The truth about small capacity turbo engines | Auto Expert John Cadogan

I guess if you grew up before the Internet, a 1.5 or 1.6-litre engine does seem insufficient to the task of dragging the sorry arse of a mid-sized SUV all over town.

Perception ain’t reality, tough.

While you were perhaps unconscious, Rip van Winkling away the past three decades, in addition to that pesky Internet, internal combustion underwent something of a revolution, with the introduction of electronic fuel injection, variable valve timing, direct injection, and turbocharging.

Just to smash those rose-coloured glasses of retrospectivity, a 1990 Honda Civic had a 1.5-litre engine and a carburettor (remember those?). It developed 73 peak kilowatts and 122 peak Newton-metres.

If we fast-forward almost three decades, the capacity hasn’t changed but the output certainly has: The 1.5-litre turbo engine in the Honda CR-V is 140kW and 240 Newton-metres.

The performance has doubled in 30 years as a result of engineering braniackery - another non-word that cries out to be included in the lexicon, stat. Today’s 1.5 turbo engine goes about the same as a three-litre atmo engine, back in the day before Dirty Harry needed a Zimmer frame to grease punks with that enormous six shooter.

People also ask me about wear and tear. Such a small engine, wound up so tight. Surely it will wear out quicker. This seems logical but is also bullshit. These things are integrated designs.

Manufacturers do a great deal of accelerated-life testing, and they put engines through hell in R&D, to ensure all the bits work together to deliver reasonable durability. They don’t always get it right, but mostly they do. So there’s no reason to infer premature failure from a 1.5 or 1.6-litre turbo engine.

I’d bear in mind, however, that turbos are driven by exhaust gas, so they get very hot.

Exhaust outlet temperatures near the manifolds can be in the region of 850 degrees C when you’re up it for the rent. The driven side of the turbo is swimming in high-temperature gas, and it’s lubricated by engine oil.

So it’s fair to say turbos are hard on engine oil. And for this reason, I would not be disrespecting the service interval. Blowing up a turbo is far more expensive than just getting the car serviced on time.
Nor would I be shutting the engine down immediately after a hard run. If you do that, you consign the lubricating oil in a hot turbo housing at the time the car is shut down, to (literally) a living hell.

There’s a section of road I use routinely for road-test evaluations. It’s a 200-metre vertical climb over about 4000 metres of twisty road near my joint, with about a dozen places where you can use full throttle out of the bends. And there’s a cafe right at the top. Called ‘Pie in the Sky’, appropriately enough.

The wrong way to do this is to thrash the car to the top of the hill, then pull in, shut down and order a double espresso. It’s a really good idea to idle the engine for a couple of minutes to bleed that heat out of the turbo housing, no matter how caffeine deficient you are in the moment.

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