Cool CHTs

[takair]

This is the opposite of the typical issue.  Not even sure if I want to call it a problem.  My '64 E has always run cool CHTs.  This is not an indication problem, as I have had it this way with two analyzers and the factory indication.  Now that we are living back in CT and doing winter flying I figured I should explore it.  In cruise, even at high power, and high EGT, with OAT near 0C, my CHTs are below the green (less than 300).  In climb, I barely break the green.  Today I climbed with the cowl flap closed and that got me 320 on the hottest.  In the summer...even in the south...I might get 330, but even then 2 cylinders would be below 300.  I have tried this at 100ROP, 50ROP, 25ROP, peak, and 25LOP.  Does not make a huge difference.  I checked cowl flap rigging today.  They call for 2" full open for 64.  Mine is actually closed a little from that, 1.5"... as called for later vintage Es.  Oil temp is good at an average of 180.

Questions:

1.  Anybody else have similar situation?

2. Would this affect oil burn or break in?  I have never gotten great oil consumption...5 hours/qt.  this is before and after OH over 500 hours ago.  My thinking is that the cylinder may not be at optimal operating temperature/shape.  Would I get better consumption running slightly warmer?

Thanks for any thoughts...

 

 

[rbridges]

I don't know if it affects break in, but as long as you're in the high 200's, you should be hot enough to boil off moisture and activate the lead scavenging agent in your fuel. 

[Ned Gravel]

10 hours ago, takair said:

1.  Anybody else have similar situation?

2. Would this affect oil burn or break in?  I have never gotten great oil consumption...5 hours/qt.  this is before and after OH over 500 hours ago.  My thinking is that the cylinder may not be at optimal operating temperature/shape.  Would I get better consumption running slightly warmer?

Thanks for any thoughts...

 

 

+ Since my doghouse was fixed, my engine operates pretty close to yours.  No worries for me.

The doghouse was repaired during my overhaul so I did the break in with it like yours.  Only needed about 10 hours, according to Clarence, switching from 75% to 65% an hour at a time.  WOT 2500 RPM below 5000' was the 75% recipe.  22" MAP, 2500 RPM below 5000' was the 65% recipe.  Worked OK.

As for oil consumption, how much do you keep in it? Apparently, Lycoming specifies a minimum requirement of 3 qts and my engine (IO-360-A1A) dumps everything beyond 6 qts overboard within about 4 hours, so I keep it between 5 and 6 gals.  8 hours per quart now.

[takair]

I keep between 5-6 qts.  The oil consumption has been consistent throughout the 18 years I have had the plane and before and after overhaul.  No other problems, but it bugs me that I can't get less oil consumption, so I thought maybe temp was a factor....sounds like it may not be directly linked.  I do tend to fly short trips and probably vaerage two take offs per hour flying.  I wonder if trip length plays into it.  I haven't done much cross country lately, but when I used to do long trips, I don't recall adding as much oil during the trips.   I may need to do one and see.  In the end, it may simply be the way my engine is broken in.

[Shadrach]

My F typically runs with 2 cyls (1 and 4) in the high 200s in cruise. My hottest in cruise is usually runs 330. I find that the spread tightens up LOP.

[Marauder]

I keep between 5-6 qts.  The oil consumption has been consistent throughout the 18 years I have had the plane and before and after overhaul.  No other problems, but it bugs me that I can't get less oil consumption, so I thought maybe temp was a factor....sounds like it may not be directly linked.  I do tend to fly short trips and probably vaerage two take offs per hour flying.  I wonder if trip length plays into it.  I haven't done much cross country lately, but when I used to do long trips, I don't recall adding as much oil during the trips.   I may need to do one and see.  In the end, it may simply be the way my engine is broken in.

When I am flying longer trips I see less oil "burn" than if I am doing more shorter hops. I often wondered in addition to the high power settings being more frequent on shorter trips, if the placement of the breather tube in the slipstream in more frequent climbs has anything to do with increased oil consumption.

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[Hank]

It seems to me that the 2700 RPM climbs to altitude happen more often with short trips, increasing your oil burn. On short hops, I'll generally fly 23/2300 at 3000 msl or so; on longish trips, I'll use 2500 at 8-10K, and I find the higher RPM generally increases oil consumption a little bit (either that, or the longer climbs).

How are ya'll burning less oil traveling? I have the opposite effect going on.

[Shadrach]

31 minutes ago, Hank said:

It seems to me that the 2700 RPM climbs to altitude happen more often with short trips, increasing your oil burn. On short hops, I'll generally fly 23/2300 at 3000 msl or so; on longish trips, I'll use 2500 at 8-10K, and I find the higher RPM generally increases oil consumption a little bit (either that, or the longer climbs).

How are ya'll burning less oil traveling? I have the opposite effect going on.

I don't burn less oil traveling, but I think my burn rate is less in cruise. It hard to tell. For mr the biggest factor on burn rate is age and time on the oil. I run 50hrs (+/- 5) intervals and the burn rate starts to increase a tad when the oil gets past 30hrs.

Edited January 31, 2016 by Shadrach

[takair]

I'm not really sure I burn more or less at any given time.  I do think you guys may be on to something with RPM.  I just hear about people getting 10 hours to a quart and get envious.  It's really not so much about the cost of oil...mainly curious.