Civic Si 2.4-liter i-VTEC
Honda has long been known for its world-class engine technology and a continuous advancement of innovation and improvement. At the core of Honda's powertrain engineering is the ongoing pursuit of greater performance, enhanced fuel economy and low emissions. The 2012 Civic embodies this effort with a range of gasoline, hybrid and Compressed Natural Gas (CNG) powertrains that offer unique solutions for different buyers.
For performance, the Civic's range of powertrains is led by the Civic Si with a new 201-horsepower, 2.4-liter i-VTEC® four cylinder engine matched with a close-ratio 6-speed manual transmission. For maximum fuel economy, the Civic Hybrid is powered by a 110-horsepower, ultra-efficient 1.5-liter i-VTEC four cylinder engine with Integrated Motor Assist (IMA) and a Continuously Variable Transmission (CVT). Designed as an all-around performer to meet the needs of a broad audience, the innovative 140-horsepower, 1.8-liter i-VTEC four cylinder engine is standard in the Civic Sedan, Civic Coupe and Civic HF. The Civic Sedan and Civic Coupe offer a choice of a standard 5-speed manual transmission (standard on sedan DX and LX and Standard on coupe DX, LX, EX ) or an available 5-speed automatic transmission, while the Civic HF has a standard automatic transmission. A variant of the same 1.8-liter four cylinder engine develops 110 horsepower in the Compressed Natural Gas (CNG)-powered Civic Natural Gas, which comes with a standard 5-speed automatic transmission.
- Ultimate High-Performance: Civic Si 2.4-liter i-VTEC DOHC I-4 engine
- 201 horsepower (2 percent increase)
- 170 lb-ft. of torque (22 percent increase)
- 22/31/25 estimated EPA city/highway/combined fuel economy (6MT)
- Ultimate Economy: Civic Hybrid 1.5-liter i-VTEC SOHC I-4 engine with Integrated Motor Assist
- 110 horsepower
- 127 lb-ft. of torque (3 percent increase)
- 44/44/44 EPA-estimated city/highway/combined fuel economy (CVT)
- All-Around Performance: Civic 1.8-liter i-VTEC SOHC I-4 engine
- 140 horsepower
- 128 lb-ft. of torque
- 28/39/32 EPA-estimated city/highway/combined fuel economy (5AT)
- High Fuel Efficiency Civic HF: 1.8-liter i-VTEC SOHC I-4 engine
- 140 horsepower
- 128 lb-ft. of torque
- 29/41/33 estimate EPA city/highway/combined fuel economy (5AT)*
- Compressed Natural Gas (CNG) Civic Natural Gas: 1.8-liter i-VTEC SOHC I-4 engine
- 110 horsepower
- 106 lb-ft. of torque
- 27/38/31 estimate EPA city/highway/combined fuel economy (5AT)*
- 6-speed manual transmission with limited-slip differential (exclusive on Civic Si)
- Continuously Variable Transmission (CVT) (exclusive on Civic Hybrid)
- 5-speed automatic transmission (available on Civic Sedan and Civic Coupe; std. on Civic HF, Civic GX, Civic EX w/navi, EX-L)
- 5-speed manual transmission (standard on Civic Sedan DX and LX and Coupe DX, LX, EX)
Civic Si Powertrain
Available in either a coupe or sedan, the 2012 Civic Si is powered by a new 2.4-liter inline four cylinder engine that is the largest and most powerful in Civic history in America. A range of innovative features help this new powerplant deliver a cutting-edge combination of performance, fuel efficiency, and low emissions. With the i-VTEC "intelligent" valve-control system and new friction-reducing technologies and the Civic Si has prioritized exhilarating acceleration, improved fuel economy and low exhaust emissions.
The Civic Si engine is a dual overhead cam (DOHC) all-aluminum, 2.4-liter inline 4-cylinder design that uses 16 valves, the i-VTEC system and a specially tuned high-volume intake manifold. The Civic Si produces 201 horsepower, up 4 horsepower versus the 2.0-liter engine it replaces. A key difference is the 0.4-liter larger displacement, which helps put the peak power at a more accessible 7000 rpm instead of the previous engine's 7800 rpm peak. The increased displacement contributes to a substantial 22-percent increase in peak torque, reaching 170 lb-ft. at just 4400 rpm, which is 1700 rpm less than the previous engine's 139 lb-ft. at 6100 rpm.
Despite an increase in engine size, horsepower and torque, the 2012 Civic Si's engine delivers an estimated EPA 1 mpg increase in city driving (22 mpg) and a 2 mpg increase in highway driving (31 mpg) compared to the 2011 Civic Si.
In keeping with Honda's proven commitment to the environment, the Civic Si engine meets strict Ultra-Low Emission Vehicle (ULEV-2) tailpipe emissions standards.
