Block Heating in Winter

Block Heating warms up your vehicle faster, reduces fuel used on cold start, reduces the worst tailpipe emissions after engine startup, makes your engine last longer, and saves money, even after you pay for the electricity to run the block heater! They pre-heat engines in Formula 1 race cars, so you can too! 

Did you know that preheating your car engine with an engine block heater to 104 F (40 C) before starting it, dramatically reduces cold start wear on the engine, while also reducing cold start fuel consumption by allowing the engine to get to its full operating temperature faster. This works particularly well to prevent the engine block from freezing in vehicles parked outside during the winter. I got the idea from a PriusChat forum posting related to Hypermiling, or ways to further improve fuel economy.

Pre-Heating our 2nd Gen. Prius 

In our 2005 Prius I installed a 350w engine block heater that I purchased from a Toyota dealer in Canada, where this optional feature much more popular due to the very cold winter weather conditions in many parts of Canada. I leave the electrical connector cord sticking out of the front grille, connecting it to an outdoor electrical outlet via a 50 ft 12-3 extension cable, such that I take electrical energy from the deck outlet at our apartment, running it along the bushes on the side of the building & to the front of the car to connect the block heater to heat the engine. I do this for 3-5 or more hours before driving. 

Block Heating Energy Cost Analysis

Using $0.10-0.40 of electricity in the block heater reduces cold start gasoline consumption in the 04-09 Prius by about 30 oz during the transition from cold start to full 186 F ( 85.5C ) operating temperature, if the engine preheated to 104 F (40C) by electric block heating.  A gallon of gasoline, regular unleaded 87 octane sold at typical gas stations nearby costs around $5 USD2022. So $5 divided by 128oz then multiplied by 30oz, means $1.17 in gasoline saved by using $0.25 USD2022 of grid electricity, saving about $1 in fuel costs, while also allowing the car to warm up faster, reducing engine cold start wear, which is significant sin cold staring is where about 90% of engine wear occurs, since no oil film present when the engine first cranked to start it. 

Additional Benefits of Block Heating

The best part of pre-heating a vehicle engine, it improves air quality & public health by reducing cold start tail pipe emissions, which have the highest concentration of air pollutants, especially the neurologically toxic HC or hydrocarbon vapors, since the catalytic converter not working during the cold startup & the fuel system operate a rich mix to burn off in the cat to warm it up, all of which make the first few minutes of vehicle startup produce most of the vehicles toxic emissions, especially near your home. So block heating also improves health & wellness by reducing pollutants near your home. 

Extension Cord Block-Heating

The real cost, the labor to plug in the block heater extension cord. If you park inside a garage, you can use an outlet timer, such that you plug in the block heater when you done driving for the day, then have the timer set to start the block heater 3-5 hours before you leave for work. In cold locals & areas with cold winter conditions, this can dramatically improve vehicle warmup times, reduce exhaust emissions of toxic rich fuel mix tailpipe pollutants, reduce wear in your engine, makes your engine lubricating oil last longer, reduces friction in the engine, and helps with defrosting & deicing your vehicle. 

Thaw Out Your Car Faster when retiring to it after Skiing or Snowboarding

I have used a portable generator with the block heater, when snowboarding, so that I could defrost & deice & warm up my car faster to drive home. No one ever bothered the small relatively quiet Honda eco-setting EU2000, the extension cord; never unplugged it or turned off my generator, never stole anything. In testing, it took 15 minutes to remove the snow & defrost the windows without block heating, and about 8 minutes to do so with 5+ hours of block heating. So in addition to all the other benefits of block heating, it can save time too, time that you would have spent waiting for your car to warm up, to deice your car, to remove snow. Its good for your budget, good to save time, reduces engine wear & emissions, its all around better! Block heating an engine a great idea in cold weather! 

Preheating Expands Aluminum Engine

F1 engines are so tightly manufactured with the ultimate high precision that they have to be heated to above 154 F (67 C) before they can be started with an electric engine starter. This allows all the metals to expand to roughly their full temperature operating state. Nearly all metals & metal alloys & most other materials expand & contract when heater or cooled. 

Most passenger & main commercial vehicles feature an aluminum engine block that expands & contracts significantly with thermal cycling, such that the engine very tight when cool or cold, especially when frozen or very cold. As the engine heats up after startup, waste heat from the combustion of fuel heats the engine oil & coolant & exhaust system, all of which dump heat energy in various different forms into the engine bay & under the vehicle.

Engine Warmup Expansion & Oil Film Lubrication 

It can take anywhere from a few minutes to a few tens of minutes of idling after starting up a cold engine for a typically passenger car engine to achieve full operating temperatures, where the aluminum block & other aluminum engine parts in heat are fully expanded; which reduces wear by enabling a better oil film between the journal bearings & other frictional interfaces inside the engine, the head, the valve train, gearing, the crankshaft bearings, piston wrist pins, piston rings & cylinder wall interface & other surface metal to metal interfaces. 

Once the engine oil heated, the viscosity or thickness of the oil decreases, becoming thin & runny when warmed up, more like hot honey. At low temperatures engine oil is thicker like cold honey. The warmer oil lubricates the engine better by more easily forming the protective oil films that radically reduce metal on metal wear between engine components. 

Temperature Control in Electric Vehicles 

In electric vehicles, the batteries & electric motors & motor controllers operate best around room temperature. Freezing inhibits the battery current output & charging rates, while very high temperatures are bad for the motor magnets, bad for the life of the motor controller electronics, and bad for the battery, as lithium ion batteries fade or lose their ability to hold a charge faster at higher temperatures. This is why Tesla has electric warmers & cooling capacity in the battery energy storage systems of their exceptional electric passenger vehicles. 

This is also why common EV motors & controllers have a coolant system to take away waste heat or heat that would make the magnetic flux worse, cause the motor to lose its peak toque & peak power out in kw or horsepower faster, cause its magnets to loses their magnetic field strength faster, basically high temperatures cause electronics to fail faster too. This is why nearly all computer chips are equipped with a fan cooled heat sink, liquid cool or other thermal management such as spray cool with non-conductive fluids like dielectric cooling fluids or dielectric coolant that is electric insulating or that does not conduct electricity like normal water with some electrolyte or mineral content. It is true the ultra-pure water a poor conductor of electricity, but that can still short out sensitive computer electronics.