Break-in Fuel Flow

[flyboy0681]

If all goes as planned, I'll be breaking in the overhauled -360 next week on a long trip to Texas. The shop sent instructions of the break-in process and it calls for leaning 100° rich of peak EGT.

Anybody know what kind of fuel flow I could expect for flight planning purposes at around 5,000 feet?

[clh]

On my E, I was running 75-80% power and adding fuel to keep the CHT's in check.  I was told to run it hard, so at first it was indicating 16 or so gph and after a few hours, I backed it down to 75%+ power and was running about 13-14 gph.  I didn't spend a lot of time looking at the fuel flow.  Just the CHT and EGT's  I am sure there are more experienced folks on the list,  so YMMV.

[flyboy0681]

14 minutes ago, clh said:

On my E, I was running 75-80% power and adding fuel to keep the CHT's in check.  I was told to run it hard, so at first it was indicating 16 or so gph and after a few hours, I backed it down to 75%+ power and was running about 13-14 gph.  I didn't spend a lot of time looking at the fuel flow.  Just the CHT and EGT's  I am sure there are more experienced folks on the list,  so YMMV.

Exactly what I was told, run it hard. I just hate to think of taking a huge trip like this at high FF, but I do understand the reasoning behind it,

[clh]

You will see the temperatures come down quite dramatically when the rings seat....  This would allow you to back down the fuel flow required a bit, but I was told to keep running it hard for the first 10 hrs or so..

[carusoam]

Break-in flights can be fun...

They are typically done at lower altitudes than we normally find acceptable.  High MP so the rings are hard at work...

They are typically done at higher power settings than we find acceptable.  High RPM so the wear-in step is high in the cylinders...

They are typically done at higher FF rates than we can find economically acceptable.  More Cooling to avoid glazing the cylinder walls...

They are typically done altering power settings MP and rpm every 15 minutes. More variations to keep steps from actually forming in the cylinder walls...

Flight planning included a few things that aren't usually high on the usual priority list.  More safety in the event of an engine-out or other calamity.  Select various milestones to use as power change reminders.  Jersey shore flights allow for a safe low altitude flight with a lot of Plan B locations.  A few major rivers get crossed every 15 minutes for milestones...

I brought someone with me for a few flights just to make sure I didn't forget anything that could lead to expensive parts replacements....

I checked the JPI data after the flights looking for CHTs to have a step change after the rings were broken in...  I never actually saw the CHTs change.  The break-in runs at the Continental factory must have done the hard work...(?)

fun stuff,

-a-

[Hank]

One longer trip or several shorter trips, the break-in will still require the same number of hours. At least you will be getting a direct benefit from your break-in time.

This would be a great opportunity to do a 3-way GPS speed check, and post the pictures along with the result! Your plane should be plenty fast, down low with high MP!

[flyboy0681]

Nothing in the instructions of bringing power back, just gunning it the whole way for the first eight hours.

[flyboy0681]

1 minute ago, Hank said:

Your plane should be plenty fast, down low with high MP!

Gulping lots of gas

[Hank]

8 minutes ago, flyboy0681 said:

Gulping lots of gas

You gotta do that to break in the engine. Or you can have a 400-hour Top Overhaul . . .

Most guys I've heard about break in their engines going nowhere. You will just have an expensive trip, instead of just burning the whole pile of gas money . . . 

[flyboy0681]

2 minutes ago, Hank said:

You gotta do that to break in the engine. Or you can have a 400-hour Top Overhaul . . .

Most guys I've heard about break in their engines going nowhere. You will just have an expensive trip, instead of just burning the whole pile of gas money . . . 

Expensive indeed. Not taking winds into account, I'll count on 15gph and plan on a fuel stop three hours into the trip just to be on the safe side. And I won't be going if there is serious IMC conditions somewhere along the route.

[Hank]

Hey, wow! You'll be getting 182 mileage, but still too much speed. Maybe you should keep track of everything and report back to the guy trying to decide between a Mooney or a 182?

[jetdriven]

You can also break in LOP at 27+ inches of manifold pressure, 11 gph that's 83% power LOP which is comparable to the ROP 75% value. it will also likely run cooler at that configuration

[flyboy0681]

3 minutes ago, jetdriven said:

You can also break in LOP at 27+ inches of manifold pressure, 11 gph that's 83% power LOP which is comparable to the ROP 75% value. it will also likely run cooler at that configuration

Perhaps good advice for some, but I'm not going to stray from the shops written word one bit. The warranty depends on it.

[jetdriven]

Then I would run it at full throttle at least 24 inches of manifold pressure, vary the RPM every 15 minutes and throw fuel at to keep the hottest CHT at 340 or even less.  The cylinder barrels are running hotter than in normal operation, and normal  CHT may not be indicative of much higher temperatures on the rings. 

