‘ Hot’ engines and
lubrication
Passenger car engines have become dramatically smaller over the last decade. But they offer more power and performance. How did engineers manage to do that?
There was a time when passenger car buyers, especially those in the market for a doublecab bakkie as a family vehicle, would not consider anything with an engine smaller than 2.5-litres. Yet today, there are many popular double-cab and SUV models powered by 2-litre engines, with no complaints about highway overtaking performance from owners.
Engines have become smaller because, in most American and European governmentmandated test cycles, smaller engines naturally produce lower emissions and, theoretically, lower fuel consumption. But what has been most impressive is that engineers have managed to retain the power density required to deliver the highway and towing performance that passenger-car and commercial-fleet owners need from their vehicles.
The solution has been advanced turbocharging. Direct injection fuel systems have solved many of the issues that made legacy turbopetrol engines annoying to drive and terribly maintenance-intensive. Direct injection allows for higher compression ratios and enhanced intake cooling, an ideal combination for turbocharged engines.
Most compact turbopetrol engines now run hotter than larger-displacement engines from a generation ago. And that’ s an issue worth noting for South African drivers and fleet operators. Why? Because in summer months, South African midday ambient temperatures can be extreme, asphalt absorbs, amplifies, and radiates that heat, further increasing road temperatures. That’ s why advanced lubricants are so important in modern‘ hot’ turbopetrol engines.
Powertrain engineers have been under severe pressure to extract every last bit of thermal efficiency from modern petrol and diesel engines. Running engines at higher thermal thresholds results in marginally better fuel consumption. But‘ hotter’ powertrain parameters also get the engine to an operating temperature where catalytic converters can operate more effectively. Hot engines have, in principle, been engineered for emissions compliance.
In Europe, the seasonal engine heat and lubrication risks are very different from those in South Africa. The effective European summer driving season is only a few weeks long, limiting exposure to the added cooling, lubrication, and component strain that‘ hot’ engines can endure during the long South African summer.
It’ s crucial to remember that turbochargers use engine lubricants to remain healthy. Most of South Africa’ s mid-size SUVs and large family vehicles, like double-cab bakkies, are turbocharged and operate at‘ hot’ engine temperature thresholds. Making lubrication awareness crucial to engine and turbocharger durability, to prevent costly component failures and rebuilds.
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