Volvo's XC70 crossover SUV offers a choice of two six-cylinder engines for 2010. The base 3.2 AWD has a normally aspirated 3.2-liter engine, while the T6 AWD comes standard with a turbocharged 3.0-liter version.
Both engines are part of Volvo's SI6 (short-inline 6) family, launched in 2006. Thanks to its unusual accessory drive layout, which mounts the power steering pump and air conditioning compressor behind the engine, the SI6 is one of the world's most compact inline sixes; its overall length is within a few millimeters of Volvo's earlier inline five. Both SI6 engines have a variable-length intake manifold, 24 valves, and dual overhead camshafts, with variable lift and timing for the intake cam.
Volvo rates the base XC70's 3.2-liter engine at 235 horsepower and 236 lb-ft of torque. Although it is smooth and very quiet, many critics find its power and torque unimpressive in the heavy XC70, providing only average acceleration. Fuel economy is not outstanding, either. The EPA rates the 3.2 AWD at 16/22 city/highway, and Volvo recommends premium fuel.
The T6 AWD's 3.0-liter turbocharged engine is similar to the 3.2, but with a smaller bore and stroke and a lower compression ratio. The 3.0-liter engine features an intercooled twin-scroll turbocharger, with a separate exhaust inlet for each set of three cylinders. The twin-scroll arrangement allows the turbo to 'spool up' much more quickly than a conventional turbocharger, reducing lag. Volvo rates the 3.0-liter engine at 281 horsepower and 295 lb-ft of torque, and claims that it produces its maximum torque over a wide rev band, from 1,500 to 4,800 rpm. Reviewers say the turbocharged engine has almost no turbo lag, and it provides much stronger performance than its normally aspirated sibling. It is somewhat thirstier than the 3.2; EPA ratings are 16/21 city/highway, again on premium fuel.
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