Car tuning

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Car tuning is the modification of the performance or appearance of a vehicle. For actual "tuning" in the sense of automobiles or vehicles, see engine tuning. Most vehicles stay the factory set up for an average driver's expectations and conditions. Tuning, on the other hand, has become a way to personalize the characteristics of a vehicle to the owner's preference. Cars may be altered to provide better fuel economy, produce more power, or provide better handling and driving.

Car tuning is related to auto racing, although most performance cars never compete. Tuned cars are built for the pleasure of owning and driving. Exterior modifications include changing the aerodynamic characteristics of the vehicle via side skirts, front and rear bumpers, spoilers, splitters, air vents and lightweight wheels. Other visual modifications include different paint schemes or wraps to change the appearance of the vehicle to the owners liking.


Cars have always been subject to aftermarket modification. The golden age of car tuning was the decades between World War II and the beginning of air pollution restrictions. Both moderate and radical modification have been commemorated in the popular songs Hot Rod Race and Hot Rod Lincoln. The names of Abarth and Cooper appear on models styled after the cars they modified. Cosworth went, with support from Ford, from modifying Ford of BritainEnglish Flathead engines for Lotus Sevens to dominating Formula One racing.

In the 1970s and 1980s, many Japanese performance cars were never exported outside the Japanese domestic market. In the late 1980s and early 1990s, grey import vehicles of Japanese performance cars, such as the Nissan Skyline,[1][1][2][3] began to be privately imported into Western Europe and North America. In the United States, this was in direct contrast to the domestic car production around the same time, where there was a very small performance aftermarket for domestic compact and economy cars; the focus was instead on sporty cars such as the Ford Mustang and Chevrolet Corvette, or on classic muscle cars.

Because of their light weight and the increasing availability of low-price tuning equipment, economy and compact cars exhibit high performance at a low cost in comparison to dedicated sports cars. As professional sporting and racing with such vehicles increased, so did recreational use of these vehicles. Drivers with little or no automotive, mechanical, or racing experience would modify their vehicles to emulate the more impressive versions of racing vehicles, with mixed results.

Areas of modification[edit]

The essence of modification of a tuner car is an attempt to extract the greatest possible performance—or the appearance of high performance—from the base motor vehicle through the addition, alteration or outright replacement of parts. Although this largely involves modifying the engine and management systems of the vehicle to increase the power output, additional changes are often required to allow the vehicle to handle this power, including stiffened suspension, widened tires, better brakes, improved steering and transmission modifications such as the installation of a short shifter. Although largely invisible from outside the vehicle, certain modifications such as low profile tires, altered suspension, and the addition of spoilers can change the overall appearance of the car, as well as adding downforce to increase traction.


A stock audio system is one specified by the manufacturer when the vehicle was built in the factory. A custom audio installation can involve anything from the upgrade of the radio to a full-blown customization based around the audio equipment. Events are held where entrants compete for the loudest, highest quality reception or most innovative sound systems. Some common modifications include higher quality speakers and subwoofers, amps, a better wiring system, etc.


All cars competing in each class must adhere to a strict set of regulations. As in some well-known racing events, like NASCAR and NHRA, sanctioned events often require a minimum vehicle weight. In such cases, the interior is stripped, and the required weight is achieved by adding ballast that allows precise control over weight distribution.

Along with weight requirements, safety requirements are present. Requirements differ for different classes. Roll cages, fire extinguishers, reinforced bucket seats, seat harnesses, and the like are some of the required safety modifications. Roll cages may be difficult to install when the original equipment interior is present. Some tuners will have "gutted" interiors, or omit features that many ordinary drivers would find desirable or necessary, such as audio systems, air conditioning and soundproofing in order to reduce vehicle weight.

Engine tuning[edit]

Engine tuning is the process of modifying the operating characteristics of an engine. In a typical engine set-up, there are various mechanical and electronic elements such as the intake manifold, spark plugs, Mass air flow/ Volume air flow, etc. Modern engines employ the use of an ECM to provide the best balance between performance and emissions. Via the OBD communications protocol, the electronically controlled aspects of the engine can be modified in the process known as 'mapping'. Mapping can either be performed by changing the software within the ECU (chip tuning via firmware modification), or by providing false data via plug-in hardware. Mechanical components can also be replaced, such as turbochargers or superchargers.

