Don’t know what something means?

 Here is a list of automotive terms that we have put together to help you.



2WD – Only one pair of wheels are driven by engine power

4WD – One or both pairs of wheels are driven by engine power.


ACOUSTIC-TUNED – Tuned for a pleasing sound.

ACTUATOR – A device to open and close a wastegate in response to turbocharger boost pressure.

AIR DENSITY – Number of air molecules within a given space. Greater air density will produce more power. Cool air has a greater air density than warm air.

AIR DUCT – A device to direct air into the engine.

AIR FILTER HOUSING – Enclosure surrounding the air filter element to ensure that air will pass through the filter.

AIR FILTER HOUSING COVER – A removable portion of the air filter housing to allow access and replacement of the filter element.

AIR PUMP – Used to pump air into exhaust system to reduce emissions.

AIR TUBE – Individual nozzle to direct air into exhaust flow for emissions reduction in the exhaust manifold/header.

ALUMINIZED TUBING – Steel exhaust tubing with a thin aluminum coating added to extend the life by minimizing rust.

AMBIENT TEMPERATURE – Natural temperature of outside air uninfluenced by artificial heating/cooling.

ANEROID – A device which limits the smoke of a diesel engine during acceleration by temporarily limiting the amount of fuel injected into the engine cylinders during speed and/or load transients below the steady-state limit.

ATMOSPHERIC PRESSURE – The pressure due to the weight of the earth’s atmosphere. At sea level, this is about 14.6 lb./sq. in. and less at higher altitudes.


BACKPRESSURE – System pressure created in exhaust piping by restrictions to exhaust flow.

BLOWER – A mechanically driven compressor designed to force air into the engine at greater than atmospheric pressure. Blowers typically produce less additional power (vs. turbo/powerpacking) because, unlike turbochargers, they use engine power to run themselves. Blowers create more heat while compressing the air which reduces the air density, producing less power and possibly causing engine damage.

BOOST – A greater than atmospheric air pressure in an engine’s intake system created by turbocharging or supercharging. The additional pressure creates a higher air density which can produce more power.

BOOST GAUGE – A pressure gauge indicating the level of boost above atmospheric pressure.

BOOST PRESSURE – A measurement of boost, usually expressed in pounds per square inch.

BOOST TUBE – An air duct to direct air from a turbocharger’s compressor to an engine’s intake system.


CALIBRATION – (1) Balancing: The setting of delivery of an injection system or the setting of the rack pointer on a single unit pump in relation to predetermined positions of a quantity control member. (2) Adjustment: Fixing fuel delivery and speed adjustments to specified engine requirements.

CAMSHAFT PUMP – An injection pump containing a camshaft to operate the pumping element or elements. It can be classified as “in-line,” “distributor,” “submerged,” ect.

C.A.R.B. (California Air Resources Board) – The standard setting organization of the state of California that regulates and enforces exhaust emissions by motor vehicles.

CARBURETED – A gasoline engine using a carburetor to mix fuel with air in the intake system. Generally replaced by fuel injection systems in later models.

CATALYTIC CONVERTER – A device placed in a vehicle’s exhaust system that contains a substance which reduces emissions upon contact with the exhaust.

CAT-BACK – That portion of an exhaust system behind the catalytic converter extending out to the tailpipe.

CAT-FORWARD – That portion of an exhaust system between the catalytic converter and the vehicle’s engine.

C.D.R. (Crankcase Depression Regulator) VALVE – A valve used to prevent excess pressure from building in an engine crankcase that could cause oil leakage past engine seals. Used in engine ventilation systems on diesel engines.

CHAMBERED MUFFLER – A muffler body with several partitions forming chambers that dampen the exhaust pulsations to quiet exhaust noise.

CHASSIS – The basic frame of a vehicle to which body, engine and suspension are mounted.

COMPRESSOR WHEEL – The impeller wheel in a turbocharger that spins to compress air, creating boost pressure.

CONTROL RACK – The rack or rod by means of which the fuel delivery is regulated.

CONTROL SLEEVE (Control Pinion) – A collar engaging the plunger and having a segment of gear teeth, integral or attached, which mesh with the control rack. By this means, linear motion of the control rack is transformed into rotary movement of the plunger to regulate the amount of fuel delivered by the pump.

