Engine Pre-Heater

  With Winter temperatures plummeting into the single digits, cold starts are especially brutal to the engine. The AeroVee uses pretty thick oil to begin with (20W-50), and chilled to temperatures below freezing it just about turns into playdough! Only after the engine has run for a bit does the oil heat up and begin to flow properly. This creates a situation where a cold (thus tight) engine has less than optimal lubrication when it needs it the most...after sitting all night (or week) and the oil has drained off everything!

To get around the playdough problem, and to ensure quicker starts in general, I constructed a simple engine pre-heater. All the materials were purchased at Lowe's and Wal-Mart for about $40, and it took about an hour to make. This thing really pumps out the hot air, too!

But the real question is, "Does it really make a difference?" The answer, is most definitely! The engine starts pretty well in temperatures over about 40 degrees. When the temperature is below that, engine starting can be more difficult. When the temperature is below about 20 degrees, starting can be downright frustrating, and may result in a dead battery before getting started. Using the pre-heater for approximately 30-60 minutes or until the oil temp reads around 50 degrees, or the EGT's reach about 20 deg. At this point, starting is effortless!

Doing some quick math, I figure that I will use the pre-heater approximately twice a month in the winter months, for 30-60 minutes per occasion (call it 45 minutes average). The heater draws 1500 watts for 45 minutes, so that's 1.1 KW-hr. At $0.10 per KW-hr, the pre-heater costs $0.11 per use. If I use the pre-heater for 5 years (30 uses total), that makes the total cost of construction and usage $43.30, or approximately $1.50 per use.

$1.50 per pre-heat. Is it worth it? You decide.

NOTE:  photos link to full size image

The first item is the heater unit itself. I tried a couple of different heaters, and the best was a low-cost ceramic element fan driven unit. I used a 1500 watt Lasko, Model 5420 ($20 from Wal-Mart). Stay away from "radiant" heaters, as the elements emit IR as they glow. IR is good for heating you all the way across the room, but lousy at heating the air itself, which is what you want. Additionally, you don't want a heater with "Safe Heat" or a tip over safety switch, as these safety features will cause the heater to keep shutting down on you.
The next items comprise the duct, or "snorkel". I used a 4" dryer vent hose, a 6"-to-4" reducer/expander, and a roll of foil-backed fiberglass pipe wrap insulation. The dryer vent hose is trimmed to a suitable length (the shorter the better to maximize heat going into the engine), taped onto the reducer using aluminum duct tape, then wrapped with the insulation and sealed up well with duct tape.
The snorkel is then taped to the heater with aluminum duct tape. The tape sticks well even when the heater is running and won't come loose. I left the top corners of the heater uncovered to ensure that air could still circulate through the heater.
The dryer vent hose is flattened slightly so that it can be slipped into the oil cooler inlet.
This directs the warm air against the oil sump to quickly heat the oil, and as the warm air rises through the engine is warms the cylinders and heads as well.
The whole this is simple and effective to use.


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Updated: 04 Jan 08