On our recent flying vacation I decided we needed an engine heater, but with ten days of food and rum, and wine, and bourbon, plus a canteen of water in the plane, weight was a major concern. I came up with a pretty simple system which worked rather slick.
Now make no mistake, this is an engine heater for people who plan on wearing shorts most of the day, but who just doesn’t want to start a 30 or 40 degree engine early in the morning. It’s not Arctic quality. It could also burn your plane to the freaking ground, so don’t use it. The following information is for entertainment and novelty purposes only.
I decided to use my trusty MSR International Whisperlite stove as my heat source, since it’s what I cook with, but any gas stove would work fine, so long as it’s reliable. I experimented with several ways of getting the heat from the stove to the engine, and what I ended up with is two 4” multidirectional elbows and two pieces of 4” by 2.5’ rigid aluminum dryer vent. And some safety wire…gotta make it airplane grade, don’t you know.
The bottom multidirectional elbow is metal and the top one is aluminum. I place my stove at the front of the plane, and while I boil water for coffee I put the two pieces of rigid ducting together with an elbow on each end. When the coffee is done I simply put the metal elbow over the stove flame and run the ducting up into the engine cowling, safety-wiring it into position. The top elbow allows me to direct the hot air up under the cowling. By pointing the elbow away from sensitive items and wrapping a piece of fire shelter (read heavy aluminum foil) around the hoses and cables directly above the pipe, I avoid any hot spots. As a final touch I drilled a hole in the top elbow where I stick a probe thermometer.
With a medium power setting on the stove I get about 250 degrees out the top of the pipe, and I let it run while I’m striking camp and loading the plane. With a couple cowling plugs to keep the heat in, an hour of this brought my oil and cylinder head temps up twenty to twenty-five degrees. Again, it's not Arctic grade, but starting a 55 degree engine feels a lot better than starting a 30 degree engine…
Needless to say, there is potential for disasters both large and small with this system. I never leave it unattended, and I check the bottom of the cowling frequently to make sure nothing is getting too hot. I’ve been using the same Whisperlite stove for thirteen years, so I’m familiar with its habits and don’t worry about it gushing a big fountain of yellow flame up the pipe. This, more than anything else, strikes me as being key to success. I wouldn’t try this with a stove I was unfamiliar with. I keep a fire extinguisher close at hand just in case.
I was worried that the aluminum ducting wouldn’t hold up to the heat, but that’s been a non-issue. In fact, I’m not so sure I even needed a metal elbow sitting on the stove, as an aluminum one might hold up fine…have to experiment with that. When I’m done heating the engine I take the pieces apart, unsnap the the rigid ducting pieces and wrap it all together. The whole thing fits in the stuff sack for a folding chair and weights about two pounds.
There are undoubtedly better systems and better heat sources, but I didn’t want to carry anything extra. All in all I was quite happy with the results.