Other standalone engine management systems are available. These systems replace the factory computer with one that is user programmable.

Improper, incorrect and poorly executed engine modifications can have a detrimental effect on performance. Mechanical and electrical components will suffer or simply fail as a result. An example would be the use of an air compressor such as a turbocharger to increase the volume of air used in power stroke of the otto cycle. In a typical chemical reaction, the air-fuel ratio must be a minimum of 14:1 (see Stoichiometry). If higher ratios are used,[clarification needed] higher pressures and temperatures are observed in the cylinders, which can quickly push an engine beyond its intended design limits. Neglecting such operating parameters can lead to premature failures, such as warped cylinder heads and walls (temperature related), disintegrated piston rings, cracked or bent connecting rods and crankshafts (excessive amount of torque applied), total cooling system failure, engine fire, engine detonation, engine seizing, and even blowouts. This can all lead to very expensive repairs, as well as being very dangerous.

Suspension tuning[edit]

Suspension tuning involves modifying the springs, shock absorbers, swaybars, and other related components of a vehicle. Shorter springs offer greater stiffness and a lower center of gravity at the possible cost of unwanted changes of suspension geometry. Stiffer shock absorbers improve the dynamic weight shifting during cornering and normally have shorter internals to stop them from bottoming out when shorter springs are used. Stiffer sway bars reduce body roll during cornering, thus improving the grip that the tires have on the surface by reducing suspension geometry changes caused by roll; this also improves handling response due to faster weight shifting (similar to stiffer springs.) The danger with overly stiff swaybars is the lifing of the inner wheel, which changes the traction of that end at a discontinuous rate. By increasing the roll resistance of on end, weight transfer is concentrated at that end, causing it to slip more than the other. This effect is used to control the over/under steer characteristic as well as to reduce roll. Other components that are sometimes added are strut bars, which improve the body stiffness and help better maintain the proper suspension geometry during cornering. On some cars certain braces, anti-roll bars, etc., can be retrofitted to base model cars from sports models.

For offroad vehicles, the emphasis is on lengthening the suspension travel and installing larger tires. Larger tires, with or without larger wheels, increase ground clearance, ride over short obstacles and holes more smoothly, provide more cushioning and decrease ground loading which is important on soft surfaces.

These suspension modifications are in contrast to Lowriders with hydraulic or pneumatic suspensions. Lowriders use another type of suspension tuning in which the height of each individual wheel can be rapidly adjusted by a system of rams which, in some cases, makes it possible to "bounce" the wheels completely clear of the ground.

Body tuning[edit]

Body tuning involves adding or modifying spoilers and a body kit in order to improve not just the physical looks of the car, but most importantly, the aerodynamic performance of a vehicle. Through the generation of downforce, cornering speeds and tire adhesion can be improved, often at the expense of increased drag. To lighten the vehicle, bodywork components such as hoods and rearview mirrors may be replaced with lighter weight components.

A Lamborghini Aventador equipped with a Liberty Walk widebody kit and aftermarket wheels.

Often, body modifications are done mainly to improve a vehicle's appearance, as in the case of non-functioning scoops, wide arches or other aesthetic modification. Aftermarket spoilers or body kits rarely improve a car's performance. The majority, in fact, add weight and increase the drag coefficient of the vehicle, thus reducing its overall performance. Roof chops and sectioning the body are also used to improve aerodynamics, dating back to the 1940s.

Increasing the wheel track width through spacers and wide body kits enhance the cars cornering ability. Lowering the center of gravity via suspension modifications is another aim of body tuning. Often, suspension tuners unfamiliar with spring dynamics will cut stock springs, producing a harder, bouncy ride. It is also common to lower the car too far, beyond the optimal height for performance, purely for appearance.

Competition cars may have lightweight windows, or the windows may be completely removed, as auto glass adds significant weight high up. Plastic windows are much more vulnerable to scratches which reduce service life.


