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Old 05-23-2022, 07:29 AM   #8 (permalink)
Isaac Zachary
High Altitude Hybrid
Join Date: Dec 2020
Location: Gunnison, CO
Posts: 1,977

Avalon - '13 Toyota Avalon HV
90 day: 40.45 mpg (US)

Prius - '06 Toyota Prius
Thanks: 1,049
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I think it depends on the particular block heater. They all work, but the more the wattage the more heat you can get into the engine. In other words, if you run a 200W block heater for 2 hours you get 400Wh of heat, but the engine will be warmer if you run a 1,200W block heater for 20 minutes. It's still the same 400Wh of electricity you'll spend on, but the heat has less time to dissipate out of the engine.

Facing the sun helps. I have tried opening the hood so the sun heats it directly, but I don't know if that helps all that much and there's a chance the battery will be robbed, or maybe something else since my battery is in the trunk.

Also, if the interior gets really hot you could run the heater in recycle mode, especially if you have an electric heat pump since that can allow you to do this with the engine off. That way you add heat to the engine by passing the hot interior air through the heater core which then pumps the warmed coolant through the engine.

I don't think heated seats use all that much electricity. They might use only 40 or 50W. Of course we're talking summer now, but when winter comes heated seats are the way to go.

I never noticed much of a difference with blocking the grill, but I never was that scientific about it. I think maybe insulating the engine might be better. I think I'd like to use mineral wool as it's more flame resistant than fiber glass. Of course if you have an oil leak it will become a giant wick ready to be ignited.

I'd like to try an exhaust to coolant heat exchanger some day. One that goes on after the catalytic converter.

I love the idea of a giant thermos to put the coolant after a drive and then back into the engine before the next. Sadly, I don't get that warm of engine temps on my routes: I just got home from work with an engine temp of 104F.
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