OVERVIEW
The new CL is available with two V-6 powerplants. The 3.2 CL receives
a powerful, 225-hp VTEC V-6 engine, similar to the CL 's sibling, the
3.2 TL performance luxury sedan. The all-aluminum block with Acura's
renowned VTEC system improves horsepower output by 12.5-percent when
compared to the previous 3.0 CL coupe.
The high performance Type S model raises the 3.2 CL's engine output to even higher levels. Several enhancements to the 3.2 CL's VTEC V-6 engine, including a high flow capacity dual-stage induction system and free-flowing exhaust; help the Type S develop a maximum 260 horsepower and 232 lb-ft of torque.
In addition, the patented Acura VTEC technology, first utilized in the NSX supercar, provides both the 3.2 CL and Type S models with an incredibly flat torque curve, boosting power and responsiveness at all engine speeds.
Both CL powerplants transfer their power through the new 5-speed automatic transmission with a Formula One race car-inspired Sequential SportShift system. As in the Acura NSX, the SportShift allows the driver to select the forward gears just like a manual transmission while enjoying the convenience of a full-fledged automatic transmission.
Performance is not at the expense of Acura's commitment to the environment, as both the 3.2 CL and Type S meet tough Low Emission Vehicle (LEV) and Ultra Low Emission Vehicle (ULEV) (for 3.2 CL California models only) emission standards.
Powertrain Overview
Engine
- Type S with 260 horsepower at 6100 rpm &endash; the most power in its class
- Type S with 232 lb ft of torque between 3500 &endash; 5500 rpm
- Type S engine with high volume, dual-stage induction system
- Type S with high-flow exhaust system with tuned sports exhaust note
- 3.2 CL with 225 horsepower at 5600 rpm
- Variable Valve Timing and Lift Electronic Control (VTEC)
- Computer controlled Programmed Fuel Injection (PGM-FI)
- Direct Ignition System
- 105,000-mile tune-up intervals
5-Speed Automatic Transmission
- Quick-response 5-speed Sequential SportShift allows semi-manual operation
- Torque converter lockup area increased to improve performance and fuel efficiency
- 5-speed design helps improve acceleration and fuel economy
- Direct-control automatic transmission is managed by the Powertrain Control Module (PCM) for smoother shifting
- Grade Logic Control to ease shifting when driving through hills
Emissions/Fuel Economy
- 3.2 CL EPA (preliminary) fuel economy of 19/29 mpg (city/hwy)
- Type S EPA (preliminary) fuel economy of 18/28 mpg (city/hwy
- All CL coupes meet LEV standards; 3.2 CL California models meet ULEV standards
- Electronically controlled Exhaust Gas Recirculation (EGR)
Noise Vibration and Harshness (NVH)
- Smooth firing 60-degree V-angle
- Full-floating piston pins eliminate piston slap during warm-up
- Elimination of separate camshaft holders allows for a more compact, rigid cylinder head
- Lightweight pistons and connecting rods
- Three hydraulic engine mounts
- Transmission gear noise reduction through tighter gear-teeth-mesh contact ratio
- High rigidity cylinder block (ribbed) on Type S
ENGINE ARCHITECTURE
An advanced 3.2-liter, 24-valve, all-aluminum, 60-degree V-6 engine
powers both the 3.2 CL and the Type S. Remarkably compact and
lightweight, the CL power plant and transmission incorporate a wide
variety of advanced technologies, including the VTEC system, high
flow air filter and throttle body along with a unique, dual-stage
induction system exclusively on the Type S. Similar to the powertrain
in the 3.2 TL performance luxury sedan, the CL's performance
capabilities have vastly improved from the previous generation 2.3 CL
and 3.0 CL coupes.
ENGINE BLOCK
Die-cast and heat-treated, the compact aluminum block is extremely
rigid, with a high natural frequency and minimal resonant vibration.
