Deep Dive: Inside the New Volkswagen EA888 B-Cycle 2.0 TSI I-4
Miller-cycle motor replaces the 1.8T and last-gen 2.0 TSI
Starting with the all-new 2018 Tiguan, Volkswagen's mainstream four-cylinder powerplant is being updated in the pursuit of improved fuel efficiency. A modified version of the EA888 2.0-liter turbocharged I-4 used in the outgoing Tiguan and CC, it will also effectively replace the 1.8-liter TSI engine currently seen in the Passat, to start.
The key update to this new 2.0-liter "B-Cycle" four-cylinder turbo (codenamed EA888 3B) is the use of a modified Miller-cycle combustion process that closes the intake valves much earlier. The shorter intake phase means a longer expansion phase. A higher geometric compression ratio is used to make up for the reduced intake stroke along with the benefit of decreased internal temperatures. Variable valve timing on the intake camshaft adjusts valve openings depending on engine load, allowing for full power when needed and better efficiency at idle and under light load. Other significant changes include a modified cylinder head and a more responsive turbo.
This new 2.0T makes 184 hp and 221 lb-ft of torque, 14 hp and 35 lb-ft more than the 1.8T, while fuel economy is up by eight percent. If you're wondering why Volkswagen didn't just apply the B-Cycle combustion process (named after the engineer who invented it, Dr. Ralph Budack) to the existing 1.8T, there's a good explanation. These changes actually reduce horsepower due to reduced volumetric efficiency, and less than 170 hp would have been uncompetitive across the automotive landscape. So, the decision was made to apply the B-Cycle to the EA888 2.0-liter, which, owing to its slightly larger displacement from a longer piston stroke, could spare the horses. The bigger engine is also better suited to higher loads, a concern when trends are moving more and more toward crossovers that are inherently heavier and less aerodynamic.
The 221 lb-ft of torque in this engine is up 14 lb-ft from the outgoing Tiguan's but, as Volkswagen says, power is down from 200 hp to 184 hp. Also new for the Tiguan is an eight-speed automatic transmission.
We got the chance to drive in a pre-production Passat equipped with the new B-Cycle 2.0-liter turbo, and while it's miles away from a barn-burner, it's an incremental improvement over the 1.8-liter it replaces. The Passat is smoother off the line, less peaky, quieter, and max power arrives considerably earlier at 4,400 rpm rather than 6,200 rpm. That said, the 1.8T did have a more pleasant zip to it, and the new engine feels less eager to rev.
As far as the bigger, heavier 2018 Tiguan is concerned, the new engine and eight-speed automatic transmission will be a big boost to the lackluster fuel economy of the current Tiguan, which sits at 20/24 mpg city/highway. Expect the new Tiguan, when it is EPA-rated, to hit 30 mpg on the highway and perhaps 23-25 mpg city.
The 2018 Volkswagen Tiguan will go on sale in late summer, with pricing to be announced in mid-June. The B-Cycle 2.0-liter will then expand to the Passat, the Beetle, and presumably then beyond in VW's lineup.