Car engines?

Question

Why does an internal combustion engine go faster just because you feed it more fuel and air. The burning of fuel in the combustion chamber has a fixed and maximum rate of burn so how can it speed up?

Answer 1

Horsepower = torque X rpm/5250 assuming that the torque is constant for argument's sake, you can see that increasing rpm's alone will give you more power which allows you to go faster. Higher rpm's mean that the engine is consuming more fuel and air. Just like when you run faster you burn more calories and breathe harder.

But, to answer your question, your engine goes faster when you feed it more fuel and air because limiting fuel and air is its natural brake. The Int. com. eng. is a runaway design. Give it enough fuel and air and it will destroy itself.

Answer 2

The burn rate may not change, but it happens so fast that it really doesnt relate to the question. The key to understand is that the more fuel and air you cram into the cylinder, the more chemical energy potential you have, and when the mixture is burned, that chemical energy is converted into heat, which causes the gases to expand in the cylinder, pushing the piston down. The expansion of the gas transfers that heat energy into mechanical energy in the form of the piston moving down. The more energy put into the cylinder, the more energy you'll get out of the piston as it moves, in essence, speeding up the engine (if the load on the other side is not increased).

I guess there would be a theoretical RPM where the gas burning could not keep up with the piston movement, but it would be well beyond a normal engine operating range.

Answer 3

More fuel and air igniting in the same volume gives a greater pressure. The fuel burns almost instantaneously so the engine speed is relatively slow compared to the speed of combustion. The greater pressure acting on the same area gives a greater force, since the mass is constant this force causes an acceleration.
The main limitation on engine speed is the time it takes for the valves to close and provide an effective seal for the combustion chamber.

Answer 4

The speed does not depend upon the amount of fuel but due the mechanisim of internal combustion.The ignition plug when it gives out the first spark,a small part of the air and fuel mixture is burnt at the same instant a number of hot spots this leads to combustion at large rate,thus producing large amount of energy giving high speed as output

Answer 5

THe more proper air-fuel mixture fed into the engine, the more powerful the explosion in the cylinder, the more powerful, the faster the piston is driven downward, and also the return to the upstroke, thus resulting in more speed.