The V-6's iron cylinder liners have their bore pitch set at a close
98-mm spacing to reduce overall engine size. The free-revving CL
engine is oversquare with a bore of 89 mm and a stroke of 86 mm to
give the engine a total displacement of 3210 cc. The CL employs an
engine cylinder bank V-angle of 60-degrees, allowing for a narrower
angle with improvements in engine smoothness and reduction in overall
bulk and weight. The block has an unusually short deck height,
resulting in an overall reduction in the height and width of the
assembled engine. The Type S engine also incorporates separate,
spin-cast cylinder wall liners that are cast into the engine block
during the initial manufacturing stage. These spin-cast liners allow
for additional weight reduction over traditional engine block
cylinder walls and provide added heat rejection to avoid engine
knocking. Additionally, by reducing the number of machined surfaces,
spin-cast cylinder liners ease the manufacturing process.
CRANKSHAFT/CONNECTING RODS/PISTONS
A rigid, forged crankshaft and narrow 19 mm connecting rods allow a
reduction in overall engine length as well as width. The rods in the
V-6 do not employ the use of conventional nut-and-bolt type
fasteners, but instead utilize lighter bolts (without nuts) called
plastic-region fasteners. This allows a downsizing of the rod bolts
while maintaining the proper clamping force and strength margins.
The V-6 incorporates compact pistons made from lightweight, cast aluminum alloy. The unique dome shaped design allows for maximum volumetric efficiency in the combustion chamber, producing a 9.8:1 combustion ratio in the 3.2 CL. The Type S achieves a 10.5:1 ratio thanks to an increased dome shape on the piston allowing a more condensed combustion volume in the chamber. The pistons utilize a 3-ring design with the Type S engine incorporating a unique angled top ring for an improved seal within the cylinder to accommodate the higher combustion pressure.
CYLINDER HEAD
The 3.2-liter V-6 pressure-cast aluminum alloy cylinder heads reflect
Acura's latest thinking in engine design. Utilizing 4 valves per
cylinder and a compact combustion chamber with a generous squish
area, the cylinder head is a key component for the high output CL
engines. The Type S also features special, race designed intake
valves to further improve flow into the combustion chamber. The
single camshaft in each cylinder head is installed from the
timing-belt end of the engine, eliminating the need for bolt-on caps
&endash; a savings of weight of complexity. Driven by the crankshaft
via a glass-fiber reinforced toothed belt, the cams actuate the
valves via friction reducing roller followers.
VARIABLE VALVE TIMING AND LIFT ELECTRONIC CONTROL (VTEC)
The Variable Valve Timing and Lift Electronic Control (VTEC)
valve train is a major contributing factor to the CL's remarkable
combination of high power delivery and fuel economy. With the lift
and opening duration of the larger intake valves altered
automatically based on engine rpm, the engine develops strong
low-speed torque without sacrificing high rpm power.
The VTEC-equipped engine delivers a substantial amount of horsepower, coupled with greatly increased torque at low-to-mid speed range. At low rpm, the VTEC intake valves follow a set of low-lift, short-duration cam lobes with timing that optimizes cylinder filling. Additionally, the timing of the intake valves is staggered and their lift is asymmetric, creating a swirl effect within the combustion chambers. This increases burn speed and improves combustion stability and allowable EGR rate. As the engine accelerates through 4400 rpm (4800 rpm on Type S), the intake rocker arms transition to actuation by high-lift, long-duration cam lobes designed to optimize high rpm output.
The exclusive camshafts found in the Type S engine further increase power output by providing longer intake valve duration, more vale overlap and additional lift for the exhaust valves.
DUAL-STAGE INDUCTION SYSTEM
Fitted exclusively on the Type S model, this revolutionary induction
system is the heart of the class-leading 260 horsepower engine. This
system uses a large, two-chamber intake plenum separated by a valve,
which opens at 3800 and is actuated by a separate electric motor.
During this valve's closed-stage at low to mid engine speed operation, a Resonance Charge condition exists when pressure pulsations between cylinders assist the adjoining cylinder for each bank. In doing so, air filling the cylinders increases with the resonance energy (Helmholz principle).
