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How to keep engine warm when flying in winter

hoyden

Well Known Member
As winter settles in I'm having a hard time keeping my CHTs and oil temps at the desired temperatures. I installed the Anti-Splat-Aero oil cooler shutter on the firewall side and that helps bring the oil temp above 150F. My CHTs are running between 250-300F.

I am flying an RV-6 with IO-360 and CS prop. I typically fly very LOP, or at peak EGT with power levels between 30-40% except for WOT takeoff to cruise altitude (typically less than 2K AGL). This is flying around the patch missions.

I am considering installing some sort of plate to reduce the cowl opening area. Before starting a science fair experiment I wanted to ask how others keep their temps up on cold days.
 
As winter settles in I'm having a hard time keeping my CHTs and oil temps at the desired temperatures. I installed the Anti-Splat-Aero oil cooler shutter on the firewall side and that helps bring the oil temp above 150F. My CHTs are running between 250-300F.

I am flying an RV-6 with IO-360 and CS prop. I typically fly very LOP, or at peak EGT with power levels between 30-40% except for WOT takeoff to cruise altitude (typically less than 2K AGL). This is flying around the patch missions.

I am considering installing some sort of plate to reduce the cowl opening area. Before starting a science fair experiment I wanted to ask how others keep their temps up on cold days.


I’m heading out flying today if it isn’t too cold. It’s now minus 26 Celsius here and if it gets a few degrees warmer I’ll go flying.
I’ll take note of my temps and my flying profile during stages of the flight. I’ll let you know my observations.
 
Lyc recommends OT no lower than 160. Not sure how big of a deal it is to run at 140 or 150. I suspect that the only issue, assuming a 20w50 oil is used, is that moisture removal from the oil is slower at lower temps. Both of my planes run in the 160 range in the winter months. Doesn't concern me. I know the oil gets less viscous as the temps rise, so it is possible that Lyc thinks that puts more strain on the oil pump. It is likely that they have a good reason for setting this recommendation and therefore good to take steps to get your temps there or close to it. Also possible that it is an issue like running LOP, where they recommend against it, not because it is bad per se, but because of other reasons. I think by now it is safe to say that running LOP on a Lycoming is not bad for the engine, yet they still recommend against it.

I fly a good amount in the winter and often see CHTs in the upper 200's. Too me, this is good not bad, I don't know the low end limit for CHT's, but suspect it is well below 250 and that would be for engine performance, not potential damage or wear. If it were of concern for engine longevity, I am confident that a low end recommendation would be found in the Operators manual, just like the low end for OT. There is no reference.

For decades, planes didn't have CHT instruments. Things seemed to work fine in all different climates.

Larry
 
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Hoyden:

Here in the south part of BC (Okanagan Valley), we have pretty reasonable winter temperatures, -5C to -15C on ground.

I have a manufactured 'flapper' on the aft side of the oil cooler and will put a strip of 'gun tape' on the forward side if temperatures dictate.


I put overlapped strips of 'gun tape' on the cowling intakes as required: two initially; more as the season progresses and the temperatures fall.


Cruising at 2300-2400 RPM (FP), I see CHTs of 350 and OTs of 170-180.

Replace the gun tape on the cowl every 3 - 4 weeks; if not, the glue will bake on the cowl and be a bear to get off...
 
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I'm no mechanic, but I watch a lot of Mike Busch's webinars. (I think everyone knows who he is). Anyway, I "think"? he said, don't run your CHT's below 350*. Reason----lead deposits start to form on your valves, and particularly, the exhaust valve, which of course is not good.
I've got one cylinder running about 320*, and don't know how to get it higher---forget now which one it is til I fly again.
 
I'm no mechanic, but I watch a lot of Mike Busch's webinars. (I think everyone knows who he is). Anyway, I "think"? he said, don't run your CHT's below 350*. Reason----lead deposits start to form on your valves, and particularly, the exhaust valve, which of course is not good.
I've got one cylinder running about 320*, and don't know how to get it higher---forget now which one it is til I fly again.

I have 800 hours on my 320 in the 6. I fly a lot in the winter with CHTs from 275-325. Checked the exh valves a few hours ago and zero lead deposits on the valves. Need to be cautious with some of Mike's guidance, as it appears to be spit balling and non-fact based assumptions or at least generalization. Lead deposits are all about the combustion and exhaust temps, as well as valve stem temps which don't necessarilly correlate directly with CHTs, as they can have wide swings with the same combustion temps due to air temp and volume / velocity over the fins,

Larry
 
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I've heard similar; don't run with CHTs below 350. OTOH, I subscribe to Savvy's analysis program and at every update I get kudos for my CHTs:

"Outstanding! The maximum CHTs attained during your flights has been exceptionally low, with a median lower than 80% of the cohort. We think you can expect above-average longevity of your cylinders if you continue operating with your current power settings. Keep doing what you're doing!"