Tires have large effects on a car's behavior and are replaced periodically, therefore tire selection is a very cost-effective way to personalize an automobile. Choices include tires for various weather and road conditions, different sizes and various compromises between cost, grip, service life, rolling resistance, handling and ride comfort. Drivers also personalize tires for aesthetic reasons, for example, by adding tire lettering.


Detuning is returning a modified car to its original factory status or reducing its performance in a particular area of tuning. For example, a car may be "detuned" to allow increased traction where the track grip is not sufficient to handle the increased power of the tuned engine.

Styles of modification[edit]

Modified cars can be significantly different from their stock counterparts. A common factor among owners/modifiers is to emulate the visual and/or performance characteristics of established styles and design principles. Sometimes these similarities are unintentional. Some of the many different styles and visual influences to car modification are:

  • An example of a Rat rod style car
    Rat rod /Rat style: Style of hot rod and custom cars, imitating the "unfinished" appearance of some hot rods in the 40s, 50s, and 60s. Rat style also defines a car that is kept on the road no matter what, and at a low cost
  • Euro style: One-off paint/small wheels and lowered or stance'd with shaved features to define car body lines.
  • Lowrider: Hydraulic setups, flashy paint, custom interior, bling wheels. Others may look like straight restorations, aside from a low stance.
  • Import scene /JDM: Japanese Scene that uses Japanese vehicles, aftermarket parts and Race details.
  • DUB/DONK: Extremely large designer wheels, loudspeaker set-ups, and abnormally high ride height.
  • SLAB: Originated in the Houston, TX area since the mid-1980s - usually a full-size luxury car (primarily a Cadillac, Buick, Oldsmobile, or Lincoln inclusive with several lowered-tier brands e.g. Chevrolet, Ford, Chrysler; in recent years some malaise era GM front wheel drive luxury sedans and imports e.g. Mercedes-Benz, Jaguar, Lexus are included), custom wire wheels (primarily the discontinued Cragar Star Wire originally optioned for the 1983 and 1984 Cadillac Eldorado now manufactured by Texan Wire Wheels) fitted with Vogue Tyres (known as 83s, 84s, Swangaz, Elbows), loud speaker set-ups (same as the DUB/DONK), neon signage inside the trunk panel, hydraulic-actuated trunk panels (known as a pop trunk), flashy paint (several coats of clearcoat on a paint job known as candy paint (named after the Jolly Rancher or Now & Later candy products), vertical stainless steel trim on the trunk panel (known as belt buckles) aftermarket grille (similar to a Rolls-Royce or Bentley as homage to the 1970s-era pimpmobiles), and the use of a Cadillac front end sheetmetal conversion (from the use of 1990-92 Brougham sheetmetal or if a large truck or SUV, the front sheetmetal from an Escalade). Vehicle interior usually clad in beige or tan (known as peanut butter interior), and a Grant GT steering wheel clad in woodgrain (known as a Wood Grain Wheel). Usually connotated with Houston Hip Hop music.
  • Bōsōzoku/zokusha: This Japanese motorbike style features additional fairings and exaggerated exhausts.
  • VIP style: Japanese style that evolved from Bōsōzoku that emulates the Extreme style with a more modern vibe, e.g. ridiculously low ride heights, camber, body kits, lights.
  • A MK3 Volkswagen Polo displaying the "stanced" look with aftermarket air suspension, light blue paint and BBS RM wheels with negative camber.
    Stance (vehicle): – This style is mostly associated with lowered sports cars, sedans, hatchbacks, vans and other body styles of passenger cars. Such cars are lowered with a help of sports springs, coilovers or air suspension components. Custom wheels with low profile tires (sometimes stretched) play a big role in this style and often feature aggressive sizes, offsets, and camber.
  • Cal Look: Classic beach look (bright colours and polished) and subtle features added to give a California sense.
  • Military/service style: Cars designed to look like certain service vehicles (e.g. Military, Navy, Police).
  • Hot rod: Style largely consisting of period specific vehicles, components, and finishes to reproduce characteristics of early Drag-rods from the 1930s and 1940s.
  • Custom cars: Cars built for the showroom floor can be any manner of car.
  • Sleeper (car): This is where a car owner will put every effort into performance and try to keep the car looking stock, usually to avoid raising suspicion.
    A Nissan 350Z modified for drifting.
  • Rallying: Cars built to compete in events known as 'rallies', made of closed-roads timed sections, and road sections, and where a co-driver is present in the car to read pace notes.
  • Drifting (motorsport): Cars engineered to drift (skid in a controlled manner).
  • Drag racing: Cars engineered for straight-line acceleration.
  • South London Look: Subtly modified 50's-70's British Fords that are lowered, pastel paint, 13 inch Lotus Cortina steels or RS, Minilite, Revolution mag wheels. Often running a tuned Ford Kent, Pinto engine.
  • German Look: A VW Type 1, Type 3 or Karmann Ghia lowered and fitted with late model Porsche mag wheels and touring car influenced styling. Heavily modified suspension and drivetrain with emphasis on handling and cornering.

