Downsized and turbocharged I-4s have been replacing V-6s in luxury sedans for a few years now, but the idea of 2.0L engines taking over for powerful V-6s in premium 7-passenger CUVs still seemed like a stretch.
That is, until Volvo introduced its superb T6 4-cyl. in the Volvo XC90. By adding the low-end grunt of a supercharger to the already strong turbocharged T5 2.0L that took home a Wards 10 Best Engines trophy last year, Volvo has created an engine that can match big naturally aspirated V-6s in power and torque and also cream them in real-world fuel efficiency when powering big vehicles.
This isn’t the first time an automaker has tried mating supercharging with turbocharging in a small engine, but it is the first time it’s been done so well.
“Turbocharging and supercharging is a match made in Swedish heaven,” says editor Tom Murphy.
Last year, we tested the first version of the T6, making 302 hp in the S60 sedan, but Volvo at the time was finishing up improvements that would allow the T6 to fit in the engine bay of vehicles soon arriving from the new Scalable Product Architecture, including the XC90.
Those upgrades include integrating new double-water jacket cooling to offset the additional heat generated and redesigning the head with high-strength aluminum to improve heat management. Exhaust backpressure was reduced with a new catalyst, and the air intake system also was improved to mitigate noise from the supercharger.
The block and crankshaft are all-new, and the diameter of the main bearing was reduced from 60 mm to 53 mm to reduce friction. The improvements also prepare the T6 for hybrid duty in the T8 XC90 coming this year.
The standard XC90 weighs in at a hefty 4,627 lbs. (2,098 kg) but it never feels underpowered and there is no waiting for thrust when you need it in a hurry to pass on a 2-lane country road.
That shouldn’t be a surprise considering the engine makes 316 hp and 295 lb.-ft. (400 Nm) of torque beginning at 2,200 rpm and accelerates to 60 mph (97 km/h) in 6.1 seconds.
What is surprising is how it all works so seamlessly. The supercharger provides almost V-8-like grunt at low rpms and then passes the baton to the turbocharger as it spools up, creating a robust and continuous flow of power to the wheels.
“Smooth and refined, especially considering it’s a 4-cyl. doing the work of a big 6-cyl. or small V-8,” says editor Bob Gritzinger.
And when editors looked at the trip computer, we were even more impressed, logging around 21 mpg (11.2 L/100 km) or better in city driving and up to 24.9 mpg (9.4 L/100 km) on long trips.
We’ve tested more than a few highly boosted engines that require a very light foot to meet their official fuel economy numbers, but we had no such trouble with Volvo’s T6.
After 2,009 miles (3,233 km), including a roadtrip to Lincoln, NE, we averaged 24.2 mpg (9.7 L/100 km), right on the money with its official EPA 20/25 mpg (11.8-9.4 L/100 km) city/highway, and considerably better than its 22 mpg (10.7 L/100 km) combined number.
“I’m a big fan of this engine, and the XC90 is the perfect fit for this high-tech power-puncher,” says editor James Amend.
The T6 promises to be a perfect fit for a lot of Volvos coming down the road. It also is proving out a new strategy for squeezing more performance and efficiency from smaller and smaller engines.