The analysis compares 61 flights between Nov 12, 2020 and Nov 12, 2021, compared with 956 flights by a cohort of 34 RV-6 aircraft.

As a Hail Mary to lead fouling valve stems I run at peak EGT (35% power, 19" map, 1900 rpm) which typically is around 1300. I've run at extreme LOP and low power for more than 5 years. When I'm flying around the patch (southern MN) I'm never in a hurry so I putter along at 100 kts.

One reason for starting to build an RV-9 after flying my RV-6 for more than 20 years is to reap some benefit from the bigger wing and willing to sacrifice some performance for better low and slow flying. Plus I want to build an RV-9 now that I have the space and I want a slider this time.

It's a mystery.
 
I'm no mechanic, but I watch a lot of Mike Busch's webinars. (I think everyone knows who he is). Anyway, I "think"? he said, don't run your CHT's below 350*. Reason----lead deposits start to form on your valves, and particularly, the exhaust valve, which of course is not good.
I've got one cylinder running about 320*, and don't know how to get it higher---forget now which one it is til I fly again.

I love Mike Busch...he has done a lot to advance aviation maintenance and safety, but one needs to take his guidance in context. Maintaining a range of 350-400 in a lyc is impossible in all flight regimes.

Within the greater scope of safety...
  • In the pattern, fly the airplane. Knowing the health of your engine is great, but there's too much variability in power to focus on temps. If the airplane is producing normal power...fly it.
  • OP mentioned flying very lean...if you're lean, and producing much less than rated power, there's less fuel to generate heat. I fly very lean also, and because I'm not producing much power, my temps are usually between 280-300. Well within Lycoming's recommendations. The lower fuel flow also means less lead for the potential to cause valve deposits. I think we're better served looking outside, commanding our craft and mitigating the valves issues through other means.

I'm in the same camp as Larry...you're ok with those temps.
 
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I love Mike Busch...he has done a lot to advance aviation maintenance and safety, but one needs to take his guidance in context. Maintaining a range of 350-400 in a lyc is impossible in all flight regimes.

...

I also wonder if he would change his guidance if running unleaded, since the reason for the higher temps is to avoid lead deposits.
 
If you guys really want to go down the rabbit hole a bit here read the last 3 pages of this thread. I emailed Mike Busch about this topic and multiple emails were received from Mike and Ed Kollins (the gent that Mike formulated his theory on; or somewhat copied it anyways...).
 
Hoyden:

Here in the south part of BC (Okanagan Valley), we have pretty reasonable winter temperatures, -5C to -15C on ground.

I have a manufactured 'flapper' on the aft side of the oil cooler and will put a strip of 'gun tape' on the forward side if temperatures dictate.


I put overlapped strips of 'gun ape' on the cowling intakes as required: two initially; more as the season progresses and the temperatures fall.


Cruising at 2300-2400 RPM (FP), I see CHTs of 350 and OTs of 170-180.

Replace the gun tape on the cowl every 3 - 4 weeks; if not, the glue will bake on the cowl and be a bear to get off...

I think the tape over the Cowl intake is a great idea, but aren’t you at least a little worried that the tape could end up inside the cowl?
Do you have a picture of this? Now that you’ve brought it up I think I might do this as well, seems simple enough, haha. What is there that can’t be fixed with a bit of duct tape these days!
 
Mike Busch just put out a webinar last week on YouTube called "How Hot is too Hot". You might find some information in there that pertains to the colder temps.

https://www.youtube.com/watch?v=df1DwFNYFLs

I'm sure he has more data about more engines than anyone in the world. This peak CHT graph is interesting when you compare to the data that generated it.

Below I have a slide from the YT video, and my data for a recent flight.

Savvy CHT Max Temp Distribution 2021-11.png

CHT HB-YMM 2021-11-07.png

My data on Mike's graph would be at 350, when most of my flying is far below that. So far, I've only been able to find the "lead scavenging" reason for keeping the CHTs over 350°F so if you run unleaded, does that mean that there is no lower CHT number?

