2010 Honda Accord Crosstour: Powertrain

Overview
The Honda Accord Crosstour comes standard with a 271 horsepower V-6 engine, a 5-speed automatic transmission and is available with the company's innovative Real Time™ 4WD system. The 3.5-liter, 24-valve SOHC i-VTEC powerplant with Variable Cylinder Management (VCM) that builds on technologies that have been developed and refined on previous Honda vehicles. With its 60-degree V-angle, the Accord's V-6 engine is inherently very smooth and has compact overall dimensions that allow efficient packaging within the vehicle. The automatic transmission includes a new G-force hold control feature along with an RPM rev-matching featuring when downshifting.

Powertrain Summary

  • 3.5-liter i-VTEC V-6 engine with VCM
  • 271-horsepower @ 6200 RPM, 254 lb-ft. of torque at 5,000 RPM
  • Standard 5-speed automatic transmission and available Real Time 4WD
  • City/highway fuel economy of 18/27 miles per gallon (2WD)1
  • Emissions: ULEV-2 (CARB) / Tier 2, Bin 5 (Federal)

New Technology and Exclusive Features

  • Expanded VCM engagement range for improved overall fuel efficiency
  • Latest version of Active Control Engine Mounts
  • Latest version of Active Lockup Torque Converter
  • Automatic transmission lateral G-force gear hold control (Honda brand first)
  • Automatic RPM rev-matching when downshifting (Honda brand first)

Engine Architecture
The Accord Crosstour's engine is an advanced 3.5-liter, SOHC, 24-valve, 60-degree, V-6, aluminum-block-and-head design that is compact, lightweight and powerful. The i-VTEC valvetrain and high efficiency intake manifold optimize cylinder-filling efficiency across a wide range of engine speeds. Low-restriction intake and exhaust systems, a 10.5:1 compression ratio and roller-type rocker arms further aid efficiency and power delivery across a broad RPM range.

The Accord Crosstour's V-6 has a die-cast lightweight aluminum alloy block with cast-in-place iron cylinder liners. Made with a centrifugal spin casting process, the thin-wall liners are high in strength and low in porosity. The block incorporates a deep-skirt design with four bolts per bearing cap for rigid crankshaft support and minimized noise and vibration. Both the block and caps are heat treated for greater strength.

A forged steel crankshaft is used for maximum strength, rigidity and durability with minimum weight. Instead of heavier nuts and bolts, connecting rod caps are secured in place with smaller, high-tensile-strength fasteners that screw directly into the connecting rod. Short-skirt, cast-aluminum, flat-top pistons are notched for valve clearance and fitted with full-floating piston pins.


2010 Honda Accord Crosstour i-VTEC V-6 engine

Like other Honda V-6 powerplants, the Accord Crosstour V-6 cylinder heads are a single-overhead-camshaft design, with the cams driven by the crankshaft via an automatically tensioned toothed belt. Made of low-pressure cast, low-porosity aluminum, each cylinder head incorporates an integrated exhaust manifold to reduce parts count, improve flow and optimize the location of the close-coupled catalyst on each cylinder bank.

The cylinder head employs four-valve combustion chambers, the best approach to optimum performance with excellent fuel efficiency and very low emissions. Valves are clustered near the center of the bore to minimize combustion chamber volume and to provide ample squish area. The 10.5:1 compression ratio helps maximize thermal efficiency, power output and fuel efficiency. One centrally located camshaft per cylinder bank is driven by a fiberglass-reinforced toothed belt. Head gaskets are made of high-strength materials to contain combustion pressures.

i-VTEC with 3-stage Variable Cylinder Management™ (VCM™)
To help improve the fuel efficiency of the V-6 engine, it incorporates the latest generation of Honda's VCM, which expands the operational range of cylinder activation compared to the Accord Sedan and Coupe V-6 engine. The Accord Crosstour's VCM system can operate on three, four or all six cylinders, and is standard on both two-wheel-drive and four-wheel-drive models.

