OBJECTIVE: To provide our customers a resource of aftermarket automotive terms which may be difficult to find due to its hobby-specific nature.

Air-to-Air Intercooler - A radiator-like heat exchanger between the supercharger/turbocharger and the engine that utilizes outside air to cool the air entering the intake.

Air-to-Water Intercooler - A radiator-like heat exchanger between the supercharger/turbocharger and the engine that utilizes an external reservoir of coolant to cool the air entering the intake.

All Wheel Drive (AWD) - A vehicle drivetrain with a center differential having all four wheels under power at all times

Aluminize - A metal spray process used to coat engine components subject to high temperatures for long periods of time to increase heat dissipation to the ambient atmosphere.

Anodize - A protective oxide coating to a metal surface using the metal as the anode in an electrical cell and allowing an electrolyte to act upon it.

A-Pillar - The structural support on either side of the windshield, just ahead of the front doors.

ASE - An acronym and registered trademark of the National Institute for Automotive Service Excellence.

Back Pressure - 1. Resistance of an exhaust system to the passage of exhaust gases. This can have an adverse effect on performance, fuel economy, and emissions. Excessive back pressure may be caused by the clogged catalytic converter, or a dented or crimped pipe. 2. The excessive pressure buildup in an engine crankcase.

Blue Printing - To rebuild an engine to original equipment manufacturer (OEM) design specifications.

Boost - "Boost in automotive engineering is a positive manifold pressure in cars with turbochargers or superchargers. Boost is quantifiable as the pressure above atmospheric pressure that the turbocharger or supercharger is creating in the engine's inlet manifold, and is usually measured in bar or PSI (pounds per square inch).

Brake Caliper - The part of a disk brake system that converts hydraulic pressure back to mechanical force that applies the pads to the rotor. The caliper is mounted on the suspension or axle housing and contains a hydraulic piston and the brake pads

Brake Rotor - The disc-shaped component that revolves with-in the hub and wheel. The lining pads are forced against the rotor to provide a friction surface for the brake system, so as to slow or stop a vehicle.

By-Pass Valve - A pressure-release valve that relieves un-needed and potentially hazardous pressures created by the supercharger by recirculating it through the supercharger for later use.

Blow-Off Valve - A blowoff valve (also known as a dump valve, bypass valve or sometimes hooter valve) is a vacuum operated valve that is located after a turbocharger on an internal combustion engine, but before the throttle body butterfly valve and intake manifold. Its use is to vent extra pressure being developed by the turbocharger when the throttle is closed, such as during a shift. During a shift in a car with a manual transmission, the throttle plate is closed. The pressure produced by the turbocharger has nowhere to escape to. This excess pressure could potentially cause damage to the turbocharger's impeller and may also slow or even stop it, thus causing turbo lag when the throttle is pressed again.

CARB - A California agency responsible for regulations intended to reduce air pollution, especially that created by motor vehicles.

Camshaft - "The camshaft is an apparatus used in piston engines to operate poppet valves. It consists of a cylindrical rod running the length of the cylinder bank with a number of oblong lobes or cams protruding from it, one for each valve. The cams force the valves open by pressing on the valve, or on some intermediate mechanism, as they rotate. The relationship between the rotation of the camshaft and the rotation of the crankshaft is of critical importance. Since the valves control the flow of fuel intake and exhaust, they must be opened and closed at the appropriate time during the stroke of the piston.

Catalytic Converter - An automotive exhaust-system component, made of stainless steel, containing a catalyst to reduce oxides of nitrogen (Nox), and/or hydrocarbon (HC), and carbon monoxide (CO), in tailpipe emissions.

Cubic Centimeter (injectors) - An injector's size is measured in how much volume of fuel it can flow in a given period of time. US Domestic injectors are usually measured in pounds per hour (lbs/hr), while injectors for import engines are usually measured in cubic centimeters per minute (cc/min). You can convert between the two: To convert cc/min into lbs/hr, divide cc/min by 10.5. For example, the stock 295 cc/min injectors works out to 28 lbs/hr. To convert lbs/hr to cc/min, multiply pounds per hour by 10.5.

Center Differential - A differential used in four-wheel-drive systems to distribute power to the front and rear differentials. Also called a Transfer Case.

