Engine break-in
Encyclopedia
Break-in or breaking in, also known as run-in or running in, is the procedure of conditioning a new piece of equipment by giving it an initial period of running, usually under light load, but sometimes under heavy load or normal load. It is generally a process of moving parts wearing against each other to produce the last small bit of size and shape adjustment that will settle them into a stable relationship for the rest of their working life.
One of the most common examples of break-in is engine break-in for petrol engine
s and diesel engine
s.
s of the engine and the cylinder
wall. There is no universal preparation or set of instructions for breaking in an engine. Most importantly, experts disagree on whether it is better to start engines on high or low power to break them in. While there are still consequences to an unsuccessful break-in, they are harder to quantify on modern engines than on older models. In general, people no longer break in the engines of their own vehicles after purchasing a car or motorcycle, because the process is done in production. It is still common, even today, to find that an owner's manual recommends gentle use at first (often specified as the first 500 or 1000 kilometers or miles). But it is usually only normal use without excessive demands that is specified, as opposed to light/limited use. For example, the manual will specify that the car be driven normally, but not in excess of the highway speed limit.
. Each engine has specific preparation needs of its own due to factors such as the many different types of engine models, the vehicles it belongs to, and conflicting expert instructions. For example, each engine should be lubricated and run on oil specified by its designers which can be found in a manual.
The main reason is that the factories in which they are produced are now capable of better machining and assembly. For example, it is easier to hold tighter tolerances now, and the average surface finish
of a new cylinder wall has improved. Manufacturers decades ago were capable of such accuracy and precision
, but not with as low a unit cost
or with as much ease. Therefore, the average engine made today resembles, in some technical respects, the top-end custom work of back then. For some equipment, break-in is now done at the factory, obviating end-user break-in. This is advantageous for several reasons. It is a selling point with customers who don't want to have to worry about break-in and want full performance "right out of the box". And it also aligns with the fact that compliance rates are always uncertain in the hands of end users. As with medical compliance
or regulatory compliance
, an authority can give all the instructions it wants, but there is no guarantee that the end user will follow them.
The other reason for shorter break-in regimens today is that a greater amount of science has been applied
to the understanding of break-in, and this has led to the realization that some of the old, long, painstaking break-in regimens were based on specious reasoning. People developed elaborate theories on what was needed and why, and it was hard to sift the empirical evidence in trying to test or confirm the theories. Anecdotal evidence
and confirmation bias
definitely played at least some part. Today engineers can confidently advise users not to put too much stock in old theories of long, elaborate break-in regimens. Some users will not give credence to the engineers and will stick to their own ideas anyway; but their careful break-in beliefs are still harmless and serve roughly like a placebo in allowing them to assure themselves that they've maximized the equipment's working lifespan through their due diligence.
manufacturers recommend a period of break-in, for example by playing white or pink noise.
One of the most common examples of break-in is engine break-in for petrol engine
Petrol engine
A petrol engine is an internal combustion engine with spark-ignition, designed to run on petrol and similar volatile fuels....
s and diesel engine
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
s.
Engine break-in
A new engine is broken in by following specific driving guidelines during the first few hours of its use. The focus of breaking in an engine is on the contact between the piston ringPiston ring
A piston ring is a split ring that fits into a groove on the outer diameter of a piston in a reciprocating engine such as an internal combustion engine or steam engine.The three main functions of piston rings in reciprocating engines are:...
s of the engine and the cylinder
Cylinder (engine)
A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before receiving precision machine work...
wall. There is no universal preparation or set of instructions for breaking in an engine. Most importantly, experts disagree on whether it is better to start engines on high or low power to break them in. While there are still consequences to an unsuccessful break-in, they are harder to quantify on modern engines than on older models. In general, people no longer break in the engines of their own vehicles after purchasing a car or motorcycle, because the process is done in production. It is still common, even today, to find that an owner's manual recommends gentle use at first (often specified as the first 500 or 1000 kilometers or miles). But it is usually only normal use without excessive demands that is specified, as opposed to light/limited use. For example, the manual will specify that the car be driven normally, but not in excess of the highway speed limit.
Goal
The goal of modern engine break-ins is the settling of piston rings into an engine's cylinder wall. A cylinder wall is not perfectly smooth but has a deliberate slight roughness to help oil adhesion. As the engine is powered up, the piston rings between the pistons and cylinder wall will begin to seal against the wall's small ridges. If the engine is powered up too quickly or not enough (depending on engine), the rings may grind against the ridges and wear them down. The tighter the piston rings are set in, the longer an engine is expected to last.Preparation
There are important preparations which must be made before the actual process of running the engine. The break-in can take place either in the vehicle or on an engine standEngine stand
An engine stand is a tool commonly used to repair large heavy gasoline or diesel engines. It uses a heavy cantilevered support structure to hold the engine in midair so that the mechanic has access to any exposed surface of the engine....
. Each engine has specific preparation needs of its own due to factors such as the many different types of engine models, the vehicles it belongs to, and conflicting expert instructions. For example, each engine should be lubricated and run on oil specified by its designers which can be found in a manual.
