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Break In - when is it done?

az_gila

Well Known Member
A question for the Lycoming experts.

How do you know when a new engins is broken in?

I have a newly built up narrow deck O-360-A1A that had 1.5 hrs on a test stand and was then installed on my RV-6A.The plane first flew in May, but I then spent 4 weeks in the UK and returned to the AZ June heatwave...:)

Living at 3000 MSL and with the lows in the 80s it's hard to get the high percent power all of the literature tells you to run at. CHTs are still running hot in climb and also when I try to lean at 2500 rpm (FP Sensenich). Oil consumption is pretty low, perhaps less than 1/4 in on the dipstick in 7 hours.

Is there any other way of checking for break-in completion? I'm going to do a first oil change soon, so if I remove the plugs could a borescope tell me anything?

Test flying progress -

IAS issues. Non-standard flush static ports have been modified but the now arrived monsoon season doesn't give still air for accurate testing even in the early morning.

The old, but sat quietly on the shelf, Facet 40108 fuel pump failed after 6 flights.
 
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I would say that since it had 1.5 on the dyno/test stand, plus a bit of your flying and your oil usage has stabilized that it is good to go.
 
I would say that since it had 1.5 on the dyno/test stand, plus a bit of your flying and your oil usage has stabilized that it is good to go.

I was sort of thinking the same thing, but when the literature says oil consumtion stabilises, how much oil is used before this stabilisation, ozs or quarts?

The literature also says to expect CHTs to drop, but I don't see that yet.
 
Break In

Gil-
I have a 0 320 with 10-1 pistons, fixed pitch prop, Lycoming nitride cylinders. Wittman Tailwind. All my testing was done in late July, 100-120 plus temps for takeoff.
There was a small but identifiable drop in CHT after only a couple of hours. Less than half a quart oil the first 10 hours and zero oil consumption after that. I did everything necessary to keep the CHT below 400. I did see 425 momentarily on the first flight, reduced power and increased speed, it dropped below 400. I ran high power for the first ten hours but probably not quite 75%. I did not lean at all for at least ten hours.
Once the rings are seated 425 CHT in initial climb will not hurt anything.
Apples to Oranges but the six cylinder Continentals run near red line all summer in AZ, both oil and CHT.
 
A question for the Lycoming experts.

How do you know when a new engins is broken in?

CHTs are still running hot in climb and also when I try to lean at 2500 rpm (FP Sensenich).

How hot are your CHTs getting?

Does it recover any when you level off and speed up?
 
Gil-
I have a 0 320 with 10-1 pistons, fixed pitch prop, Lycoming nitride cylinders. Wittman Tailwind. All my testing was done in late July, 100-120 plus temps for takeoff.
There was a small but identifiable drop in CHT after only a couple of hours. Less than half a quart oil the first 10 hours and zero oil consumption after that. I did everything necessary to keep the CHT below 400. I did see 425 momentarily on the first flight, reduced power and increased speed, it dropped below 400. I ran high power for the first ten hours but probably not quite 75%. I did not lean at all for at least ten hours.
Once the rings are seated 425 CHT in initial climb will not hurt anything.
Apples to Oranges but the six cylinder Continentals run near red line all summer in AZ, both oil and CHT.

Using the 410 F limit on SavvyAnalysis with the Skyview data, my excursions above that number are only for 2 to 4 minutes, usually on takeoff.

Oil temps are good, and have never passed 194 F

Perhaps after one more flight I'll do the oil change and keep an accurate track of the consumption.

Anyone have any opinions on having an oil analysis on a 10 hr new engine? Is it worth it?
 
How hot are your CHTs getting?

Does it recover any when you level off and speed up?

Abolute peak has been 433, but for only a few minutes. Speeding up a bit in climb (to 110 - 120 kts) doesn't seem to help with the FP prop since it just gets more rpms. Pulling the throttle back helps...:)

Leveling off for cruise they are just below 400 F and all close - within 15 F - with #4 usually being the hottest with the oil cooler mounted behind it. EGTs are also close, usually within 30 F.

TAS (acutally GPS ground spoeed due to IAS issues) is about 150 kts and I'm still flying without any wheel pants or gear farings. I'll put them on when I do the oil change.
 
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My experience

I was flying a spam can with a new O320. Mechanic told me to run WOT as much as possible. Cruising along just after climbout, the rpm started to pick up and Noticeable increase in power. It was quite dramatic, like it gain 10 horsepower. Not sure if this is typical or not.
 