The Civic Si is available exclusively with a 6-speed manual transmission fitted with a short-throw shifter assembly. Designed to be compact and lightweight, the 6-speed has also been engineered to provide a short, firm and direct shift action. The Civic Si also includes a clutch system with a torsion mechanism that enhances refinement in terms of engagement and feel.
Civic Si Powertrain Summary
- Aluminum block with cast-in iron liners for light weight and durability
- One-piece crankshaft carrier with iron main bearing caps for improved rigidity and durability
- Dual balance shafts for exceptional smoothness
- High-strength connecting rods with lightweight aluminum pistons that deliver a 11.0:1 compression ratio
- 16-valve DOHC i-VTEC "intelligent" valve-control system
- High performance camshafts with maintenance-free silent-chain camshaft drive
- High flow air intake system
- Performance-tuned intake manifold
- Drive-by-Wire™ throttle control system
- Computer-controlled Programmed Fuel Injection (PGM-FI)
- Direct ignition system
- Torque rod engine mount system consists of an upper and lower torque rod, a hydraulic engine mount and a front beam stopper
- Maintenance Minder™ system
- Maintenance-free serpentine accessory drive with auto-tensioner
- EPA-estimated fuel economy of 22/31/25 mpg (city/highway/combined) (6MT)
- Ultra-Low Emission Vehicle (ULEV-2) emissions
6-Speed Manual Transmission
- Precise shift feel with short throws between gears
- Short clutch-pedal stroke for low effort use
- Helical-type limited-slip differential
Civic Si: Engine Block/Crankshaft and Low Friction Engine Design
The Civic Si engine features a compact aluminum cylinder block with cast-in iron liners— a design known for its light weight, 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. Further adding strength is a stiff, cast-aluminum oil pan. The crankshaft is a highly rigid, forged-steel design that uses a 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. Compared to the smaller engine in the previous generation, the new Civic Si engine has a 1mm increase in bore (now 87mm) and a 13mm increase in stroke (now 99mm). Through the application of new piston coatings and cylinder sleeve plateau honing, operating friction is reduced. Plateau honing lowers the friction level between the pistons and the cylinders by creating an ultra smooth surface. Plateau honing is a 2-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. Ion-plated piston rings and low viscosity oil (0W-20) are also used to reduce friction.
Civic Si: i-VTEC Overview
The 2.4L inline 4-cylinder engine features the Honda i-VTEC® "intelligent" valve control system that pairs Variable Valve Timing and Lift Electronic Control (VTEC®) with Variable Timing Control™ (VTC™). The system delivers improved low-rpm torque, exhilarating high-rpm power, and outstanding fuel efficiency.
Civic Si: i-VTEC Valvetrain
The Civic Si engine uses an aluminum cylinder head fitted with dual overhead camshafts, 4-valves-per-cylinder and the i-VTEC valvetrain system. High performance camshafts are used that allow for aggressive intake valve openings to boost the rate that air moves into the cylinder. The camshafts are operated by a silent-chain drive that helps provide smooth, refined performance.
The VTEC component of the i-VTEC system adjusts the lift and duration of intake valve opening 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 the intake valves for maximum power output. At lower rpm, the valves follow low lift, short duration camshaft profiles to help boost low-end torque. Above 5,000 rpm, the intake valves are operated by high-lift, long-duration cam profiles, for maximum high-rpm horsepower. When combined with VTC, both cam profiles help the Civic Si engine produce a remarkably broad and smooth power band with both excellent 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, 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 valves 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 rpm 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: High-Flow Induction System
The induction system is designed for high flow as well as to create an aggressive sound. The lightweight composite intake manifold has fixed-length intake runners that are tuned in length, diameter and shape to provide an optimal blend of low-rpm torque and high-rpm response.
Civic Si: Drive-by-Wire Throttle Control
An electronic Drive-by-Wire throttle control system helps enhance the driving character of the Civic Si. With smart electronics connecting the throttle pedal to the throttle body attached to the inlet of the intake manifold, the engine response can be optimized to suit the driving conditions and to better match the driver's expectations. The Civic Si uses a DC motor to control the throttle body opening position in the intake tract. To establish the current driving conditions, the system monitors items such as 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 Si engine features Programmed Fuel Injection (PGM-FI) that 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 (altitude), air flow, air/fuel ratio, along with the position of the crankshaft and camshafts. Special multi-hole fuel injectors mounted in the lower intake manifold spray directly toward the intake ports. The multi-hole injector design means that fuel droplet size is reduced for better fuel atomization, resulting in improved cold weather start-up, better fuel efficiency and higher horsepower.