During startup, acceleration or when climbing hills - any time high power output is required - the engine operates on all six cylinders. During moderate speed cruising and at low engine loads, the system operates just one bank of three cylinders. For moderate acceleration, higher-speed cruising and mild hills, the engine operates on four cylinders.

With three operating modes, the VCM system can finely tailor the working displacement of the engine to match the driving requirements from moment to moment. Since the system automatically closes both the intake and exhaust valves of the cylinders that are not used, pumping losses associated with intake and exhaust are eliminated and fuel efficiency increases. The VCM system combines maximum performance and maximum fuel efficiency - two characteristics that do not typically coexist in conventional engines.

VCM deactivates specific cylinders by using the VTEC (Variable Valve-Timing and Lift Electronic Control) system to close the intake and exhaust valves while simultaneously the Powertrain Control Module cuts fuel to those cylinders. When operating on three cylinders, the rear cylinder bank is shut down. When running on four cylinders, the left and center cylinders of the front bank operate, and the right and center cylinders of the rear bank operate.

The spark plugs continue to fire in inactive cylinders to minimize plug temperature loss and prevent fouling induced from incomplete combustion during cylinder re-activation. The system is electronically controlled, and uses special integrated spool valves that do double duty as rocker-shaft holders in the cylinder heads. Based on commands from the system's electronic control unit, the spool valves selectively direct oil pressure to the rocker arms for specific cylinders. This oil pressure in turn drives synchronizing pistons that connect and disconnect the rocker arms.

The VCM system monitors throttle position, vehicle speed, engine speed, automatic-transmission gear selection and other factors to determine the correct cylinder activation scheme for the operating conditions. In addition, the system determines whether engine oil pressure is suitable for VCM switching and whether catalytic-converter temperature will remain in the proper range. To smooth the transition between activating or deactivating cylinders, the system adjusts ignition timing, drive-by-wire throttle position and turns the torque converter lock-up on and off. As a result, the transition between three-, four-, and six-cylinder operation is unnoticeable to the driver.

Active Control Engine Mounts (ACM)
See the body section for information on the Active Control Engine Mounts.

High-Flow Exhaust System with Dual Outlets
A low-restriction, high-output, exhaust system is crucial to efficient power and torque production. A completely new exhaust system on the Accord accommodates its increased power output. Tubing diameter has been increased and new dual silencers are used. High-chromium stainless steel is used throughout the exhaust system for excellent durability. The Accord Crosstour's exhaust system is customized based on whether the vehicle is front-wheel-drive or four-wheel-drive. The front-wheel-drive exhaust system utilizes one large and one small resonator prior to the splitter that goes to each muffler. For packaging considerations with the propeller shaft and gas tank on four-wheel drive models, two smaller resonators are placed after the splitter that divides the exhaust route to each rear muffler. Both exhaust systems achieve the same flow rate of 135 l/s.

Key contributors to the engine's low emissions performance are its high-efficiency catalytic converters. The engine has its exhaust manifolds cast directly into the aluminum alloy cylinder heads to reduce weight and position each primary catalytic converter as close as possible to the combustion chambers. High-efficiency close-coupled converters mount directly to the exhaust port of each cylinder head for extremely rapid converter activation after engine startup. A third converter is positioned shortly downstream, beneath the passenger compartment floor. Both converters use a thin-wall design that increases internal reaction area and improves efficiency.

Powertrain Control Unit (PCU)
A 32-bit, 96MHz powertrain control unit (PCU) within the powertrain control module calculates injection timing and duration after assessing an array of sensor signals: crankshaft and camshaft position, throttle position, coolant temperature, intake manifold pressure and temperature, atmospheric pressure and exhaust-gas oxygen content. The PCU controls the Programmed Fuel Injection (PGM-FI) and i-VTEC valvetrain and also communicates with processors that regulate the five-speed automatic transmission.

Drive-By-Wire (DBW) Throttle System™
The Accord Crosstour's drive-by-wire throttle system uses smart electronics instead of a conventional cable system to connect the throttle pedal to the throttle butterfly in the intake tract. Besides allowing engineers to program the relationship between throttle pedal movement and engine response, the system optimizes engine response to suit driving conditions. The system monitors throttle pedal position, throttle butterfly position, vehicle speed, engine speed and engine vacuum. This information is used to define the throttle control sensitivity.