FWIW I have broken in several engines (3 Lycomings, 2 Continentals) and this is how I was told and did it.

1 - Minimize the taxi and idle time. Keep track of oil consumption.
2 - After takeoff, keep the engine between 75-85% power at all times during cruise.
Fly for at least 1hr at between 75-85% power.
3 - After the engine has 3+hrs on it, do a "long" cross country of
2+ hours at about 75% power. Let the engine cool to the touch
(can anybody say lunch) then fly back at about 75% power.
4 - After this the oil consumption should have stabilized. If not, do as
many "long" cross countries needed until it stabilizes never cruising
below 75% power..

If you have CHT on each cylinder, at some point you will see a significant drop in CHT over what you had when you started. Mine dropped almost 75degF but they did not drop at the same time. In the last break in (Conti O-200) the #3 cylinder took almost 15hrs before the CHT dropped significantly.

I was flying a spam can with a new O320. Mechanic told me to run WOT as much as possible. Cruising along just after climbout, the rpm started to pick up and Noticeable increase in power. It was quite dramatic, like it gain 10 horsepower. Not sure if this is typical or not.
I have had that same experience in all 5 of my break ins. Was told this is typical of when a cylinder is broken in. When all cylinders have broken in the increase is noticeable over when you started.

YMMV

:cool:
 
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Anyone have any opinions on having an oil analysis on a 10 hr new engine? Is it worth it?
IMHO the 1st oil analysis is to establish a baseline in order to compare all others. Until the engine is fully broken in and not running "break in" oil (typically 100% mineral), any oil analysis would have little to no value as a baseline. Until the engine is broken in and internal parts fall into their permanent state, you will have all kinds of "weird" oil sample indications.

I do the 1st oil analysis after the break in is complete and after I have one oil change with the oil I will be running (typically ashless dispersant).

:cool:
 
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FWIW I have broken in several engines (3 Lycomings, 2 Continentals) and this is how I was told and did it.

1 - Minimize the taxi and idle time. Keep track of oil consumption.
2 - After takeoff, keep the engine between 75-85% power at all times.
Fly for at least 1hr at between 75-85% power.
3 - After the engine has 3+hrs on it, do a "long" cross country of
2+ hours at about 75% power. Let the engine cool to the touch
(can anybody say lunch) then fly back at about 75% power.
4 - After this the oil consumption should have stabilized. If not, do as
many "long" cross countries needed until it stabilizes never cruising
below 75% power..

If you have CHT on each cylinder, at some point you will see a significant drop in CHT over what you had when you started. Mine dropped almost 75degF but they did not drop at the same time. In the last break in (Conti O-200) the #3 cylinder took almost 15hrs before the CHT dropped significantly.

YMMV

:cool:

Thanks for the info -


1 - Minimize the taxi and idle time. Keep track of oil consumption.


I've tried, but have a long taxi to the runwway. My first few flights were from a borrowed hangar with a short taxi distance. I never did "taxi testing". The last flight had a very slow taxi behind a Waco with a student under instruction.

Oil consumption was reasonably tracked as I mentioned.

2 - After takeoff, keep the engine between 75-85% power at all times.
Fly for at least 1hr at between 75-85% power.


Can't seem to do that percentage with our temperatures and altitude. Our absolute daily lows give a take off DA of about 4500 ft.
My test flights have been much shorter though as I examined the instrumentation, aerodynamics and control.

3 - After the engine has 3+hrs on it, do a "long" cross country of
2+ hours at about 75% power. Let the engine cool to the touch
(can anybody say lunch) then fly back at about 75% power.


Haven't done that, but sounds like a good idea for my next flight. The cross country will be have to be a zig-zag with the 100 nm mile Phase I limit. :)


4 - After this the oil consumption should have stabilized. If not, do as
many "long" cross countries needed until it stabilizes never cruising
below 75% power..


Sounds like a good plan. Perhaps I should do this before chasing IAS accuracy issues.
 
Thanks for the info -


1 - Minimize the taxi and idle time. Keep track of oil consumption.


I've tried, but have a long taxi to the runwway. My first few flights were from a borrowed hangar with a short taxi distance. I never did "taxi testing". The last flight had a very slow taxi behind a Waco with a student under instruction.

Oil consumption was reasonably tracked as I mentioned.

2 - After takeoff, keep the engine between 75-85% power at all times.
Fly for at least 1hr at between 75-85% power.


Can't seem to do that percentage with our temperatures and altitude. Our absolute daily lows give a take off DA of about 4500 ft.
My test flights have been much shorter though as I examined the instrumentation, aerodynamics and control.

