2022 Nissan Rogue Gets a VC Turbo Triple
The new 1.5-L 3-cylinder with variable compression ratio may be one of Nissan’s last clean-sheet IC engine programs – and it’s a perfect match for the compact SUV.
Nissan’s best-selling Rogue entered its third generation as an all-new vehicle for 2021, missing the significant powertrain change that arrives in 2022 models. The all-new 3-cylinder gasoline engine – potentially one of the company’s last clean-sheet IC engine programs – and a similarly new Jatco-engineered Xtronic CVT, may have taken longer to certify than Nissan engineers had planned, but the wait (for ’22 customers) was worth it.
SAE Media recently drove a pre-production Rogue on a variety of Michigan roads and found its new non-electrified powertrain to be a perfect match for the unibody SUV. The vehicle felt invigorated, with crisp throttle response across the vehicle speed range, and a 3-mpg increase (to 33 mpg) in EPA combined fuel economy compared with the ’21 Rogue. Engine/transmission calibration was spot-on and worthy of any Infiniti.
The new engine is a 1.5-L turbocharged DOHC triple featuring a vacuum-low-pressure die-cast aluminum block and head and incorporating Nissan’s variable compression-ratio (VC) combustion system. Coded KR15DDT, it is SAE-rated at 201 hp (150 kW) at 5600 rpm, and 225 lb-ft (305 Nm) from 2800 to 4000 rpm – an increase of 11% and 24%, respectively, versus the 2021 Rogue’s 2.5-L 4-cylinder.
The broad span of torque was a key design bogey, noted Robin Moreo, senior manager of product planning, who said Rogue is now the peak-torque king in its segment. The triple’s output and power characteristics were deemed more than sufficient for it to replace the larger PR-family 4-cylinder as Rogue’s only available engine. And the smaller engine, even with its VC and turbo hardware, helped Rogue shed 18 lb. (12.7 kg) versus the previous model.
Nissan’s VC technology entered production in 2019 on the KR family 2.0-L 4-cylinder and is well documented . The 3-cylinder VC engine can infinitely vary piston stroke between 88.9 to 90.1 mm (3.31 x 3.50 to 3.55 in.), which enables effective compression ratios of between 8:1 and 14:1. Company engineers believe it solves the challenge of increasing a turbocharged gas engine’s fuel efficiency and performance under varying load conditions while avoiding detonation (on 87-RON fuel).
The VC benefits come at the expense of mechanical complexity, mass, friction and increased NVH. The latter becomes a greater potential issue with the all-aluminum 3-cylinder, so the new Rogue is fitted with a new engine mounting system that features a pair of lower torque rods and larger hydraulic engine mounts. Active noise cancellation is also employed. While early 2.0-L VC engines exhibited some noise and vibration in their first Infiniti QX50 application, the system in the new Rogue is effective. Drivers won’t be aware of the reciprocating crankset or the transitions from low to high compression ratios.
The KR-series triple is a case study in IC engine evolution as global tailpipe emission regulations tighten. It gains a new high-pressure direct fuel injection system and liquid-cooled EGR, as well as friction-reduction measures – a “stainless mirror-bore” finish on the 84-mm cylinder walls, rolling-element bearings supporting the camshafts (on the side opposite the phasers) and a special textured contact surface on the bucket-type valve lifters. Lubrication is provided by a new stepless, variable-displacement oil pump.
Paired with the new engine is the latest version of Jatco’s CVT8, which Nissan calls Xtronic. The new CVT features revised control valving and a new twin oil pump system employing mechanical and electric pumps. The mechanical pump delivers a lower rate of oil flow, for slow shifting between low and high ratios. The electric pump delivers greater oil flow for more rapid shifting under higher loads. With an 8.2 overall ratio spread, Nissan claims the new Xtronic offers 17% wider gear ratio coverage and 32% lower friction than the previous CVT8, while helping to boost the Rogue’s fuel economy.
The 3-cylinder VC engine is built at Nissan’s Decherd, Tenn., powertrain plant which supplies engines and electric machines for the company’s U.S.-assembled vehicles.