Buyer's Guide: Turbos offer economy and more power
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Turbochargers not just reserved for the boy racers these days
Dan is a regular reader of Driven and is asking for some clarification regarding vehicles fitted with turbochargers on petrol engines. “On more than one occasion I seem to remember reading past comments made about avoiding these vehicles as they were considered too high risk. Admittedly the comments were aimed mainly more at the budget end of the buying scale but I am keen to find out your opinions on the newer vehicles fitted with turbos” says Dan.
Yes you have a good memory as we have in the past suggested buyers avoid vehicles fitted with turbochargers when their budgets were limited. Our comments were based more around the fact that a high number of turbochargers on vehicles were installed mainly to increase engine performance and little else. As these vehicle age and their histories become a little vaguer it can be almost impossible to tell whether engines may have been stressed or whether other modifications may have been carried out to increase performance even further.
Lack of regular servicing or even not using the correct grade of oil can also create doubt for potential buyers with possible expensive repairs becoming a high probability.
But times have changed and petrol turbo technology has been used in a much different way in recent years. It is now more about manufacturers trying to strike a balance between achieving low fuel economy and reduced tail pipe emissions, along with boosting performance.
It’s much like the hybrid technology but with fewer complications. It doesn’t match the hybrids in terms of achieving zero emissions or overall better fuel consumption, but it does achieve a two-engines-in-one benefit.
So what has changed?
Well first up let’s try and get a grasp on how the turbocharger works and why manufacturers use them.
The main ingredients used to get any internal combustion petrol engine to run are air, spark and fuel. Of the three key players, air is the one with the most limitations. Fuel can be dumped into an engine in copious amounts while spark is provided by spark plugs which these days can last up to 100K in many cases.
Air intake is limited by the intake or downward stroke of the pistons and an engine can only take in so much atmospheric air in one gulp. The turbocharger is designed to make use of the wasted exhaust gases to spin a turbine at very high speeds which in turn delivers compressed air into the combustion chamber under increased pressure. Hence the term “forced induction”.
So more air means more fuel can be added as required and bingo we have more power. The amount of power assistance offered by the turbocharger can also be varied by the electronic engine management system.
Ford with their EcoBoost engines have been one of the major players in bringing turbocharger technology to a number of different models including offering it as an option on the new Mustang due for launch later this year.
In a nut shell these small capacity engines can run on economy mode around town while producing additional power as and when required on the open highways.
The technology has now spread throughout the industry with more manufacturers bringing the small engine thinking to the showroom.
It’s also an alternative to diesel power units which can deliver on torque and fuel economy but struggle to match the hybrids and turbocharged petrol engines when it comes to refinement, noise levels and emission reduction.
Lexus like its sister brand Toyota are one of the major motor manufacturers who have embraced and delivered on hybrid technology over many years. They have also invested in turbo technology and have recently added a small turbocharged 2.0 litre petrol engine to their new NX Sports Utility Vehicle model line-up.
Buyers tend to drift toward brands like Lexus looking for high levels of quality, comfort and safety plus there is a high expectation of smooth and ample engine performance. A 2.0 litre petrol engine in a price bracket that starts north of $75K may be seen as a barrier for some potential buyers however, the claimed performance figures should put their minds at rest. Both the 2WD and AWD options produce175kW of power but more importantly the diesel like torque figures of 350Nm (starting at just 1650rpm and peaking at 4000rpm)are testament to the benefits of having a turbocharged engine under the bonnet. Fuel consumption figures aren’t quite as good as the hybrid but are still impressive at between 7.7 and 7.9 L/100km’s depending on model.
I recently drove the Lexus NX 2.0 litre 2WD and was impressed with the total package including the overall performance from the turbocharged power unit.
Regular servicing using high quality oil is still vitally important during ownership with any vehicle fitted with a turbocharger to ensure ongoing reliability.
Further down the track the caution flag should still be waved however for those on limited budgets. Turbochargers work under the extremes of heat and speed and repairs if required are never cheap.