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Engine tuning is the adjustment or modification of the internal combustion engine or
Engine Control Unit An engine control unit (ECU), also commonly called an engine control module (ECM), is a type of electronic control unit that controls a series of actuators on an internal combustion engine to ensure optimal engine performance. It does this by re ...
(ECU) to yield optimal performance and increase the engine's power output, economy, or durability. These goals may be mutually exclusive; an engine may be de-tuned with respect to output power in exchange for better economy or longer engine life due to lessened stress on engine components. Tuning can include a wide variety of adjustments and modifications, such as the routine adjustment of the
carburetor A carburetor (also spelled carburettor) is a device used by an internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the venturi tube in the main meteri ...
and ignition system to significant engine overhauls. Performance tuning of an engine can involve revising some of the design decisions taken during the development of the engine. Setting the idle speed, air-fuel ratio, carburetor balance, spark plug and distributor point gaps, and ignition timing were regular maintenance tasks for older engines and are the final but essential steps in setting up a racing engine. On modern engines equipped with electronic ignition and fuel injection, some or all of these tasks are automated but they still require periodic calibration.


Engine tune-up

The term "tune-up" usually denotes the routine servicing of the engine to meet the manufacturer's specifications. Tune-ups are needed periodically according to the manufacturer's recommendations to ensure the vehicle runs as expected. Modern automobile engines typically require a small number of tune-ups over the course of an approximate or a 10-year, lifespan. This can be attributed to improvements in the production process in which imperfections and errors reduced by computer automation, and significant improvement in the quality of consumables such as the availability of
synthetic engine oil Synthetic things are composed of multiple parts, often with the implication that they are artificial. In particular, 'synthetic' may refer to: Science * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic o ...
. Tune-ups may include the following: * Adjustment of the carburetor idle speed and the air-fuel mixture, * Inspection and possible replacement of ignition system components like
spark plugs A spark plug (sometimes, in British English, a sparking plug, and, colloquially, a plug) is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air ...
, contact breaker points, distributor cap and distributor rotor, * Replacement of the air filter and other filters, * Inspection of emission controls, * Valvetrain adjustment. The term "
Italian tuneup Italian tuneup is a slang automotive term for attempting to restore engine performance by driving a car at high engine speed (RPM) and load. The term originated from Italian mechanics in the 1950s using this practice to burn off carbon deposits fr ...
" denotes the driving of a performance car, such as a
Ferrari Ferrari S.p.A. (; ) is an Italian luxury sports car manufacturer based in Maranello, Italy. Founded by Enzo Ferrari (1898–1988) in 1939 from the Alfa Romeo racing division as ''Auto Avio Costruzioni'', the company built its first car in ...
, by mechanics finishing the tune-up to burn out any built-up carbon.


Chip tuning

Modern engines are equipped with an
engine management system An engine control unit (ECU), also commonly called an engine control module (ECM), is a type of electronic control unit that controls a series of actuators on an internal combustion engine to ensure optimal engine performance. It does this by re ...
(EMS)/Engine Control Unit (ECU) that can be adjusted to different settings, producing different performance levels. Manufacturers often produce a few engines that are used in a wider range of models and platforms. This allows the manufacturers to sell automobiles in various markets with different regulations without having to spend money developing and designing different engines to fit these regulations. This also allows a single engine tuned to suit the particular buyer's market to be used by several brands.


Remapping

Remapping is the simplest form of stage one engine tuning; it is performed mostly on
turbocharged In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pro ...
vehicles containing a modern
Engine Control Unit An engine control unit (ECU), also commonly called an engine control module (ECM), is a type of electronic control unit that controls a series of actuators on an internal combustion engine to ensure optimal engine performance. It does this by re ...
(ECU). Almost all modern vehicles have an ECU, primarily supplied by Bosch or Delphi Technologies. The ECU has
firmware In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide h ...
that controls the various parameters under which the engine runs. These parameters include achieving the appropriate balance between fuel consumption, power, torque, fuel emissions, reliability and service intervals. In seeking this balance many factory firmwares do not prioritise power or torque, which means it is possible to increase the performance of the engine by remapping the ECU. Many manufacturers build one engine and use several firmware versions, known as maps, to achieve different power levels to differentiate vehicles that essentially have an identical engine. This gives users an opportunity to unlock more power from the engine with a few changes to the factory software by reading and editing the factory firmware from the ECU using specialist tools plugged into the
on-board diagnostics On-board diagnostics (OBD) is a term referring to a vehicle's self-diagnostic and reporting capability. OBD systems give the vehicle owner or repair technician access to the status of the various vehicle sub-systems. The amount of diagnostic inf ...
(OBD) port. The tools can be connected to the OBD port on any car to read the factory file that is saved on the ECU. Software to read specific types of factory files is available. Parameters of factory files such as fuel injection, boost pressure, rail pressure, fuel pump pressure and ignition timing, are adjusted to safe limits that are set by an expert so the unlocked performance does not compromise the car's safe levels of reliability, fuel consumption and emissions. The map may be customized for city use, for on-track performance, or for an overall map giving power throughout the band in a linear manner. Once adjusted, the edited file is written back to the ECU with the same tools used for the initial reading, after which the engine is tested for performance, smoke levels, and any problems. Fine-tuning is done according to the feedback, producing a better-performing and more efficient engine. Remapping may increase the temperature of exhaust fumes.