Programmed Fuel Injection (PGM-FI)
The Accord Crosstour's PGM-FI continually adjusts the fuel delivery to yield the best combination of power, low fuel consumption and low emissions. Multiple sensors constantly monitor critical operating parameters, such as throttle position, intake air temperature, coolant temperature, ambient air pressure, intake airflow volume, intake manifold pressure, exhaust air-fuel ratio and the position of the crankshaft and cams.

Direct Ignition and Detonation/Knock Control
The Powertrain Control Unit (PCU) monitors engine functions to determine the best spark timing. An engine-block mounted acoustic detonation/knock sensor "listens" to the engine, and based on this input, the PCU retards the ignition timing to prevent potentially damaging detonation. An ignition coil unit for each cylinder is positioned above each spark plug's access bore.

Regular Unleaded Fuel
To keep operating costs at a minimum, all Accord models are designed to use relatively less-expensive regular unleaded fuel, thanks to compact 4-valve combustion chambers and precise fuel injection and spark control.

Maintenance Minder System and Tune-Up Intervals
The Accord Crosstour's Maintenance Minder system calculates the engine's tune-up schedule based on driving conditions (tracked by the PCU). When determining proper maintenance intervals, the system minimizes owner guesswork about whether the vehicle is being operated in standard or severe conditions. The Accord Crosstour's Maintenance Minder information appears in the odometer display, and indicates when to change the oil, oil filter (every other oil change), air cleaner, transmission fluid, spark plugs, coolant, Real Time 4WD differential fluid as well as when to rotate the tires. A tune-up is not required until about 100,000 miles. (100K+/- Miles No Scheduled Tune-ups may vary with driving conditions. Does not apply to fluid and filter changes. Exact mileage is determined by actual driving conditions. The owner's manual contains full details). Long-life fluids have been used for reduced maintenance costs and environmental impact (fluid disposal). As a result, engine coolant changes are needed about every 10 years or approximately 100,000 miles, and engine oil changes are required around 7,500 miles under normal driving conditions, or annually if fewer miles are driven per year. The maintenance minder system calculates the exact miles between service intervals.

5-Speed Automatic Transmission with Grade Logic Control
The Accord Crosstour's 5-speed automatic transmission has several features engineered specifically to match its performance requirements, including extra-wide gear ratios for good low-end response and comfortable highway cruising; a computer-controlled lock-up torque converter; a rigid alloy case; and a 4-shaft design. Honda Grade Logic Control technology is designed to hold the vehicle in a lower gear when climbing or descending a steep grade for improved performance.

The transmission features an expanded complement of smart logic controls. A computer-controlled lock-up torque converter is provided to maximize fuel efficiency. Torque-converter lock-up and shift timing are both managed by a CPU working in cooperation with the engine's central processing unit. An over-running clutch is provided for first gear to smooth upshift quality. A direct-control strategy is used to provide real-time pressure management of the transmission's clutches. Various control strategies exclusive to the Accord Crosstour are utilized to allow for smooth coordination of engine and transmission operations. For example, the driveline shock that often accompanies gear changes is minimized by momentarily reducing engine torque during shifting.


2010 Honda Accord Crosstour 5-speed automatic transmission

To reduce gear "hunting" and unnecessary shifting, Grade Logic Control and Shift Hold Control systems are integrated into the shift programming of Accord automatic transmissions. Grade Logic Control alters the 5-speed automatic's shift schedule, reducing shift frequency while traveling uphill or downhill. Using inputs monitoring throttle position, vehicle speed and acceleration/deceleration, Grade Logic compares the operating parameters with a digital map stored in the transmission computer. When the system determines the Accord is on a hill, the shift schedule is adjusted to automatically hold the transmission in a lower gear for better climbing power or increased downhill engine braking.

