So if an internal combustion engine is idling, when we add more gas/air by opening the throttle why does the engine accelerate? Do the explosions in the cylinders increase in velocity? I would have assumed that the explosions occur at the same speed regardless of the amount of fuel/air in the cylinder. So I don’t understand why the engine rpm increases.
thanks
In: Engineering
The explosions absolutely change in strength and in timing.
Accelerating the engine, you want the spark plug to fire earlier in the rotation of the engine, because a fire does take a specific time go get to maximum compression, and that time doesnt change, but if the engine is spinning faster, the spark has to happen earlier in the crankshafts rotation in order to be making maximum compression when the piston starts its downtravel on the ‘power’ stroke.
And an explosion isnt equal at idle and wide open throttle. You get a lot more air with the throttle blades open, which requires a lot more fuel to burn at optimum mixture (stoichiometric ratio if you’re interested) which is about 14.7:1, air (in weight) to fuel. Adding 1cc of air and the appropriate amount of fuel is not the same explosion as 1000cc of air and the proper amount of fuel
Latest Answers