Turbo Lag is known as the time needed to take the turbine up to a speed where it's capable of operating effectively providing intake boost pressure. This is a marked hesitation in throttle application breaking off an idle. This is a characteristic amount of time it takes for the exhaust system driving the turbine to build a high pressure and for the turbine rotor to overpower its rotational inertia and achieve the velocity required to supply boost pressure.

Lag can be decreased by lowering the rotational inertia of the turbine. By utilizing lighter parts to grant the spool-up to happen more speedily is one way to reduce lag. Ceramic turbines are of benefit in this respect and help reduce lag, unfortunately, their relative delicacy restrains the maximum boost they're able to provide. Additional way to cut back lag is to modify the aspect ratio of the turbine by reducing the diameter and increasing the gas-flow path-length. Increasing the upper-deck air pressure and bettering the wastegate reaction helps reduce lag but there are trade offs and dependability disadvantages. Lag is also reduced by applying a foil bearing instead of a traditional oil bearing. This cuts back friction reducing lag time and adds to quicker acceleration of the rotating assembly.

Lag may be cut back with the utilization of multiple turbochargers. Another basic technique of equalizing turbo lag is to have the turbine wheel "clipped", or to reduce the surface area of the turbine wheels revolving blades. By cutting a small part off the tip of each blade of the turbine wheel, fewer limitation is enforced upon the escaping exhaust gases. This adds fewer resistance onto the flowing of exhaust gases at low RPM, permitting the vehicle to retain more of its low-end torque, but also thrusts the effective boost RPM to a slightly higher degree. The quantity of turbine wheel clipping is a very application-specific solution to lag.

Some lag reduction techniques are:

• Lowering the rotational inertia of the turbine, lighter parts
• Ceramic turbines, but unfortunately relatively delicate  
• Bettering the wastegate reaction
• Utilization of multiple turbochargers
• Turbine wheel clipping is a very application-specific
• Using a foil bearing instead of a traditional oil bearing