CRANKCASE – The lower portion of an engine block below the pistons containing the connecting rods, crankshaft, oil pan and engine oil.

CRANKCASE VENT HOSE – A hose used to route engine combustion gas pressure out of the crankcase and into the engine’s air intake system. The combustion gasses are reburned to reduce emissions.

CROSS-OVER PIPE – An exhaust pipe that joins one exhaust manifold with the manifold on the opposite side of a V8 engine so exhaust may exit through a single pipe. Also known as a Y or T pipe.

CUBIC INCH – The size of an engine relating to it’s air intake displacement.

CYLINDER – That portion of an engine where combustion takes place and pressure is exerted against a piston to turn the engine’s crankshaft.


DIAPHRAGM – The internal portion of an actuator used to open of close a wastegate on a turbocharger.

DELIVERY VALVE ASSEMBLY – A valve installed in a pump, interposed between the pumping chamber and outlet, to control residual line pressures and which may or may not have an unloading or retraction function.

DELIVERY VALVE HOLDER – A device which retains the delivery valve assembly within the pump.

DIFFERENTIAL ANGLE – The difference between the angles of the seat face of the valve and that of the seat in the body provided to insure its effective seating.

DIFFERENTIAL RATIO – The ratio between the guide diameter of the needle valve and the effective diameter of the needle seat valve.

D.I. (Direct Injection) – A diesel engine in which the injected fuel is sprayed directly into the combustion chamber (cylinder). D.I. engines are typically louder than I.D.I. (Indirect Injection Injection) diesel engines.

DISTRIBUTOR PUMP – An injection pump where each metered delivery is directed to the appropriate engine cylinder by a distributing device.


E.F.I. (Electronic Fuel Injection) – Electronically controlled nozzles for mixing fuel with air in an engine’s intake system. EFI  has typically replaced carburetors on late model engines.

E.G.R. (Exhaust Gas Recirculation) VALVE – Feeds a portion of engine’s exhaust back into the intake manifold for a reduction of emissions.

EMISSIONS LEGAL – A product granted an Executive Order exemption by C.A.R.B. or the EPA

ENGINE OIL COOLER – A small radiator that removes heat from and maintains a proper operating temperature of the engine oil.

ENGINE OIL TEMPERATURE GAUGE – A dash-mounted instrument that displays the temperature of the engine oil in degrees fahrenheit.

EXCESS FUEL DEVICE – Any device provided for giving an increased fuel setting for starting only, generally designed to restore automatically action of the normal full load stop after starting.

E.O. (Executive Order) – An authorization granted by C.A.R.B. to allow a product to be advertised and sold in the state of California after meeting criteria that shows it will not adversely affect exhaust emissions.

E.P.R. (Exhaust pressure Regulator) VALVE – Directs exhaust, from an engine’s exhaust manifold, under a carburetor or fuel injector plenum to provide quick warm-up and lower emissions through better vaporization of the fuel. Formerly known as Heat Riser Valve.

EXHAUST MANIFOLD – A pipe with multiple inlets and one outlet for directing the exhaust from each cylinder into a single exhaust pipe.

EXHAUST PORT – The exit opening on an engine cylinder head where exhaust emerges and then flows into an exhaust manifold or exhaust header.

EXHAUST SYSTEM – All parts used to direct exhaust out and away from an engine’s cylinder head to some point on the perimeter of a vehicle. May consist of exhaust manifolds/headers, muffler, catalytic converter and exhaust piping.


FORCED INDUCTION – A method of increasing the air flow into the engine through raising the intake air pressure by turbocharging or supercharging.

FULL LOAD STOP – A device which limits the maximum amount of fuel injected into the engine cylinders at the rated load and speed specified by the engine manufacturer.


GEAR SPLITTER – An optional set of gears added to a vehicle changing the final gear ratio in the driveline to a higher or lower gear ratio. Does not make any additional power, it only moves the engine speed into a higher operating range where it can more easily move the vehicle, but results in a loss of fuel economy.

GLASS-PACKED MUFFLER – A muffler utilizing fiberglass strands packed in a “mat-like” form to absorb exhaust sound. Eventually, these strands either blow out of the muffler or melt together in the form of small pellets like “BBs,” rendering the muffler useless. These mufflers typically have too much restriction and are noisy even when new.


