Michael Fernie profile picture Michael Fernie 5 years ago 95

What Is Overboost?

Manufacturers keep mentioning something called overboost when talking about their latest turbocharged cars, so what is it?

Remind me later
Ford - What Is Overboost? - Blog

In a world full of downsizing and turbocharging, manufacturers have listened to the plight of us petrolheads and have decided to add in some fun features to keep us all satisfied with the motoring experience. One such feature is ‘overboost’, a feature that is becoming present in hot hatches like the Ford Fiesta ST and VW Golf GTI Clubsport.

It’s a fairly simple concept that brings some much needed drama to the fairly linear power delivery of modern turbocharged vehicles.

Ford - What Is Overboost? - Blog

The ECU is programmed to set the turbocharger to full boost for a given period of time, sending around ten percent more power to the wheels as the turbocharger forces air slightly faster into each cylinder. In the case of the new Golf GTI Clubsport, power is upped from 261bhp to 286bhp for a 10-second window. This is perfect for a quick overtake or for getting the maximum drive out of a corner on a race track.

Ford - What Is Overboost? - Blog

VW says that this temporary function is to aid fuel consumption and add performance without having to re-engineer engine components to withstand a higher boost pressure all of the time, but there might be some marketing shenanigans at play here.

The small burst of power puts the Clubsport perilously close to the 300bhp Golf R, therefore it would make sense to keep the standard power output down to 261bhp to not step on the hotter hatche’s toes. So, Would you buy the GTI with this temporary boost on tap or would you spend the extra cash and go for the full-blooded Golf R?

Although overboost may seem like a bit of a con, it’s heart-warming to know that car manufacturers are keeping performance as a priority while engines are getting smaller and cleaner in the war against emissions.