Turbocharging - the replacement for displacement?

There’s no replacement for displacement” – so the old motoring enthusiast’s saying goes…but does it still ring true in 2015?

Whereas once, engine size was THE determining factor in the power and performance of an engine, things are definitely changing.

As smaller engines fitted with turbochargers take over from larger naturally aspirated motors, we explore whether they can ever truly replicate the responsiveness and performance of a bigger engine.

The debate explained
Fans of bigger engines have always argued that there’s no better way to get more power and performance out of an engine than to make it bigger.

To these people, turbochargers, superchargers and cam modifications are poor substitutes and their inherent downsides – lag, weight, torque range, will mean they will never truly replace an extra litre or two when it comes to adding power.

Not just about the numbers
The argument has never been about the HP numbers. Even the staunchest big engine fans concede that you can slap a turbo on a smaller engine and achieve similar maximum power and torque.

However, they would argue that in terms of real world responsiveness, a bigger naturally aspirated engine would always outperform a smaller turbocharged one that produced the same HP and torque figures.

To these people, Turbo lag (see last month’s blog “what is turbo lag?”), changing power bands and a lack of instant response will always mean that bigger is better.

But does this argument stand up today?

Whilst it was certainly true with earlier turbocharged engines, modern powertrains are a little different….

Modern turbo tech
The simple truth is that turbocharging technology has changed to the point that its downsides have been virtually eliminated.

Gone are the days of waiting seconds for the turbo to kick in - turbo lag is now so minimal in modern engines that most simply won’t notice it. In fact, it’s now possible to eliminate lag completely, thanks to new assisted turbocharging tech and electric turbocharging.

Turbocharged engines are getting smaller in terms of capacity all the time, and yet power, acceleration and engine efficiency continue to go up. It’s now possible to completely replicate the power and torque band of a larger naturally aspirated engine, using multi-stage and assisted turbocharging technology.---

Turbocharging - the replacement for displacement?
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