HEADER – A type of exhaust manifold made from formed tubing welded to a steel inlet flange and an outlet collector. less restrictive than a factory iron exhaust manifold and can be “tuned” to provide additional power through scavenging by optimizing tube length.

HEADER, 4-TUBE – A type of exhaust header where tubes from four cylinders join together at the same point in a common collector.

HEADER, TRI-Y – A type of exhaust header where two pairs of tubes from four cylinders each join together in a Y collector, whose outlets join in a third Y collector.

HEAD PIPE – That section of exhaust piping that attaches to an engine’s exhaust manifold at the cylinder head.

HYDRAULIC GOVERNOR – A mechanical governor having a hydraulic servo-booster to increase output force.

HYDRAULIC HEAD ASSEMBLY (Head & Rotor) – The assembly containing the pumping, metering and distributing elements (and may include the delivery valve) for distributor type pumps.


IGNITION INJECTION – A small charge of fuel used to ignite the main gas charge in dual fuel engines.

I.D.I. (Indirect injection) – A diesel engine in which the injected fuel is sprayed into a pre-chamber, where combustion is started and then travels to the main combustion chamber. I.D.I. diesel engines are typically quieter than D.I. (Direct Injection engines).

INJECTION LAG – The time interval (usually expressed in degrees of crank angle) between the nominal start of injection pump delivery and actual start of injection at the nozzle.

INJECTION PUMP – The device which meters the fuel and delivers it under pressure to the nozzle and holder assembly.

INJECTION TIMING – The matching of the pump timing mark, or injector timing mechanism, to some index mark on an engine component, such that injection will occur at the proper time with reference to the engine cycle. Injection advance or retard is respectively an earlier or later injection pump delivery cycle in reference to the injection cycle.

INLET METERING – A system of metering fuel delivery by controlling the amount of fuel entering the pumping chamber during the filling or charging portion of the pump’s cycle.

IN-LINE PUMP – An injection pump with two or more pumping elements placed in a line, each pumping element serving one engine cylinder only. A pump which has the elements arranged in a line and in more than one bank, for instance, in two banks forming a “V,” is a specific case of an inline pump.

INTERCOOLER – A device used to remove the engine heat produced in intake air that has been compressed by a turbocharger or supercharger.

INTERMEDIATE PIPE – A section of the exhaust piping usually used between a catalytic converter and a muffler in an exhaust system.


LEAK-OFF – Fuel which escapes between the nozzle valve and it’s guide. (This term can also be used to describe the leakage past the plunger of a fuel pump.)

LITER – A metric unit of volume to measure the size of an engine relating to it’s air intake displacement.

LOAD-SENSING GOVERNOR – An engine speed control device for use on engine-generator sets to control engine fuel settings as a function of electrical load to anticipate resulting changes in engine speed. It may or may not incorporate a mechanical speed-sensing device as well.


MANDREL BENT – A tube bending process that supports the inside of the tube with a mandrel where the tube is being bent. This prevents the inside of the bend from being flattened, causing a restriction to exhaust flow.

MAXIMUM-MINIMUM GOVERNOR – Any one of the above varieties which exerts control only at the upper and lower limits of the designed engine speed range, intermediate speeds being controlled by the operator setting the fuel delivery directly by throttle action.

MECHANICAL GOVERNOR – A speed sensitive device of the centrifugal type, which controls the injection pump delivery solely be mechanical means.

MOTORHOME, CLASS A – A motorhome constructed on a heavy duty truck chassis.

MOTORHOME, CLASS C – A motorhome constructed on a van chassis, usually having a truck or van cab section with the rear portion only provided by the motorhome manufacturer.

MUFFLER – The component of an exhaust system designed to reduce exhaust noise to an acceptable level.


NATURALLY (Normally) ASPIRATED – An engine that inducts its air only through the use of surrounding atmospheric pressure. (Not turbocharged/supercharged)

NOZZLE – The assembly of parts employed to atomize and deliver fuel the the engine.

NOZZLE BODY -The part of the nozzle which serves as a guide for the valve and in which the actual spray openings can be formed. These two parts, the body and the valve, are considered as a unit for replacement purposes.