Centrifugal Supercharger - A mechanically driven, forced-induction system using centrifugal force to increase air pressure.

Ceramic Coating - Ceramic coatings are used as a barrier between dissimilar metals to reduce friction, which cause heat, creating unwanted wear of internal engine components. By applying ceramic coatings to these dissimilar metal components, it will allow them to interface with one another more uniformly and compatibly.

Cubic Feet per Minute - Stands for Cubic Feet per Minute. A measurement of airflow that indicates how many cubic feet of air pass by a stationary point in one minute. The higher the number, the more air is being forced through the system.

Chassis - The lower structure of a vehicle to which the body and running gear are attached.

Cubic Inch Displacement (CID) - The metric measure for the volume of space displaced by the piston as it moves from BDC to TDC.

CNC - Computer Numerically Controlled milling machines which have a margin of error as low as one ten-thousandth of an inch; they enable us to cut and shape aluminum pieces, with much greater precision than is possible working by hand alone

Cold-Air Intake - "A cold air intake is an intake system specifically designed to bring down the temperature of the air going into a car for the purpose of increasing the power of the internal-combustion engine. This is achieved by placing the filter element far away from teh motor, where air heated by the engine and radiator are not in it's path. A secondary goal is to increase the appeal of a car by changing the appearance of a car's engine bay and creating an attractive intake noise. These aftermarket parts come in many different colors and many different sizes, and are an inexpensive way to increase performance.

Compression Ratio - The compression ratio is a single number that can be used to predict the performance of any internal-combustion engine. It is a ratio between the volume of a combustion chamber when the piston is at the bottom of its stroke, and the volume when the piston is at the top of its stroke. The higher the compression ratio, the more mechanical energy an engine can squeeze from its air-fuel mixture. Higher compression ratios, however, also make detonation more likely

Compression Test - A test of the engine compression through the spark plug hole to determin if the cylinder is sealing adequatly

Conical Filter - A cone shaped filter that removes dust, dirt, and particles from the air passing into the engine.

Cooling System - 1. An air conditioner. 2. A system of parts that circulates coolant through the engine to remove heat. 3. A system to remove heat from a heat-generating mechanism.

Cylinder - 1. A storage tank for gases, such as refrigerant. 2. The round hole(s) inside and engine block that provide space for the reciprocating piston(s).

Cylinder Head - That part of the engine that covers the cylinders and pistons.

Detonation - A phenomenon of internal combustion where the compressed air/fuel charge explodes violently instead of burning smoothly, usually due to the creation of a second flame front in the combustion chamber, away from the spark plug. Sometimes resulting in an audible knocking noise but always harmful to the engine.

Differential - The section of the rear-axle assembly that provides three functions: it allows the wheels to revolve at different speeds during turns, provides the final gear reduction and changes the angle of drive 90 degrees.

Direct Ignition System (DIS) - A type of fuel-injection system that injects fuel directly into the cylinders.

Disc Brakes - A brake system in which only one of the two pads are energized and move the caliper so that it is caught between both pads.

Double Overhead Camshaft (DOHC) - An engine having a two camshafts mounted over each cylinder head.

Downpipe (Exhaust) - The pipe that exists the back of the turbo and meets either the catalytic converter or exhaust rear section

Driveline - mechanism that transmits power from the engine to the driving wheels of a motor vehicle comprised of the: engine, clutch, flywheel, driveshaft, differential, axle and hubs.

Driveshaft - An assembly of one or two universal joints connected to a shaft or tube used to transmit power from the transmission to the differential.

Dynammeter (Dyno) - A machine on which a vehicle may be driven, simulating actual driving conditions for emissions and diagnostic purposes.

ECM - An acronym for electronic control module. The on-board computer that controls fuel delivery, emissions, and on-board diagnostics, for the vehicle's engine management systems.

ECU - A digital computer that controls engine and transmission functions based on data that it receives from sensors, relative to engine rpm and temperature, air temperature, intake-manifold vacuum, and throttle position.

EFI - A fuel-injection system that injects gasoline into a spark-ignition engine that includes an electronic control to time and meter the fuel flow.

