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Looks, Lux and Lightning

Loaded ’05 Acura RL features an all-wheel-drive system that could be the benchmark for luxury performance sedans.

The RL, as in Acura RL, must stand for “Really Loaded,” because it really is. There simply are no factory options whatsoever on the new ’05 and the standard equipment is so comprehensive and the systems so sophisticated it seems every need is provided for or exceeded. Buying this automobile is pretty much an open and shut case of pick your color and pony up the MSRP of $48,900.

Real-time traffic for 20 of the largest U.S. metropolitan centers, XM Satellite radio, OnStar (one year standard), navigation system with voice recognition, hands-free telephone interface, GPS linked solar sensing, dual-zone, dual-mode automatic climate control system, Bose 10-speaker surround sound with 6-disc CD, DVD-Audio and DTS changer, keyless access and starting system, active noise cancellation: all standard comfort and convenience features and this only touches on a few of the higher tech bells and whistles on the ,’05 RL.

This is a much sleeker automobile than the old Acura RL, just inches shorter, slightly wider, but much, much wilder. Through its evolution from concept car to production automobile, the new RL has retained its wedge- like shape with forward sloping beltline and short deck lid. It achieves a very attractive yet powerful, aggressive look and stance.

The RL’s luxury cockpit is a great place to experience the new AWD system.
The star Acura’s SH-AWD system is a rear differential that can split torque right to left as well as front to rear, spinning the outside rear wheel up to five mph faster than the front wheel, which aids in cornering stability.
The new RL is longer and wider than its competition in the sector, claims Acura, and has significantly wider front and rear track. It sits on 17 in. alloy wheels and Michelin tires.

If Acura has taken some of the fun out of buying a car, it has certainly reinvested that fun into driving the new ’05 RL. The 3.5 L 24-valve VTEC V6, rated 300 hp at 6,200 rpm, packs 75 hp more than the previous 3.5 L RL powerplant. Acura attributes the gains to a new dualstage, high inertia intake manifold (+15 hp), higher internal engine efficiencies and lower pumping losses (+40 hp) and a variable flowrate exhaust system (+20 hp). The engine is fitted with variable valve timing and lift electronic control (VTEC), with 4 valve per cylinder, belt-driven, single overhead camshaft.

Peak torque for the engine is 260 lb.ft. at 5,000 which is redlined at 6,800 rpm. Bore and stroke is 3.5 in x 3.66 in. (89 mm x 93 mm). The engine has a relatively high compression ratio of 11.0:1, which compares with 9.6:1 for the previous 3.5 L RL powerplant.

The new engine has a forged steel crankshaft with revised counterweights to handle the greater weight of the higher compression pistons. These have taller reinforced crowns. Pistons are oil jet cooled on the underside. Connecting rods are made of forged steel, with the big end split by fracturing, providing for a perfect bearing cap fit.

The engine is of 60 degree V configuration, with a heat-treated die-cast aluminum alloy block with cast-in centrifugally cast-iron liners. Cylinder heads, also of aluminum, incorporate the tuned exhaust manifolds as an integral part of the casting.

The VTEC system operates the intake valves in two modes to optimize volumetric efficiency and complete combustion of the airfuel mixture. The intake valves have low lift and are open for a comparatively short duration at low engine speed. The intake valves switch to a high lift, longer duration mod to provide optimal volumetric efficiency at higher engine speed where breathing is more critical. The engine shifts modes at 4,950 rpm and it is absolutely seamless to the driver.

By using a three-rocker valve actuation, each intake valve is controlled by its own lowspeed cam lobe. This is what permits the staggered valve lift and opening duration.

At 4,950 rpm, the powertrain control module opens an electric spool valve routing pressurized oil to small pistons in the intake valve rocker arms. Sliding into position in all six cylinders, the pistons lock together the three intake rockers which then provides the highlift, long-duration cam lobe valve actuation.

Tuned intake is provided by a two-piece, dualstage intake manifold. This serves to boost torque across the full operating range of the engine. The volume of the manifold’s plenum is tuned to resonance together with the length of the inlet passages to amplify intake pressure waves thereby assisting charge, air filling of each cylinder.

