2003 Honda Accord -- Drivetrain - Part 1

7/29/2002 1:58:11 PM

Two engines are available in the 2003 Accords: a new 2.4-liter 4-cylinder and an extensively revised 3.0-liter V6. Both have more peak power and torque than their predecessors, as well as improved midrange and bottom-end performance. Along with these power gains come lower emissions and improved fuel economy that puts the Accord's engine choices at the head of their respective classes.

 Four-cylinder 2003 Accord models come with a new 5-speed manual transmission that's lighter and more compact and has improved shifting feel. Two new 5-speed automatic transmissions have been developed (replacing 4-speed automatics in previous generation Accords), one matched to the 4-cylinder and one for the V6 engine. The manual transmission in the V6 powered "Ultimate Sport Accord Coupe," is a short-throw 6-speed manual transmission. 

2.4-liter 4-cylinder highlights

Power

  • Displacement increase from 2.3-liters to 2.4-liters
  • 160 hp (10 hp/7 percent increase vs. previous 4-cylinder)
  • 161 lb.-ft. of torque (9 lb.-ft./6 percent torque increase vs. previous 4-cylinder)
  • New i-VTEC system incorporates Variable Valve Timing Electronic Control (VTEC) with continuously variable phasing of the intake camshaft (VTC)
  • Internal balance shaft for additional smoothness Improved fuel economy 24/33 mpg (expected EPA City/Hwy estimate from 23/30) with 5AT, 26/34 mpg with 5MT (from 26/32)

Emissions

  • New high-efficiency rear facing exhaust manifold/pipe structure reduces the distance to the catalytic converter for more effective operation
  • Addition of a Linear Air Fuel ratio sensor to all variations assures air/fuel control (previously SULEV only)
  • Increased VTEC swirl ratio
  • Internal EGR effect (new i-VTEC technology)

California SULEV version features:

  • Mass air flow meter (MAF) for improved A/F control
  • Enhanced and larger catalytic converter

NVH

  • Rigid block and pan assembly
  • Dual balance shafts
  • Silent cam chain drive

3.0-liter V6 highlights

Power

  • 240 hp (20 percent/40 horsepower increase vs. previous V6)
  • 212 lb.-ft. of torque (19 lb.-ft./9 percent torque increase vs. previous V6)
  • Compression ratio increases to 10.0:1 from 9.4:1
  • 3-rocker VTEC system
  • New Electronic Throttle Control (ETC) system
  • New high-inertia intake manifold design
  • Uses regular unleaded gasoline
  • High-flow/low-restriction exhaust system cuts back pressure by 30 percent
  • Fuel economy improved from 20/28 to 21/30 mpg (expected EPA estimated City/Hwy with new 5AT)

Emissions

  • Significantly reduced emissions (all models meet the new LEV II LEV standards except in California where they meet the new LEV II ULEV standards)
  • Close-coupled catalysts for faster light-off
  • Addition of a Linear Air Fuel ratio sensor assures precise air/fuel control

NVH

  • New engine mounting system also benefits ride and handling
  • Rigid engine block

Transmissions

New 5-Speed Automatic Transmission for 4-Cylinder

  • Replaces previous 4-speed automatic
  • Lightweight, compact design
  • Best-in-class performance and shift feel
  • New direct electronic control and control-logic circuitry
  • High-efficiency, ultra-thin torque converter
  • Optimized gear ratios
  • Second-generation Active Lockup torque converter contributes to improved fuel economy
  •  Grade Logic circuitry

New 5-Speed Automatic Transmission for V6

  • Replaces previous 4-speed automatic
  • Lightweight, compact and high torque design
  • Wide ratio range optimizes total performance and fuel economy
  • Integration with the new Electronic Throttle Control (ETC) system provides best-in-class shift quality
  • Low one-way clutch
  • Grade Logic circuitry
  • ATF temperature sensor allows temperature compensation for even smoother shifts

New 6-Speed Manual Transmission for V6 Coupe

  • Compact, lightweight design
  • Precise, short-throw shifting action
  • Dual mass flywheel
  • Self-adjusting clutch
  • Close-ratio gears enhance performance
  • Multi cone synchronizers on first through fourth gears
  • Synchronizer applied to reverse gear

New 5-Speed Manual Transmission for 4-cylinder

  • Lighter and more compact than the previous gearbox
  • Smoother, quieter operation
  • Lighter shift feel with shorter throws
  • Multi-cone synchronizers on first through fourth gears
  • Low-effort clutch with short pedal stroke
  • Optimized gear ratios

4-Cylinder Engine Overview
Representing the state-of-the-art combination of performance, economy, and ultra-clean operation, the Accord's standard 2.4-liter i-VTEC engine is a showcase of Honda's latest technologies. Building on the solid foundation of the original VTEC design, this latest 16-valve i-VTEC engine transforms the character of the 4-cylinder Accord, providing unprecedented levels of acceleration and fuel efficiency with minimal tailpipe emissions.