2010 Accord Crosstour
Gear Ratios
Gear Ratio
1 2.697
2 1.606
3 1.071
4 0.766
5 0.612
Reverse 1.889
Final 4.533

Shift Hold Control prevents up shifts to higher gears (fourth and fifth) in repeated winding-road situations where the throttle is quickly released and the brakes are applied. This reduces disturbance to the chassis when entering a corner, and ensures strong power is available without a downshift. Shift Hold Control improves throttle responsiveness and reduces unnecessary shifting on curving roads.

In addition to Grade Logic Control and Shift Hold control, the Accord Crosstour has Cornering G Shift Control, which is new to the Honda brand. This system measures the difference between right and left
wheel speeds using sensors to determine when the vehicle is in a corner. If the vehicle is cornering, it prevents the transmission from up shifting until the vehicle has exited the corner.

For manual gear operation using the gear selector, the Accord Crosstour exclusively features automatic RPM rev-matching when downshifting - a Honda brand first. The system uses the Drive-by-Wire throttle control's ability to "blip" the throttle and more closely match the engine's RPM to the transmission.

Real Time™ 4WD
The available four-wheel drive system on the Accord Crosstour is Honda's original designed Real Time 4WD. The objective of the technology is to best match the majority of driving situations that CUV's realistically encounter. The fully automatic Real Time 4WD system is designed to enhance all-weather and light-duty off-road capabilities when driving in rain, snow, dirt roads and sandy conditions - without the significant weight, fuel economy and handling performance drawbacks of a conventional four-wheel-drive system that requires a heavy transfer case and related parts.

The system sends power to the rear wheels only when there is insufficient traction for the front-wheel-drive system. The system consists of the conventional front-wheel-drive system, a compact transfer case that distributes torque to a propeller shaft running the length of the vehicle, a dual-pump system with a multi-plate clutch, a cam unit mechanism, the rear differential, and left and right rear-wheel driveshafts.

The core of the system is the dual-pump unit. It consists of two hydraulic pumps, one driven by the front wheels via the propeller shaft and one driven by the rear wheels via the rear differential. A hydraulically actuated, multi-plate clutch, similar to the clutches used in Honda automatic transmissions, connects the propeller shaft to the rear differential.


2010 Honda Accord Crosstour Real Time 4WD rear differential

When the vehicle is operating with the front and rear wheels turning at the same speed, for example on dry pavement, the front and rear hydraulic pumps operate at the same rate. Hydraulic fluid circulates between the two pumps and no pressure is generated. If the front wheels begin to turn faster than the rear wheels, as would be the case if they were spinning on snow or ice, the two hydraulic pumps would turn at a different rate and hydraulic pressure proportional to the difference in their speeds of rotation would be generated. The resulting hydraulic pressure opens a valve body and feeds pressure to the multi-plate clutch, which engages the front propeller shaft to the rear differential. The rear differential then feeds the drive torque to the right and left rear wheels.

To provide a quick torque transfer response time for transparent 4-wheel drive operation to the driver, the multi-plate clutch is supplemented by a one-way ball cam unit mechanism. The cam unit mechanism consists of two plates separated by six ball cams (large bearings) that move within ramped grooves. When a slight difference in rotation speed exists between the rear wheels and front wheels when driving forward, the ball cams move within the ramped grooves and create pressure that instantly begins the engagement of the main clutch (prior to the build-up of sufficient hydraulic pressure). By engaging the main clutch at a sufficient force even before the hydraulic pressure is generated by the two hydraulic pumps, the driving torque is transferred without a hint of time lag.

Overall system operation is completely automatic; no electronics or driver action is involved. The greater the degree of front-wheel slippage, the greater the amount of torque fed to the rear wheels. Real Time 4WD is also low maintenance. The Maintenance Minder system will indicate that the dual pump fluid should be changed.

Towing
The Honda Accord Crosstour has a maximum towing capacity of up to 1,500 pounds when properly equipped. Towing requires the addition of the Honda accessory trailer hitch, hitch ball and related accessories. Please see the owner's manual for details.

1 Based on 2010 EPA mileage estimates, reflecting new EPA fuel economy methods beginning with 2008 models. Use for comparison purposes only. Do not compare to models before 2008. Your actual mileage will vary depending on how you drive and maintain your vehicle.

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