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Winterization mod to keep oil temps high

michjor

Member
My winter flying saga…….after the first winter season flying and summer at altitudes where OAT is 60F and below, I can never get my engine oil temps to desired working range 180F - 210F. When OAT was 35F and below never saw oil temp over 140F. My research over the summer on the forums to address the issue for my plane led me to some key concepts.
https://youtu.be/U4eGTEGOkRk
The video link is to one of my test flights using the 2" winterization plate, pulling data from the Dynon EFIS logs and displaying overlayed on the camera view so I could review the results in more detail after the flight.
1. Installed an adjustable OIL COOLER AIR SHUTTER - https://antisplataero.com/products/oil-cooler-air-shutter which only helps when OAT > 32F. Anything below, I fly up to 0F temps, the door does nothing to help
2. Checked the vernatherm is working OK
3. Tested covering the cowl inlets, first using painter's tape for correct position and width
4. Prototyped an aluminum rib for the cowl inlets to hold different width plates
5. Testing so far OAT variance: 1" plate for 45F - 60F, 2" plate for 32F - 60F, 2.5" plate for 20F - 32F. Not flown yet below 20F to do any testing
6. Vertical rib is attached to cowl with nut plates 1 x top and 2 x bottom (to prevent twisting sideways under wind pressure), easily removable
7. Winter weather is notorious for temperature inversions, so plates can be replaced quickly with prior flight planning or just land at next airport and change them out
8. The oil shutter door acts as a proxy cowl flap allowing me to adjust the temp range up and down by 20 degrees F when winterization plates are on
9. For comfort make sure the connections at the scat tube ends from outside air vents are sealed as they let in a lot of air - good for summer flying but not in winter.

Other items that make the extended flying season more pleasurable:
1. Cellular/LTE/4G Remote Power Control Switch - https://switcheon.com/
2. Engine Preheat System - https://www.reiffpreheat.com/
3. Bruce's Engine Cover - https://aircraftcovers.com
4. Lycoming winter recommendation is to idle engine between 1000 and 1200 rpm for ground operations by adding some throttle. Helps with oil circulation when engine temps are low. (Brake pads are cheaper than engine overhauls).
5. They also recommend on approach into airports to start 10 miles sooner and do a "power-on" descent to maintain higher CHT's.
6. Also every 30 minutes, in flight cycle the prop to push hot oil through the governor and nose prop.

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I went with a butterfly valve that gives practically infinite adjustments available year 'round.
Due to the location of the oil cooler intake and the physics of the airflow, it is interesting to watch how any change to the valve resulting in a temp change for the oil will have an almost equally opposite effect on the #6 cylinder head temp.
 
Oil shutter door

Michjor , you say the oil shutter doesn’t work for you under 32 degrees.. do you have the shutter door in front or on the back of your oil cooler? It seems to work much better on the front.
 
Oil airflow gate

This was my design and solution. Oil cooler is secured to the engine mount with three welded steel brackets. The intake air to the cooler is a 2 inch fitting from the back of the baffling. Oil cooler "box" is welded aluminum plate with an oil cooler "gate" to regulate outflow of air, controlled from a cockpit control.

One never knows how well something like this is going to work until it is flown. I had heard that RV-4s were difficult to keep cool so I designed an oil cooler gate that would keep the oil cool but be regulated. My findings of oil temperature were the opposite. The oil cooler gate worked very well but, below 60-70F OAT, the intake fitting from the baffling needs to be covered completely. Oddly enough, the gate still works to keep oil in the desired temperature range. Searching back in my logs the coldest flying temperature I found was 3C/37.4F with a consistent oil temperature of 140. A little lower than I would like but where the gate was wasn't noted in my travel log. I'll have to keep track of that in the future. I also have a smaller intake restrictor for higher temperatures.

Bottom line: oil cooler in this configuration works VERY well but is also easily regulated by both intake restriction and gate movement.

I have not restricted air flow to the cylinders but like the ideas presented in this post...... I need to experiment with a little duct tape.....:)
 

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Michjor , you say the oil shutter doesn’t work for you under 32 degrees.. do you have the shutter door in front or on the back of your oil cooler? It seems to work much better on the front.

My experience too. I was having almost the exact experience as OP, albeit in a -9A. I’m also in Minnesota, about 90 miles west of him. Blocking the back of the oil cooler only helped down to a point. I put an AntiSplat oil shutter between plenum and cooler, on a Bowden cable, and on the first 20 degree flight after installation this year I actually had to open the shutter a little when the oil temp got above 200.
 

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