2006 Honda Civic Powertrains

Advanced Technology for Performance, Economy and Low Emissions

8/31/2005 6:48:39 PM


As the world's largest engine producer, continuous improvement to vehicle powertrain technology is an integral part of Honda's engineering culture as every new engine design tends to become more powerful, efficient and cleaner while also becoming smaller in size and weight. Advancements in powertrain technology lead the way to improvements in vehicle packaging, interior space and overall desirability that give Honda products an edge in an ultra-competitive automotive industry. The 2006 Civic is no exception, and the new powertrain technology on all models delivers in true Honda fashion.

The Civic is available with three powertrains that consist of a 197-horsepower, 2.0-liter i-VTEC engine in the Civic Si; a 115-horsepower and ultra-efficient 1.3-liter i-VTEC engine with Integrated Motor Assist in the Civic Hybrid; and an innovative 140-horsepower, 1.8-liter i-VTEC engine in the Civic Sedan and Civic Coupe. The 1.8-liter i-VTEC engine provides off-the-line acceleration performance at low rpm equivalent to that of a 2.0-liter engine, and efficiency that is up to 6 percent better than the current 1.7-liter Civic engine, making it one of the world's most efficient 1.8-liter engine designs. A 6-speed manual transmission with a limited slip differential is standard in the Civic Si, a Continuously Variable Transmission (CVT) is standard in the Civic Hybrid, and the Civic Sedan and Coupe are equipped with a standard 5-speed manual or an available 5-speed automatic transmission.

Powertrain Summary


  • Ultimate High Performance: 2.0-liter i-VTEC DOHC 4-cylinder engine
    • 197 horsepower (1) (23 percent increase)
    • 139 lb-ft. of torque (1) (5 percent increase)
    • 22/31 EPA estimated city/highway fuel economy (2)
  • Ultimate Economy: 1.3-liter i-VTEC SOHC 4-cylinder engine with Integrated Motor Assist
    • 110 horsepower1 (24 percent increase)
    • 123 lb-ft. of torque1 (29 percent increase)
    • 50/50 EPA estimated city/highway fuel economy (2)
  • Best All-Around Performer: 1.8-liter i-VTEC SOHC 4-cylinder engine
    • 140 horsepower(1) (10 to 21 percent increase depending on trim level)
    • 128 lb-ft. of torque(1) (12 to 16 percent increase depending on trim level)
    • 30/40 EPA estimated city/highway fuel economy (5AT) (2)

(1) 2006 horsepower and torque calculations reflect new SAE J1349 procedures revised August, 2004.
(2) Fuel economy values determined from manufacturer test results. Official 2006 EPA mileage estimates not available at time of printing. Mileage figures shown for comparison purposes only. Actual mileage may vary.

  • 6-speed manual transmission with a limited slip differential (exclusive on Si)
  • Continuously Variable Transmission (exclusive on Hybrid)
  • 5-speed automatic transmission (available on Civic Sedan and Coupe)
  • 5-speed manual transmission (standard on Civic Sedan and Coupe)
Civic Si Powertrain

The 2006 Civic Si incorporates a host of innovative features designed to deliver a cutting-edge combination of performance, fuel efficiency, and low emissions. Most apparent is the i-VTEC "intelligent" valve-control system, a technology that combines VTC (Variable Timing Control) - which continuously adjusts camshaft phase-with Variable Valve Timing and Lift Electronic Control (VTEC) - which changes valve lift, timing, and duration. Combining these two systems results in impressive horsepower and high torque with good fuel economy and low exhaust emissions.

The Civic Si engine is a dual overhead cam (DOHC) all-aluminum, 2.0-liter inline four-cylinder design that uses 16 valves, a high-performance version of the i-VTEC system and a specially tuned high-volume intake manifold. The Civic Si produces 197 horsepower at 7800 rpm, up from 160 horsepower at 6500 rpm and torque increases from 132 lb-ft. at 5000 rpm to 139 lb-ft. at 6200 rpm. At nearly 100 horsepower per liter, it has one of the highest specific outputs of any production engine in the world.

In keeping with Honda's proven commitment to the environment, the Civic Si engine meets strict Low Emission Vehicle-2 (LEV-2) tailpipe emissions standards. Engine, fuel tank and catalytic converter modifications made for 2006 have lowered evaporative emissions by 75 percent to achieve a LEV-2 Evaporative Emissions rating.

The Civic Si is available exclusively with a short-throw 6-speed manual transmission. The final gear ratio is a low 4.765:1 that complements the additional horsepower and provides enhanced acceleration. Designed to be compact and lightweight, the 6-speed has also been engineered to provide the lightning-quick shift action of a racecar transmission. Synchronizers (triple cone on gears 1 and 2, double cone on gears 3 and 4, and single cone carbon on gears 5 and 6) help reduce shifting load for a light, responsive feel. The Si also includes a short-throw clutch with a torsion mechanism that enhances clutch refinement in terms of engagement and feel.

