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Variable compression ratio
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<p>Variable compression ratio (VCR) is a technology to adjust the <a href="/facts/Compression_ratio/QNJXIT08">compression ratio</a> of an <a href="/facts/Internal_combustion_engine/Ju4BXzj0">internal combustion engine</a> while the engine is in operation. This is done to increase <a href="/facts/Fuel_efficiency/URhdQ7Wl">fuel efficiency</a> while under varying loads. Variable compression engines allow the volume above the piston at <a href="/facts/Dead_centre_(engineering)/2rj7bHWc">top dead centre</a> to be changed. Higher loads require lower ratios to increase power, while lower loads need higher ratios to increase efficiency, i.e. to lower fuel consumption. For automotive use this needs to be done as the engine is running in response to the load and driving demands. The 2019 <a href="/facts/Infiniti/9Evzuy22">Infiniti</a> <a href="/facts/Infiniti_QX50/wBTYrch8">QX50</a> is the first commercially available vehicle that uses a variable compression ratio engine. </p>