3 - After the engine has 3+hrs on it, do a "long" cross country of
2+ hours at about 75% power. Let the engine cool to the touch
(can anybody say lunch) then fly back at about 75% power.


Haven't done that, but sounds like a good idea for my next flight. The cross country will be have to be a zig-zag with the 100 nm mile Phase I limit. :)


4 - After this the oil consumption should have stabilized. If not, do as
many "long" cross countries needed until it stabilizes never cruising
below 75% power..


Sounds like a good plan. Perhaps I should do this before chasing IAS accuracy issues.
Oh I forgot. Don't worry about leaning at all unless your DA causes the engine to run rough. If so only lean until the engine runs smooth. During the break in, keep the mixture as rich as possible for engine cooling and to prevent detonation. Until the engine breaks in don't worry about fuel consumption. After break in (the rest of the engine lifespan) fuel consumption for a given amount of power will be significantly better than if you ran it too lean during the break in.

:cool:
 
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Thanks for the info -


1 - Minimize the taxi and idle time. Keep track of oil consumption.


I've tried, but have a long taxi to the runwway. My first few flights were from a borrowed hangar with a short taxi distance. I never did "taxi testing". The last flight had a very slow taxi behind a Waco with a student under instruction.

Oil consumption was reasonably tracked as I mentioned.

2 - After takeoff, keep the engine between 75-85% power at all times.
Fly for at least 1hr at between 75-85% power.


Can't seem to do that percentage with our temperatures and altitude. Our absolute daily lows give a take off DA of about 4500 ft.
My test flights have been much shorter though as I examined the instrumentation, aerodynamics and control.

3 - After the engine has 3+hrs on it, do a "long" cross country of
2+ hours at about 75% power. Let the engine cool to the touch
(can anybody say lunch) then fly back at about 75% power.


Haven't done that, but sounds like a good idea for my next flight. The cross country will be have to be a zig-zag with the 100 nm mile Phase I limit. :)


4 - After this the oil consumption should have stabilized. If not, do as
many "long" cross countries needed until it stabilizes never cruising
below 75% power..


Sounds like a good plan. Perhaps I should do this before chasing IAS accuracy issues.



The Lycoming website indicates:

"A new, rebuilt or overhauled engine should receive the same start, warm-up and preflight checks as any other engine. There are some aircraft owners and pilots who would prefer to use low power settings for cruise during the break-in period. This is not recommended. A good break-in requires that the piston rings expand sufficiently to seat with the cylinder walls. This seating of the ring with the cylinder wall will only occur when pressures inside the cylinder are great enough to cause expansion of the piston rings. Pressures in the cylinder only become great enough for a good break-in when power settings above 65% are used."

"Full power for takeoff and climb during the break-in period is not harmful; it is beneficial, although engine temperatures should be monitored closely to ensure that overheating does not occur. Cruise power settings above 65%, and preferably in the 70% to 75% of rated power range, should be used to achieve a good engine break-in."

"Remember that if the new or rebuilt engine is normally aspirated (non-turbocharged), it will be necessary to cruise at lower altitudes to obtain the required cruise power levels. Density altitudes in excess of 8000 feet (5000 feet is recommended) will not allow the engine to develop sufficient cruise power for a good break-in.
"
 
True, but this is where theory runs into reality.

Unless the engine is on an accurate dynamo very few people can accurately measure a 5% difference in power even with advanced engine monitoring systems installed in the aircraft. Too many uncontrolled variables while flying. In an engine break in, going slightly above the requirement is better than going slightly below the requirement. Besides we all want to "baby" our expensive engine so we will tend to do things on the lower side of the requirement.

:cool:
 
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The Lycoming website indicates:

"A new, rebuilt or overhauled engine should receive the same start, warm-up and preflight checks as any other engine. There are some aircraft owners and pilots who would prefer to use low power settings for cruise during the break-in period. This is not recommended. A good break-in requires that the piston rings expand sufficiently to seat with the cylinder walls. This seating of the ring with the cylinder wall will only occur when pressures inside the cylinder are great enough to cause expansion of the piston rings. Pressures in the cylinder only become great enough for a good break-in when power settings above 65% are used."

"Full power for takeoff and climb during the break-in period is not harmful; it is beneficial, although engine temperatures should be monitored closely to ensure that overheating does not occur. Cruise power settings above 65%, and preferably in the 70% to 75% of rated power range, should be used to achieve a good engine break-in."

