The pog bang, also called ALS (Anti-Lag System), consists of a management technique of the engine whose goal is to minimize the turbo latent period. This software modification allows your vehicle to be more sporty. This phenomenon provokes exhaust backfiring during the release of the acceleration pedal; also known as crackle map.
The pog bang
In order to make a pog bang, it is necessary to provoke an important delay in the low load ignition on an area of precise speed, all by injecting gas. To continue injecting gas while the gas pedal is released, it is imperative to leave the valve slightly open (about 2%) in order to allow a little air to enter; which will generate a good combustion based on air and gas.
The combustion is delayed and ends up in the exhaust phase. For this reason, the exhaust valves will open even if the combustion is not yet complete. This mixture which is not yet burned provokes small explosions between the valves and exhaust caused by its very high temperature. This process causes the backfiring of the pop bang.
The difference between the bang bang and the pog bang?
It is well known that the turbo-compressors have a definite latent period. In other words, a necessary duration for the turbine to achieve its full speed starting from an intermediary speed rotation condition.
The bang bang is used for rallies, more particularly on Japanese cars such as Mitsubishi Lancer, Subaru Imprezza, etc. to diminish the turbo lag. In fact, when you release the gas or change gears, the valve stops and the totality of air in the supercharge circuit is ejected through the dump valve. In this way, the turbo is obligated to take a certain amount of time to recharge; it is what we call the lag (the latent period). To minimize this lag, the engineers found a solution that consists of leaving the valve open about 25% in order for more air and gas to be introduced during ignition delays. This system will consequently have the turbo starting earlier.
In all, the difference between the pop bang and the bang bang is situated in the opening of the valve, and consequently, in the quantity of air and gas obtained. Otherwise said, withing the framework of bang bang, the backfirings are more consequent and the temperatures can climb up to 1,200 °C.