Performance tuning

Performance tuning is the tuning of an engine for
motorsport Motorsport, motorsports or motor sport is a global term used to encompass the group of competitive sporting events which primarily involve the use of motorized vehicles. The terminology can also be used to describe forms of competition of two ...
s. Many such automobiles may never compete but are built for show or leisure driving. In this context, the power output, torque, and responsiveness of the engine are of premium importance, but reliability and
fuel efficiency Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, wh ...
are also relevant. In races, the engine must be strong enough to withstand the additional stress placed upon it and the automobile must carry sufficient fuel, so it is often far stronger and has higher performance than the mass-produced design on which it may be based. The
transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission *** ...
, driveshaft and other load-transmitting powertrain components may need to be modified to withstand the load from the increased power. There are many techniques that can be used to increase the power and/or efficiency of an engine. This can be achieved by modifying the air-fuel mixture drawn into the engine, modifying the static or dynamic
compression ratio The compression ratio is the ratio between the volume of the cylinder and combustion chamber in an internal combustion engine at their maximum and minimum values. A fundamental specification for such engines, it is measured two ways: the stati ...
of the engine, modifying the fuel used (e.g. higher
octane Octane is a hydrocarbon and an alkane with the chemical formula , and the condensed structural formula . Octane has many structural isomers that differ by the amount and location of branching in the carbon chain. One of these isomers, 2,2,4-Tri ...
, different fuel types or chemistries), injection of water or methanol, modifying the timing and dwell of ignition events, and compressing the intake air.
Air fuel ratio meter The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing ...
s are used to accurately measure the amount of fuel in the mixture. Fuel weight will affect the performance of the car, so fuel economy (thus efficiency) is a competitive advantage. Ways to increase power include: * Increasing the engine displacement by one or both of two methods: " boring" - increasing the diameter of the cylinders and
piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tig ...
s, or by "stroking" - using a
crankshaft A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...
with a greater throw. * Using larger or multiple carburetors to create a more controllable air/fuel mixture to burn and to get it into the engine more smoothly.
Fuel injection Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines. All comp ...
is more often used in modern engines, and may be modified in a similar manner. * Increasing the size of the poppet valves in the engine, thus decreasing the restriction in the path of the fuel–air mixture entering the cylinder and the exhaust gases leaving it. Using multiple valves per cylinder results in the same effect, though it is often more difficult to fit several small valves than to have larger, single valves due to the valve gear required. It can also be difficult to find space for one large valve in the inlet and a large valve on the outlet side, and sometimes a large exhaust valve and two smaller inlet valves are fitted. * Using larger bored, smoother, less-contorted
inlet manifold In automotive engineering, an inlet manifold or intake manifold (in American English) is the part of an engine that supplies the fuel/air mixture to the cylinders. The word '' manifold'' comes from the Old English word ''manigfeald'' (from th ...
and
exhaust manifold In automotive engineering, an exhaust manifold collects the exhaust gases from multiple cylinders into one pipe. The word ''manifold'' comes from the Old English word ''manigfeald'' (from the Anglo-Saxon ''manig'' anyand ''feald'' old and refe ...
s helps maintain the velocity of gases. The ports in the cylinder head can be enlarged and smoothed to match. This is termed
cylinder head porting Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve their air flow. Cylinder heads, as manufactured, are usually suboptimal for racing applications due to being design ...
. Manifolds with sharp turns force the air–fuel mix to separate at high velocities because fuel is denser than air. * The larger bore may extend through the exhaust system using large-diameter piping and low back pressure mufflers, and through the
intake system An intake (also inlet) is an opening, structure or system through which a fluid is admitted to a space or machine as a consequence of a pressure differential between the outside and the inside. The pressure difference may be generated on the ins ...
with larger diameter airboxes and high-flow, high-efficiency air filters. Muffler modifications will change the sound of the engine, usually making it louder. * Increasing the
valve opening height A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings ...
