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I was wondering if anyone as found a less expensive alternative to preheat the Jabiru engine that the kit that aircraft spruce sells.
I purchased a kat's silicone heater 150 watt. I was going to install it to warm up the oil. But I am concerned to install it because it seams to get really hot.
I would appreciate any input.
I would be reluctant to try that..... the silicone would be more of an insulator than heat conductor.
If you have power and are in a hangar, I like the Hornet aircraft engine heaters. They're thermostatically controlled and explosion-proof. They circulate warm air under the cowl, so the entire engine is warmed, and the battery, too, if you have it on the firewall. I just set mine up in the bottom of the cowl, put a blanket over the cowl, and plug the cooling intakes.
I'm in a moderate (East Tennessee) climate - not sure how well a Hornet would work in Canada!
i use a hairdryer, place it near the nose gear pointing up. 20 mins and the engine starts like its the middle of summer. I have tried other heater contraptions and this is the simplest and most cost effective i have found.
some times simple is better!
Not sure how cold it is where you are but I'd be nervous about doing that in freezing cold temps... 20 minutes will do nothing for the oil temp when it's -20c out... The oil will be cold! Sure fire disaster on the bearings and such!!!
I really like those heater pads from Spruce... the one I want is about 200$ but only weighs a few ounces. Since it's on the oil pan it gets the oil nice and warm, which is what you need. I'm debating on it still since I park my plane when the day time temps get to -5c or so, just too hard on everything to run it in those temps, at least for me up here.
I'm not a fan of continuous preheat systems unless you fly your plane a lot in the winter. I think you might promote corrosion in the engine if it just sits.
I use a milkhouse heater (walmart), a tin floor duct, some screws, a hose clamp and a length of heater vent. Stuff it in the cowl from below and let it run for 45-60 minutes while I go get coffee. An old sleeping bag wrapped around the cowling helps. Some guys get fancy and use timers or cell phone control but I'm seldom in that big a hurry.
I had a cousin who was an engineer and did commercial heat and air-handling systems for industry. He said to be cautious adapting small portable heaters (particularly cheap plastic-cased ones!) to pre-heaters by fabricating and attaching ducts to them. The fans on most small heaters were never meant to "push" or pressurize air so it will flow through ducts - they're intended for "free flow" with no back pressure. If the duct is too restrictive, it is possible for the fan to lug or stall and when that happens, the heater isn't adequately cooled and there is a risk of fire due overheating!
When adapting a heater, it is best to use an all-metal heater and ducting, and set it to one side of the cowl, not directly under it, so that in the event of a fire it doesn't burn the plane! Some heaters have an over-temp switch to shut them down if they overheat and of course, that would be preferable. Tim's set-up looks like a good design!
I had a "home-brew" system that I used for years, but now I use one of the Hornet heaters - thermostatically controlled, explosion proof, can't thermally run-away, and compact - I just set it in the lower cowl to keep the entire cowl, engine, and battery at a constant temperature.
John has made some good points. My heater is all metal with both a tip switch and a thermostat. Hopefully the use of the large plenum and 4 inch ducting does not excessively restrict the airflow from the heater. Since the photo was taken I've attached the heater to a piece of plywood that has four casters underneath.
Thank you for the reply guys.