"Remember that if the new or rebuilt engine is normally aspirated (non-turbocharged), it will be necessary to cruise at lower altitudes to obtain the required cruise power levels. Density altitudes in excess of 8000 feet (5000 feet is recommended) will not allow the engine to develop sufficient cruise power for a good break-in.
"

And the DA is my problem in this heat and monsoon season.

I think a long zig-zag cross-country out in the wilds of the Gil Bend area where the ground is 1000 to 1500 msl is called for.

I just prefer not to fly that low over the empty, unpopulated AZ desert wilderness miles from civilization. :)
 
My breakin was weird; I never did determine if or when it was done. After two hours I mumbled a prayer, made the sign of the cross over the engine and called it complete. My cylinders are Cermichrome, and I didn't experience any significant oil consumption at all; I still don't after 175 hrs. These days I'll usually add 1/2 qt. between 25 hr. oil changes so I guess I must have accidentally done something right. I did experience high CHTs (440ish) for the first few hours, but that was before I drilled out my carburetor jet. My takeoff fuel flow was only 8 GPH when it should have been more like 11 GPH for my O-290-D2.
 
My breakin was weird; I never did determine if or when it was done. After two hours I mumbled a prayer, made the sign of the cross over the engine and called it complete. My cylinders are Cermichrome, and I didn't experience any significant oil consumption at all; I still don't after 175 hrs. These days I'll usually add 1/2 qt. between 25 hr. oil changes so I guess I must have accidentally done something right. I did experience high CHTs (440ish) for the first few hours, but that was before I drilled out my carburetor jet. My takeoff fuel flow was only 8 GPH when it should have been more like 11 GPH for my O-290-D2.

That's exactly what happened after a TOH on my Tiger a few years back, and why I'm not sure what to expect, or what I'm seeing, on the RV-6A. :)
 
And the DA is my problem in this heat and monsoon season.

I think a long zig-zag cross-country out in the wilds of the Gil Bend area where the ground is 1000 to 1500 msl is called for.

I just prefer not to fly that low over the empty, unpopulated AZ desert wilderness miles from civilization. :)
The good thing is that you probably only have to do it once or maybe twice for a good engine break in. 7,500' DA at WOT, as rich as possible for smooth operation for 2hrs is close enough to 75% and should do the trick.

;)
 
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Break In

I pay a lot of attention to what Mahlon Russell says and not so much to others. I do not have access to my notes but my recollection is that Mahlon recommends an absolute maximum of 425 CHT until you are CERTAIN the rings have seated. Anything higher and you are in an area where glazing the cylinder walls is likely.
Pulling the throttle back for a minute of two on initial climb is FAR BETTER than glazing the cylinders.
With the 0 320 at 6000' PRESSURE ALTITUDE 21" mp and 2650 r/m I was still at 75% according to the Lycoming power chart.
If you are close to full throttle and below 5k pressure altitude you should be fine. How many total hours??
 
I pay a lot of attention to what Mahlon Russell says and not so much to others. I do not have access to my notes but my recollection is that Mahlon recommends an absolute maximum of 425 CHT until you are CERTAIN the rings have seated. Anything higher and you are in an area where glazing the cylinder walls is likely.
Pulling the throttle back for a minute of two on initial climb is FAR BETTER than glazing the cylinders.
With the 0 320 at 6000' PRESSURE ALTITUDE 21" mp and 2650 r/m I was still at 75% according to the Lycoming power chart.
If you are close to full throttle and below 5k pressure altitude you should be fine. How many total hours??

Total hours are now at 6 1/2 actual airborne time. The trouble is that I live at 5000 ft DA even early in the morning in the monsoon season.

When the CHTs show 410 red on the Skyview at less than 500 ft AGL during climb out I'm a little wary of pulling back the throttle.
 
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Break In

At Havasu I was a bit better off on DA but not by much. I had to pull the power back below 500' to control the CHT. At 130 kts IAS I could go back to full throttle. My afternoon flights were with temps in the 120 range.
The Tailwind weighs 925 empty and I would typically have 25 gal fuel. I think the Tailwind accelerates better and goes quite a bit faster than the RV6. Also I had gear fairings for the initial flights and wheel pants very early in testing. My wheel pants added 8 kts.
I have considerably less cowl inlet and outlet than a typical RV. I also have a plenum which seems to work extremely well.
I have the cooler behind #3 and the single CHT is on 3. 360-380 CHT in cruise in hot weather. Oil gets too cold below 60 degrees ambient.
Again 10-1 pistons which most of the experts say will cause cooling problems. That has not been the case for me.
 
