How an ignition timing could affect engine performance?
If the ignition timing is too advanced, too much of the gas will burn while the piston is still rising. The work that must be done to compress this gas will decrease the net work produced. These competing effects cause there to be a maximum in the IMEP as a function of ignition timing advance.
What happens when the advance of the spark is increased?
Note that both NO x and HC generally increase with increased advance of spark timing. BSFC and torque are also strongly influenced by timing. Fig. 4.13 shows that maximum torque occurs at a particular advanced timing (called advanced for mean best torque) denoted MBT.
How does ignition timing and spark advance ignition timing work?
Ignition timing and spark advance IGNITION TIMING Most engines (except diesels) use an electric spark to ignite a fuel/air mixture. The fuel burns and powers the car. This electric spark has to happen at exactly the right time or the engine will not run properly. This is called “Ignition Timing”.
What’s the difference between spark advance and vacuum advance?
This is called “Spark Advance”. Older cars had vacuum advances, centrifugal advances, or a combination of both. On newer cars the computer controls the spark advance. A vacuum advance is on the side of the distributor, usually a cone shaped metal unit with a vacuum hose connected to it.
How does the electronic spark advance system work?
However, there is yet another variable to be controlled, which assists the engine control system in meeting exhaust gas emission regulations. The electronic spark advance (ESA) system calculates duration for keeping the electric power on and the timing of ignition, and outputs an ignition signal depending on the crank angle.
Note that both NO x and HC generally increase with increased advance of spark timing. BSFC and torque are also strongly influenced by timing. Fig. 4.13 shows that maximum torque occurs at a particular advanced timing (called advanced for mean best torque) denoted MBT.
Is the ignition timing before or after the spark?
This is always before or after, the piston reaches the top dead center (TDC). Consequently, this measurement is better known as, advanced or retarded timing. If the spark ignites the fuel, before the piston reaches (TDC); the ignition timing is said to be advanced.
What happens when you increase the ignition advance?
Optimum timing from a fixed (locked) ignition advance occurs at only one engine speed. The engine speed operating range affects where the timing is the best. Increasing the timing advance raises the high-end power, reducing the low-end.
How is the spark advance changed in a fast correction?
In the fast correction scheme, the spark advance is decreased for the next engine cycle by a fixed amount (e.g., 5 degrees) whenever knock is detected. Then, the spark advance is incremented in one-degrees increments every 5–20 crankshaft revolutions. The fast correction ensures that minimum time is spent under heavy knocking conditions.