What’s turbo lag and can we reduce it?

The increased power from turbochargers comes at the cost of lag, but solutions are being developed to counter it.

11th August 2016
What’s turbo lag and can we reduce it? (Volvo)

A turbocharger works by forcing exhaust gases back into the combustion chambers (cylinders), therefore increasing power. The problem is that it takes time to build exhaust pressure and to ‘spool’ a turbo. That’s why, when you put your foot down at a low engine speed (rpm) you experience ‘lag’ before the turbo wakes up. It’s especially evident in diesel engines, which rely on compression ignition rather than spark plugs.

Various systems exist to overcome this, but Volvo hopes to cure it completely with a system called Powerpulse, featuring a compressor that draws clean air from the airbox and stores it in a tank. When the driver suddenly accelerates, a valve opens, sending high-pressure air from the tank into the exhaust stream, quickly spooling up the turbo and resulting in a pulse of power. Hence the name.


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