Break In

Forgot to mention I now have a Whirlwind GA prop which is a huge improvement over the previous Sterba which had way too much pitch. I am extremely happy so far with the Whirlwind. Cruise has not changed much but takeoff and climb are improved dramatically.
 
Gil,

With oil consumption that low, I'd say that you are probably broken in - especially since it got a test stand run-in for 1.5 hours, as you stated. When I was at Lycoming school, they indicated as much.

One of the reasons that you are seeing higher CHT's is because you aren't stuffing enough air (cooling) molecules through the cowling because you don't have the pants on. Adding 12 knots will give you measurably better cooling. Leaving them off does not make the engine "work harder" - it generates power based on throttle setting and prop pitch, and will go as fast as it can at full throttle - and if you make it go slower with more drag, you have lowered the cooling airflow, which is not good.

If you can find Mahlon's instructions, they are basically "run it hard until CHT's drop and oil temp stabilizes", and since it could very well have broken in during the test-stand run-in, you won't actually see either of those. A fresh engine (running but not broken in) might use half a quart an hour until it drops to very small amounts.

And remember that you can get much lower CHT's with LOP operations. I have climbed out of Casa Grande this time of year back when we flew between Houston and Big Bear a lot, and it was always a challenge to keep things cool - we'd climb shallow to keep the speed up to keep oil temps down, and go LOP as soon as power was below 75% to keep CHT's reasonable.

Paul
 
Gil,

With oil consumption that low, I'd say that you are probably broken in - especially since it got a test stand run-in for 1.5 hours, as you stated. When I was at Lycoming school, they indicated as much.

One of the reasons that you are seeing higher CHT's is because you aren't stuffing enough air (cooling) molecules through the cowling because you don't have the pants on. Adding 12 knots will give you measurably better cooling. Leaving them off does not make the engine "work harder" - it generates power based on throttle setting and prop pitch, and will go as fast as it can at full throttle - and if you make it go slower with more drag, you have lowered the cooling airflow, which is not good.

If you can find Mahlon's instructions, they are basically "run it hard until CHT's drop and oil temp stabilizes", and since it could very well have broken in during the test-stand run-in, you won't actually see either of those. A fresh engine (running but not broken in) might use half a quart an hour until it drops to very small amounts.

And remember that you can get much lower CHT's with LOP operations. I have climbed out of Casa Grande this time of year back when we flew between Houston and Big Bear a lot, and it was always a challenge to keep things cool - we'd climb shallow to keep the speed up to keep oil temps down, and go LOP as soon as power was below 75% to keep CHT's reasonable.

Paul

Thanks Paul... it's nice to get some details, and it says my engine is probably already broken in

The wheel pants on or off has always confused me a bit, especially when Vans Flight Test section in the instructions specifically mentions flying pantless with new engines. Opinion seems divided when I ask others.

I like your logic on cooling, and Mondays breakfast for 3 local newly made RV-6A's has been monsoon postponed - so an oil change and pant fitting will occur before the next test flight. I'll also repeat a compression test and timing check.

I'll report the flight test results later in the week....:)
 
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1/4 quart oil consumption in 6 hours = 1quart in 24 or less. It's broken in! No worries about glazing. 425F in the climb is Ok now and as Paul says it will get better as time goes by and the aircraft is cleaned up.
Good Luck,
Mahlon
 
The wheel pants on or off has always confused me a bit, especially when Vans Flight Test section in the instructions specifically mentions flying pantless with new engines. Opinion seems divided when I ask others.

I also don't get that. The goal is to run the engine fairly hard and keep it cool. You don't have to run it any harder with wheel pants off than with them on, but having them on speeds things up and should help with cooling. Seems counterintuitive. The main reason I see to leave pants off during testing is to be able to keep a good eye on the wheels, tires and brakes while everything is new.
 
My #4 cylinder was running 10-15 degrees hotter than the others and routinely >400F in cruise unless managed with faster speed, less power or more fuel. Once I installed the gear fairings and gained ~20 Kts, the engine is much easier to keep cool even in the hotter summer temps.
 
Geography

I also don't get that. The goal is to run the engine fairly hard and keep it cool. You don't have to run it any harder with wheel pants off than with them on, but having them on speeds things up and should help with cooling. Seems counterintuitive. The main reason I see to leave pants off during testing is to be able to keep a good eye on the wheels, tires and brakes while everything is new.