Based on what I'm reading, it looks like there are several things that are important for colder weather operations and my questions about a solution that does not require higher heat:

  1. Remove the water from the oil - engine dryer?
  2. Ensure that the oil will flow - multigrade oil like 15w-50?
  3. Encourage lead scavenging - run fuel with no lead?
 
Mickey:

usually my CHT's run much cooler than 350 F and i investigated if that could be a problem. i use 100 LL in one tank only for takeoff/climb/landing, so most time the engine consumes unleaded fuel from the other tank.

my non-expert-conclusion on using mogas is: no tetraethyl lead = no ethylene dibromide = no lead-2-bromide = no problem (if there was any problem in first place).

i consider CHT's around 300 F to be a good thing and sleep well.
 
I built an "anti cowl flap" about 11 inches from the rear of the cowl scoop forward, 4" wide at the leading edge, 9" wide at the outlet, with sides like a sugar scoop. The tapered flap lessens turbulent airflow at the forward end, no need for vortex generator, when closed and flush against the bottom skin (slight bend on the trailing edge for closure) there is less noise, vibration, and a bit of speed increase. I used a cable on one aircraft, now use an electric servo on the current aircraft, cheap, easy, and effective.
DAR Gary
 
Did you say firewall side?

It would be easier just to install the shutter on the cold side of the oil cooler and not the hot side. Much more effective on the air inlet side of the HX and should completely solve your oil temp issue.
 
dave_091

I don't have a picture but the duct tape is placed vertically between the upper and lower cowls. I've found that a couple of inches on either half is sufficient. In six years, there's never been any 'loosening' or loss of tape...
 
Based on what I'm reading, it looks like there are several things that are important for colder weather operations and my questions about a solution that does not require higher heat:

  1. Remove the water from the oil - engine dryer?
  2. Ensure that the oil will flow - multigrade oil like 15w-50?
  3. Encourage lead scavenging - run fuel with no lead?

Engine dryer will not remove water from oil. Water is heavier than oil, and therefore settles down when not being pumped (mixed) with the oil.
 
Firewall side seemed easier but I wondered if it would make a difference. I may put some aluminum tape on engine side to block it off and see how that affects temperature.
 
Firewall side seemed easier but I wondered if it would make a difference. I may put some aluminum tape on engine side to block it off and see how that affects temperature.

Good idea, I have no issues down to -10F or so maybe below that, I just don't remember. Mine will stay on the vernatherm and 180F at those temps. My friend had his shutter on the back and had to tape his front side in winter. We regularly get -10F and sometimes -20F
 
Engine dryer will not remove water from oil. Water is heavier than oil, and therefore settles down when not being pumped (mixed) with the oil.

I believe the concern is water's escape from emulsification through thermal cycles and thus internal corrosion once parts loose their oil film from inactivity. In that case, the dryer would do the trick.

Anyways...I commonly fly at the same temps of the OP, and water never shows up in my oil analysis, so I think it's a moot point.
 
Heh, Galin! It's easier for me to stay warm in the winter than cool in the summer. I grew up in the south and migrated north after leaving school. The plane deals with the warmer weather better than the pilot.

I'm going to try tape across the cowl inlet using a triple-thick 2" wide layer of blue painters tape. I used 200 mph duct tape years ago and the residue is still on my gear leg fairing.
 
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Lyc recommends OT no lower than 160. Not sure how big of a deal it is to run at 140 or 150. I suspect that the only issue, assuming a 20w50 oil is used, is that moisture removal from the oil is slower at lower temps. Both of my planes run in the 160 range in the winter months. Doesn't concern me. I know the oil gets less viscous as the temps rise, so it is possible that Lyc thinks that puts more strain on the oil pump. It is likely that they have a good reason for setting this recommendation and therefore good to take steps to get your temps there or close to it. Also possible that it is an issue like running LOP, where they recommend against it, not because it is bad per se, but because of other reasons. I think by now it is safe to say that running LOP on a Lycoming is not bad for the engine, yet they still recommend against it.

I fly a good amount in the winter and often see CHTs in the upper 200's. Too me, this is good not bad, I don't know the low end limit for CHT's, but suspect it is well below 250 and that would be for engine performance, not potential damage or wear. If it were of concern for engine longevity, I am confident that a low end recommendation would be found in the Operators manual, just like the low end for OT. There is no reference.

For decades, planes didn't have CHT instruments. Things seemed to work fine in all different climates.

Larry

I know several cases where guys had stuck valves. The engines shook like crazy and lost power and scared the **** out them. They had to do the rooe trick and clean the valve stems, and in some cases their shorts. So I’m not sure that things worked fine. The claim is being made by Mike Busche, based on some evidence, that low chts can contribute to deposits on the valve stems that can lead to sticking valves. I hav’t seen any hard evidence that this is not the case. Just opinions.
 
