What is the Q word in the 4 100Q engine for?

4 100Q engine represents four cylinders, and the cylinder diameter is 100. As for Q, some represent several generations, such as Q2. Theoretically speaking, the second-generation ignition advance angle of this engine should be calculated according to the flame propagation speed, the combustion time of the mixer and the rotating speed, but it can be said that the first two can not be accurately calculated. So in fact, the ignition advance angle is "tried". The most sensitive control quantity to the ignition advance angle is the rotational speed. With the increase of rotating speed, the ignition advance angle increases. When idling, the ignition advance angle can be as small as 0 degrees, and when the speed reaches five or six thousand revolutions, the ignition advance angle can reach 40 degrees. A more accurate range is generally found in textbooks, so you can look it up. On the basis of the above, parameters such as throttle opening, air intake, water temperature and air temperature will also affect the ignition advance angle, so you can't calculate it by providing the engine model.