Stuff you can do to improve your winter mileage

[efusco]

1) Check your tire pressure...often. I run mine higher than most people, but lower than some. A safe and fairly comfortable target would be 44psi in the Front and 42psi in the rear. This will reduce your rolling resistance...I can feel when my tire pressure drops even 4 or 5 psi b/c of decreased glide distance.

2) Wear a coat, gloves, and maybe a hat (see #3 below)

3) Leave your heat set as follows:
a) Max Cool
b) A/C OFF
c) Auto OFF
d) Fan at lowest setting
*This is the same as the 'vent' setting you'd use in warmer weather.
Trust me here, in all but the coldest weather, esp. if you park in a garage, it takes a while for the temp to get that cold, and even if you have the heat on it takes a while to warm up. If you turn on the heat at all the electric heaters in the circuit come on and force the ICE to run more, drain for the electric heaters cause a hit, and the air circulating around the ICE keeps it cool longer making warm up take longer.
You can turn on the heat once you're warmed up.

4)Install an Engine Block Heater
Inarguably the single best thing you can do. Your ICE temp starts b/w 110F and 130F and takes far far less time to hit 157F (fully warmed up). That means you get to turn on the heat sooner. Obviously it can be hard to tell what your ICE temp is unless you have a Scan Gauge or some other means to monitor. But if you know what Stage IV is and you can get into Stage IV then you're fully warmed up.

5) Install Grill blocks
Using foam pipe insulation jammed into the grill slats, upper and lower, will reduce air flowing around the ICE. This is safe to do any time temps are below 50F outside...you can even do the upper at warmer temps than that. This really has a dramatic effect by keeping the ICE warmer while gliding/stealthing and allows for much faster warm up times...

6) Avoid Defrost
Pretty self explanatory, the defrosters put the fans on max, engage the AC, and cause a huge power drain while on. Clearly think safety first and use it as necessary, but leaving it on until the windows are crystal clear all around will take a huge hit to your FE. Following #1 above will often help you avoid the need for defrost. Scrape your windshield before starting the car to get rid of snow and ice. Use an anti-fog on the inside of the windshield to avoid minor fogging and reduce the need to use the defrosters.

*I'll add links and pics later if I remember to.
**Apparently great minds think alike. MSantos produced a brilliant article 3 days before I posted this one that also puts this one to shame...seriously. It's posted over at Cleanmpg.com and though I'm not one to advertise other sites, if one is seriously interested in all the things you can do to prepare for winter his is the article to go to...
http://www.cleanmpg.com/forums/showthread.php?t=17560

[john1701a]

If you have an aftermarket device, like ScanGauge, watch for 145°F.

When the coolant temperature drops below that, the engine will start back up. Until then, you can take advantage of the Max Hot setting with the blower on a low speed.

It's nice knowing exactly how much heat is still available when sitting there waiting for the stoplight to change.

.

[Stefx]

The EBH isn't very powerful at 400W.

Did anyone add a ~250W oil-pan pad heater to pre-warm the engine even more?

such as this one:

http://www.warehouseautoparts.com/Sp...pan_heater.htm

[Norm611]

Originally Posted by Stefx

The EBH isn't very powerful at 400W.

Did anyone add a ~250W oil-pan pad heater to pre-warm the engine even more?

such as this one:

http://www.warehouseautoparts.com/Sp...pan_heater.htm

The warehouseautoparts site indicates that the 100W heater should be used for oilpans with a capacity of 2-5 quarts. (the Prius takes 3.5 to 3.9 quarts). The 250W heater is recommended for oilpans in the 8-20 qt range.

Norm

[Stefx]

Originally Posted by Norm611

The warehouseautoparts site indicates that the 100W heater should be used for oilpans with a capacity of 2-5 quarts. (the Prius takes 3.5 to 3.9 quarts). The 250W heater is recommended for oilpans in the 8-20 qt range.

Norm

Good point, I didn't verify that.

[PaulHS]

This is one of those half-thought-out ideas so bear with me.

Has anyone considered mounting an electric ceramic heater between the grille and the radiator, connected to the same timer as the EBH? With grille-blocking, it should provide some general pre-warming to the coolant in the radiator as well as the engine compartment.