Civic Si: Direct Ignition System and Detonation Knock Control
A strong ignition spark is critical to produce strong power and reduce emissions. The 2.4L I-4 features a direct ignition system that uses individual coil units for each cylinder that are positioned directly above each spark plug. The Powertrain Control Module (PCM) continually monitors several engine parameters to determine optimum spark timing based on specific driving conditions.
Additionally, a block-mounted acoustic detonation (knock) sensor sends information per each rotation, so that the engine can analyze each frequency with high precision. This signal is sent to the PCM, which then controls ignition timing as needed to help prevent damage.
Civic Si: Exhaust System
The Civic Si features an exhaust manifold design that is integrated directly into the cylinder head casting. This unique design allows the high-density catalytic converter to be positioned very close to the cylinders for faster converter light-off after a cold engine start for 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 secondary catalytic converter, positioned downstream under the passenger compartment floor. To help boost engine torque, a high-flow, low backpressure exhaust system is standard on the Civic Si. Large-diameter stainless-steel tubing used throughout the exhaust system increase flow; beyond the under-floor catalytic converter, the exhaust system passes through a pre-chamber (located under the second-row floorboards), and then to a free-flow silencer fitted with a chrome exhaust finisher.
Civic Si: Noise, Vibration and Harshness (NVH) Control
In addition to its outstanding power and response, the Civic Si engine has been designed for class-leading smoothness and refinement. The 2.4-liter, 4-cylinder engine employs such NVH-reducing features as a chain-driven balancer unit in the oil pan; 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 attached to the subframe helps reduce engine rocking and isolates powertrain NVH from the passenger compartment. The torque-rod engine mount system consists of upper and lower torque rods attached to the engine mount and a front beam stopper.
Civic Si: Maintenance Minder System
The Civic Si features as standard equipment a Maintenance Minder™ system that automatically monitors the vehicle's operating condition. The driver is alerted via a message on the intelligent Multi-Information Display (i-MID) when maintenance is required. The system helps eliminate unnecessary service stops, while ensuring that the vehicle is properly maintained.
The Maintenance Minder™ system monitors operating conditions such as coolant and oil along with engine speed, and then determines the proper service intervals. The Multi-Information Display shows the remaining percentage of engine oil life, and a percentage-based countdown to the next service is displayed when the car is within 15 percent of the end of the service interval. The type of service required is shown in an alphanumeric code, and if a service is missed, the i-MID indicates its urgency by showing past-due mileage. The system can be reset manually by the owner, and monitors all normal service parts and systems, including oil and filter, air-cleaner, tire rotation, coolant, spark plugs, brake pads and more. Maintenance alerts are presented on the instrument cluster when the ignition is first turned on, and not while driving.
Civic Si: 6-Speed Manual Transmission
To provide driving enthusiasts with exceptional control and feel, the high-performance Civic Si is available exclusively with a short-throw, close-ratio 6-speed manual transmission. Compared to a 5-speed transmission, the 6-speed gearbox allows closer gear ratio spacing. Such tighter gear spacing enables the engine to operate closer to its power peak during acceleration for better performance.
The compact transmission case is cast of aluminum to reduce weight. Additionally, the highly rigid casting helps damp out noise and vibration. Multi-cone synchronizers on First through Fourth gears reduce and smooth shifting effort. With the substantially improved torque output of the new Si engine, the Second through Sixth gear ratios have been made slightly higher (lower numerically). This allows the larger displacement engine to operate comfortably in the heart of its powerband under acceleration and to reduce highway cruising rpm.
The close-ratio 6-speed manual transmission teams with a lightweight, high-capacity clutch, and a specially designed clutch pedal assembly that delivers low-effort actuation and has a broad engagement band for greater control and smoother launches.
Civic Si: Limited-Slip Front Differential
Powerful performance cars with conventional "open" differentials can suffer from excessive wheelspin, particularly from the inner drive wheel when cornering. The Civic Si's helical-type limited-slip differential (LSD) helps insure that excessive wheelspin doesn't happen, by putting more of the engine's power effectively to the pavement.Under power, the limited-slip differential works to equalize the speed of the two drive wheels. The system never locks the speed of the two drive wheels together as would a locking differential, but instead allows different wheel speeds to accommodate the longer distance the outer wheel must travel when cornering. The LSD allows the Si to accelerate harder on surfaces with uneven traction, to generate reduced wheelspin when exiting corners, and to enhance the vehicle's responsiveness to throttle inputs in corners.
The term "helical" describes the way the differential's gear teeth are cut— which is at an angle to the gear's shaft. Helical gears are quieter in operation and can transmit greater torque than straight-cut (or spur) gears.
