2006 Honda Civic Powertrains

Advanced Technology for Performance, Economy and Low Emissions

8/31/2005 7:28:01 PM

The Power Control Unit (PCU) electronically controls the flow of energy to and from the IMA's electric motor. Using the latest in computer chip technology, the PCU's response time is quickened over previous versions, and a new inverter and DC/DC Converter help contribute to the IMA's overall increase in peak power.

The battery pack stores electricity in a bank of Nickel Metal-Hydride cells. This bank of 132 1.2-volt units stores up to 158 volts of electrical energy for the IMA motor compared to 144 in previous versions. A new Panasonic(R) dual module casing reduces weight from previous hybrid battery packs and also allows it to increase efficiency of the electrical flow. The 12 percent smaller volume of the battery pack accommodates more cargo space.

The Integrated Cooling Unit offsets the heat generated by the constant flow of electricity to and from the battery pack with an integrated cooling system mounted directly on the battery pack's outer box. Interior cabin air is continually flowed over the battery pack and re-circulated via a small vent placed on the rear seat shelf.

Civic Hybrid: Cooperative Regenerative Brake System

Hybrid-powered vehicles recapture kinetic energy via regenerative braking and store this energy as electricity in rechargeable battery packs. The Civic Hybrid is no different, as its IMA electric motor also acts as a generator that can recharge its battery pack during braking, steady cruising, gentle deceleration, or coasting.

New for 2006, a cooperative regenerative braking system debuts on the Civic Hybrid with the added capability to intelligently proportion braking power between the hydraulic brakes and the electric motor to extract even more electricity from the vehicle's kinetic energy. Less reliance on the traditional braking system and reduced engine pumping losses translate into greater electrical regeneration (170 percent more than the 2005 Civic Hybrid) and ultimately improved fuel economy.

When braking, a brake pedal sensor sends a signal to the vehicle's IMA computer (IPU). The computer activates a servo unit in the brake system's master cylinder that proportions braking power between the traditional hydraulic brakes and the electric motor to maximize regeneration. Previous versions of Honda's IMA systems proportioned braking power at a pre-set rate below the maximum regeneration threshold and with no variable proportioning.

Civic Hybrid: Continuously Variable Transmission

Honda's fourth generation of Continuously Variable Transmission (CVT) is standard equipment on the Civic Hybrid and provides a 9 percent wider range between the maximum and minimum gear ratios to enhance acceleration and minimize engine rpm at high speeds. The transmission provides smooth and predictable transitions and helps keep the IMA system operating at its peak efficiency.

Unlike a conventional transmission with four of five gears that change the final drive ratio in steps, a CVT uses a steel belt and a variable pulley to infinitely change the final drive ratio between a minimum and maximum setting. The variable pulley with its angled internal sides moves in and out by hydraulic pressure to expand or reduce the radius traveled by the steel belt. Improvements to the new CVT include:

  • 9 percent wider ratio range of 2.52 - 0.421:1 (previously 2.36 - 0.407:1)
  • Final drive ratio of 4.94:1 (previously 5.58:1)
  • Expanded pulley axial distance from 143 mm to 156 mm
  • Expanded pulley ratio range to 6.0 mm from 5.8 mm
  • Double hydraulic piston used on variable pulley increases pressure by 170 percent
  • Improved low friction construction for overall efficiency increase
  • Torque handling capacity increases by 18 percent

Overall, a CVT provides a fuel economy benefit greater than a conventional automatic transmission with gears, approaching that of a manual transmission. It helps the engine stay in its most efficient operating range for both performance and economy, and the need to shift gears is eliminated.

Civic Sedan and Coupe Powertrain

The Civic Sedan and Civic Coupe benefit from a new generation of Honda engine technology that provides performance similar to a 2.0-liter engine and fuel economy similar to a 1.5-liter engine. The new engine offers significantly improved low rpm torque and top end power. A new 5-speed automatic transmission (available) extracts this extra power to its fullest potential. Additional new Civic technology includes a drive-by-wire throttle control and a dual-stage air intake manifold.

For 2006, all Civic Sedan and Civic Coupe models are powered by a Single Overhead Cam (SOHC) 1.8-liter inline four-cylinder design with 16 valves, a new version of i-VTEC, and a dual-stage intake manifold. The engine produces 140 horsepower @ 6300 rpm (up from 127 horsepower at 6300 rpm, EX trim level), 128 lb-ft. of torque at 4300 rpm (up from 114 lb-ft. @ 4800 rpm, EX trim level) and an estimated EPA city/highway fuel economy of 30/40 miles per gallon (up from 29/38 miles per gallon on LX with automatic transmission). Emissions in all 50 states are rated as ULEV-2, an improvement from the ULEV-1 emission standard on the 2005 model. The engine performance differences are even greater when compared the 2005 Civic's LX and DX trim levels that produced 115 horsepower @ 6100 rpm and 110 lb-ft. of torque @ 4500 rpm.

Civic Powertrain At-A-Glance


  • High rigidity aluminum block with low friction internal components
  • i-VTEC "intelligent" valve control system
  • Composite dual stage intake manifold
  • Drive-by-wire throttle control
  • Programmed Fuel Injection (PGM-FI)
Emissions / Fuel Economy
  • Estimated EPA fuel of 30/40 city/highway (automatic transmission)
  • Ultra Low Emissions Vehicle-2 (LEV-2)
  • Standard 5-speed manual transmission
  • Available 5-speed automatic transmission
High Rigidity Aluminum Block and Low Friction Engine Design

Compact, rigid, lightweight and low friction describes the end result of new engine technology that helps to enable the new Civic to achieve high power and high fuel economy. Compared to its predecessor, the aluminum engine block is more compact, has a higher power-to-weight ratio, operates with less internal friction and creates less noise and vibration.

A narrow width cam chain, a chain case with a built-in oil pump and ferrous spin cast cylinder sleeves are used to make the engine approximately 13 mm shorter, allowing for greater packaging efficiency.

To make the engine more rigid, extensive analysis was used to create reinforced areas in the aluminum block construction. Furthermore, a lightweight and super stiff steel crankshaft is used with a high balance ratio that also benefits from a lower block design with extremely high crank support rigidity. At the very bottom of the engine, an aluminum oil pan with integrated stiffeners further refines the rigidity. The high rigidity block design benefits low noise output and also provides the foundation for lower friction in the engine.

Low friction, a key component to producing more power, is achieved through the application of Molybdenum Di-Sulfide (MoS2) piston coatings and cylinder sleeve plateau honing. Plateau honing lowers the friction level between the pistons and the cylinders by creating an ultra smooth surface. Plateau honing is a two stage machining process that uses two grinding processes instead of the more conventional single honing process. This also enhances the long-term wear characteristics of the engine. A low friction ion plated piston ring further reduces friction. In addition low viscosity oil (5W-20) is used to reduce friction.

Cracked Connecting Rods

High strength cracked connecting rods are used that minimize weight and size, while also increasing connecting rod rigidity and long term durability. A "cracked" connecting means that the rod and cap are forged as a complete unit during the manufacturing process, and then cracked apart to create a custom fit between the two matching surfaces. The use of high strength steel contributes to the connecting rod's slender shape and results in a 50 percent increase in fatigue resistance for a long lasting engine.

The design allows for the elimination of connecting rod bolt pins, since the connecting rod bolts can be precision machined to fit the cap to the rod. The end result is a connecting rod that is 13 percent lighter and has a 20 percent smaller cross section, resulting in less rotating mass inside the engine and less space occupied by the connecting rod - a significant component to creating a powerful, efficient and compact engine.

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