driving at higher altitudes in the winter. The air is less dense and you still get decent gas mileage. That's because there is less air resistance. later, Nick In our diesel engines, the ECU is not trying to maintain stoich fuel ratio. Blocking the rad also blocks the intercooler, so it will raise intake temps.