Op temps during winter

[6182]

Looking for avg temps with/without blocking front vents. (Cape May winter) Have shown 190/210* recently during break-in with new cylinders at 80% Pwr with lean mix. Previously used to 150/160 and lower during most of the year, without blocking.

[a64pilot]

Which engine?
In. Fl Winter, say temps approaching freezing, if I block both the lower vents and the blast tube, I may see 150 or 160 or so, regardless of power setting
I’m a C-85 and don’t lean, which is why I asked which engine, particularly during break in, I wouldn’t lean.
Some will say but what about high altitude, and I’d answer that you avoid high altitude during the break in process, because you wants to keep it at or above 75% power, and just as a general statement for most all engines, don’t lean above 75% power.

[hotrodmac]

Looking for avg temps with/without blocking front vents. (Cape May winter) Have shown 190/210* recently during break-in with new cylinders at 80% Pwr with lean mix. Previously used to 150/160 and lower during most of the year, without blocking.

I'm in the Charlotte, NC area and I did some oil temp testing over last weekend. I have a C-85 with a little over 100 hrs since major and I struggle to get warm enough oil in the the winter. Last Sunday with the air temp in the high 40s, low 50s F, with the small cowl holes and blast tube taped over, and 2 inches of tape over the inboard end of both cylinder grills I almost got 150F oil temp on the gauge. Air temp at 3000 ft was around freezing. After I landed I pulled the tape off the cylinder grills, but left the smaller holes covered, and then repeated the flight. My oil temp never got above 125. I'm having a set of winterization covers built. I can't say I'm excited about flying around with the grills partially blocked since I don't have a CHT gauge, but It's the only thing I can think of to get reasonable winter Oil Temp. I don't know how the owners that get a real winter do it. Sorry for the fuzzy pic, it was a little bumpy out.

[6643]

It's OK to cover the inboard side of the grills, in front of the cylinder barrels; just don't cover the portion where the cylinder heads are.

I assume when you refer to the small holes you mean the two ovals under the prop opening.

Wag Aero sells the blanket for the oil tank. It's good for about 10 more degrees.

Have you calibrated the oil temperature gauge?

[hotrodmac]

John, I do mean the small ovals under the prop opening. The gauge was calibrated a little over 2 years ago when it was installed by the previous owner, I haven't checked it myself. Probably wouldn't hurt to do it though.

L.

[6182]

Info: Rebuilt c85-12f with new 0200 crank, rods Etc, new cylinders. No CHT. Just breaking in as per Millinium cyl info and forum advise. Initially flown for 2hrs with no vent/grill obstruction., never got above 165. Using mixture as per new MS carb. Recent flight, 30 deg day, 3500 ft, partially covered grills with hose sections allowing restricted air flow and covered the two round vents below. Leaned and temp went steadily to 200 and generally stayed there. Varied pwr 70 to 85%, rpm 2400 to 2500. Oil pressure 35-40. Just concerned, don't want to ruin the investment and hopefully the rings are seating correctly. Tks for input.

[6641]

My 46 also struggles to get good oil temperature (O-200). I keep the blast tube covered all year, the oval holes well into springtime and some tape over the grills below 40 OAT. I monitor CHT.
A friend has a 47 and has the opposite problem. I believe that the 46 cowling is too loose and Cessna tightened it up in 47.
It seems most of the complaints are 46 owner????

Joe

[6643]

My 46 with a C90 never has a problem running too hot, on the contrary, getting up to 180 degrees is usually difficult on anything other than a hot summer day. There's supposed to be a lip on the bottom of the cowl to increase the low pressure area and I don't think mine really meets the specs. I think the key is good seals around the cylinders and where the baffles meet the sides of the cowl. Oh, I also have the "summerization" kit.

[6182]

Finally (!!?) checked the POH from 1946, indicated a max temp of 225. I believe I got a little too close to that , 210, for comfort. I will remove the partial grill coverings during remainder of break in hours to be on the safe side.

[6863]

165 degrees oil temp after 30 minutes aloft, 30 F degrees OAT, oval nose bowl openings closed, cylinder head grills unrestricted open, blast tube blocked, C-90 with no oil tank blanket, 2300 RPM, toes toasty, nose cold but still having fun.