Some useful terminology[edit]

  • Map - A calibration for the engine management system, an electronic system known interchangeably as PCM (Powertrain Control System) or ECU (Engine Control Unit). A map is essentially a data file that gives the PCM the elements it needs to operate the engine according to the standards set by the manufacturer. The data is mostly organized in lookup tables known as "maps", and the set of tables and other parameters is referred to as "a map" or "a calibration".
  • Tune - A modified map, most often aimed at increasing the engine torque and power output. A tune is 'flashed' to the PCM or ECU either by the tune vendor or the end-user itself, often using a stand-alone accessory connected to the car's OBDII connector, or through a special cable connected to a portable computer. A tune typically voids the powertrain warranty, unless sanctioned by the car manufacturer (most tunes are not). Typical changes include modified ignition timing, modified fueling, modified wastegate control on turbo engines, and modified limits such as RPM limits, boost limits etc).
  • Tuner - An individual or company creating tunes, usually for profit, and often selling supporting elements such as intakes and exhausts.
  • Stock Map or Stock Tune - The OEM calibration.
  • OTS Map or OTS Tune - An Off-the-Shelf tune sold together with the accessory used to flash tunes to a car's engine control unit. The OTS tunes typically offer modest performance improvements and are often used as bases for further modifications.
  • Custom Tune - A tune that has been customized for a particular car, often modified in specific ways that require some adjustments to the OTS calibration.
  • Rolling Road - A chassis dynamometer, often simply called "a dyno", which includes a metered brake that allows torque measurements, as well as speed measurements, which enable to measure the torque and power produced at the wheels. Together with the inferred transmission ratio and a number of corrections related to atmospheric conditions and friction and losses, the software associated with the dyno can produce estimates of the flywheel power and torque figures.
  • Dyno - A chassis dynamometer.
  • Hub dyno - A chassis dynamometer where the dyno's brakes are connected directly to the driven wheel's hubs after the wheels have been removed. Those dynos are more accurate than rolling road dynos as they eliminate one significant source of slippage (the tires), producing more accurate results. Hub dynos are also more compact, the hub brakes being the size of small laundry wash machines.
  • Pull - A full-throttle RPM sweep in straight-line on a level street, or on a rolling road (dyno), usually in 3rd or 4th gear and from low RPMs all the way to the engine speed limiter. Pulls are made to record logs (see below) or to measure torque and horsepower on a chassis dyno.
  • Log - A recording of the engine operating parameters (RPM, throttle position, boost pressure, various temperatures...) made using a device connected to the car's OBDII connector and usually collected during one or more pulls.
  • eTuner - A tuner working remotely to provide custom tunes via email, usually after the customer sent recordings (logs) of one or more pulls on the street.
  • FBO - Full Bolt-Ons - A car which has all the (engine-related) add-ins that can literally be bolted-on without extensive modifications. These include aftermarket air intakes, intercoolers, and exhaust piping and mufflers. Those are often described as "supporting mods" or "supporting hardware" going along with a "tune".
  • Stage 0 - Stock performance.
  • Stage 1 - The state of the car after the first round of modifications, which can be just a tune, or a tune along with simple supporting modifications such as an aftermarket air filter element, or an aftermarket intake. Stage 1 implies a modest power/torque increase over stock.
  • Stage 2 - The state of the car after more extensive add-ons have been installed, typically "FBO", with a "tune" targeting higher torque and power than Stage 1, with optional "forging" (see below).
  • Stage 3/4 - A car with extensive mechanical modifications made to the powertrain, sometimes including a bigger turbocharger for cars so-equipped, forged internals, head work (flowing, uprated camshafts, larger valves) and fuel-system modifications such as secondary injector rail (to augment the engine's fuel-flow capacity, or to inject alternative fuels) and sometimes an aftermarket or motorsport ECU, which is said to be "mapped" or "calibrated" specifically for that car. The power and torque outputs at this stage are significantly higher than stock, often prompting supporting modifications to the transmission and drivetrain.
  • Forging - Replacing some of the engine's bottom-end internal elements by forged-metal ones. The most common "forging" includes forged connecting rods, and forged pistons. Stage 3 cars can sometimes include a forged crankshaft. Forged-metal elements are usually lighter and stronger than cast-metal ones.
  • Catback - The portion of the exhaust system downstream of the catalytic converter.
  • Turboback - The entire exhaust system from the turbine housing of the turbocharger, composed of the downpipe (including the catalytic converter) and the "catback" portion.
  • Resonator - A noise-reduction device inline with the exhaust pipe and usually straight-through, which dampen sound waves by the means of packed absorption material placed around a perforated tube section. Exhaust systems equipped with one or more resonator(s) are said to be "resonated", as opposed to "non-resonated" for those without such devices.
  • Decat - A straight exhaust downpipe without a catalytic converter. On some vehicle, decat downpipes allow flames to be visible at the exhaust tips on throttle closure.