We've had a cold snap here in PA (morning temps around 26 degrees F) and I was disturbed to find my scangauge reading a low 85 degrees (normally closer to 120 degrees until now) when the ICE first powered up.

Any thoughts one way or the other?

[efusco]

Originally Posted by PaulHS

This is one of those half-thought-out ideas so bear with me.

Has anyone considered mounting an electric ceramic heater between the grille and the radiator, connected to the same timer as the EBH? With grille-blocking, it should provide some general pre-warming to the coolant in the radiator as well as the engine compartment.

We've had a cold snap here in PA (morning temps around 26 degrees F) and I was disturbed to find my scangauge reading a low 85 degrees (normally closer to 120 degrees until now) when the ICE first powered up.

Any thoughts one way or the other?

It would certainly help warm the engine compartment. I think the issue becomes how much energy are you going to use to save how much gas (aka energy)? IOW, will the ICE be that much warmer using another 600W+ energy.

What I have considered, but not yet had the guts to try to fabricate, is a small low wattage heater to put in the intake vent for the battery. Warming the battery, esp. keeping it above about 40F, seems to have distinct advantages in efficiency in really cold weather.

[PaulHS]

Originally Posted by efusco

It would certainly help warm the engine compartment. I think the issue becomes how much energy are you going to use to save how much gas (aka energy)? IOW, will the ICE be that much warmer using another 600W+ energy.

Although I don't make a lot of 30+ minute trips, I've noticed that when I do, there seems to be a slight boost in efficiency beyond the 30 minute mark. Without any empirical evidence, I've attributed that to the entire HSD reaching thermal equilibrium, as opposed to only certain components achieving a minimum level of efficiency. (This would be during mild to cool ambient temperatures.) So the theory is that warming the other components of the system would help simulate that 30 minute mark. ??? It may be well worth the energy cost.

What I have considered, but not yet had the guts to try to fabricate, is a small low wattage heater to put in the intake vent for the battery. Warming the battery, esp. keeping it above about 40F, seems to have distinct advantages in efficiency in really cold weather.

Interesting. Any idea how much benefit you might expect? How would you power your heater?

You have indirectly pointed out something I have misunderstood. It is very noticeable that in the winter months, the battery charges into the green much faster. I've been assuming that to indicate the same charge capacity as in warmer months. I see now that I was wrong. Obviously the battery holds less total charge when cold, just like most other batteries.

[ken1784]

Hello from Japan,
This is the first introduction on PriusChat forum which Japanese Prius drivers used since 2006.

Do you think we could improve our winter mileage to keep the engine coolant temperature higher than normal?
Do you think it is better to keep the engine room temperature higher than normal?
Have you ever felt the Prius engine is easy to be cooled down because of the engine-off coasting?

If you answered yes on one of these questions, you'll be a good candidate for the following modification.

The standard coolant thermostat opens at 82C(180F) and we see the nominal 88C(190F) coolant temperature after complete warming up.
There is a higher temperature thermostat which opens at 88C(190F) on the market and the nominal coolant temperature can be seen 6C(10F) higher than normal.
CAR-FLAP Thermostat WV56TA-88? - Yahoo! shopping
(Please note this internet shop is for Japanese customer only.)

edit: note that the gasket also needs to be replaced at same time.

Please refer to the attached chart for the coolant temperature graph.
The sky blue line is for the normal thermostat at 17C(63F) ambient temperature and the other lines are 88C thermostat used.

We see a few percent mileage improvement, but no ill effects can be seen even in hot summer for these two years.
Please install it at your own risk.

Enjoy your winter driving.
Ken@Japan

[ph43drus]

Thank you for this interesting idea and the supporting graph Ken!

For English speakers: I can't read Japanese, but I know a few characters. I believe the various lines on the graph are labeled something like:

Dark blue: Outside air temperature 4-6 centigrade, cloudy weather with snow
Green: Outside air temperature 10-13 centigrade, clear sky
Purple: Outside air temperature 6-7 centigrade, rain
Turquise: Outside air temperature 17 centigrade, clear sky, standard "samo"

"Samo" is written phonetically in way used for foreign words; I'm guessing there's no Japanese word for "thermostat", and this is more-or-less the sound of the English word (or the first two syllables, anyway).

The x-axis is labeled something like "time interval axis". I don't think the units have been specified. Y-axis is labeled water temperature.