When this valve opens during mid to high engine speed operation, an Inertial Charge condition is achieved and increased air filling occurs when the manifold volume (plenum) is increased and the resonance condition is eliminated. This phenomenon utilizes the high flow mass to pressurize the manifold port air, producing a natural "supercharger" effect.
This increased airflow and air filling is the fundamental reason for the efficient combustion and subsequent power. Additional improvements were made to reduce air intake restriction and increase total air flow volume through a larger 64mm bore throttle body, along with a low restriction, overall air induction network, including a free flow air filter and air flow tube.
PROGRAMED FUEL INJECTION (PGM-FI)
Controlled by a 16-bit, 32 MHz Central Processor Unit (CPU), the CL's
Programmed Fuel Injection (PGM-FI) monitors and controls numerous
vehicle dynamics. Throttle position, engine temperature, intake
manifold pressure, and atmospheric pressure, exhaust gas oxygen
content and intake air temperatures are all processed by the PGM-FI.
While tracking the operation of the engine with position sensors on
the crankshaft and both camshafts, the PGM-FI CPU is also in constant
communication with a similar CPU that controls the 5-speed Sequential
SportShift automatic transmission. It controls fuel delivery by
injectors mounted in the cast aluminum, tuned-length intake manifold
featuring a large plenum chamber to help maximize airflow and
increase power and torque.
EXHAUST SYSTEM
The 3.2 CL's high-flow dual-exhaust system is designed to offer
lightweight, low restriction performance while ensuring excellent
emissions and noise control. To help the Type S achieve additional
horsepower, it receives greater exhaust flow capabilities through a
larger diameter exhaust pipe, an increased flow catalytic converter
and ultra-high flow capacity dual mufflers. These enhancements to the
Type S increase exhaust flow out of the engine by over 30 percent
compared to the 3.2 CL. The Type S exhaust note has also been tuned
to provide an aggressive, performance-oriented sound while minimizing
excessive noise at cruising speed.
DIRECT IGNITION SYSTEM/KNOCK CONTROL
Proper ignition spark timing is critical to engine performance and
emission control. This timing constantly changes from one instant to
the next depending on a multitude of factors. If there is too little
spark advance for the conditions, then efficiency suffers; if there
is too much spark, then the onset of knocking (or pinging) can result
in overheating and engine damage. To ensure a properly timed spark,
the CL relies on a new generation knock-control system. Based on a
centrally positioned sensor in the block that "hears" the first
traces of knocking, the ignition timing is advanced to the point of
peak efficiency, but not beyond, even if fuel quality is less than
the specified unleaded premium. This fine spark control allows the CL
to operate safely- (and more efficiently) with greater spark advance
than its predecessor. Another refinement to the ignition system is
the adoption of improved direct ignition coil units. These compact
and reliable units are positioned directly in the spark plug access
bores.
CONTROL OF NOISE, VIBRATION AND HARSHNESS
Though the CL's powertrain was engineered for uncompromised
horsepower and consistent torque, special effort was devoted to
attaining higher standards of Noise, Vibration and Harshness (NVH)
control. Key engine attributes were analyzed to develop engineering
targets for smoothness and noise control. Both the 3.2 CL and the
Type S engines reflect this effort with features like the compact,
rigid aluminum block and its unusually high resonant frequency, rigid
forged crankshaft, die-cast accessory mounts and stiff cast aluminum
oil pan.
100,000-MILE TUNE-UP INTERVALS
The new CL offers tune-up intervals of 105,000 miles; during that
time only routine inspections and fluid changes are required. The
roller-follower design of the VTEC valve train cuts friction and wear
to the point that the screw-type tappet clearance adjusters do not
require inspection until 105,000 miles, at which point the
platinum-tipped spark plugs are also due for replacement.
DIRECT-ACTING CRUISE CONTROL
Even though the CL is a true enthusiast's car, there may be
occasional situations where the driver of the new CL coupe decides to
allow the car to maintain cruising speeds by engaging the cruise
control. In these instances, the cruise control system's Electronic
Control Unit (ECU) directly commands downshifts to the transmission
ECU as required, allowing the vehicle to more closely maintain the
set road speed even in hilly driving conditions. The convenient
steering wheel-mounted cruise control buttons allow the driver to
adjust speed in 1 mph increments or disengage the cruise control
without touching the brake pedal.