  • Burbles - Fake exhaust noises generated by the PCM on throttle closure by combining lean combustion and retarded ignition, that mimics a rally car's anti-turbo lag system (ALS), also known as "bang-bang" but without any anti-lag effect (the burbles are just "cosmetic" sound effects). The Ford Focus RS (2016+) is one notable example of cars with a burble feature from the factory. Some tuners propose tunes with increased or decreased sound effects, depending on the owner's preferences.
  • FENG - Fake Engine Noise Generator, often called "syntonizer", a system, either acoustic or electronic, that diffuses additional engine-related noise in the cockpit, to enhance the driver's experience. On some cars (like the Ford Focus RS 2016+) the noise is computer-generated and bears no real relation to the noise of the engine itself. On other cars, the noise is conveyed by an acoustic pipe from the engine bay to the cockpit, and other systems probably exist.
  • FMIC - A front-mounted intercooler. Nowadays most turbocharged cars have their intercooler mounted frontally behind the front bumper but the term comes from the Subaru Impreza who had its intercooler mounted in an unfavorable location on top of its boxer engine. Past a certain level of power increasing modifications, the small and ill-placed intercooler becomes ineffective, and a popular modification to overcome this limitation was to install an aftermarket intercooler in the "normal" position behind the front bumper, thus the term FMIC.
  • Turbo Lag - The delay between the throttle opening and the moment the turbocharger has spooled up sufficiently to deliver significant boost pressure and the associated torque and power rush. On stock modern turbos, the lag is usually inferior to one second, while some big aftermarket turbos exhibit lags sometimes of two seconds or more.
  • BOV - Blow-off valve, a valve that let the boost pressure escape on throttle closures on turbocharged engines. A BOV can vent either to the intake system, prior to the turbocharger (this type of BOVs is essentially silent and known as "recirculating"). Other BOVs vents to the atmosphere, creating a sometimes loud Pschhhhhh! sound on throttle closures. Some BOVs vent partially to the atmosphere and recirculate the rest. All kinds of properties are associated with BOVs, the most common being to reduce turbo-lag, an assertion still needing to be proved. What they certainly do is they avoid pressure surge in the "hot" intake side (between the turbo compressor outlet and the throttle) and thus avoid popping the pipes or the intercooler. Venting the unused pressure is also easier on the turbocharger, reducing the surge that would normally occur on sudden throttle closure, and thus probably helps with the longevity of the turbocompressor's bearings.
  • CAI - Cold Air Intake, a modified replacement intake system, often suppressing the OEM airbox entirely, supposed to help the engine breath cold air (as opposed to hot air from under the bonnet). In fact on most modern cars, the inlet ducts have been developed following a great amount of CFD and NVH studies using state-of-the-art flow simulations, and it is *very* unlikely that any small independent fab could outperform, or even match, the OEM intake performance. CAIs are mostly associated with their increased induction noise more than with any tangible performance benefit. A CAI, coupled with an atmosphere-venting BOV on turbocharged cars, and a "non-resonated" and sometimes "decat" exhaust are often the early mods made by owners interested primarily in increasing the noise level of their cars, modifications providing little or no performance improvement.
  • Meth - A water-injection system where a mixture of de-ionized water and a certain proportion of methanol is injected in the intake air stream as an anti-knock, usually using a dedicated pump and reservoir, and where the unmetered injection is triggered by a pressure switch activated once a certain boost level is reached on supercharged/turbocharged engines, through one or more nozzles either at the turbo discharge (before the intercooler), after the intercooler, or in the inlet manifold. In some cases, the windscreen washer fluid reservoir is used as a tank for the water injection system (and still functions normally). Water injection is believed to have appeared shortly before WWII on aero engines notably the Rolls Royce Merlin powering the Supermarine Spitfire and later the Mustang P51-D, and the German's Juno engine powering the Bf109, following the pre-WWII work of Sir Harry Ricardo. The methanol in the mixture injected in aero engines was present strictly as an anti-freeze, as it reduces the effectiveness of water as an anti-knock adjuvant.
  • 30 roll - A two-car straight-line race, often between tuned cars, starting from a steady 30 mph speed where the two drivers stand side-by-side, and where one of the two drivers signals the rolling start by honking 3 times. The acceleration test ends at a pre-defined speed, e.g. 60 mph or 80 mph, and the car in front is said to have 'gapped' the other one. One car length is a fair gap while 3 car lengths is considered to be a lot. In the USA, those unofficial and often spontaneous races, whose videos are often published online, are frequently said to have happened "in Mexico".
  • Dig, from a dig - A race beginning from a standing start, e.g. from a traffic light.
  • RICE - Race Inspired Cosmetic Enhancement - Modifications that mimic proper race cars (including mud flaps on streetcars, aerodynamic appendices such as extra spoilers, "splitters", wings, winglets or wing extensions) whose effectiveness is doubtful (or at least unproven) but give the car some aspects of the appearance of a race car, sometimes on cars which are not even the sporty model of the line.
  • RICER - The owner of a RICE car (note the humorous deviation from Race Car)
  • Jacky (France) - a RICER.

