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Buckaroo

Another oil temp question?

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2 hours ago, Mike Koerner said:

Wow Ed,

The top picture is fantastic. It brings back fond memories of a time when I was still immortal.

But you’re changing the subject.

 

Andy,

After thorough consideration, I think you’re right. The 220F maximum oil temperature I have held myself to is arbitrary. It’s probably slowed me down by perhaps 10-20 knots on perhaps 10 to 20% of the duration of maybe 10 to 20% of my flights (that’s 1/3 of a knot overall). Though sitting here now I don’t regret the needless added hours of flying enjoyment or the reduced fuel costs resulting from this unnecessary conservatism, these were times when I would have otherwise flown faster. And to be honest, every once in a while getting there quicker (like before dark) has been important.

So, from this moment forward, my new personal limitation is 230F.

This is not arbitrary. It is the upper limit of the “normal” temperature range as stated in my operator’s manual. I feel certain the engineers at Rotax did not set this value without careful consideration and analysis. To be sure, the engine will not suddenly fail if you operate it at higher temperatures; even right up to the maximum allowed temperature if you like. But in these engineers’ opinion, running at higher temperatures is abnormal. They would only have included this statement if they expected, or at least were concerned, that higher oil temperatures would result in abnormal wear or reduced reliability.

Mike Koerner

The green on my gauge goes to 235 and we all know green supersedes the OM.

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12 hours ago, procharger said:

No pic its the bracket that attaches the flat bar to the rubber mount to the

engine it has a 180 twist in it I just made one just like factory one just

longer and slotted so I could adjust it also had to loosen rad.hoses so

it can move not hard to do. Bottom left on rad. flat bar about 5 inches long

to the bolt on the side of engine  to motor mount bracket.

That's a good idea, I might try that.

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4 hours ago, Mike Koerner said:

Wow Ed,

The top picture is fantastic. It brings back fond memories of a time when I was still immortal.

But you’re changing the subject.

 

Andy,

After thorough consideration, I think you’re right. The 220F maximum oil temperature I have held myself to is arbitrary. It’s probably slowed me down by perhaps 10-20 knots on perhaps 10 to 20% of the duration of maybe 10 to 20% of my flights (that’s 1/3 of a knot overall). Though sitting here now I don’t regret the needless added hours of flying enjoyment or the reduced fuel costs resulting from this unnecessary conservatism, these were times when I would have otherwise flown faster. And to be honest, every once in a while getting there quicker (like before dark) has been important.

So, from this moment forward, my new personal limitation is 230F.

This is not arbitrary. It is the upper limit of the “normal” temperature range as stated in my operator’s manual. I feel certain the engineers at Rotax did not set this value without careful consideration and analysis. To be sure, the engine will not suddenly fail if you operate it at higher temperatures; even right up to the maximum allowed temperature if you like. But in these engineers’ opinion, running at higher temperatures is abnormal. They would only have included this statement if they expected, or at least were concerned, that higher oil temperatures would result in abnormal wear or reduced reliability.

Mike Koerner

That makes some sense.  I am not worried so much about the speed or time of flight aspect, but keeping to an artificially low temp can hamper climb, which to me is a safety issue.  The faster you can get higher, the safer you are, and if you have to climb over obstructions you want every fpm you can get.

Remember also that we're talking about limited times at the higher temps.  While 245°F does not concern me in a climb, if that was a constant temp in cruise I would want to land and investigate.  It's not uncommon to see 220°F in cruise here in Georgia, and at low level and 5400rpm cruise, I have seen almost 230°F on a hot day.  Not ideal, but also not damaging from what I have read. 

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3 minutes ago, FlyingMonkey said:

Remember also that we're talking about limited times at the higher temps.  While 245°F does not concern me in a climb, if that was a constant temp in cruise I would want to land and investigate.  It's not uncommon to see 220°F in cruise here in Georgia, and at low level and 5400rpm cruise, I have seen almost 230°F on a hot day.  Not ideal, but also not damaging from what I have read. 

No matter how high my oil temp gets on my climb once I'm level it always settles at 235*F (I always fly WOT).  True unless ambient is 70*F or hotter then I even cruise in the yellow but that is rare.

All strategies to date have had only limited success and the only one that makes sense now 12 years later is to climb at best rate with reflex flaps looking for < 70 at my cruise altitude, then all is good.  I only have to worry about redline / 266*F if I'm climbing away from 100F+ on the ground.  Most of my summer climbs top out around 250. 

In the end I rely on the Rotax recommendation that we not run in the yellow most of the time.  Cruise and Descents I do in the green 95% of the time.

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58 minutes ago, Ed Cesnalis said:

No matter how high my oil temp gets on my climb once I'm level it always settles at 235*F (I always fly WOT).  True unless ambient is 70*F or hotter then I even cruise in the yellow but that is rare.

All strategies to date have had only limited success and the only one that makes sense now 12 years later is to climb at best rate with reflex flaps looking for < 70 at my cruise altitude, then all is good.  I only have to worry about redline / 266*F if I'm climbing away from 100F+ on the ground.  Most of my summer climbs top out around 250. 

In the end I rely on the Rotax recommendation that we not run in the yellow most of the time.  Cruise and Descents I do in the green 95% of the time.

You have things working against you for sure.  You have leaner operation (you changed your needle setting, right?) which will increase temps.  And you have less dense air, which means less air flowing over the oil cooler for a given speed.  I think you are right to accept that your temps will be higher than most, as long as they stay within limits.

I usually see 220°F in cruise on a hot day, but in the cooler months it's not uncommon to see temps under 200°F, and when it's cold out I sometimes struggle to get temps over 180°F, even using tape.  I remember one *really* cold day where I could not get the oil over about 160°F, even with the radiator about 75% taped.  The problem at that point is that with too much tape your CHTs start getting too high, so you have to walk a tightrope...

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New member and CTLSi owner here. This is a topic that has me scratching my head as well.

I come from flying an Aerotrek A240 with the 912 ULS that had a cockpit-adjustable oil cooler inlet with which I could control the oil temp very precisely.  Even on hot days, my oil would never reach the higher temps I'm seeing on the CTLSi. I gotta say, it's a bit unnerving to see the higher temps (230-255) and not have any control over it. Otherwise, what a fantastic airplane!

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Oil temps can vary from plane to plane depending on aircraft design. Seeing an oil temp up to 250F can happen. Seeing them up around 230F - 245F on a summer day during take off can be very normal and nothing to worry about. In normal level cruise (5100 - 5300 rpm) you would expect to see 215F - 225F during the hot months depending on OAT's.

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