At 4,000 rpm, the engine control opens two butterfly valves, one for each cylinder bank, and this interconnects the two halves of the plenum, effectively tuning them for resonance at the higher engine speed range where even more charge-air is required.

The direct-injection engine also features detonation/knock control retarding ignition timing to eliminate knock — of damaging potential in this high compression engine. So called Programmed Fuel Injection (PGM-FI) monitors the exact state of exhaust gas and multiple engine inputs to optimize the amount of fuel injected to each cylinder.

A drive-by-wire throttle adjusts the moment-to-moment relationship between pedal position and throttle opening and changes the amount of “gain” between the pedal and butterfly. Engine response is smooth and progressive. The gain increases at higher speed for crisp passing and hill climbing.

Because the exhaust manifolds are cast directly into the cylinder heads, the two primary catalytic converters are very close-coupled to the combustion chambers. Converters mount directly to the exhaust port of each cylinder head.

Variable flow exhaust provides a low-speed (below 4,000 rpm) flow rate of 130L per second and 150L per second at high speed.

The meticulously combed out powerplant in the RL meets highly demanding CARB LEV2/ULEV emission standards and is certified at this level for 120,000, or 20,000 more than required by the current LEV standard. As exciting as it is, the engine plays second lead in powertrain technology aboard the RL. Star billing goes to the Super Handling All- Wheel Drive System (SH-AWD). The venue for press introduction included an 80-mile sprint through the Virginia countryside followed by a test track course with lots of tight hairpins and sweeping S-curves working through changing elevations.

With the opportunity to test four competitive luxury sedans on the test track against the ’05 RL, including the ’04 RL, the Acura SHAWD clearly stole the show with everyone present. The ’04 RL generally took last place with most drivers so this is a significant shift for Acura in enhanced handling and performance. Delivering the power to the AWD system is a 5-speed automatic with Sequential SportShift, paddle shifter and Grade Logic Control. Acura claims it has the widest ratio spread of any automatic in the luxury performance class, from 2.697:1 in first to 0.481:1 in fifth.

Suspension is independent double wishbone up front and independent multi-link in the rear. The brakes are 4-wheel disc with 4-piston front calipers, equipped with ABS, electronic brake force distribution and brake assist.

According to Masaaki Saito, senior chief engineer with Acura, “The core mechanism of SH-AWD is in its rear differential. The acceleration device and the direct electromagnetic clutch flexibly control and distribute torque for each of the four wheels.

“The control system consists of ‘feed-forward’ logic which reflects driver input, and ‘feed-back’ logic which reflects the vehicle’s dynamic movement. Together, the system improves vehicle stability and achieves excellent handling.”

A steering angle sensor and throttle opening sensor detects driver input and yaw rate and lateral g force sensors detect dynamic movement of the vehicle and establish the desired front-rear and left-right torque splits. The system seems unique in the comprehensive torque splits it can direct. Not only can it put 70 percent of the engine torque on the front or rear axle, it can also put 100 percent of that 70 percent to either rear wheel delivering precisely what’s required to the outer rear wheel during hard cornering.

That wheel is driven up to 5 percent faster than the average of the front wheels and that pushes the car through the curve. It seems counterintuitive, but the more one gets on the throttle the better the car handles. This car loves the throttle and is positively lightning in the corners.

An acceleration device in the rear drive unit usually just passes the torque rearward to rear axle at very close to a one-to-one ratio but in cornering, the device’s output shaft spins faster than the input shaft resulting in great cornering feel. To meet instantaneous driving conditions, torque transmitted to each rear wheel is continuously varied between 0 and 100 percent.

For safety, the Acura employs a new body structure called the Advance Compatibility Engineering (ACE) structure, which improves occupant safety as well as reducing aggressiveness toward other vehicles in frontal collisions. It disperses collision forces over a larger frontal area.

Other safety feature include dual stage, dual threshold front airbags with supplemental restraint, front side airbags with passenger detection, standard side curtain airbags and vehicle stability assist with traction control.

Safety actually does sell cars these days and Acura is keenly aware of that and takes pride in its accomplishments, but here it has also put great emphasis on high performance handling in the Acura RL package via the increased power and novel all-wheel-drive system. The RL is really loaded sure, but really lightning as well.

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Thu. July 18th, 2024

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