Too Hot but Also Too Cold
 

I've been thinking about the mods I'm going to put on my car.

There's mods to retain heat so that the engine gets up to operating temp faster in the winter but some of those same mods result in the engine heating up too much in the summer.

What mods have y'all put on your car to help it heat up in the winter?

And what mods keep it cool in the summer?

I've found my vehicles have all continued to get better fuel economy the hotter they got. E.g. MPG numbers are better on a 95F day, than on an 80F day, even.

In winter, running a small block heater for 1-2 hours before leaving is cost effective.

It's easy to do a quickly removable (or adjustable) partial grille block using foam pipe insulation. If one day is a lot warmer than another, you can simply remove a section of the foam. On my Insight, I was able to run a 90% grille block in summer.

In winter, I also attached a piece of coroplast to block most of the opening from the wheel well to the engine bay. The primary purposes was to stop salt from being thrown all over, but it had the side benefit of also retaining heat.

I used to own a 1979 VW Dasher that had a longitudinal slant four with the radiator offset behind the left headlight, fed sideways from the center grille.

It came with OEM ducting that I can't find a picture of (:() that had a sliding section to block or unblock the air by lifting the hood and sliding it [the slider] sideways.

I like very powerful block heaters. You can run them for minutes and get the same effect as you can from a typical stock block heater.

2nd gen Toyota Priuseses... Prii, have a thermos that takes the coolant from the engine when you turn it off and then pumps that hot coolant back into the engine the next time you go to start your engine.

3rd gen Toyota Prii have an exhaust to coolant heat exchanger that has an exhaust valve that reroutes the exhaust away from the coolant once it gets up to temperature.

Another idea I've had is to put coolant lines under the dash and use it as a hot water solar panel ran by a small solar powered water pump. That way I can heat my engine and cool my dash at the same time when I have to park under the sun. Maybe not the greatest idea for winter, but nonetheless, better than nothing.

I was more looking at engine temps. Operating temp for my car is 192F, Low Fan Speed at 223F and High Fan Speed at 230F, people say that the coolant will boil at 260F. How hot should I let my engine get before taking action? And how does engine temp impact MPG?

I'm going to install an OEM Block heater before this winter so I'm all good on that front!

I currently have a Upper and Lower side grill block in place and the hottest my engine has been is 208F.

It'll really vary from engine to engine. In my last car, the thermostat started opening at 180F, was fully open at 192, the fan would come on at 200, and it would be "seriously overheating" at 220F. Anything above 200F and it would pull progressively more ignition timing.