IGNITION TIMING SIMPLIFIED | The secrets of spark tuning revealed

we all know that here fuel and spark is the recipe for combustion and gasoline engines but from the three spark is probably the least understood and underestimated variable the ignition timing refers to the moment relative to crankshaft angle when the mixture is ignited started in Russian process there is often a misconception that spark is triggered when the piston is at top dead center but the truth is that fuel does not start burning the instant the spark is lit therefore ignition timing must be advanced typically by about 10 to 30 degrees before top dead center the objective behind us is to get the most out of every power stroke by allowing enough time for pressure to build up and achieve its peak approximately between 8 and 12 degrees subject top design the spark advance value that yields the highest torque is known as MVP and it stands for maximum brake torque timing or minimum timing for best torque since pressure is what pushes down the piston generating power it is usually a good reference point to measure performance if ignition starts too late in the cycle the piston can literally run away from the expanding explosion this is especially inefficient for power performance since the build pressure is wasted but it also creates catalyst overheating and higher emission problems as less of the combustion occurs inside the cylinder on the other hand if the ignition starts too soon the pressure will be reached before the piston even gets to top dead center on this scenario the piston find itself fighting against very large forces as it moves up in the compression stroke this often creates a large amount of not therefore possible damage to your engine a typical ignition timing map is composed of two combined tables an MBT map and a NOC map for the MBT map calibrators compare the relationship between spark timing and torque until they find the value that generates the best performance for the knock map timing is slowly advance until knock occurs this point is known as knock limit then that variable is about one to two degrees as a safety margin this is the reason why aftermarket tuners have some area for improvement once these two tables have been established the lowest value for speed and load is selected for the ignition timing up why you ask let's think of an example if NB t occurs at ten degrees before top dead center and not limit is at fifteen degrees there is no reason to go past ten degrees on the contrary let's assume that NB t happens at fifteen degrees before top dead center but not limit is at ten degrees you don't want to damage the engine so the same thing is stable of ten degrees there are many factors that affect ignition timing switches fuel octane air fuel ratio and in temperature engine speed and engine load so let's take a look at this sample ignition timing member on the x-axis we have engine speed in revolutions per minute on the y-axis we have engine load denoting the percentage of measuring take care compared to the theoretical maximum right away we notice that there is a wide range of values but typically our engines regardless of make and model follow the same trend timing decreases lost load increases and it increases as engine speed increases let's understand the reasons behind this since there is higher vacuum at low load timing is increased to compensate for the lack of power as load increases timing is to prevent not from the larger pressure next assuming a constant air fuel ratio a higher engine speed means the flame expansion speed is the same but there is less time between cycles so therefore ignition timing must be advanced to achieve maximum pressure at the optimal point you have probably already noticed that to finalize this map it would take very long time for instance 13 inches beats ten loads 20 ignition timing samples 15 minute per point it would take 39,000 minutes or approximately 81 days in eight-hour shifts this is why calibrators used a method called design of experiments or de where the relationship between the multiple variables is studied by collective strategic sample points between the low and high limits in this specific case 600 to 6000 rpm 10 to 100 percent load and 0 to 35 degrees before top dead center the data is then converted into a mathematical model to display the results graphically and the surface becomes a month finally the last step is collect data outside of your sample pool to confirm the model accuracy and adjust accordingly this greatly reduces the time and resources needed to complete a calibration well that's it for today's episode don't forget to Like and subscribe for more content [Music]

Channel: Engineering Cars Universe

Views: 33,440

Rating: 4.9046106 out of 5

Keywords: Ignition timing, spark timing, engine calibration, engine tuning, how cars work, how engines work, spark plug, gasoline engine, ecu tuning, engine reflash, ignition tuning, how to increase horsepower, how to calibrate ignition, engine animation, EFI, EFI tuning, engine knock, how to prevent knock, what is ignition timing, spark advance, spark retard, BTDC, ATDC, Electronic Fuel Injection, MBT, minimum timing for best torque, maximum torque timing, internal combustion engine

Id: oVIrebbfdlA

Length: 5min 24sec (324 seconds)

Published: Fri Apr 10 2020

Reddit Comments

[u/destroyerx101]

good friend of mine who works for one of the big automotive companies made this video. you dont see these topics covered in good detail like this. Hope you all enjoy it.