I think it is generally accepted that blocking the radiator helps cold weather mileage, at least for us mortal, non hypermilers.

Has anyone come up with a more elegant solution than shoving a piece of cardboard between the grille and radiator? I've noticed that commercial engines use a thermostatically operated shutter, but I've got to believe there is a way of adapting a common object to serve the function, especially if it can be easily reversed for a rare warm day.

Thanks in advance for any ideas.

 

I'm not so sure this is a good idea. The engine will theoretically warm up a bit quicker without air moving through the grill, but the thermostat will prevent flow to the radiator until the engine is at operating temperature. Once you reach operating temperature, the thermostat will keep the engine temperature constant. The only times I have seen this make a difference is with old cars (no fan clutch) and extended idling (traffic jams) in zero degree weather. In any normal condition, the engine temperature stays constant.

 

Ken, what you say makes sense, but I recall a number of posts last winter from people that were blocking the radiator with success. Could part of it be the cooling from the engine and trans surface directly to the air moving through the engine compartment? In my area large trucks and school buses regularly block the radiator, so it has to have an effect.

 

Thermostat controlled airflow (radiator dampers) are better than thermostat controlled waterflow. When the water flow is reduced, cooling water does not cool the block evenly, causing uneven wear. And other porblems if the engine design is poor. In the winter, there are cold spots where the water enters the cooling jacket. The higher the water flow, the less this is an issue. The good news? You shouldn't see this type of wear on modern engines until several hundred thousand miles.

Blocking the radiator will keep the thermostat further open, and that is good. I expect the engine will not cool as fast, either. That saves energy.

 

The thermostat is a 190'F one.
My car usually runs at below this, and my fans only
spin in summer. I don't think the thermostat even
plays a significant role in this car.

EV is possible when water temperatures are above
140'F. Thus, we need to invent ways to keep engine
water temperatures above 140'F whenever possible.
This is not easy when the engine runs for only 20 minutes
per hour of city driving!!!

The radiator block is mostly to prevent forced air
from travel speeds from cooling down the engine
compartment.
The thermostat is closed. The fans are not running.
But forced air will still cool down the engine, and
quite a bit really.

Without a radiator block, you loose 25% of your fuel
economy in below freezing winters. With a radiator
block, I see more like 10% less FE in winter.

To me, this is a gimmie. Free fuel back in my tank
for 5 minutes of effort.

You put the cardboard INSIDE the plastic trim, not
outside, which makes it invisible to passer-bys to
boot.

I bought some thin, clear plexiglas last winter to build a plastic shutter system, but the free, quick, easy cardboard worked so well, I never put the effort into making a "more elegant" system. I too worried about the occasional warm day, but even at 60'F I was fine last year. Of course I own a ScanGauge where I can constantly monitor temperatures, so I don't have to relay on the MIL ( Malfunction Indicator Lamps ) on the dash.

Just remember, this car has not two, but THREE radiators. One for engine water, one for electronics / transmission water, and one for A/C condenser.
With the radiator ASSEMBLY blocked, the A/C is most dramatically affected, but you shouldn't be using this in winter anyhow, but you may try it in a hot parked car on a 60'F day and get poor A/C results.

-John

 

Also you could blow the high pressure A/C safety plug and loose all your freon.

 

OK, I'm going to try to answer my own question.

The radiator is roughly 16" high by 25" wide. I cut two pieces of cardboard each 8" by 25". On one piece I attached a foot long length of 1/8" nylon cord to both two corners on one long side. I removed the two top attaching bolts from the grill and loosened the hood release lever enough to rotate the lever out of the way. With the grill loose, one can lower the cardboard pieces to the bottom of the radiator opening. I threaded the two ropes through an existing oval hole on each side at the top of the grille.

So the nominal operating position for cold weather is to have the bottom half covered by both 6" pieces (one behind the other). When it gets colder, I can just pull up the ropes and have the top half covered also. I think I'll get some of the those rope clinchers at REI like are used on ski jackets, etc. In the meantime, I'll just tie the ropes. When it warms up, just lower the ropes to uncover the top half. Next spring, I'll pull out both pieces.

I just used ordinary cardboard, I will have to see if it warps in the weather. If so, I'll go to some kind of plastic sheet.

 

Great information and description! I will definitely be borrowing your ideas. Being able to quickly and easily adapt to warmer weather is necessary in my area as it is common with our "Chinooks" to see temperature fluctuations of 20 degrees celcius in a matter of hours. Thanks!