I see two issues: running LOP and fuel mixture. I've had low CHTs ever since I learned how to run LOP from John Deakin's "Mixture Magic" Pelican's Perch article. That was about 21 years ago.

I remember reading John's article when I was still flying a C-150. I understood the limits of the red knob with a carburetor. When I bought Athena (RV-6, CS, FI) from Teri Jantzi in 2020 I already knew I had new red knob options.

I wonder what role, if any, mixture plays. My Savvy analysis never dings me for low CHTs, and as previously noted, gets high praise. I borescope the cylinders and valves at each annual and so far I have not seen any bad news.
 
I've heard similar; don't run with CHTs below 350. OTOH, I subscribe to Savvy's analysis program and at every update I get kudos for my CHTs:

"Outstanding! The maximum CHTs attained during your flights has been exceptionally low, with a median lower than 80% of the cohort. We think you can expect above-average longevity of your cylinders if you continue operating with your current power settings. Keep doing what you're doing!"

The analysis compares 61 flights between Nov 12, 2020 and Nov 12, 2021, compared with 956 flights by a cohort of 34 RV-6 aircraft.

As a Hail Mary to lead fouling valve stems I run at peak EGT (35% power, 19" map, 1900 rpm) which typically is around 1300. I've run at extreme LOP and low power for more than 5 years. When I'm flying around the patch (southern MN) I'm never in a hurry so I putter along at 100 kts.

One reason for starting to build an RV-9 after flying my RV-6 for more than 20 years is to reap some benefit from the bigger wing and willing to sacrifice some performance for better low and slow flying. Plus I want to build an RV-9 now that I have the space and I want a slider this time.

It's a mystery.

What would your low side CHT's be?
 
I know several cases where guys had stuck valves. The engines shook like crazy and lost power and scared the **** out them. They had to do the rooe trick and clean the valve stems, and in some cases their shorts. So I’m not sure that things worked fine. The claim is being made by Mike Busche, based on some evidence, that low chts can contribute to deposits on the valve stems that can lead to sticking valves. I hav’t seen any hard evidence that this is not the case. Just opinions.

I believe there are many variables that impact build up on the exhaust valves. In fact, there is still argument about what the build up is (I still believe it is carbon from oxidized oil, others think lead, maybe it's both - I know it is jet black in color, so it cannot be pure lead - Would be interesting if we knew whether or not stuck valves have occurred on engines running Mogas). There seem to be plenty of folks that rarely go below 350 and still get deposits on the guide. Untill someone does the research around this, the anecdotal evidence is just too variable to make the kind of claims that Mike is making. I only posted my anecdotal evidence to show that Mike's claim is not universal.

Also, every engine experiences periods of low CHTs. Warm up, Run up, taxi, decsents, time in the pattern, etc. How do you factor that in or out? Still unclear whether it takes minutes, hours or hundreds of hours for the build up to occur, because we still don't fully understand why it is happening. It could be a little build up occurs within a few minutes, hundreds of times or it could be a very small incremental build up gradually over hundreds of hours. How do we know it is not from time spent above 400, for example, as many planes seeing 300 in the winter, also see 400+ during climbs in the summer.

Untill we understand exactly what variables (environmental, chemical and mechanical) must be in place for deposits to occur, it seems we will be guessing on ways to prevent it.

Larry
 
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Went flying yesterday with temps on the ground 15F and 5-7F at 2.5k agl. With 2" painters tape across cowl inlets the CHTs were 270-280F. Oil cooler blocked with aluminum foil tape on front side except for 2"x2" opening, and on back side by shutter. Oil temps typical struggling to stay above 150F.

The 2" painters tape was a success. I would like to see how the tape affects CHTs in warmer temps. If the temps are like yesterday I'll add another 1" to each cowl inlet make the tape dam 3" wide.
 
I am surprised that the painters tape held up. Is there a reason you didn’t use duct tape or another stronger tape? Any gunk left from the tape would be easily cleaned.

How are your exhaust temps? Those are what get hot on mine and I have to pay attention to keep them under 1400 over 2300 rpm.
 