Maybe the Vans Flight test instructions are based on cooler, near sea level weather in Oregon, and things can diverge greatly when testing is performed at higher altitude and warmer weather areas of the country?

Right now, I'm 20 F hotter than Portland and 3000 ft higher, and it's a cooler than expected day after thunderstorms during the night.
 
I think he wrote '1/4 inch' on the dipstick, not 1/4 quart.
What's missing is the fuel flow information. How far (in EGT degrees) rich of peak are you running?

Yes I gave it in inches, but I think 1/4 inch is less than 1/2 quart.

I don't know the EGT readings ROP since the CHTs rapidly rise when I attempt to lean. As others have recommended, I'm running pretty close to full rich at the moment.

Assuming the Floscan calibration is correct, at one typical sample point I'm showing 11.7 gph at 2510 rpm, and a DA of 6700 ft. (4360 ft actual). CHTs range from 380 F to 404 F and IIRC this was with slight leaning. EGTs are all close at 1301 F to 1333 F
 
Unless there's a noticeable loss of power or engine roughness I'd run full rich, to help keep CHT temperatures down. That said, I think your break in is done. Flying out of 400' MSL I have no issues with CHTs, but taking off from meteor crater on a hot day I had to step climb and run full rich and CHTs were still over 410F.
 
Much better

Thanks Paul... it's nice to get some details, and it says my engine is probably already broken in

The wheel pants on or off has always confused me a bit, especially when Vans Flight Test section in the instructions specifically mentions flying pantless with new engines. Opinion seems divided when I ask others.

I like your logic on cooling, and Mondays breakfast for 3 local newly made RV-6A's has been monsoon postponed - so an oil change and pant fitting will occur before the next test flight. I'll also repeat a compression test and timing check.

I'll report the flight test results later in the week....:)

Flew to breakfast with two other local newly minted RV-6A's.

The wheel pants and fairings made an amazing difference, a lot slower CHT rise in climb to reach 400+ degrees and I could now lean in cruise.

At 10 am after breakfast the air was too turbulent to get good readings - the monsoon storms were starting - so I'll try again over the next few days. First estimate is plus 12 kts and much cooler CHTs.

SO

If you fly Phase I and break-in your new engine where it is hot and high (DA higher than central Oregon) I would say to disregard the Plans Instructions and fly with the pants and gear fairings on.
 
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Flew to breakfast with two other local newly minted RV-6A's.

The wheel pants and fairings made an amazing difference, a lot slower CHT rise in climb to reach 400+ degrees and I could now lean in cruise.

At 10 am after breakfast the air was too turbulent to get good readings - the monsoon storms were starting - so I'll try again over the next few days. First estimate is plus 12 kts and much cooler CHTs.

SO

If you fly Phase I and break-in your new engine where it is hot and high (DA higher than central Oregon) I would say to disregard the Plans Instructions and fly with the pants and gear fairings on.

Definitely fly with the wheel pants and gear fairings on. 20-years ago, on my 1st flight in SoCAL, I never flew without the gear fairings on but did make the first flight with wheel pants off. Temperatures were high and improvements were made with less drag. I was doing test flying the hottest month of the year.

I am with Paul Dye that they all need to be installed for all of Phase I flying. A local RV-9A was having cooling issues in Phase I. I like Paul, recommended to get the wheel pants on. Temperatures came down with their installation and proper attention to temperatures could now be addressed.

Sounds like your engine is broke in well enough to do what ever is necessary.

I like to run new engines hard when not testing airframe and airspeeds keeping power settings high but not holding same RPM longer than 15-minutes for the first 100-hours. Yes the engine does not need it but it appears to get the rings sealed well with little oil consumption. The last two sets of cylinders (2 different engines) I broke in have had oil consumption in the 30+ hours per quart when I ran them at 75% power or more as much as possible for the 1st 100-hours. Yes there was some flying at less than 65% power but I alway would run hard by myself.

I typically never added any oil between oil changes for the first 100-hours.
 
Maybe the Vans Flight test instructions are based on cooler, near sea level weather in Oregon, and things can diverge greatly when testing is performed at higher altitude and warmer weather areas of the country?

Right now, I'm 20 F hotter than Portland and 3000 ft higher, and it's a cooler than expected day after thunderstorms during the night.

That makes sense. Out here, for me to run hard, 75% power or more, I was right on the edge of the yellow without pants. The extra drag allowed me to keep pushing on bumpy days. The general "consensus of the local masses" was to run 25 squared, rich, and low.
Cooling in these parts is rarely a concern.
 
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