High Performance Terms
High Performance Glossary of Terms
Here are some basic automotive performance terms we use at Motiva Performance Engineering:
Basemapping is a creating a graphic representation of the performance generated by an unmodified stock engine’s control module. Basemapping employs computer programs to measure a variety values: fuel-air mixtures at various RPMs and boost pressures, ignition quality, etc., cam timing. An engine’s basemap looks like a 3-D rendering of a slightly crumbled piece of graph paper. The purpose of basemapping to create a computerized representation of the amount of air entering the engine at any given time, specifically the volume of air entering the cylinders of the engine – or volumetric efficiency.
A Blowoff Valve is a pressure-relief system on a turbocharged engine. Its purpose is to prevent compressor surge and reduce wear on the turbocharger. Blowoff valves relieve the damaging effects of compressor “surge loading” by allowing the compressed air to vent to atmosphere, making a distinct hissing sound.
Boost is the increase in pressure generated by the turbocharger in the intake manifold that exceeds normal atmospheric pressure. Atmospheric pressure is approximately 14.7 psi. Anything above this is considered to be boost.
De-tuning is what car manufacturers do to their vehicles at the factory. They adjust the ECU of a car to operatre across the widest range of conditions, fuel octanes, altitudes, etc. This maximizes vehicle manufacturing and production, but restricts the potential power each individual car can produce. Every engine, even directly from the manufacturer, is unique and different. Motiva Performance Engineering’s engine tuners remap the ECU to boost performance according to the wants and desires of their customer, the individual car owner.
Dyno is shorthand for Dynamomter testing. Motiva utilizes an industry standard Dynojet Dynamomter. Motiva tethers a car to be tested on a platform with the drive wheels sitting on drums on the Dynojet test platform. The speed at which these drums turn, plus electronic inputs from sensors mounted through the car’s powertrain, are used to calculate power generated at various points along the car’s drivetrain. The result is a Dynojet graph showing horsepower and torque. Computer programs and other sensors used in conjunction with the Dyno test also provide detailed information in fuel-air mixture rates at various points in the power curve.
An Engine Control Module or Engine Control Unit is an electronic box within the engine that acts as the engine’s “brain” and controls fuel injection and ignition timing and sometimes even Camshaft lift and timing to maximize performance and fuel efficiecny. Motiva Performance Engineering specializes in understanding the factory coding within major manufacturers’ performance models (Ford Mustangs, Chevrolet Corvettes, Camaros and Truck platforms, Chrysler Dodge SRT8 Challengers, Charger, Magnum and 300c) and mating its performance accessories to work with the ECM/ECU to maximize performance.
ECU remapping (tuning) fine tunes the program that controls with engine performance to make the computer chip or “brains” of the engine produce more power at desired RPM settings, to eliminate flat spots in the power curve or produce more torque to avoid low-speed hesitation. Before remapping can occur to boost performance, the engine tuner must first perform an engine basemap to identify potential areas for improvement.
Electronic Fuel Injection is a system for mixing fuel with air in an internal combustion engine. It almost completely replaced carburetors in the late 1980s. Electronic fuel injection systems use computer firmware to precisely measure and inject fuel into the cylinders, according to the power demands of the engine, as determined by throttle input signals. Fuel is supplied to the injector nozzle under pressure from a fuel pump.
Horsepower is a unit of measurement of power. The most common definitions equal between 735.5 and 750 watts. Motiva Performance uses a Dynojet dynamometer to measure HP at the wheels of cars it tests. Motiva can also calculate horsepower losses in areas of the drivetrain to determine where the vehicle is losing horsepower. Horsepower was originally defined to compare the output of steam engines with the power of draft horses. The unit was widely adopted to measure the output of piston engines, turbines, electric motors, and other machinery.
An Intercooler is an air-to-air or air-to-liquid heat exchange device used on turbocharged and supercharged engines. Getting more air to the engine means it can produce more power. But achieving a higher volume through compression heats the air, which is actually counterproductive. That’s because hotter air produces less power than cooler air. An intercooler improves an engine’s volumetric efficiency by cooling the air before it reaches the combustion stage.
Manifold Vacuum in an internal combustion engine is the difference in air pressure between the engine's intake manifold and Earth's atmosphere. Manifold vacuum is an effect of a piston's movement on the induction stroke and the choked flow through a throttle in the intake manifold of an engine. It is a measure of the amount of restriction of airflow through the engine, and hence of the unused power capacity in the engine.
Nitrous is short for Nitrous Oxide, which uses basic chemistry to enhance an engine’s performance. Nitrous comes in liquid form in pressurized bottles. Because of its low boiling point, when injected into an engine intake, it immediately turns to gaseous form. Because nitrous oxide breaks down into nitrogen and oxygen when burned, injecting nitrous oxide during the combustion cycle increases the amount of oxygen in the combustion mix by about 50 percent over normal air. It also acts as a cooling agent for the intake mix. Both the cooling and oxygen boost serve to increase power.
A Supercharger is an air compressor used for forced induction of an internal combustion engine. the greater mass flow-rate provides more oxygen to support combustion than would be available otherwise, which allows more fuel to be burned and more work to be done per cycle, increasing the power output of the engine. Power for supercharger can come mechanically by a belt, gear, shaft, or chain connected to the engine's crankshaft.
Torque, also called moment or moment of force, is the rotational force applied to something such as a wheel rotating about an axis. Torque is also known as twisting force and is measured in foot-pounds. Torque is what breaks the wheel free from the pavement under acceleration. It is also what tightens a nut or a bolt.
A Turbocharger is a gas compressor used to increase the pressure of air entering the engine (forced induction) of both internal combustion engines and external combustion engines. The compressor is powered by a turbine which is driven by the engine's exhaust gases.
A Wastegate is a valve that diverts exhaust gases away from the turbine wheel in a turbocharged engine and helps regulate the rotating speed of the compressor. The primary function of the wastegate is to regulate the boost pressure in turbocharger systems. Often times, this is to protect the engine and the turbocharger, but sometimes this is used to manage power delivery to avoid tire spin.