Everything I've read says to basically ignore the absolute EGT number, but use them to find peaks.

https://resources.savvyaviation.com...ticles_eaa/EAA_2010-10_egt-myths-debunked.pdf

I don't agree with that. Watching EGT's is important for monitoring engine health. for example, the quickest way to identify a mag or EI failure is to observe a 100-150* rise in EGT. How would you know that if you completely ignored absolute EGT temps. changes from normal EGT (normal being relative to a given ambient temp, advance and mixture) can also point to other engine issues, like exh valve problems and ignition timing drift.

Larry
 
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I don't agree with that. Watching EGT's is important for monitoring engine health. for example, the quickest way to identify a mag failure is to observe a 100-150* rise in EGT. How would you know that if you completely ignored absolute EGT temps. changes from normal EGT can also point to other engine issues, like exh valve problems and ignition timing drift.

Larry

I think what Mickey is trying to convey is that many people try and keep them below some arbitrary number which most agree isn't necessary. As you suggest, they are still great for troubleshooting. In other words, if your EGTs show low 1400s at a power setting you like there is no reason to try and bring them under 1400.
 
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I think what Mickey is trying to convey is that many people try and keep them below some arbitrary number which most agree isn't necessary. As you suggest, they are still great for troubleshooting. In other words, if your EGTs show low 1400s at a power setting you like there is no reason to try and bring them under 1400.

Exactly - you explained it better than I did. :)
 
I chose the painters tape to avoid the residue left over from duct tape. I still have residue from when I used duct tape to hold down a gear leg fairing from 10 years ago.

Three layers of painters tape is holding up well. Today's OAT at 2.5K AGL was 19F. Cruising at 35% power I had CHTs 280-300F; a little warmer from yesterday. Oil temps were 160 in cruise and up to 180 after takeoff and leveling out. I like 2K VSI on these cold days plus no bugs to clean off.

My EGTs are consistent at 1300F.
 
I chose the painters tape to avoid the residue left over from duct tape. I still have residue from when I used duct tape to hold down a gear leg fairing from 10 years ago.

Three layers of painters tape is holding up well. Today's OAT at 2.5K AGL was 19F. Cruising at 35% power I had CHTs 280-300F; a little warmer from yesterday. Oil temps were 160 in cruise and up to 180 after takeoff and leveling out. I like 2K VSI on these cold days plus no bugs to clean off.

My EGTs are consistent at 1300F.

Thanks for the info. Im glad the painters tape is working - it sure is easier to get off. I taped my ridder to the Vert stabilizer one time while parked and had quite a bit of tape gunk left behind. It came off OK but wasnt fun!

My cylinder temps are all OK and below 400 even in climb so I guess Im ok. I mostly used the exhaust temps to lien when they were below 1380.

There is so much to learn!
 
I chose the painters tape to avoid the residue left over from duct tape. I still have residue from when I used duct tape to hold down a gear leg fairing from 10 years ago.

Three layers of painters tape is holding up well. Today's OAT at 2.5K AGL was 19F. Cruising at 35% power I had CHTs 280-300F; a little warmer from yesterday. Oil temps were 160 in cruise and up to 180 after takeoff and leveling out. I like 2K VSI on these cold days plus no bugs to clean off.

My EGTs are consistent at 1300F.

Do you have a picture of your tape set up?
 
Do you have a picture of your tape set up?

I don't but it's really simple. I placed a vertical piece of 2" tape centered in the cowl opening and extending about 3" on to the upper and lower cowl. I put 3 layers on top of each other. After two flights (about 3 hours total time) the tape shows no signs of deterioration.

Next time I will pay attention to the threads that detail how to post pictures.
 
I don't but it's really simple. I placed a vertical piece of 2" tape centered in the cowl opening and extending about 3" on to the upper and lower cowl. I put 3 layers on top of each other. After two flights (about 3 hours total time) the tape shows no signs of deterioration.

Next time I will pay attention to the threads that detail how to post pictures.

Got it thanks, what aircraft/engine?
 
I don't but it's really simple. I placed a vertical piece of 2" tape centered in the cowl opening and extending about 3" on to the upper and lower cowl. I put 3 layers on top of each other. After two flights (about 3 hours total time) the tape shows no signs of deterioration.

Next time I will pay attention to the threads that detail how to post pictures.

I'd suggest you go ahead and block the entire front of the oil cooler as an experiment. It will simulate the shutter on the front w/RTV sealing. Then you can have data on your system to decide if it is worth the effort to change the location.
 
300-350º

There's an article from 2006, from Mike Busch, with data showing an engine that is operated with CHTs above 400ºF on a regular basis will show up to five times as much wear metal in oil analysis when compared to an identical engine that is consistently limited to CHTs of 350ºF or less.

