Why does the car exhaust pipe spit fire?

Many attentive riders will notice that many supercars, modified cars and racing cars will spit fire from their tails when shifting gears, cornering or even braking, and they will make a bursting sound, which is very shocking. Someone can't help but ask: What is the principle of the rear end of the car? Does breathing fire harm the car? Most importantly, will my family car spit fire?

There are two common types of exhaust pipes, one of which is a modified car: a straight exhaust system with a shorter exhaust system. In order to make the engine more powerful when the engine speed is high, the fuel injection will be enriched, causing part of the unburned fuel to be discharged into the exhaust pipe to continue burning, and sometimes you can hear the "boom" of the exhaust pipe firing.

The other is the off-time ignition system (the fuel is still injected when the throttle is closed, but the ignition time is later than usual or even no ignition, allowing gasoline to enter the exhaust pipe to be ignited by high temperature, and the resulting explosion impacts the turbine rotor, making the turbine rotor It can continue to rotate at high speed when collecting oil, and be ready for the next pressurization).

The first one is easy to understand, and the second one is not very well-recognized. Let's talk together.

Principle of off-time ignition system:

The existence of the off-time ignition system is to eliminate turbo lag. The principle of the off-time ignition system is very simple. When the accelerator is loosened such as turning or decelerating, the ECU will order the car’s fuel supply system to inject a large amount of gasoline into the engine, but it will not Ignite, let these misty gasoline pass through the engine directly into the exhaust system with extremely high temperature (about 800 to 900 degrees Celsius) without burning. When the mist of gasoline enters, it will automatically detonate due to high temperature. Use the generated pressure to push the turbine blades to continuously accelerate, so that the car can maintain the speed of the turbine blades even when decelerating (about 14000-20000rpm), thereby eliminating the phenomenon of turbo lag, so that the car has both turbocharged horsepower and Has the smoothness of natural inhalation. Moreover, the powerful explosion flame will also rush along the exhaust pipe all the way to the tail pipe, so when the off-time ignition system operates, sparks will be ejected from the exhaust pipe!

The working principle of car turbocharging is to use the pressure in the exhaust manifold to push the turbine (that is, a kind of fan) to rotate. This fan is like a blower, which can increase the air flow in the intake manifold, thereby improving the engine. Combustion efficiency, thereby increasing vehicle power. When the car is receiving oil or shifting gears, even the shift time calculated in milliseconds will reduce the engine speed due to the decrease in the engine fuel supply, which will cause the exhaust manifold pressure to decrease, and then further cause the turbine speed to drop. The final result is an increase. The pressure value decreases and the engine power decreases. At this time, fuel is added. First, the fuel must be burned in the engine, and then the exhaust gas enters the exhaust manifold, and then pushes the turbine to rotate, and then the intake air volume increases, and then the engine will restore the original power, which is the so-called turbo lag.

The principle of off-time ignition is that when the fuel is collected, the ECU will force the injection system to continue to inject fuel, but does not perform the combustion stroke, so that a large number of air-fuel mixers enter the high-temperature exhaust manifold without combustion, and deflagrate in the exhaust manifold. And continue to push the turbine to rotate, so as to ensure that the exhaust manifold pressure does not drop during oil collection, thereby ensuring that the turbine speed does not drop, and thereby ensuring that the intake flow does not drop, thereby eliminating turbo lag. The flame produced by the direct combustion of a large amount of fuel in the exhaust manifold will directly spray out from the exhaust port. This is the flame that we often see rally cars with the "pop" noise.

The off-time ignition system also has the advantage that the gasoline itself has high volatility and can absorb part of the heat of the engine. When the highly volatile gasoline enters the engine and exhaust system, it can effectively reduce the temperature of the engine. Therefore, a turbocharged racing car needs to burn a very dense mixture of gases, which can reduce the high temperature of the engine although it causes fuel consumption. From this perspective, it can increase the durability of the engine.

But in contrast, shortcomings are inevitable. The powerful force and high temperature generated by the high-concentration mixture in the exhaust system explosion will increase the load on the exhaust head section, the turbine exhaust end blades and the valve surroundings, and shorten the turbine, exhaust system and engine exhaust valves. Service life. Although these weaknesses can be mitigated by the coordination of various parameters, they are still inevitable. In addition, the off-time ignition system will greatly reduce the effect of engine braking, because the crankshaft and piston are in a state of inertial rotation without ignition and external force, which is like stepping on the brake in neutral gear, and the engine cannot provide sufficient braking force, so the vehicle When entering a corner, you must rely entirely on the brake system to bear the burden, and the setting of the brake system for vehicles with ALS cannot be ignored. On the whole, the damage to the machinery caused by the off-time ignition system is still more harmful than good. Except for the use in racing cars where every second counts, general modified cars are still not suitable for modification.

The principle of the modification for family cars on the market is to install a spark plug at the tail end of the exhaust pipe. As long as you press the button in the car, you can synchronously control the injector to inject more fuel and ignite the discharged gas. It caused fire, but it was a bit of a waste of fuel, and could not see any more meaning other than "playing handsome".

"Handsome" is really "handsome", but traveling at home is not as exciting as a racetrack. Effective modification is important.

The principle of the modification for family cars on the market is to install a spark plug at the tail end of the exhaust pipe. As long as you press the button in the car, you can synchronously control the injector to inject more fuel and ignite the discharged gas. It caused fire, but it was a bit of a waste of fuel, and could not see any more meaning other than "playing handsome".

"Handsome" is really "handsome", but traveling at home is not as exciting as a racetrack. Effective modification is important.

After all, refitting is a cool thing, and things related to coolness, how could it be missing the GRWA brand.