Advisor
Tips & Tricks
Turbo lag
What is turbo lag and can you plug it?
0 Comments
Turbo lag
What is turbo lag and can you plug it?
The phenomenon of turbo lag is on everyone's lips as soon as we talk about increasing the performance of modern engines. This is because turbo lag only appears where a turbocharger is installed. Since almost every engine these days is turbocharged, we also often encounter questions like "what is turbo lag?", "where does turbo lag come from?" and "how can turbo lag be closed?". We get to the bottom of these questions.
What is turbo lag - in a nutshell?
Turbo lag describes the moment when the engine has not yet reached the rpm required by the turbo for the desired acceleration. You press on the gas and nothing happens at first. There is a pause in performance, the "turbo lag".
How a four-stroke engine works
To clarify where turbo lag comes from, we may first look at how a modern engine with a turbocharger looks and works. Turbocharging compresses the air, increasing power and torque. Turbocharging always works according to the following scheme, even if the type of turbocharging is not always the same: The air required for combustion is compressed to such an extent that its volume is only a fraction of the original volume. In this way, much more air can be used for combustion, so the engine also gets much more power available. The four-stroke engine works in four steps or cycles:
- Intake
- Compression & Ignition
- Work
- Exhaust
During intake, the piston moves from the top (top dead center) down to the crankshaft (bottom dead center). During this movement, fresh air, gas mixture or air-fuel mixture is drawn into the cylinder, depending on the engine. The first stroke is completed as soon as the piston reaches bottom dead center and the intake valve is closed.
The second stroke (compression and ignition) begins with the piston moving upward to top dead center, compressing air or mixture. The compression ratio is highly dependent on your engine (use our compression ratio calculator to quickly determine the ratio). The compression heats up the air or the mixture extremely. Shortly before the piston reaches top dead center, the ignition happens (with the diesel engine the pre-injection happens accordingly).
Cycle 3, working, describes the independent combustion of the oxygen-fuel mixture after reaching top dead center. Here the temperature and pressure in the engine reach their maximum values. During the downward movement, the combustion gas cools down again and the exhaust valve opens.
The final stroke begins when the piston leaves bottom dead center again and the upward movement pushes the exhaust gas out of the cylinder to the exhaust manifold and into the exhaust system. Before the piston reaches top dead center, the intake valve already opens, even before the exhaust valve is closed. This moment is called valve overlap.
This is how turbo lag occurs
When starting and accelerating, your engine does not yet reach particularly high speeds. These are the moments when turbo lag occurs. This is because your turbo needs a certain speed, i.e. a certain amount of exhaust gas, to develop its full power. Before that, it runs rather sluggishly and needs a little "push" to come through the exhaust stream. Once the turbo turbine is in motion, the suction also works with much more power, which means that the compression also runs better. At that moment, the turbocharger develops its full power and the turbo lag is overcome. In old vehicles, the time it took for full power to develop used to be seconds. Nowadays, everything happens much faster and turbo lag is hardly noticeable in modern vehicles.
How can you reduce turbo lag?
The amount of turbo lag depends on the response of your turbocharger. When we try to reduce turbo lag, it's always about one thing: the turbo has to reach enough charge pressure even at low revs.
One of the ways this is achieved is through improved and variable turbine geometry. Some turbochargers are supported by electric motors in the low speed range. A combination of compressor and turbo is also used by some manufacturers to achieve this goal.
In connection with the turbocharger, however, it is not only the turbo lag that needs to be considered. If the effect of your turbo is too violent at high revs, you can't get around the corresponding Wastegate which regulates the charge pressure and the power is used sensibly.
Upgrade Turbocharger: Better response and less turbo lag
If you achieve above-average performance, an ordinary turbocharger is no longer sufficient for you. In racing and motorsport, appropriate upgrade turbochargers are used that have improved response, are designed for extreme performance and are particularly durable. These have special turbine wheels, reinforced support and are overall optimized for the high demands.
Questions about the turbo and turbo lag?
If you have any questions, take a look at our FAQ, write us in the chat or use the contact form. We look forward to hearing from you!
Create comment
Please leave us a comment.
His first car was a Polo Mk1 with a 40 Weber twin carburetor and 129 PS (95 kW). His second was an Audi 50. Today Bartek tunes Lamborghinis to 1000 PS (735 kW). Even as a young boy, Bartek disassembled vehicles and put everything back together better. He wrote his high school diploma with oil on his fingers. The trained automotive mechanic with a focus on engines and gearboxes was determined to go into motorsports. In his 10 years in Formal 1, he supervised 73 races, including as engine mechanic for Ralf Schumacher at Toyota. Since 2010, he has dedicated himself fully to his company BAR-TEK® and helps his customers to bring VW and Audi engines to peak performance.
Expert in
Engine
Gearbox
