Insight Grill Block Thermodynamics

[jime57]

This time of year we are all thinking of grill blocks. Last year I blocked the entire top grill opening and about 90 % of the bottom on my gen 1 Insight. It worked well to promote aero and quick warm-ups, but now I am thinking it wasn't quite right.

The insight motor is so small and loses so much heat through the block that it will run most times in winter without ever opening the thermostat. It will run at 195F and the thermostat does not open until 204-206F. I run 206-208F in the "warmer" winter days with the current setup. It occurs to me that I am wasting energy by opening the thermostat when radiator cooling would actually be unnecessary if I found the correct amount of grill block.

I could enlarge my grill block opening to put the "warm" winter day temp at 204, just on the edge, and on cold days the thermostat would never open. What think ye thermodynamics experts?

[Cobb]

As a newer insight owner I am in a different boat, sort of. The t stat seems to open around 180, the electric fan kicks on at 205 and about 188+ the engine starts to retard timing and upping the cvt ratio.

Having said all that the more of the grill you block the better the mpg is and accleeration in the 60-70 range.

Having said that x2, I try to find a happy medium where the car doesnt run the radiator fan and the temp stays below 200 degrees under acceleration, merging onto the interstate, yet doesnt fall below 180 cruzing.

With that being said I find if I use the ac I block the upper grill and leave half the lower open. In the weather where it may reach a high of 60 with a low of 30 I block all but an inch by 3 and leave the heater on low. If the car gets warm inside Ill crack the window and leave the heat set at 85 degrees. Any more and it will not do the fuel cut off thing or enter ev mode under extreme light loads.

Running the half block of the lower grill I was seeing 175 the past week with this colder weather since the hurricane passed through.

[Phantom]

Originally Posted by jime57

It occurs to me that I am wasting energy by opening the thermostat when radiator cooling would actually be unnecessary if I found the correct amount of grill block.

I could enlarge my grill block opening to put the "warm" winter day temp at 204, just on the edge, and on cold days the thermostat would never open. What think ye thermodynamics experts?

I would not worry about having having the t-stat open as it takes no real energy to open and it will drop the temps down and close itself. When it is open it will lose some heat and warm up the radiator causing it to heat the air around the engine and it will give off heat longer after the engine is shut off due to the larger thermal mass that will be heated. Also there will be less drag with more blocked off saving energy.

If the fans are coming often or running for a long time then I would open it a bit.