NOZZLE and HOLDER ASSEMBLY (Injector) – The complete apparatus which injects the pressurized fuel into the combustion chamber.

NOZZLE HOLDER ASSEMBLY – The assembly of all parts of the nozzle and holder assembly other than those comprised in the nozzle.

NOZZLE HOLDER CAP – The cap nut or other type of closure which covers the outer end of the nozzle holder.

NOZZLE HOLDER SHANK LENGTH – The distance from the top of the cylinder shank to the seating face of the nozzle holder.

NOZZLE OPENING PRESSURE – The pressure needed to unseat the nozzle valve.

NOZZLE RETAINING NUT – The nozzle holder part which secures the nozzle or nozzle tip to the other nozzle holder parts.

NOZZLE TIP – The extreme end of the nozzle body containing the spray holes (may be a separate part).

NOZZLE, CLOSED – A nozzle incorporating either a poppet valve or a needle valve, loaded in order to open at some predetermined pressure.

NOZZLE, DIFFERENTIAL – A closed nozzle provided with a spring-loaded needle valve.

NOZZLE, HOLE-TYPE – A closed nozzle provided with one or more orifices through which the fuel issues. Nozzles with one or more orifice are known as multihole nozzles.

NOZZLE, OPEN – A nozzle incorporating no valve.

NOZZLE, PINTLE – A closed nozzle provided with a spring-loaded needle valve. The body of the nozzle has a large orifice into which enters a projection from the lower end of the needle, this projection being so formed as to influence the rate an shape of the fuel spray.

NOZZLE, POPPET – A closed nozzle provided with an outward opening, spring-loaded poppet valve.


OVER-AXEL PIPE – A portion of the exhaust system bent to go up and over the rear axel of a vehicle.

OVERDRIVE – A set of gears in a transmission or added to a vehicle driveline allowing the engine to turn slower than the driveshaft once the vehicle is up to cruising speed. This is an aid to fuel economy because the engine does not have to run at a high speed.

OVERSPEED GOVERNOR – A mechanical speed sensitive device that, through mechanical or electrical action (operation of a switch), acts to shut down the engine and limit the speed by cutting off fuel and/or air supply should the engine speed exceed a preset maximum.


P.C.V. (POSITIVE CRANKCASE VENTILATION) VALVE – A valve used to prevent excess pressure from building in an engine crankcase that could cause oil leakage past engine seals. Used in engine ventilation systems.

PEAK INJECTION PRESSURE – The maximum fuel pressure attained during the injection period.

PICKUPS, STANDARD CAB – A 2-door pickup with no additional seating behind the standard front seat(s).

PICKUPS, EXTENDED CAB – A 2-door pickup cab with additional seating seating behind the front seat(s).

PICKUPS, CLUB CAB – Another term for “Extended Cab” used by Dodge.

PICKUPS, CREW CAB – A 4-door pickup cab with full seating areas in front and rear.

PICKUPS, SUPER CAB – Another term for “Extended Cab” used by Ford.

PILOT INJECTION – A small initial charge of fuel delivered to the engine cylinder in advance of the main delivery of fuel.

PINTLE VALVE – A special type of a “needle valve” wherein an integral projection from the lower end of the needle is so formed as to influence the rate and/or shape of the fuel spray during operation.

PLUNGER and BARREL ASSEMBLY (P&B’s) – The combination of a pump plunger and it’s barrel constituting a pumping element. The plunger and barrel assembly may also perform the additional functions of timing and metering.

PNEUMATIC GOVERNOR – (1) Vacuum or suction governor: One operated by a change in pressure created by the air actually consumed by the engine. (2) Air Governor: One operated by air displaced by a device provided for this particular purpose and driven by the engine.

POPPET VALVE – An outwardly opening valve used with certain forms of closed nozzles.

PORT CLOSING – A term refering to the fuel injection pump of the port and helix or sleeve metering type in which the timing is determined by the point of the closing of the port by the metering member, corresponding to the nominal start of pump delivery.

PORT and HELIX METERING – A system of metering fuel delivery by means of one or more helical cuts in the plunger and one or more ports in the barrel. Axial rotation of the plunger alters the effective portion of the stroke by changing the points at which helices close and/or open the port or ports.

