Modifying the compression ratio of a running engine sounds like a recipe for disaster but, after driving Nissan’s variable-compression 4-cyl., we can attest it’s ready for production. Bob Gritzinger reports.
Shinichi Kiga cracks a smile as we lead-foot our Infiniti QX50 test mule down the back straightaway here at Nissan’s desert proving grounds.
Kiga, Nissan’s chief powertrain engineer-gasoline engine project group, has good reason to be pleased, considering what’s happening under the hood and how long he’s worked to bring it to fruition.
Running full bore, snapping off one aggressive redline shift after another, Infiniti’s 2.0L variable-compression turbocharged 4-cyl. – VC-Turbo, for short – is showing no signs of problems or strain, let alone catastrophic failure.
That’s remarkable given that, during operation, the engine is instantly and continuously varying the length of the stroke as much as 6 mm to change the compression ratio from 8:1 to 14:1, thereby achieving both remarkable power on demand and fuel efficiency in one tidy package.
The idea of the VC-Turbo isn’t new – Nissan had the idea as early as 1996 and engineers invented the Japanese automaker’s patented multilink device to make it work two years later but, until now, no one has been able to put the concept into production. This article first appeared in WardsAuto.
08 Jan 2018, LAS VEGAS, USA
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