5-SPEED AUTOMATIC TRANSMISSION
To maximize the performance capabilities of both the 3.2 CL and Type
S V-6 engines, an advanced 5-speed automatic transmission with a
Sequential SportShift system was developed. Though the new engine
commands a significant role in the new CL's improved performance, the
new 5-speed automatic transmission figures heavily in measured
performance gains and seat-of-the-pants driving feel.
The close ratio settings match the demands of varied driving situations while the new transmission's tall top gear ratio results in low cruising rpm's for reduced engine noise and lower fuel consumption.
Immediately noticeable from the driver's seat is a marked improvement in shift quality, relative to the four-speed automatic transmission in the 1999 CL. The new 5-speed transmission downshifts more quickly, with less shift shock, and is tuned much more aggressively to take advantage of the new, more powerful engine.
By sharing the idler and third gear clutches, the new transmission provides a total of five ratios without a significant increase in size or weight over typical 4-speed transmissions. Other improvements include the addition of a first gear one-way clutch for smoother shifts and a new heat exchanger design that moderates transmission operating temperature more quickly and with less complexity. An expanded torque converter lockup area provides a more direct driveline feel, similar to a manual transmission.
Using Direct Control shift technology, the new transmission uses a 16-bit, 20 MHz ECU directly controlling transmission operation in concert with the engine management system. Linear solenoids provide precise, real-time control of the clutch on/off pressure in the CL's transmission. With superior clutch-engagement accuracy, the sophisticated control logic system operates smoothly under all conditions. To reduce noise, a bearing supports the idler shaft, and gear-mesh contact ratio was refined.
Multiple safety and control strategies use interaction between engine and transmission controllers to manage overall powertrain operation. By limiting engine output torque and/or transmission clutch pressure, sharp driveline shocks are eliminated. The engine is also prevented from exceeding 5000 rpm in neutral and park.
SEQUENTIAL SPORTSHIFT SYSTEM
Both the 3.2 CL and the Type S are equipped with a Sequential
SportShift system, similar to the one originally introduced in the
NSX sports car. The CL's SportShift transmission operates as an
automatic or puts gear selection in the hands of the driver, much
like a manual transmission. By moving the console-mounted
transmission selector handle to the left of the "Drive" position into
a special SportShift gate, upshifts and downshifts can be commanded
with a quick fore or aft motion. Gear selection is indicated by an
LED display located in the tachometer face.
To foster the immediate feel of a manual transmission, in SportShift mode, the transmission logic commands firmer shifts that are approximately 10 percent quicker than in automatic mode. Additionally, the system is engineered to deliver an unusually quick response time to shift commands as compared to other semi-manual automatic transmissions.
Typically, the CL's transmission responds to a shift command in just 0.35 second, with the total shift completed in just over 0.9 second from the initial lever movement. These figures are quicker than those of semi-manual automatic transmissions of sports cars costing twice as much as the CL.
The Sequential SportShift system parallels the operation of a manual gearbox, but with built-in safety override features. The logic will not allow a downshift that would cause the engine to over-rev in the driver-selected lower gear. The transmission will stay in the selected gear until the vehicle approaches a complete stop and then will shift into first automatically. During acceleration, except for shifting between 1st and 2nd, the transmission will not up-shift automatically in SportShift Mode; however, should the driver fail to command an upshift in time, the engine ECU's will cut off the fuel flow to prevent the engine from over revving.
GRADE LOGIC CONTROL
By monitoring throttle position, vehicle speed and
acceleration/deceleration, then comparing these inputs with a map
stored in the transmission computer, the Grade Logic Control System
"knows" when the car is on a hill. The shift schedule is then
adjusted automatically to hold the engine in a lower gear for better
climbing power, increased downhill engine braking and reduced shift
frequency.