Legal requirements[edit]

Many countries or municipalities have legal requirements which govern vehicle modifications. For example, all vehicles in Victoria, Australia, must conform to construction standards to ensure vehicle safety.[4] There are also restrictions for P Plate drivers which can prevent young drivers from driving modified vehicles.[5]

Many developed countries have "smog rules", which generally forbid any modifications to engines or related components, unless the modifications themselves are type smog certified, like production car models. Such modifications, even if they do not actually result in increased emissions, prevent legal use on public roads.[6]

Sanctioning organizations[edit]

Many organizations involved in competitive motorsports establish safety guidelines that far exceed legal requirements placed on street-legal vehicles. The NHRA, IHRA and SOLO programs all require that vehicles pass inspection to ensure that all regulations are being complied with.

See also[edit]


  1. ^ a b Chang, Richard (Summer 2008), "Access Denied", 0-60 Magazine
  2. ^ LeftlaneNews R32, R34 Nissan Skyline imports halted
  3. ^ LASD Inmate Information Center - Booking Details Archived December 16, 2009, at the Wayback Machine
  4. ^ Vehicle Standards Information Bulletins Archived September 13, 2007, at the Wayback Machine
  5. ^ High Powered Vehicle Restrictions Archived September 14, 2007, at the Wayback Machine
  6. ^ an old issue of Hotrod Magazine