Process
The main area of controversy among engine break-in instructions is whether to run the engine slowly or quickly to initiate the process. Those who promote raising the power settings steadily will recommend changing the engine setting from low to high powers as to not work the engine too hard and create excessive glazing on the cylinder wall (which would require the pistons to be removed and wall fixed). Other experts disagree and believe that to start the engine at a high power is the best way to effectively set in the pistons. The following are examples of how the two processes can be carried out:Start high power
- Start with Revolutions per minuteRevolutions per minuteRevolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...
(rpm) between 2500 and 4000, and run the engine for about 20 minutes while watching so that the oil pressure does not get too high, which is dangerous. After changing oil and checking that the engine functions, drive using lower power settings. - A high power setting is relative to the vehicle type, so half as many rpm may be necessary if a car has a smaller cylinder wall.
Start low power
- Setting will be around 1500 rpm, run for about half an hour while like the other method checking oil pressure and begin again should there be any over-boiling of the engine's coolantCoolantA coolant is a fluid which flows through a device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, and chemically inert, neither causing nor...
, which is a combination of air, oil, and water. Once this initial step is completed, drive in varying speeds on the road (or stand) by accelerating between speeds of 30 and 50 miles per hour.
Consequences
The following are consequences of a bad engine break-in:- Oil will be allowed to gather in the cylinder wall, and a vehicle will use much more of it than necessary.
- If a ring does not set into the grooves of the cylinder wall but creates friction against them each time an engine runs, the cylinder wall will be worn out.
- Unsuccessfully setting piston rings into a cylinder wall will result in the necessity of new engine parts, or the entire engine depending on how extensive the damage is.
Modern versus older break-in regimens
For many kinds of equipment (with automotive engines being the prime example), the time it takes to complete break-in procedures has decreased significantly from a number of days to a few hours, for several reasons.The main reason is that the factories in which they are produced are now capable of better machining and assembly. For example, it is easier to hold tighter tolerances now, and the average surface finish
Surface finish
Surface finish, also known as surface texture, is the characteristics of a surface. It has three components: lay, surface roughness, and waviness.-Lay:...
of a new cylinder wall has improved. Manufacturers decades ago were capable of such accuracy and precision
Accuracy and precision
In the fields of science, engineering, industry and statistics, the accuracy of a measurement system is the degree of closeness of measurements of a quantity to that quantity's actual value. The precision of a measurement system, also called reproducibility or repeatability, is the degree to which...
, but not with as low a unit cost
Unit cost
The unit cost of a product is the cost per standard unit supplied, which may be a single sample or a container of a given number. When purchasing more than a single unit, the total cost will increase with the number of units, but it is common for the unit cost to decrease as quantity is increased...
or with as much ease. Therefore, the average engine made today resembles, in some technical respects, the top-end custom work of back then. For some equipment, break-in is now done at the factory, obviating end-user break-in. This is advantageous for several reasons. It is a selling point with customers who don't want to have to worry about break-in and want full performance "right out of the box". And it also aligns with the fact that compliance rates are always uncertain in the hands of end users. As with medical compliance
Compliance (medicine)
In medicine, compliance describes the degree to which a patient correctly follows medical advice...
or regulatory compliance
Regulatory compliance
In general, compliance means conforming to a rule, such as a specification, policy, standard or law. Regulatory compliance describes the goal that corporations or public agencies aspire to in their efforts to ensure that personnel are aware of and take steps to comply with relevant laws and...
, an authority can give all the instructions it wants, but there is no guarantee that the end user will follow them.
The other reason for shorter break-in regimens today is that a greater amount of science has been applied
Applied science
Applied science is the application of scientific knowledge transferred into a physical environment. Examples include testing a theoretical model through the use of formal science or solving a practical problem through the use of natural science....
to the understanding of break-in, and this has led to the realization that some of the old, long, painstaking break-in regimens were based on specious reasoning. People developed elaborate theories on what was needed and why, and it was hard to sift the empirical evidence in trying to test or confirm the theories. Anecdotal evidence
Anecdotal evidence
The expression anecdotal evidence refers to evidence from anecdotes. Because of the small sample, there is a larger chance that it may be true but unreliable due to cherry-picked or otherwise unrepresentative of typical cases....
and confirmation bias
Confirmation bias
Confirmation bias is a tendency for people to favor information that confirms their preconceptions or hypotheses regardless of whether the information is true.David Perkins, a geneticist, coined the term "myside bias" referring to a preference for "my" side of an issue...
definitely played at least some part. Today engineers can confidently advise users not to put too much stock in old theories of long, elaborate break-in regimens. Some users will not give credence to the engineers and will stick to their own ideas anyway; but their careful break-in beliefs are still harmless and serve roughly like a placebo in allowing them to assure themselves that they've maximized the equipment's working lifespan through their due diligence.
Speakers and headphones
Some speakerLoudspeaker
A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
manufacturers recommend a period of break-in, for example by playing white or pink noise.