PORT OPENING – A term referring to a fuel injection pump of the port and helix or sleeve metering type in which timing is determined by the point of the opening of the port by the metering member, corresponding to the nominal end of pump delivery.

PRESSURE ADJUSTING SCREW (Shims) – The screw (shims) by means of which the spring load on the nozzle valve is adjusted to obtain the prescribed opening pressures.

PRESSURE CHAMBER – A plenum chamber that collects and diffuses the compressed air from a turbocharger before it enters an engine’s intake manifold.

PULSE CONVERTER – A Y shaped junction of two exhaust tubes that use the low pressure wave behind the exhaust flow in one tube to help scavenge exhaust from the other tube.

PULSE TUNED – An exhaust manifold that uses selected lengths of tubing along with the principle of pulse conversion to help scavenge exhaust from an engine at a predetermined engine speed.

PUMPING LOSS – Power created by an engine that is lost by pulling air into and pushing exhaust out through restrictions in the intake and exhaust system and within the engine. If these restrictions are reduced, this lost power can be used to propel the vehicle.

PYROMETER – An exhaust gas temperature gauge used to monitor the heat generated in a turbocharger exhaust system to check engine performance. Commonly called an EGT gauge or a Pyro.


QUICK TURBO – A Banks marketing term used to describe products to upgrade a factory-installed turbocharger, such as adding a wastegate. Currently available for the Dodge 5.9 Cummins and Ford Powerstroke pickups.


RAM AIR – Banks product line of high performance engine air intake components. More commonly used to describe air-intake ducting helping to “ram” air into an engine while a vehicle is moving.

REACTION VOLUME – The volume of fuel retracted from the high-pressure delivery line by action of the delivery valve’s retraction piston in the process of the delivery valve returning to it’s seat following the end of injection.


SAC HOLE – The recess immediately within the nozzle tip and acting as a feeder to the spray hole(s) of a hole-type nozzle.

SEATING FACE – The face upon which the nozzle and holder assembly seats to make a gas-tight seal with the cylinder head. Commonly, this face is on the nozzle retaining nut.

SECONDARY INJECTION – The fuel discharged from the nozzle as a result of a reopening of the nozzle valve after the main discharge.

SLEEVE METERING – A system of metering fuel delivery by incorporating a movable sleeve with which port opening and/or port closing is controlled.

SPILL VALVE – A valve used to terminate injection at a controllable point on the pumping stroke by allowing fuel to escape from the pumping chamber.

SPINDLE – A spindle transmits the load from the spring to the valve.

SPRAY ANGLE – The included angle of the cone embracing the axis of several spray holes of a multihole nozzle. In the case of nozzles for larger engines, more than one spray angle may be needed to embrace all the sprays; for example, an inner and an outer spray angle.

SPRAY DISPERSAL ANGLE – The included angle of the cone of fuel leaving any single orifice in the nozzle or tip including pintle type.

SPRAY INCLINATION ANGLE – The angle which the axis of a cone of spray holes makes with the axis of the nozzle holder.

SPRAY ORIFICE(S) – The opening(s) in the end of the nozzle or up through which the fuel is sprayed into the chamber.

STEP UP PIPE – The front part of a two piece over-axel pipe.

SUBMERGED PUMP – A pump with the mounting flange raised to limit pump projection above the mounting face.

SUPERCHARGER – A mechanically driven air compressor designed to increase power in an engine by forcing air into the system.

SUPPLY PUMP – A pump for transferring the fuel from the tank and delivering it to the injection pump.

SWEET SPOT – A range of engine speed where the engine produces the greatest pulling power (torque). The wider the sweet spot, the less shifting the driver will have to do and the better the fuel economy will be. Also known as Peak Torque.


TACHOMETER – A gauge showing engine speed measured in revolutions per minute (rpm).

T.B.I. (Throttle Body Injection) – A fuel injection system having the fuel nozzles centrally located above the throttle blades on the intake manifold. This type of system is used on many GM gasoline engines.

TIMING DEVICE – A device responsive to engine speed and/or load to control the timed relationship between injection cycle and engine cycle.

TORQUE – The force or pulling power that an engine produces.

TORQUE CONTROL – A device which modifies the maximum amount of fuel injected into the engines cylinders at speeds below rated speed to obtain the desired torque output.