EGR - An emissions-control system that reduces an engine's production of oxides of nitrogen by diluting the air/fuel mixture with exhaust gas so that peak combustion temperatures in the cylinders are lowered.

Emissions - Unwanted, harmful chemicals and chemical compounds that are released into the atmosphere from a vehicle, especially from the tailpipe, crankcase, and fuel tank including unburned hydrocarbons, carbon monoxides of nitrogen, particulates, and sulfur.

Engine Block - The basic framework of an engine to which all other parts and assemblies are installed or attached.

Engine Mount - Precisely engineered with specific shapes, rubber hardness (durometer measurement) and air gaps, called "voids" that mount to the engine to the chassis.

Engine - A device that burns fuel to produce mechanical power; to convert heat energy into mechanical energy.

Equal Length Headers - An exhaust system having equal length tubes from each cylinder to the collector.

Exhaust Manifold - A component, generally of cast iron, with passages of unequal lengths that carry the exhaust gases from the exhaust ports tot the header of the exhaust system.

Exhaust System - "The exhaust system refers to the mechanism which conveys the burnt gases from an internal combustion engine and typically includes a collection of pipes. In the most basic sense, the exhaust system just vents waste gases from the engine. Depending on the overall system design, the exhaust gas may flow through a turbocharger to increase engine power, a catalytic converter to reduce air pollution, and a muffler to reduce noise. Also see Cat-back exhaust and Turbo-back exhaust

Exhaust (Turbo-back) - "Refers to the portion of the exhaust system from the outlet of a turbocharger to the final vent to open air. Turbo-back systems are generally produced as aftermarket performance systems for cars with turbochargers. Some turbo-back (and header-back) systems replace stock catalytic converters with others having less flow restriction. Some systems eliminate the catalytic converter (sometimes called catless or no kitty), which may or may not be legal depending on geographic location and whether the car will be driven on public roads.

Exhaust (Cat-back) - "Refers to the portion of the exhaust system from the outlet of the catalytic converter to the final vent to open air. This generally includes the pipe from the converter to the muffler, the muffler itself, and the final length of pipe to open air. Cat-back exhaust systems are a very popular aftermarket performance enhancement. They generally use larger diameter pipe than the stock system. Good systems will have mandrel-bent turns that allow the exhaust gas to exit with as little back pressure as possible. The mufflers included in these kits are often glasspacks, again to reduce back pressure. If the system is engineered for a rice burner it may be tuned to enhance the lower sounds that are lacking from high-RPM low-displacement engines.

Flywheel - 1. A heavy metal wheel with a starter ring that is mounted at the rear of the crankshaft. It absorbs energy on power stroke(s), return energy on other stroke(s), and transfers power to the clutch or torque converter. 2. Front-most part of a clutch assembly that is bolted to the engine crankshaft with a rear surface to provide a smooth friction area for the disc-front facing to contact during clutch engagement.

Final Drive Ratio - The ratio between the drive pinion and ring gear. The taller the gear the faster the accelleration. One downside to increased final drive ratios is an overall shortening of the time that can be spent in each gear and a loss of gas mileage. Example: a 3.53:1 final drive will accelerate slower than a 3.91:1 final drive.

FMU - An acronym for fuel management units. They act as a fuel pressure regulator for forced induction applications. Mounted inline after the factory fuel pressure regulator, the FMU is boost sensitive and increases the amount of fuel pressure as the boost pressure increases. At idle, or when only moderate throttle is applied, the FMU remains idle and has no effect on the fuel system, allowing the fuel system to retain all of it's stock characteristics for like stock drivability.

Front Wheel Drive (FWD) - A vehicle having its drive wheels located on the front axle.

Fuel - 1. Any combustible liquid, such as gasoline, that can be used to fuel an engine. 2. As slang, any fuel other than gasoline that is used to fuel an engine.

Fuel Filter - A device located in the fuel line to remove impurities from the fuel before it enters the carburetor or injector system.

Fuel Injection - A system that sprays fuel under pressure into the intake manifold or directly into the cylinder intake ports, allowing more precise control of the air/fuel mixture for improved performance, fuel economy, and reduced exhaust emissions.

Fuel Injector - A mechanical or electro-mechanical device that meters fuel into an engine.

