Engine tuning


Engine tuning is the adjustment or modification of the internal combustion engine or Engine Control Unit 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 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.
Tune-ups may include the following:
The term "Italian tuneup" denotes the driving of a performance car, such as a Ferrari, by mechanics finishing the tune-up to burn out any built-up carbon.

Chip tuning

Modern engines are equipped with an engine management system /Engine Control Unit 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 vehicles containing a modern Engine Control Unit. Almost all modern vehicles have an ECU, primarily supplied by Bosch or Delphi Technologies. The ECU has firmware 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. Many factory firmware fail to utilise the full potential of the engine, and as such leave the end-user with an under-tuned engine.
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 potential 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 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 motorsports. Many such automobiles 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 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, driveshaft and other load-transmitting powertrain components may need to be modified to withstand the load from the increased power.
Some people are interested in increasing the power output of an engine. Many techniques have been devised to achieve this, all of which operate to increase the rate and sometimes the efficiency, of combustion in the engine. This is achieved by putting more air-fuel mixture into the engine, increasing the compression ratio that requires higher octane gasoline, burning it more rapidly, and removing the waste products more rapidly to increases volumetric efficiency. Air fuel ratio meters are often used to check the amount of the air/fuel mixture. The weight of this fuel will affect the performance of the car so fuel economy is a competitive advantage. The performance-tuning of the engine should take place in the context of the development of the vehicle.
Ways to increase power include:
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 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

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 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

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 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, 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.