This strong running engine equals or betters the old engine's peak torque figure over an impressive 3000-rpm range. Even though it develops significantly more horsepower (+7 percent) and torque (+6 percent), this engine also meets stringent LEV II LEV emission standards. In SULEV spec for the California market, the engine does not compromise power, and requires only the addition of a Mass Air Flow sensor, an enhanced catalytic converter and the use of low sulfur fuel to meet this extremely rigorous emissions standard. This allows this engine to be used in all LX and EX automatic transmission vehicles for California and become a high volume, mainstream engine in the California market for the first time.

Displaying typical Honda attention to engineering detail, this compact and lightweight 4-cylinder engine comes well prepared to serve as the powerplant of choice for roughly 70 percent of Accord buyers. Fitted with internal balance shafts for additional smoothness and cast-in iron cylinder liners to enhance durability, it is designed from the start to deliver years of trouble-free operation. Save for inspections and fluid changes, the first scheduled maintenance comes at the 105,000-mile mark.

Engine Comparison: 2003 Accord Vs. 2002 Accord

.

'03 Accord

'02 Accord

Engine

In-Line 4
DOHC i-VTEC

In-Line 4
SOHC VTEC

Displacement

2354cc

2254cc

Compression Ratio

9.7:1

9.3:1

Fuel Type

Regular Unleaded

Regular Unleaded

HP @Rpm

160 @ 5500

150 @5700

Torque @rpm

161 @ 4500

152 @4900

Transmission

5MT/ 5AT

5MT/ 4AT

City/Highway MPG

24/33 (AT)

23/30 (AT)

Emissions Certification

LEV II LEV/SULEV

LEV I - LEV/ ULEV/ SULEV

Key 4-Cylinder Engine Technologies
The 2.4-liter Accord engine incorporates a host of advanced technologies, highlighted by the adoption of Honda's latest i-VTEC ("intelligent") valve-control system. Developed from technology initially seen in the world of Formula One racing, Honda's original VTEC (Variable valve Timing and lift Electronic Control) system changed the valve lift, timing and duration to suit the engine's running condition.

With continuous phase adjustment of the intake camshaft, i-VTEC adds VTC (Variable Timing Control) to the mix. This latest enhancement, first used on the Acura RSX and also found on the new Honda CR-V and Civic Si engines, provides further improvements to power and torque figures while optimizing overall operating efficiency and minimizing tailpipe emissions. With its greater output, the i-VTEC engine provides the new Accord with better total performance under all types of driving conditions and terrain.

With all-aluminum construction and a 16-valve DOHC design, the new 2.4-liter Accord develops 160 horsepower at 5,500 rpm and 161 lb.-ft. of torque at 4,500 rpm in both LEV and SULEV forms. The combination of VTEC technology with the new VTC provides the engine with even stronger low- and mid-range punch as well as a robust high end. This "intelligent" variation on the basic theme retains the original VTEC hardware that permits the optimization of valve lift and duration as the engine transitions from low-speed to high-speed operation, while adding the ability to continuously vary phasing of the intake cam based on both rpm and load factors. The net result is optimized idle stability, emissions, torque and power.

To further improve its operating efficiency, the engine has been rotated 180 degrees from the previous Accord four. This change permits the catalytic converter to be mounted closer to the exhaust manifold (now on the rear side of the engine), which promotes quicker light-off and thereby helps further reduce cold-start emissions.

Major 4-Cylinder Components

Cylinder Head and Valvetrain
The i-VTEC engine is crowned by a compact, lightweight cylinder head made of pressure-cast aluminum alloy. Its 4-valve-per-cylinder design has double overhead camshafts activated by a silent chain drive to ensure extremely precise control of the cam phasing. The cam drive is maintenance-free throughout the life of the engine. The combustion chamber is designed with a relatively large "squish" area that promotes faster flame propagation on the ignition stroke. This results in more complete burning of the air-fuel mix and subsequently, lower levels of CO and HC emissions.

4-Cylinder i-VTEC
Ushering in a new era of performance technology, Honda's original VTEC (Variable Valve Timing and Lift Electronic Control) has been elevated to a new plateau with the introduction of i-VTEC. This "intelligent" form of the highly effective VTEC package adds a new element to the mix in the form of VTC (Variable Timing Control), which provides for continuously variable phasing of the intake camshaft.

The formidable pairing of VTEC and VTC results in several major improvements to drivability, including more horsepower and torque at lower rpm levels, enhanced fuel economy and significantly lower emissions.

The VTEC system on the new 2.4-liter DOHC four employs two rocker arms with friction-reducing roller followers for each pair of intake valves, along with an intake cam that has separate lobes configured to optimize both low- and high-speed operation. Depending on engine load and rpm, an electronic controller determines which cam profile will be used and exactly how each intake will operate.