The metal in cylinder heads gets continuously more ductile as it climbs above 250º and then that curve turns upward as temperature passes 400º toward the ultimate limit of 500º (and gets destructive above that), but wear in the 350-400º range is also more accelerated than below 350º. That's talking about the top end of the temperature band.

On the bottom end of the temperature range, the brittle end, the pistons, rings and cylinders are all expanding as they heat up, and it's not until right around 250º that everything "settles out" with thermal expansion and joins the linear portion of the ductile curve (google that...).

I had a previous engine that the manufacturer, limited rpm until CHT got above 250º for that exact reason. I personally continue the same limitation on all of my air-cooled engines, although that is my limit, not Lycoming's.

And then there are combustion by-products (lead deposition, acid formation, sludge formation), which start resolving in the 250-300º range, but are best resolved in the higher end of the temperature band around 350º, making 350º a very good temperature to target. But it also gives us a CHT range of 250-350º for a good band of normal operation with the lowest wear of the rings and cylinder walls, understanding that CHT elevated above 350º is pretty normal for lots of folks and acceptable by Lycoming. Ideally, 300-350º is the best nexus of lowest wear and good combustion byproduct removal.

To the OP, if you're above 250º at all times, but managing to reach 300º, you're probably fine. I do recommend being religious with oil changes and oil analysis and look for trends.

P.S. I would never fully block off my oil cooler without the ability to unblock in flight, but that's me...
 
This was my solution for keeping my engine warm flying in cold weather. I also completely stop cold air to the oil cooler. Cyl. temp at 325-350F.

Michel
 

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I'm flying an RV-6 with an IO-360, CS, FI. I typically cruise at 35-40% power 1800 rpm and 18" map except for WOT takeoff.

I appreciate everyone sharing their perspective and ideas. I like the idea of a more permanent cowl restrictor like Michel's. For now I can't complain about how the painters tape is working.

Next time I have the cowl open I will block off the last bit to simulate having the shutter up front. I'm not too worried anymore about high oil temps since I consider myself luck to get up to 180. I remember one time a few springs ago I took off in 50F temps with the removable oil cooler blocking plate in place. The temps got up to 190 and I returned to base to remove it.
 
minus 24 degrees C today

Hi guys,

Completed a 1.5 hour flight today in minus 24 degrees C. I did not have any mods (Duct tape) attached to the cowl for this flight, I wanted to get a baseline for the temps.

After a full night of preheating, the oil temp was in the mid 70 degrees F, I'm very happy with the Reiff preheat we installed.

In a very steep very slow climb from 2k feet to 9.5k feet I managed to get the oil temp up to 163 degrees F, CHT's were about 380 degrees in the climb.

flying around straight and level at 2450 RPM my oil temp was low at 135. CHT's were low 300's hight 200's. It was hard to stay below VNE today, the aircraft flies great in this cold weather.

I saw the CHT's get too low for my comfort when I was cleared to land and reduced the throttle for descent. They were in the 170's pretty quickly. This makes me think that without a winter cowl mod ccts would be too hard on the CH's.

After the flight I put 3 overlapping strips of duct tape over the inside of the intake. Probably 3.5 - 4 inches of the cowl is now covered by duct tape. I'm hoping this will aid in keeping the oil a little warmer and help prevent the CH's from shock cooling when reducing the power for landing descents.

On another note, it was an awesome flight! digging out the aircraft, removing the covers, warming myself up in the car, etc, etc, is longer than the flight itself. I envy all you people with Hangars!
 
Quoted from Walter Atkinson...Gami injectors person, amongst a host of other experience on many types


"A couple of things to remember:

Lycoming publishes a min operating CHT of 150dF. TCM has not published a min CHT, but set the liquid cooled CHT to run at 240dF. Reading between the lines in TCM’s writings suggests that anything above 200dF is acceptable.

TCM data on oil temp from Bob Mosely (RIP) suggests 180-190 for one hour gets rid of the water. Consider that the oil (water in the oil) is hitting the under side of pistons and cylinder walls which are above the boiling point of water and being vaporized.

As for runup, based on above and a hundred years of experience in all forms of aviation engines and data from multiple engine manufacturers oil temp should be above 90dF (some radial recommendations are 100dF) and CHTs above 200dF. Based on Lycoming’s min CHT above, 150dF should be enough. FWIW, my personal rules are 90 on oil and 200 on CHT.

Some of this might be altered with different oil weights and multi-vis stuff. I know of no hard data breaking all of that down.

_________________
Walter Atkinson "
 
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