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mixu- · 05-31-2015, 06:31 PM

Where I'm from the summer mornings are pretty cool. Typically when I go to work I'd expect maybe 10C (50F) in the morning. I've noted that the small 1.3l engine of Honda Jazz takes about 1,5km (1 mile) to reach the level of "not-so-terrible" efficiency. During that distance it consumes twice the gas it usually does. I lose about 5l/100km worth of efficiency for that distance when the engine is cold.

So that got me thinking how to reduce that distance - to zero even? And now I have! This morning I plugged in the 550W block heater and had it on for about 2 hours. When I got in the car the engine coolant was already at toasty ~50C, instantly giving me good mileage.

Doing the math:
Electricity: 550W * 2h = 1,1kWh = 0,11 euros
Gasoline: 5l/100km * 1,5 km = 0,075l = 0,11 euros (1,5€/liter)

So in my case 2 hours is the break-even point. At 2 hours it doesn't really make a difference if I use electricity or gas to warm up the engine. More tests will follow to see if I can find an optimal time for pre-heating. There might be a sweet spot somewhere around 60-90 minutes? I'm also interested to see the impact at the fuel pump.

05-31-2015, 06:31 PM	#1 (permalink)
mixu- EcoModding Lurker Join Date: Mar 2015 Location: Finland Posts: 17 Jazz - '11 Honda Jazz Elegance Team Honda 90 day: 44.64 mpg (US) Thanks: 5 Thanked 16 Times in 9 Posts	Block heater in the summer time Where I'm from the summer mornings are pretty cool. Typically when I go to work I'd expect maybe 10C (50F) in the morning. I've noted that the small 1.3l engine of Honda Jazz takes about 1,5km (1 mile) to reach the level of "not-so-terrible" efficiency. During that distance it consumes twice the gas it usually does. I lose about 5l/100km worth of efficiency for that distance when the engine is cold. So that got me thinking how to reduce that distance - to zero even? And now I have! This morning I plugged in the 550W block heater and had it on for about 2 hours. When I got in the car the engine coolant was already at toasty ~50C, instantly giving me good mileage. Doing the math: Electricity: 550W * 2h = 1,1kWh = 0,11 euros Gasoline: 5l/100km * 1,5 km = 0,075l = 0,11 euros (1,5€/liter) So in my case 2 hours is the break-even point. At 2 hours it doesn't really make a difference if I use electricity or gas to warm up the engine. More tests will follow to see if I can find an optimal time for pre-heating. There might be a sweet spot somewhere around 60-90 minutes? I'm also interested to see the impact at the fuel pump.