[Guest]

Here's what a Lycoming has to say about break in procedures.

https://www.lycoming.com/sites/default/files/Lycoming Reciprocating engine Break-In and Oil Consumption.pdf

Clarence

[aaronk25]

Jetdriven is right on the money. Lop is a great way to break in a engine. Sets the rings with a cleaner burn. Before the rings are set ROP throws a lot of hot abrasive gases over the cam diluting the oil mist creating a bad environment for a brand new cam and lifters.




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[mooniac15u]

11 hours ago, aaronk25 said:

Jetdriven is right on the money. Lop is a great way to break in a engine. Sets the rings with a cleaner burn. Before the rings are set ROP throws a lot of hot abrasive gases over the cam diluting the oil mist creating a bad environment for a brand new cam and lifters.




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Combustion in an oxygen rich environment (LOP) will tend to promote the formation of nitrogen oxides and sulfur oxides.  In the presence of the water formed during combustion these can form nitric acid, nitrous acid, and sulfuric acid.  I'm not sure it's safe to assume that exhaust gases from LOP operations are less corrosive than those from ROP.

[aaronk25]

It's a cleaner combustion. Look how much cleaner the oil stays running lop. 100ll has 2.8g of lead way more than auto fuel ever had so I don't think it makes sense to fly the first few hours carboning up all the new part (rings) with deposits and lead.

I broke in exactly how Byron described and fill to 6qts and at 20 hours I add one qt to bring back to 6qts.

I think these shops are out dated in their instructions to owners.


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[mooniac15u]

7 minutes ago, aaronk25 said:

It's a cleaner combustion. Look how much cleaner the oil stays running lop. 100ll has 2.8g of lead way more than auto fuel ever had so I don't think it makes sense to fly the first few hours carboning up all the new part (rings) with deposits and lead.

I broke in exactly how Byron described and fill to 6qts and at 20 hours I add one qt to bring back to 6qts.

I think these shops are out dated in their instructions to owners.


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Cleaner from the standpoint of visible residue in the oil.  That doesn't mean it's less corrosive.  You can't determine acidity by visual inspection.

[ArtVandelay]

10 minutes ago, mooniac15u said:

Combustion in an oxygen rich environment (LOP) will tend to promote the formation of nitrogen oxides and sulfur oxides.  In the presence of the water formed during combustion these can form nitric acid, nitrous acid, and sulfuric acid.  I'm not sure it's safe to assume that exhaust gases from LOP operations are less corrosive than those from ROP.

As always it depends, the nitrous oxides peak on the LOP side, but then decline as you further lean, if you lean too much, the combustion is incomplete and the hydrocarbons rise (unburnt fuel). This doesn't take into account additives. But since cars all run lean, there is a happy medium, which is just before combustion efficiency starts to drop.

[mooniac15u]

Just now, teejayevans said:

As always it depends, the nitrous oxides peak on the LOP side, but then decline as you further lean, if you lean too much, the combustion is incomplete and the hydrocarbons rise (unburnt fuel). This doesn't take into account additives. But since cars all run lean, there is a happy medium, which is just before combustion efficiency starts to drop.

Of course the absolute quantity of oxides produced depends on the the conditions.  However, regardless of where you are on the LOP side, the oxygen rich environment will promote oxide formation more than ROP operations.

[ArtVandelay]

3 minutes ago, mooniac15u said:

Of course the absolute quantity of oxides produced depends on the the conditions.  However, regardless of where you are on the LOP side, the oxygen rich environment will promote oxide formation more than ROP operations.

Are talking nitrogen oxides, or all oxides?

Dont forget nitrogen is competing with carbon and hydrogen for the oxygen molecules.  So the absolute quantity of nitrogen oxides will be less if sufficiently LOP then if substantially ROP, water and carbon dioxide will increase until the combustion process begins to be less efficient.

[aaronk25]

Boom


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[mooniac15u]

Just now, teejayevans said:

Are talking nitrogen oxides, or all oxides?

Dont forget nitrogen is competing with carbon and hydrogen for the oxygen molecules.  So the absolute quantity of nitrogen oxides will be less if sufficiently LOP then if substantially ROP, water and carbon dioxide will increase until the combustion process begins to be less efficient.

The farther you go lean of peak, the less oxygen is used in the combustion process and the more is available to form oxides.  I was trying to keep it simple in my first post regarding nitrogen and sulfur oxides.  In reality, with sufficient excess oxygen you will also generate some organic alcohols and acids.

[mooniac15u]

In a perfect combustion event the hydrocarbons are converted entirely to carbon dioxide and water.  Once that conversion is complete any excess oxygen in the combustion chamber will potentially promote formation of oxides.  At high enough temperatures some of the normally relatively inert nitrogen in the air will be oxidized.