What's Anti-lag? Let This Pair Of 400 Horsepower EVO X and EVO VII Show You
It Makes Your Exhaust Go Pop Pop Pop
Turbocharged engines are fantastic for producing massive amounts of power and letting you do so without requiring massive amounts of cylinders. When you have larger turbos that benefit is much greater, given the amount of air you can further compress. This allows the engine to produce much more power at a higher engine speed. However, the major drawback to any turbocharged engine is the presence of turbo-lag, the period of time where there is very little response in power after you step on the accelerator.
The reason for that turbo-lag lies in the exhaust not generating enough air flow to drive the turbine. This explains why there's greater lag in larger turbos. Larger turbines have more inertia than smaller ones. More inertia means more energy required to spin it. The more energy required, the higher exhaust pressure you'll need to produce. This is where Anti-lag systems (ALS) work around this shortcoming. The resulting sound is just pure madness
There are several ALS methods but the intent behind this idea is to keep the turbine side of the turbo spinning when you're not generating enough exhaust gas pressure. So in moments where you've lifted off the throttle, or even idling, the ALS will feed extra fuel, making the air-fuel mixture more rich, and it will retard the timing of the ignition. This forces the combustion to occur a bit later where the majority of the air-fuel mixture is still unburned when it enters the exhaust manifold, and before the turbine.
At that moment, ignition occurs, and the combustion happens partially in the cylinders and the exhaust. This delayed combustion event produces a lot of energy (that's typically contained within the cylinder) and will spin the turbine at a higher rate of speed, keeping up boost pressure on the compressor side of things. This eliminates any lag found in normal turbocharged cars and will give you that turbo potential that you typically find in higher RPMs.
With that said, do you need ALS? Not unless you plan on racing your car and have the right equipment. The major drawback to having ALS is that your turbo and engine components will face much higher temperatures for longer periods of time. This means the normal stainless steel ball bearings and turbine elements will be exposed to temperatures beyond their design specifications, where they can prematurely fail. If ALS is the route you want to take, make sure to look into ceramic ball bearings and turbines, components that can handle higher temperatures, in addition to upgrading the rest of the engine.
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Comments (1)
That was boring