Subaru is torque of town as revised diesels delight

Mon, 09/01/2012


Subaru’s diesel engines are becoming even more frugal and clean for the 2012 model year, with the added benefit of even better torque at low and mid speeds – and smoother gear changing.

Both Forester and Outback 2.0D variants benefit from even better fuel efficiency – 6.2 per cent improved in the combined cycle - and lower emissions, thanks to engine and six-speed manual gearbox refinements.

The Model Year 2012 diesels now produce 350 Newtonmetres of torque at 1600-2400 rpm, compared to 1800-2400 rpm in the last model year. The result: better pulling power in the low and mid speed ranges.

Power remains at 108 Kilowatts @ 3600 rpm (110 kW in Outback).

Fuel consumption and emissions

Model Year 2012 Forester 2.0D
(MY11 in brackets)

Model Year 2012 Outback 2.0D
(MY11 in brackets)

Combined litres/100km

6.0 (6.4)

6.0 (6.4)

Urban l/100km

7.2 (7.5)

7.3 (7.7)

Extra urban l/100km

5.3 (5.7)

5.3 (5.6)

CO2 emissions combined grams/kilometre

158 (168)

158 (168)

Multiple changes, including a new cam profile, have achieved improvements ranging from turbo efficiency to lower friction.

Other changes include an over-revving warning, a gear shift down indicator.

Forester 2.0D Premium also gets a new luminescent instrument cluster.

Improved gear change is achieved in both Outback and Forester diesels through several refinements including low friction bearings and lower spin loss.

Nick Senior, Managing Director, Subaru Australia, said: “Diesel variants now represent up to 20 per cent of respective Forester and Outback range sales.

“These significant refinements to engine and transmission make an even more compelling case. The smoother gear change helps more efficient driving and better fuel economy, which is a major focus for Subaru diesel customers.”

For the technically minded, the engine changes – all benefitting fuel efficiency - include:

  • Turbocharger efficiency enhanced– lower exhaust gas temperature and pumping loss
  • New exhaust-cam timing– pumping loss reduced
  • EGR cooler efficiency improved– high grade fins result in lower EGR temperature and better EGR ratio
  • Coolant circuit modifications– independent of left and right cylinder blocks for optimized flow rate; requires less torque to drive the coolant pump
  • Larger coolant pump pulley –diameter increased, lowering torque required to drive the coolant pump
  • Lighter connecting rods– 4.0 per cent reduction in weight
  • Addition of journal knock pins on cylinder block (#2, #4)– Journal positions more stable, minimizing deformation during operation and friction reduced
  • Vacuum pump efficiency enhanced– wall pump thickness and size reduced for lower friction
  • Alternator capacity reduction- mini PTC (Positive Temperature Coefficient heater element) removed, meaning less electrical power needed

Multiple transmission changes have produced lower friction and greater efficiency:

  • Shorter stroke– ball-type design adopted for synchronizer key. Together with smaller module design for synchronizer gears, produces a larger shift stick ratio requiring less effort
  • Adoption of low friction bearings
  • Low transmission fluid charge– changes to lubrication channels have reduced friction loss
  • Addition of baffle plate into the differential chamber– reduces agitation losses
  • Spline module changes- easier gear change at low temperatures
  • Shift-rode chamfer dimension optimized– easier diagonal gear changing (e.g. second to third, fourth to fifth)
  • Over-revving warning system– to protect against excessive engine revs that may occur during gear-shift errors and intentional downshifting.

 

ABOUT SUBARU
Every Subaru sold in Australia features Symmetrical All-Wheel Drive and a horizontally-opposed Boxer engine, standard Vehicle Dynamics Control electronic stability program, and a five-star rating for occupant safety from the independent Australasian New Car Assessment Program (ANCAP). The result - driving confidence.