Terminology
Confused with some of the Terminologies?
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Tuning terminologies can often be intertwined with complex engineering terms. This is largely due to the abbreviations used in tuning conversations, aimed at enhancing communication efficiency. The underlying rationale behind these shortened forms is that uttering the full-length terms can be quite time-consuming. Thus, we’ve curated this page to alleviate the struggle of interpreting these terms, making your tuning journey smoother and more enjoyable.
Here are some frequently used terms in the course
Torque
Engineering Term: torque is a measure of the force that can cause an object to rotate around an axis. Typically measured in Newton-meters (Nm) or foot-pounds (ft-lbs).
ECU Tuning Term: Torque or better yet, Torque% is the percentage value of MBT (Max Brake Torque). For example, 50 Torque = 50% of MBT.
Load
Engineering Term: This term refers to the demand being placed on the engine at any given time, which can vary based on speed, gear, throttle position, and other factors.
ECU Tuning Term: The calculated amount of Volumetric Efficiency. Load is a variable that gets converted a factors and formula. In theory, load should be equal to Volumetric Efficiency, calculated by the ECU.
Volumetric Efficiency
Shared Term: Volumetric Efficiency, or VE is a ratio that measures the amount of air an engine can draw in, compared to its theoretical maximum. 100% Volumetric Efficiency means a 500cc cylinder is filled with 500cc of air. 200% VE means a 500cc cylinder is filled with 1000cc of air (due to the turbocharger)
Max Break Torque
MBT is a term used in engine tuning to refer to the ignition timing advance at which torque is maximized during the combustion process. The goal of tuning an engine to MBT is to achieve the highest possible engine efficiency, which means maximizing the force exerted on the piston and thus the power output of the engine.
In other words, this is the most power that cylinder can produce, at a given load and RPM.
Scaling
In the context of ECU tuning, scaling is the process of adjusting the numerical values that an engine control unit uses to interpret sensor data accurately. For instance, when larger fuel injectors are installed, the ECU needs to be “scaled” to recognize that more fuel is being delivered for a given pulse width.
Duty Cycle
In the context of ECU tuning, a duty cycle usually refers to the percentage of time a PWM (Pulse Width Modulated) valve or gate is open. A fuel injector is one example. For instance, a 50% duty cycle means the fuel injector is open and injecting fuel half of the time of it’s cycle. A higher duty cycle indicates a longer fuel injection time, delivering more fuel to the engine. 100% Duty Cycle means it is open the whole time during it’s cycle.
Lambda
Lambda is a measure of the air-fuel ratio in an engine’s exhaust gases. A lambda value of 1 indicates a “stoichiometric” mixture, which is the ideal air-fuel mixture for complete combustion. Values above 1 indicate a lean mixture (more air), while values below 1 indicate a rich mixture (more fuel).
Delta Value
This term is often used to describe the difference or change in a value. In engine tuning, it could refer to changes in factors such as timing, fuel delivery, or boost pressure. For example, if you compare 7 to 10, the Delta is 3.
Boost
Boost is the amount of air pressure generated by a turbocharger or supercharger that exceeds the normal atmospheric pressure. It’s usually measured in pounds per square inch (psi), or bar.
Ignition Timing
This is the timing of when a spark will occur to ignite the air-fuel mixture in the combustion chamber of an engine. This timing can be adjusted (or “advanced” or “retarded”) to achieve better engine performance or efficiency. Incorrect ignition timing can result in poor performance, or even engine damage.
Absolute
In tuning, ‘absolute’ is often used to refer to a value or measurement that is not relative or dependent on other factors. For instance, absolute pressure refers to the total pressure in a system, including atmospheric pressure, as opposed to gauge pressure, which is relative to atmospheric pressure.
Interpolate
In ECU tuning, interpolation refers to the process of determining a value that lies within two known values in a table or a map. The ECU often does this in real-time to decide the optimal settings for a given situation.
AFR (Air-Fuel Ratio)
This is the ratio of the amount of air to the amount of fuel in the air-fuel mixture that enters an engine. AFR is an important parameter that greatly affects the combustion process inside the engine. A stoichiometric AFR (chemically perfect air-fuel mixture) for gasoline engines is 14.7:1, meaning that for every one gram of fuel, 14.7 grams of air are required.