Civic Si Powertrain At-A-Glance


  • Aluminum block with cast-in iron liners for light weight and durability
  • 16-valve DOHC i-VTEC "intelligent" valve-control system
  • Lightweight alloy pistons and forged steel connecting rods (11.0:1 Compression Ratio)
  • One-piece crankshaft carrier with ferrous main bearing caps for improved rigidity and durability
  • High performance camshafts
  • Performance-tuned intake manifold
  • Drive-by-wire throttle control
  • Computer-controlled Programmed Fuel Injection (PGM-FI)
  • Direct Ignition System
  • Chain-driven balancer unit mounted in oil pan
  • Torque rod engine mount system consists of an upper and lower torque rod, a hydraulic body mount and a front beam stopper
  • Maintenance Minder system
  • Maintenance-free silent-chain camshaft drive
  • Maintenance-free serpentine accessory drive with auto tensioner
Emissions/Fuel Economy
  • Estimated EPA fuel economy of 22/31 mpg (city/highway)
  • Low Emission Vehicle-2 (LEV-2) emissions

6-Speed Manual Transmission

  • Exceptionally short throws for "racecar" shift feel
  • Low final gear ratio for quick acceleration (4.765:1)
  • Advanced clutch torsion mechanism enhances clutch engagement
  • Hydraulic damper integrated with master cylinder for reduced pedal vibration
  • Short clutch-pedal stroke for effortless shifting
  • Advanced friction material for improved clutch operability
  • Helical type limited slip differential

Civic Si: Engine Block/Crankshaft

The Civic Si engine features a compact aluminum block with cast-in iron liners-a design known for its lightweight, high rigidity, and excellent durability. The block has a one-piece aluminum crankshaft carrier, which has ferrous-carbon inserts in the bearing caps for additional strength and incorporates a stiff, cast-aluminum oil pan. The crankshaft is a highly rigid, forged-steel design that uses a special micro-polished surface finish for reduced friction and increased durability. In addition, the engine uses high-strength connecting rods and crankshaft as well as high-compression cast-aluminum pistons.

Civic Si: i-VTEC Concept

The innovative Variable Valve Timing and Lift Electronic Control (VTEC) system delivers abundant low-rpm torque, exhilarating high-rpm power, and outstanding fuel efficiency. The Civic Si features the latest version of this remarkable engine system: i-VTEC. The "intelligent," i-VTEC system adds VTC (Variable Timing Control) to VTEC to provide continuously variable camshaft timing - taking the concept of variable valve timing to new heights. In the Civic Si, i-VTEC = VTEC + VTC. Not only does i-VTEC provide a substantial performance increase across a broad power band, it boosts fuel economy while also reducing engine emissions.

Civic Si: i-VTEC Valvetrain

The Civic Si engine uses an aluminum cylinder head and a dual overhead cam, four-valve-per-cylinder valvetrain incorporating the i-VTEC system. High performance camshafts are used that allow for aggressive intake and exhaust valve openings to boost the rate that air moves into and exhaust moves out of the cylinder. At high engine speeds, valve lift phase on the intake side is increased by five degrees and on the exhaust side by 10 degrees. The camshafts increase engine breathing and help deliver enhanced top-end horsepower. The camshafts are operated by a silent-chain drive that helps provide smooth, refined performance while also being maintenance-free.

The VTEC component to the innovative Civic Si i-VTEC system adjusts the lift and opening duration of the valves to help the engine produce both abundant low-rpm torque and excellent high-rpm power. At low rpm, VTEC provides valve timing and lift for optimum cylinder filling. In addition, the timing of the intake valves is staggered and their lift asymmetric-creating a swirl effect within the combustion chambers. The result is increased burn speed with improved combustion stability. As engine rpm builds, VTEC transitions to a high-lift, long-duration cam profile for improved high-rpm engine output.

The Civic Si uses a high performance version of VTEC that varies the lift and duration of both the intake and exhaust valves for maximum power output. At lower rpm, the valves follow low lift, short duration camshaft profiles to help boost low-end torque. Above 5,800 rpm, the intake and exhaust valves are operated by high-lift, long-duration cam profiles, for maximum high rpm horsepower. When combined with VTC, both versions help the Civic Si engine produce a remarkably broad and smooth power band with exceptional torque and horsepower.

Civic Si: VTC (Variable Timing Control)

The Civic Si's i-VTEC system adds VTC (Variable Timing Control) to VTEC for continuously variable camshaft phasing across the engine's entire power band. As engine rpm builds, a VTC actuator-controlled by an engine-control unit that monitors cam position, ignition timing, exhaust oxygen content, and throttle position-advances or retards the intake cam throughout the 50 degree range, optimizing engine output and reducing emissions.

