A few weeks ago I fitted 3 lengths of pipe insulation to the lower grill (see previous post) however I hadn’t tried to test its effects. I also hadn’t tried the EBH to see the maximum heating I could get from it. Together, I saw something interesting.
The idea was to see the maximum temperature the block could reach at the maximum recommended time of 3 hours. The ambient temperature in the garage was about 5°c at the time. After 3 hours of warming, the coolant was at 45°c, an impressive result.
I started the car and made note of the coolant temp (45°c) and ambient temperature (10°c by this time). The engine ran for a few seconds (40°c is the lowest temperature where the engine will start-stop). The coolant temperature actually dropped from 45°c to 43°c in the first 300m. But once I drove 750m the coolant was 58°c and about 1 km into the journey it was 68°c. It would normally take me 3-4 km to reach 70°c, so that is a marked improvement.
Remember, the EBH is at the rear of the engine block whereas the coolant temperature sensor is near the thermostat housing at the front of the engine. Coolant won’t circulate without the pump running, so the sensor was picking up warmth from the block and coolant by conduction mostly.
Why did it drop? Coolant in the radiator would have been colder than coolant near the block. As the first coolant pumped through the thermostat it would have been cooler than the coolant it replaced.
Why did it rise so quickly? As the coolant circulated through the water jacket, it picked up the heat in the block. This is its job, after all. This spread the heat from the back of the block to reach the sensor at the front.
So, it also seems that the grill block is playing its part. The coolant gets warmer and stays warmer because it isn’t being cooled by incoming air.
How hot was the engine block after 3 hours of pre-heating? Hard to say without a non-contact thermometer and a bit of a reach.
(EDIT: My measurements were a bit short in the previous version.)