At low revs, where low lift and shorter duration provide optimal operation, the timing of the two intakes is staggered and the lift asymmetrically skewed in favor of the primary valve. This helps to create a swirl effect within the combustion chamber that increases the efficiency of the burn process. At higher rpm, a hydraulically actuated spool valve causes a locking pin to engage the secondary rocker arm with the primary one, transitioning the secondary valve into a high-lift/long-duration mode that improves output on the top end.

VTC allows the timing of the intake camshaft to be continuously varied throughout the engine's entire rpm range. Along with helping boost power, VTC also provides a more stable idle (allowing idle speed to be reduced) and reduced pumping losses by effectively creating an internal EGR effect at low and mid engine speeds. The result is increased fuel economy and lowered NOx emissions. Operation of the VTC is electronically controlled and is determined by input from sensors that monitor rpm, timing, throttle opening, cam position and exhaust gases.

Depending on conditions, VTC can vary the phasing of the intake cam (change its position relative to the crankshaft) by +/- 25 degrees. VTC activation is accomplished hydraulically via a spool valve that sends high-pressure oil to passages in the cam's drive sprocket.

At idle, the timing is almost fully retarded to minimize valve overlap. In normal highway driving, the intake camshaft is advanced to provide overlap for EGR effect. With the throttle wide open, valve timing starts in an advanced condition at lower RPM and continuously changes to a retarded condition when redline is approached. This allows optimum cylinder scavenging and pumping efficiency and provides outstanding power and torque throughout the rpm range.

Engine Block, Crankshaft & Oil Pan
The 2.4-liter engine uses a two-piece, die-cast aluminum block and bearing cap design that helps maximize strength and rigidity while minimizing noise and vibration. The compact upper element features cast-in iron cylinder liners for outstanding durability and the lower element consists of a single-casting crankshaft carrier fitted with ferrous-carbon bearing-cap inserts that add to its overall structural rigidity. Each journal on the forged-steel crankshaft is micropolished to help reduce internal friction and improve durability.

Programmed Fuel Injection (PGM-FI)
The 4-cylinder engine is fitted with the latest iteration of Honda's Programmed Fuel Injection (PGM-FI) system. This ultra-precise fuel delivery package uses an array of sensors to constantly monitor a number of critical operating variables including throttle position, intake air temperature, water temperature, ambient air pressure, intake manifold pressure, and the exhaust-air ratios. Position-measuring sensors also are located on the crankshaft and both cams. Fuel is delivered to each cylinder by its own high-efficiency, multi-orifice air assisted injector.

Internal Balance Shafts
To improve smoothness throughout the rev range and help lower noise levels, the new Accord four is fitted with an internal balancer unit. Consisting of a pair of chain-driven counter-rotating shafts located in the oil pan, the balancing system helps quell the inherent second-order harmonic vibrations that normally impact in-line 4-cylinder engines.

Serpentine Drive Belt
The new Accord 4-cylinder uses a single, serpentine belt to operate all of the engine's accessory drives. In addition to saving space compared to the dual-belt system used on the previous four, this maintenance-free component features an integral auto tensioner.

Exhaust System
A high-efficiency exhaust system and a high-density catalytic converter helps the 4-cylinder engine meet stringent LEV II LEV emissions certifications and LEV II-SULEV in California. Both of these components function more effectively as the result of the engine having been rotated 180 degrees in the bay. Exhaust gases pass through a low heat-mass/dual-wall stainless steel manifold as they now exit the "downstream" side of the engine via a new double-walled pipe, that also helps limit heat loss. The combination of higher relative temperatures and a more direct path to the catalytic converter yields quicker light-off, which contributes to lower levels of hydrocarbon and NOx emissions.

Intelligent ECU
The ECU on the new i-VTEC engine is now fitted with an on-board data recorder that constatly monitors operation of both the automatic transmission and fuel-injection circuitry. The system is unique in that it tracks operating parameters before and after a fault occurs, which makes troubleshooting much simpler. The data stream can be downloaded into a diagnostic analyzer at the dealer, where the cause can be identified and proper corrective action taken.

Exhaust System with Compact Silencer
The exhaust system of the new i-VTEC-powered Accord is designed to deliver both functional and cosmetic benefits. Several elements contribute to a reduction in total system weight. These include shortening the engine-to-tailpipe distance (as the result of rotating the engine 180 degrees), eliminating a tailpipe connector flange and adopting a new design for the resonator.

Lighter and more compact than the previously fitted unit, the silencer uses a "pipe turn" internal configuration that helps attenuate exhaust noise levels by 5-7 dB. Its narrower cross section also permits the bumper fascia to be lowered by 25 mm, thereby providing a cleaner appearance to the rear of the car.