During typical operation, the intake camshaft timing is almost fully retarded at idle to help provide more stable idling while reducing exhaust emissions (NOx). As rpm increases, the intake camshaft is advanced, opening the intake valve sooner and providing additional valve overlap. This results in increased fuel economy (by reducing pumping losses) and a further reduction in exhaust emissions (by creating a large, internal exhaust gas re-circulation effect). Also, to generate additional power throughout the rev range, the intake camshaft is continuously varying the amount of advance or retard, instantly adjusting to provide additional power as required by the driver.

Civic Si: Short Length Performance Tuned Intake Manifold with High-Flow Intake

A short, high-performance single-stage cast aluminum manifold is used to help boost high-rpm power and generate a unique high performance engine sound in the Civic Si. The diameter of the intake duct measures 70 mm to increase intake flow, especially at high rpm. In addition to increasing flow, this large intake duct creates a highly pronounced sport sound under hard acceleration. Furthermore, a specially tuned resonance chamber was designed to emphasize the VTEC switch point, a unique character of many Honda vehicles. The intake duct was routed inside the fender area to take advantage of the acoustic sensitivity of the fender panel. By doing this, the desirable intake sound during high performance driving is amplified by the resonance of the fender panel.

Civic Si: Drive-by-Wire Throttle Control

An electronic drive-by-wire system helps enhance the driving character of the Civic Si. With smart electronics connecting the throttle pedal to the throttle butterfly valve in the intake manifold, the engine response can be optimized to suit the driving conditions and to better match the driver's expectations. By eliminating the direct throttle cable connection to the engine, the ratio between pedal movement and throttle butterfly movement can be continuously optimized.

The Civic Si uses a DC motor to control the throttle butterfly position in the intake tract. To establish the current driving conditions, the system monitors pedal position, throttle position, vehicle speed, engine speed and engine vacuum. This information is then used to define the throttle control sensitivity.

Civic Si: Programmed Fuel Injection (PGM-FI)

The Civic Si is equipped with a Programmed Fuel Injection (PGM-FI) system. The system monitors throttle position, engine temperature, intake-manifold pressure, atmospheric pressure, exhaust-gas oxygen content, and intake-air temperature. It controls fuel delivery by multi-holed injectors mounted in the cast-aluminum intake manifold. The ECU also tracks the operation of the engine with position sensors on the crankshaft and both camshafts.

Civic Si: Direct Ignition System

To ensure a hot, stable spark at high rpm operation, a coil mounted atop each spark plug, helps ensure a stable spark up to 8000 rpm. A sensor mounted behind one of the camshafts is the trigger for spark plug ignition. Also, specially designed iridium-tipped spark plugs help increase ignition energy and enhance plug life.

Civic Si: Exhaust System

A stainless steel, low heat-mass exhaust system is standard on the Civic Si. The system employs a high-density catalytic converter for improved light-off performance and reduced hydrocarbons and NOx. Emissions performance is further improved thanks to the engine's design, which positions the exhaust manifold on the rear of the engine-which shortens the distance that the exhaust gases must travel to the catalytic converter, resulting in faster light-off and more complete conversion of the exhaust gases. The exhaust system also incorporates an "e-shaped" dual-path pipe that optimizes the exhaust flow for improved torque and lower emissions. By employing a large diameter tail pipe (60.5 mm), an exhaust flow of 105 liters per second is achieved.

Civic Si: Noise, Vibration and Harshness (NVH) Control

In addition to its outstanding power and response, the Civic Si engine has been engineered for class-leading smoothness and refinement. The 2.0-liter four-cylinder employs such NVH-reducing features as a chain-driven balancer unit in the oil pan; a highly rigid, ferrous-carbon inserts in the main bearing caps for added rigidity; a one-piece crankshaft carrier; a silent chain cam drive; and a stiff, cast-aluminum oil pan. A torque rod damper system added to the subframe helps reduce rocking and isolate powertrain NVH from the passenger compartment. The torque rod engine mount system consists of an upper torque rod attached to the transmission and a lower torque rod attached to the engine, a hydraulic body mount and a front beam stopper. The torque rod damper system is also used on all other Civic models, but without the front beam stopper.

Civic Si: Maintenance Minder System and Tune-Up Intervals

The Civic Si's engine tune-up schedule is calculated by the Maintenance Minder system. The Maintenance Minder system automatically indicates when to have standard service performed based on actual driving conditions (tracked by the ECU) and minimizes the guesswork related to whether the vehicle is being used in standard or severe use conditions for maintenance interval purposes. The display indicates when to change the oil, air cleaner, transmission fluid, spark plugs or coolant, as well as when to rotate the tires.

A tune-up is not required until 100,000 miles or more (only routine inspections and fluid changes are required up to this point). Credit for this longevity goes to long-wearing platinum-tipped spark plugs, a long-life timing chain, and careful engineering of the precisely manufactured DOHC valvetrain-which reliably maintains proper valve tappet clearances until the first tune-up.

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