T.P.I. (Tuned Port Injection) – A fuel injection system having the fuel nozzles located above the individual intake ports near the intake valves. This type of system is used on many higher performance engines.

TRANSCOMMAND – A fully automatic power and load sensing computer converts the Ford E4OD Transmission into a heavy duty unit only when conditions demand. Reduces clutch slippage and extends transmission life during high power and heavy load situations.

TRANSMISSION COOLER – A small radiator that removes heat from and maintains a proper operating temperature of the transmission fluid.

TRANSMISSION TEMPERATURE GAUGE – A dash mounted instrument that displays the temperature of the transmission fluid in degrees Fahrenheit.

TURBINE – That portion of a turbocharger where engine exhaust spins a set of blades to turn a shaft that drives the turbo compressor.

TURBINE INLET PIPE – A pipe/manifold that directs exhaust gas into the turbine section of a turbocharger.

TURBINE OUTLET PIPE – A pipe that directs exhaust gas from the turbine section of  a turbocharger into the vehicle’s exhaust system. Also known as a turbo down pipe.

TURBINE WHEEL – A series of blades mounted on a wheel that are spun by exhaust gas to turn on a shaft that spins the compressor side of a turbocharger.

TURBOCHARGER – An exhaust driven sir compressor designed to increase power in an engine by forcing air into the engine. Also known as a Turbo.

TURBO DOWN PIPE – A pipe that directs exhaust gas from the turbine section of  a turbocharger into the vehicle’s exhaust system. Also known as a turbine outlet pipe.

TURBO OIL DRAIN – A tube used to return engine oil back to the oil pan (crankcase) after it has flowed through the turbo bearings to lubricate them.


UNIT FUEL INJECTOR – An assembly which receives fuel under supply pressure and is then actuated by an engine mechanism to meter and inject the charge of fuel to the combustion chamber at high pressure and at proper time.

UNIT PUMP – An injection pump containing no actuating mechanism to operate the pumping element(s). It can be classified as “in-line,” “distributor,” “submerged,” ect.


V-8 ENGINE – An 8 cylinder engine consisting of two rows of four cylinders joined together in a V-shape cylinder block.


WASTEGATE – A valve used to bypass exhaust around the turbine section of a turbocharger to control the speed of the turbine shaft to prevent excess boost pressure. This allows the turbocharger to speed up quicker to achieve maximum boost pressure without exceeding the safe maximum.

WATER/AIR SEPARATOR – An air inlet scoop designed to pick up cool air and create a ram-pressure effect while removing rain water and debris that could damage the engine.

WHEELBASE – The distance measured between the centers of the front and rear wheels on a vehicle. This distance often dictates which exhaust components are needed for installation of a Banks kit on Motorhomes.


Y-PIPE – A Y shaped exhaust pipe assembly joining the exhaust manifold on one side of a V-8 engine with the manifold on the other side, to provide a common exhaust outlet for both. Also known as a T-pipe or crossover pipe

Torque explained

POWER is the amount of work (ft. lbs.) that can be done per minute.  


One HORSEPOWER is equal to 33,000 ft. lbs. of work per minute. 550 ft. lbs. of WORK per second or 1,980,000 ft. lbs. of work per hour.


WORK is the amount of force required to move an object a certain distance.

TORQUE = Turning force —- TORQUE is equal to the force times the crank radius measured in (lbs.- ft).

TORQUE BACKUP or TORQUE RISE is the % of RPM drop before reaching PEAK TORQUE.

PEAK TORQUE is the the point at which the pump reaches maximum fuel delivery.

(EXAMPLE) A vehicle is rated 350 HORSEPOWER @ 2100RPM. THe vehicle is currently using all the HORSEPOWER it can develop to pull the load at 2100RPM. The road begins to start a slight incline. As the vehicle travels up the incline RPM will drop, as RPM drops the TORQUE BACKUP will increase fuel delivery and try to hold RPM. As the incline steepens the RPM drops more until PEAK TORQUE is reached. After reaching PEAK TORQUE, RPM will drop dramatically which normally requires a gear change to raise the RPM back to torque range. Lugging an engine occurs when a vehicle is constantly driven in the TORQUE RANGE whether it is from improper shifting or overloading.