Fuel Pump - A mechanical or electrical device used to move fuel from the fuel tank to the carburetor or injectors.

Fuel Rails - A conduit to deliver fuel from the distributor to the injectors of an FI system.

Fuel Pressure Regulator - A device used to control the delivery of gas at a substantially constant pressure.

Fuel Starvation - Fuel starvation in cars occurs in sweeping turns and has a similar effect to lifting in the middle of the turn, sometimes with over 1/2 tank of fuel! Since sweeping turns can be at high speed, this can have disastrous results when driving the car at or near its limits. Additionally, starvation causes a lean condition in the engine leading to possible detonation and expensive engine damage.

Fuel System - The system that delivers fuel to the cylinders, consisting of a fuel tank and lines, gauge, fuel pump, carburetor or injectors, and intake manifold or fuel rail.

Gas Grade (Octane) - Octane ratings measure a gasoline's ability to resist engine knock, a rattling or pinging sound that results from premature ignition of the compressed fuel-air mixture in one or more cylinders.

Gauge - 1. An instrument used for measuring, such as for compression. 2. A dashboard-mounted component used for visual indication of engine and system conditions, such as oil pressure.

Gear Syncros - A device that matches the speed of the gear to that of the drive shaft

Govenor - 1. A device that controls another device, usually on the basis of speed or rpm. 2. A speed-sensitive mechanical assembly in the automatic transmission driven by the output shaft, to supply primary control of when shifting is to occur.

Hard Anodize - Hard-anodizing is used for technical purposes: against corrosion and wear, for electrical insulation, and, by impregnating the surfaces with teflon particles, for achieving low friction.

Head Unit (Supercharger/Turbocharger) - The actual unit of the supercharger/turbocharger

Headers (Exhaust) - 1. A term used for exhaust manifold. 2. A special exhaust manifold with tubes of equal length from the exhaust ports to the header of the exhaust system.

Horsepower - 1.A measurement of mechanical power or the rate at which work is done. 2. A unit of power, 33,000 foot-pounds per minute. One horsepower equals 746 Watts.

H-Pipe (Exhaust) - Similar to an X-pipe but with a tube going across making the shape of an "H"

H.O. - Abbreviation for High Output

Idle - The engine speed with no load and the accelerator pedal fully released.

Ignition - The firing of a spark plug to ignite the air/fuel mixture in the combustion.

Ignition Timing - The timing of the spark, expressed in crankshaft degrees, in relation to top dead center.

Ignition Advantage - The moving forward, in time, of the ignition spark relative to the piston position.

Ignition Retard - The moving back in time of the ignition spark relative to the position of the piston.

Impeller (Turbocharger/Supercharger) - 1. A rotor or rotor blade used to force a gas or liquid in a certain direction under pressure. 2. A rotor that transmits motion such as a centrifugal pump, supercharger, turbine, or fluid coupling.

Intake Air - The air which has entered through the air filter.

Intake Manifold - A metal component used to duct 1. The air/fuel mixture from the carburetor to the intake parts. 2. Air in an injected engine to the intake ports.

Intercooler - A device used on turbocharged and supercharged internal combustion engines to improve the volumetric efficiency and increase the amount of charge in the engine, thereby increasing power. The inter in the name refers to its location compared to the compressors; the coolers were typically installed between multiple stages of supercharging in aircraft engines. Modern automobile designs are technically aftercoolers because they appear at the very end of the chain, but this name is no longer used.

Knock (Engine) - "Technically detonation—in internal combustion engines occurs when fuel in the cylinder is ignited by the firing of the spark plug and smooth burning proceeds but some of the unburned mixture in the combustion chamber explodes before the flame front can reach it, combusting suddenly before the optimum moment of the four-stroke cycle. The resulting shockwave reverberates in the combustion chamber creating a characteristic metallic ""pinging"" sound.

Knock Sensor - A sensor that signals the engine-control computer when detonation is detected, momentarily retarding ignition timing until detonation ceases.

Lean Condition - An air/fuel mixture with too much air.

Limited Slip Differential (LSD) - A differential having special friction mechanisms tending to keep both rear-axle shafts rotating at the same speed, regardless of unequal tire-to-road surface friction.