(lift) by changing the profiles of the cams on the
camshaft A camshaft is a shaft that contains a row of pointed cams, in order to convert rotational motion to reciprocating motion. Camshafts are used in piston engines (to operate the intake and exhaust valves), mechanically controlled ignition systems ...
or the lever (lift) ratio of the valve rockers in overhead valve (OHV) engines, or cam followers in overhead cam (OHC) engines. * Optimizing the valve timing to improve burning efficiency; this usually increases power at one range of operating
RPM Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimensionl ...
at the expense of reducing it at others. This can usually be achieved by fitting a differently profiled camshaft. * Raising the
compression ratio The compression ratio is the ratio between the volume of the cylinder and combustion chamber in an internal combustion engine at their maximum and minimum values. A fundamental specification for such engines, it is measured two ways: the stati ...
by reducing the size of the combustion chamber, which makes more efficient use of the cylinder pressure developed and leading to more rapid burning of fuel by using larger compression height pistons or thinner
head gasket In an internal combustion engine, a head gasket provides the seal between the engine block and cylinder head(s). Its purpose is to seal the combustion gases within the cylinders and to avoid coolant or engine oil leaking into the cylinders. Leak ...
s or by using a milling machine to "shave" the cylinder head. High compression ratios can cause engine knock unless
high-octane fuel An octane rating, or octane number, is a standard measure of a fuel's ability to withstand compression in an internal combustion engine without detonating. The higher the octane number, the more compression the fuel can withstand before detonating ...
s are used. * Forced Induction; adding a turbocharger or a
supercharger In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement. The current categorisation is that a supercharger is a form of forced induct ...
. The air/fuel mix entering the cylinders is increased by compressing the air. Further gains may be realized by cooling the compressed intake air (compressing air makes it hotter) with an air-to-air or air-to-water intercooler. * Using a fuel with higher energy content and by adding an oxidizer such as nitrous oxide. * Using a fuel with better knock suppression characteristics (race fuel, E85, methanol, alcohol) to increase timing advance. * Reducing losses to friction by machining moving parts to lower tolerances than would be acceptable for production, or by replacing parts. This is done In overhead valve engines by replacing the production rocker arms with replacements incorporating roller bearings in the roller contacting the valve stem. * Reducing the rotating mass comprised by the
crankshaft A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...
, connecting rods,
piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tig ...
s, and flywheel to improve throttle response due to lower rotational inertia and reduce the vehicle's weight by using parts made from alloy instead of steel. * Changing the tuning characteristics electronically, by changing the
firmware In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide h ...
of the EMS. This '' chip tuning'' often works because modern engines are designed to produce more power than required, which is then reduced by the EMS to make the engine operate smoothly over a wider
RPM Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimensionl ...
range, with low emissions. This is called de-tuning and produces long-lasting engines and the ability to increase power output later for facelift models. Recently emissions have played a large part in de-tuning, and engines will often be de-tuned to produce a particular carbon output for tax reasons. * Lowering the underbonnet temperature to lower the engine intake temperature, thus increasing the power. This is often done by installing thermal insulation – normally a heatshield, thermal barrier coating or other type of
exhaust heat management Exhaust heat management is the means of lessening the damaging or performance-robbing effects of internal combustion engine exhaust heat by preventing heat from escaping from the exhaust system and into the engine compartment on automobiles. Overv ...
 – on or around the exhaust manifold. This ensures more heat is diverted from the under-bonnet area. * Changing the location of the air intake, moving it away from the exhaust and radiator systems to decrease intake temperatures. The intake can be relocated to areas that have higher air pressure due to aerodynamic effects, resulting in effects similar to forced induction. The choice of modification depends on the degree of performance enhancement desired, budget, and the characteristics of the engine to be modified. Intake, exhaust, and chip upgrades are usually among the first modifications made because they are the cheapest and make reasonably general improvements. A change of camshaft, for instance, requires a compromise between smoothness at low engine speeds and improvements at high engine speeds.


