The Elowitz Single Nostril Heater

These is a picture of a preheater built by Roger Elowitz. It was fashioned out of a ceramic heater, some flexible ducting and aluminium tape. The end if the ducting is placed in the air intake opening at the front of the cowl and the warm air is forced over the engine. 

I have used a similar heater to heat the interior of my aircraft quite successfully. My only caution  is that the power cord can be brittle at very cold temperatures (-10c and below).

The cowl blankets are essential as it forces the warm air to travel down around the engine and out through the bottom of the cowl. This ensures that all of the engine is warmed.

When the hot air is forced into one nostril, it will flow over the top of the engine and down the other side too if the second nostril is stuffed with towels or a blanket. Blowing into both nostrils is not really necessary.

Keep in mind that the engine is a large piece of metal and so it will take some time for the engine core to be warmed so allow plenty of time for preheating.

This is a picture of the "adapter" that goes over the ceramic heaterand connects it to the flexible ducting.