Lockup Torque Converter - A fluid clutch designed with a clutching assembly in an automatic transmission to improve coupling efficiency at a predetermined vehicle speed.

Long Tube Header (Exhaust) - Engine exhaust headers with longer than standard length primary tubes.

LPH - An acronym for Liters Per Hour. This flow rate is typically used for fuel pumps.

MAS - A device found at the inlet of the intake manifold of an electronic fuel-injection system which supplies the computer with input as to the volume of air entering the manifold, using the temperature differential between a heated platinum wire or a plastic film and the passing air, to generate a signal of varying voltage.

Mandrel Bent - A process of bending seamless tubing with an accurate and precise inside and outside dimension; used in the construction of headers, exhausts and race-car chassis.

Manifold - 1. A device used to hold two or more gauges with fluid passages and flow provisions; used for testing ans servicing purposes. 2. A conduit-like device used to channel the air/fuel mixture into an engine. 3. A conduit-like device used to duct the exhaust gas out of an engine.

MSRP - Manufacturer's Suggested Retail Price

Muffler - 1. A hollow, tubular device used in the lines of some air conditioners to minimize the compressor noise or surges transmitted to the inside of the car. 2. A device in the exhaust system used to reduce noise.

NOS - 1. An acronym for Nitrous Oxide Systems. 2. An acronym for new old stock.

O2 Sensor - A device found in the exhaust manifold, which generates a small voltage dependent on the amount of oxygen present in the exhaust stream, used as a signal to the engine-control computer to determine the amount of fuel necessary to maintain a proper air/fuel ratio.

Octane (Gas Grade) - Octane ratings measure a gasoline's ability to resist engine knock, a rattling or pinging sound that results from premature ignition of the compressed fuel-air mixture in one or more cylinders.

OEM - Original Equpiment Manufacturer

Open Loop - A mode of computer operation in which fuel delevery calculations are based primarily on preprogrammed values, not Oxygen sensor input 2. The Oxygen sensor value is not considered when in Open Loop

Overboost (Turbocharger) - When boost exceedes the pre-determined level in such a waty that it is harmful to the motor.

OHC - A term used for overhead camshaft or overhead camshaft engines.

OHV - An I-head arrangement where the valves are located over the piston in the cylinder head.

PCM - Powertrain control module

Pinging (Knocking) - "Technically detonation—in internal combustion engines occurs when fuel in the cylinder is ignited by the firing of the spark plug and smooth burning proceeds but some of the unburned mixture in the combustion chamber explodes before the flame front can reach it, combusting suddenly before the optimum moment of the four-stroke cycle. The resulting shockwave reverberates in the combustion chamber creating a characteristic metallic ""pinging"" sound.

Piston - 1. An engine part that reciprocates in the cylinder and transfers the force of the expanding gases via the piston pin and connecting rod to the crankshaft. 2. A round, caliper component in a disc brake that is moved outward by fluid pressure to press the pads against each rotor face. 3. An aluminum or sintered-iron component of a drum brake inside a wheel cylinder that supports the cylinder cup. 4. That part of a compressor that is driven by a crankshaft to compress vapor. 5. A small cylinder fitted inside a hollow cylinder which moves back and forth by fluid pressure to transmit reciprocating motion inside the transmission.

Plenum - 1. A chamber containing air under pressure. 2. A chamber containing a gas such as air or an air/fuel mixture under higher than atmospheric pressure.

Plenum/ Angled Plenum Spacer - The billet aluminum spacer sits between the factory upper and lower plenum, creating a larger volume to rush towards the cylinders.

Porting - To enlarge the intake and exhaust passages.

Powertrain - All of the vehicles components that contribute to the generation, transmission, and distribution of drive torque to the wheels.

PSI - An acronym for pounds per square inch. An English measure for pressure or stress.

Radiator - A heat exchanger used to remove heat from the coolant in the cooling system containing a vertical- or horizontal-finned tubing section connected between two tanks.

Rear-Wheel Drive (RWD) - A drivetrain layout that provides power to the rear wheels only. Often referred to an rear drive.

Redline -

Rich Condition - An air/fuel mixture having insufficient air or excessive fuel.

