2009 Acura RL facelift features new J37A engine

Honda has launched a facelifted 2009 model year Acura RL at the 2008 Chicago Auto Show, and it features a new version J37A 3.7 litre V6. Read more full technical details and view more photos and videos after the jump.

The RL is a large executive sedan, and it is based on the Japanese Honda Legend. It has all-wheel drive – an improved version of the first generation SH-AWD that responds more quickly to changes in traction.

Acura/Honda’s SH-AWD has torque-vectoring – it can redirect rear wheel left to right torque bias to increase the rotation speed of an outside rear wheel during aggressive cornering to help the car turn more effectively while under power. BMW’s xDrive only recently gained this feature, so Honda is one of the first in the world to have it, not bad for a company not particularly known for all-wheel drive.

During straight-line cruising and moderate cornering with throttle at a less than 50% position, 70% of engine torque is delivered to the front wheels. Under full throttle straight line acceleration, the front rear bias is 60:40. Under hard cornering, the front rear bias becomes 30:70, and the rear left and right wheels can each take up to 100 of the torque applied to the rear axle.

The outer wheel can aso be overdriven by up to 5.7% with a built-in acceleration device. The acceleration device uses a compact planetary gearset to drive the output shaft to the wheel faster than the input shaft, which achieves the 5.7% overdriving. During normal conditions the acceleration device passes torque at a 1:1 ratio.

A new 3.7 litre SOHC i-VTEC V6 from the J-Series of engines is installed under the hood. The engine puts out 300 horsepower at 6,300rpm and 367Nm of torque at 5,000rpm. We first saw the J37A engine installed in the Acura MDX, but that version of the J37A only had VTEC on the intake valves. This version has VTEC on both the intake and exhaust valves, which is the first for a SOHC VTEC engine. The VTEC changeover point is at 4,900rpm. The longer duration cam increases intake valve lift by 27.9% and exhaust valve lift by 10%. The engine’s compression ratio is a high 11.2:1.

The engine also has a dual-stage magnesium intake manifold which can function as a single- or dual-plenum manifold design based on engine operating parameters. A dual plenum intake has a smaller plenum volume because it is split into two different intake chambers, which enhances low engine speed power delivery. The single plenum design takes over at high revs with a wider and straighter path. This dual-stage manifold switches over at 3,800rpm.

The engine package is also lighter than the 3.5 litre V6 it replaces, thanks to weight-saving features such as 25% lighter hollow tubular steel camshafts with splined steel lobes and journals that are pressed into place. The cylinder heads have integrated exhaust port castings to allow closer positioning of the catalyst to the cylinder bank. The exhaust system is a variable flow system which switches over at 4,000rpm to increase flow from 130 litres per second to 150 litres per second.

The engine is mated to a 5-speed Sequential SportShift automatic transmission, with F1-style steering wheel mounted paddle shifters and also a straight-gate console-mounted gear selector for those that prefer using an actual shifter to control steptronic shifts. The gearbox’s torque converter has been made more robust to handle the higher power of the new J37 engine.

Handling is improved via the improved SH-AWD system mentioned earlier, but other tweaks include a revised steering ratio, upgraded coil springs, better shock absorbers, a larger rear stabilizer bar, grippier tyres with larger wheels (18 inch versus 17 inch), and stiffer subframe mount bushings.

VIDEO: 2009 Acura RL Unveiling 1

VIDEO: 2009 Acura RL Unveiling 2

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