Infiniti Readies Variable Compression Engine

Nissan Motor Co.’s Infiniti unit is developing a variable-compression-ratio (VCR) engine it claims will provide the performance of a gasoline-powered V-6 with the fuel-efficiency of a 2.0-liter diesel.

The VCR engine is expected to debut in the upcoming QX50 SUV that will be unveiled in October at the Paris auto show before going on sale next year. This would be the first production application in the industry for the technology, according to media reports.

The system features a multi-link design with an integrated piston/crank mechanism. Higher compression ratios are used in city driving to optimize fuel efficiency and improve NVH characteristics, while lower ratios are used to boost power during acceleration and hill climbing.

The technology promises to minimize the typical tradeoffs with downsized turbocharged gasoline engines. This includes reducing the compression ratio to avoid pre-ignition under high loads.

Other carmakers and suppliers have experimented with VCR engines in the past. FEV demonstrated the technology at the 2013 SAE World Congress in Detroit.