RPM - 1. The number of times a member, such as a shaft, makes a complete revolution in one minute. 2. The rate of speed of a rotating part, such as a crankshaft.

SAE - A professional organization of the automotive industry founded in 1905, the SAE is dedicated to providing technical information and standards to the automotive industry.

Sensor - A device that converts physical quantities such as pressure, airflow, temperature and velocity into electrical signals.

SOHC - An acronym foran engine having one overhead camshaft.

Spark Plug - An ignition component threaded into the cylinder head that contains two electrodes extending into the cylinder that form a gap across which high-voltage electricity arcs to ignite the compressed air-fuel mixture.

Spark Plug Gap - The gap across a spark plug which high-voltage electricity arcs to ignite the compressed air-fuel mixture in the cylinder.

Stainless Steel - A steel alloy that is highly resistant to rust and corrosion.

Supercharger - A compressor which pumps air into the engine's induction system at a pressure much higher than atmospheric pressure.

Suspension - The system that supports the weight of the vehicle and provides for a comfortable and safe ride for the driver and passengers.

Synthetic Oil - 1. A type of engine lubricant consisting of highly polymerized chemicals. 2. A non-mineral based lubricant for use in automotive air conditioners.

Thermostat - 1. A driver-operated device used to cycle the clutch to control the rate of refrigerant flow as a means of temperature control 2. A temperature-sensitive component located in a housing at the coolant outlet of the engine that restricts coolant flow to the radiator to maintain the desired engine-operating temperatures. Often referred to as Ranco control.

Throttle Body - The housing of a throttle-body injection system that contains the valve.

Throttle Plate - A term used for a valve that controls the amount of air admitted into the induction system.

Torque - 1. The measure of a force-producing tension and rotation around an axis. 2. A twisting force which may or may not result in motion.

TPS - A variable three-wire resistor-type electrical sensor which sends a signal to the electronic control unit relative to the throttle position.

Transmission - A gearing device of a vehicle that provides variable ratios between the engine output and the differential input.

Tune Up - A routine maintenance procedure that includes replacing the rotor and spark plugs; in older cars, replacing the rotor, points, capacitor, spark plugs and adjustment of the timing.

Turbocharger - A turbocharger is an exhaust gas driven compressor used in internal-combustion engines to increase the power output of the engine by increasing the mass of oxygen entering the engine. A key advantage of turbochargers is that they offer a considerable increase in engine power with only a slight increase in weight.

Turbo Lag - The short delay in engine response when a driver punches the throttle in a turbocharged vehicle.

Vacuum Hose - An electro-mechanical device used to rid a system of excess moisture and air.

Vacuum - 1. Any pressure less than atmospheric 2. An enclosed space from which all air has been removed, having an absolute atmospheric pressure of near zero.

Valve Cover - The valve cover serves as the covering of the valve trains. This can be removed to adjust the valves.

Valvetrain - The collection of parts that make the valves operate. The valve train includes the camshaft(s), related drive components, the various parts that convert camshaft's rotary motion into reciprocating motion, and the valves and their associated parts.

VIN Number - The vehicle's identification number, located on the left front of the dashboard, which represents various data such as the model of the vehicle, year, body, style, engine type, and serial number.

Wastegate - "wastegate is a valve that diverts exhaust gases away from the turbine wheel in a turbocharger. Diversion of exhaust gases causes the turbine to lose speed, which in turn reduces the rotating speed of the compressor which reduces boost pressure in your engine. The primary function of the wastegate is to stabilize boost pressure in turbocharger systems. The wastegate is controlled pneumatically by a wastegate actuator.

WOT - Acronym for Wide Open Throttle

Wheel Hop - An undesirable suspension characteristic in which a wheel (or several) moves up and down so violently that it actually leaves the ground. Wheel hop can be caused by many problems, including excessive unsprung weight, insufficient shock damping, or poor torsional axle control.

X-Pipe (Exhaust) - An X-shapped pipe that converges two pipes into one and back into two. An X-pipe is used to regulate pressure coming from and going out of the exhaust

Y-Pipe (Exhaust) - A Y-shaped pipe, such as an exhaust pipe, that merges two passages into one.