John Haven asked: how do you guys recommend using the oil cooler door?  My plane is a IVP.  

 

John, I am no authority, but have been told by several knowledgeable people that the engine oil should run between 180-200 degrees during normal operation. 240 is max, and anything below 160 is too low—but not sure why the lower limit exists.

 

My engine typically runs very cold, so during the past winter, I have run with the knob full out (door to the oil cooler closed) during all operations except climb out. If I leave it closed for takeoff, the oil temp will typically slowly rise above 200 degrees after about 5 minutes of WOT operation. I try to catch it at 180 and just crack the door open a small amount to maintain 180 or so, then close it upon level off. At the power settings I’ve been running, the oil temp usually settles down around 160 on a cold day, to 180 on a moderate one.

 

During the summer, I take off with the oil door full open, and close it almost completely at level off to maintain 180-190 degrees.

 

My #2 CHT is affected less than 20 degrees by the position of the oil cooler door; typically about 10 degrees, so unless you’re operating with CHT’s above 420, I’d think the oil temp should be the governing factor. The problem is that you’ll probably see both high CHT and oil temp together on a hot day; especially during climb out. You can improve cylinder cooling a bit by turning on the boost pump to increase cooling fuel flow just a bit, but the most effective way to keep the engine cool is to lower the nose and increase the airspeed You can also reduce power, but this typically leans the mixture and significantly slows the climb. For these, and a couple other reasons, most folks I’ve met control engine temps with airspeed during climb.

Hope this helps!

Bob

N437RP