Definitions


Overhaul

An overhauled engine is one that has been removed, disassembled, cleaned, inspected, repaired as necessary and tested using factory service manual approved procedures. The procedure generally involves honing, new piston rings, bearings, gaskets and oil seals. The engine may be overhauled to 'new limits' or 'service limits', or a combination of the two using used parts, new original equipment manufacturer (OEM) parts, or new aftermarket parts. The engine's previous operating history is maintained and it is returned with zero hours since major overhaul. Aftermarket part manufacturers are often the OEM part-suppliers to major engine manufacturers. A "top overhaul" is composed of the replacement of components inside the cylinder head without removing the engine from the vehicle, such as valve and rocker arm replacement. It may include a " valve job". A "major overhaul" is composed of the whole engine assembly, which requires the engine to be removed from the vehicle and transferred to an engine stand. A major overhaul costs more than a top overhaul. "New limits" are the factory service manual's approved fits and tolerances to which a new engine is manufactured. This may be accomplished by using "standard" or approved "undersized" and "oversized" tolerances. "Service limits" are the factory service manual's allowable wear fits and tolerances that a new-limits part may deteriorate to and still be a usable component. This may also be accomplished using "standard" and approved "undersized" and "oversized" tolerances.


Remanufactured

Remanufacturing Remanufacturing is "the rebuilding of a product to specifications of the original manufactured product using a combination of reused, repaired and new parts". It requires the repair or replacement of worn out or obsolete components and modules. ...
means an engine assembled to match factory specifications. A buyer may sometimes take this to mean all-new parts are used, this is not always the case. At least the
cylinder block In an internal combustion engine, the engine block is the structure which contains the cylinders and other components. In an early automotive engine, the engine block consisted of just the cylinder block, to which a separate crankcase was attac ...
will be used. High-quality rebuilds will often include the fitting of new pistons and the line-boring of the crankshaft and camshaft bores. Remanufactured engines are engines that have been damaged, they are sent to machine shops to be remanufactured to the manufacturers specifications. Remanufactured engines are often known as Reman engines.


Blueprinting

Blueprinting an engine means to build it to exact design specifications, limits and tolerances created by its OEM engineers or other users, such as high-performance racing or heavy duty industrial equipment. Because few have the capability to actually blueprint, and because of the monetary incentive of claiming one has performed the work, many people have come to believe ''blueprinting'' only means that all the specifications are double-checked. Serious efforts at blueprinting result in better-than-factory tolerances, possibly with custom specifications appropriate for the application. Common goals include engine re-manufacturing to achieve the rated power for its manufacturer's design and rebuilding the engine to make it more power from a given design than otherwise intended. Blueprinted components allow for a more exact balancing of reciprocating parts and rotating assemblies so less power is lost through excessive engine vibrations and other mechanical inefficiencies. Ideally, blueprinting is performed on components removed from the production line before normal balancing and finishing. If finished components are blueprinted, there is the risk that the further removal of material will weaken them. Reducing the weight of components is generally an advantage provided balance and adequate strength are both maintained, and more-precise machining will generally strengthen a part by removing stress points. In many cases performance tuners are able to work with finished components.


History

Engine tuning originated with the development of early racing cars and the post-war hot-rod movement.


Tools

The 'Igniscope' electronic ignition tester was produced by
English Electric N.º UIC: 9094 110 1449-3 (Takargo Rail) The English Electric Company Limited (EE) was a British industrial manufacturer formed after the Armistice of 11 November 1918, armistice of World War I by amalgamating five businesses which, during th ...
during the 1940s, originally as 'type UED' for military use during World War II. The post-war version, the 'type ZWA' electronic ignition tester, was advertised as "the first of its kind, employing an entirely new technique". The Igniscope used a
cathode ray tube A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms ( oscilloscope), pictu ...
, giving an entirely visual method of diagnosis. It was invented by D. Napier & Son, a subsidiary of English Electric. The Igniscope was capable of diagnosing latent and actual faults in both coil and magneto ignition systems, including poor battery supply bonding, points and condenser problems, distributor failure and spark-plug gap. One feature was a "loading" control that made latent faults more visible. The UED manual includes the spark plug firing order of tanks and cars used by the British armed forces.Manual for the "Igniscope" UED tester, Appendix 1


See also

* Car tuning


References

{{DEFAULTSORT:Engine Tuning Tuning cs:Tuning lt:Tiuningas