Civic Hybrid Powertrain
The fifth-generation Honda IMA system in the Civic Hybrid now consists of a larger 1.5-liter i-VTEC 4-cylinder engine connected to a larger, more powerful electric motor and a Continuously Variable Transmission (CVT) to optimize the rpm of the engine and motor combination. The engine incorporates new friction-reducing technologies, and a new lithium-ion (Li-Ion) battery pack developed specially for the Civic Hybrid is used to capture and store electricity for the electric motor. The system uses a gasoline engine as the primary source of power and an electric motor provides additional power and electricity regeneration capability.
During acceleration, the engine or the engine and electric motor propel the vehicle. During cruising, the gasoline engine and/or the electric motor can propel the vehicle. During braking, the gasoline engine deactivates and the electric motor acts as generator to replenish the battery pack. At a stop, the engine can enter an idle-stop mode to save fuel and reduce emissions, and the engine remains turned off until the brake pedal is released.
Compared to the previous Civic Hybrid, the fifth-generation Honda IMA powertrain provides stronger starting and overtaking acceleration compared to its predecessor, while its EPA-estimated fuel economy of 44 mpg city and 44 mpg highway offers an improvement of 4 mpg in the city and 1 mpg on the highway. The gasoline engine and electric motor combine to produce maximum output of 110 horsepower @ 5500 rpm and 127 lb-ft. of torque @ 1000-3500 rpm.
Compared to the previous generation Civic Hybrid, the new Hybrid has the same peak horsepower, but achieves it at 500 fewer rpm. The new Hybrid has gained 4 lb-ft of torque, and it is spread over a wide rpm range, from 1000 to 3500 rpm. The previous Civic Hybrid reached its peak torque between 1000 and 2500 rpm.
The upgraded, lighter electric motor is designed to provide up to 23 horsepower, and is powered by a new lithium-ion battery system that is more powerful, lighter and more compact than the Nickel-Metal-Hydride (NiMH) battery it replaces. The Powertrain Control Unit (PCU) has been newly developed to maximize the lithium-ion battery's power and minimize energy loss. Due to the IMA system's greater power and the battery's 35-percent increase in efficiency, the Civic Hybrid can operate in EV mode a greater distance than in the past.
Civic Hybrid Powertrain At-A-Glance
- 1.5-liter i-VTEC 4-cylinder engine
- Aluminum block with thin sleeve construction
- Compact single overhead cam (SOHC) 8-valve head with i-VTEC-controlled Variable Cylinder Management (VCM)
- "Intelligent" Dual & Sequential Ignition with two spark plugs per cylinder
- Computer-controlled Programmed Fuel Injection (PGM-FI)
Integrated Motor Assist
- 23 horsepower (17 kilowatt) ultra-thin DC brushless motor
- Intelligent Power Unit (IPU)
- High-power lithium-ion battery
- Power Control Unit (PCU)
- Automatic Idle Stop
- Regenerative braking
Emissions / Fuel Economy
- Ultra Low Emissions Vehicle (ULEV-2)
- Partial-Zero Emissions Vehicle (AT-PZEV) (in CARB states)
- EPA-estimated fuel economy of 44/44/44 (city/highway/combined)
Continuously Variable Transmission
- Wide drive ratio for good low-end acceleration and a relaxed cruising
Civic Hybrid: Engine Block, Pistons and Connecting Rods
The aluminum engine block and its internal components create a lightweight package with extremely low friction qualities. To save weight, the block incorporates a thin-sleeve cylinder bore construction. Friction reducing measures include plateau honing, low friction pistons, low-tensile force piston rings and offset cylinder bores to help reduce piston lateral loads.
Plateau honing lowers the friction level between the pistons and the cylinders by creating an ultra smooth surface. Plateau honing is a 2-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. The outer skirts of lightweight aluminum pistons now feature a molybdenum coating applied in a unique dot-pattern application. The result is reduced overall friction as the pistons move within the cylinder bores.
Civic Hybrid: Cooling Control Spacer (CCS)
To lower engine friction, the Civic Hybrid incorporates a new Cooling Control Spacer (CCS) in the water jackets surrounding the cylinders. Made of a resin material, the CCS restricts the flow of engine coolant around portions of the cylinder bores to maintain a higher cylinder temperature. This higher temperature causes the cylinder bores to expand slightly, increasing the piston-to-wall clearance thereby reducing sliding friction. The result is a 0.8% to 1.0% increase in fuel efficiency.
Civic Hybrid Cylinder Head: 2-Stage i-VTEC with Variable Cylinder Management (VCM)
The Civic Hybrid uses a 2-Stage i-VTEC valve control system that provides normal valve timing, and cylinder idling functions to the benefit of low fuel consumption, high output and greater electrical regeneration capabilities.
The Civic Hybrid's single overhead camshaft (SOHC) cylinder head uses a compact chain drive system and a compact, low-friction VTEC valvetrain system. It uses a common rocker shaft for both the intake and exhaust rocker arms; placing all the rocker arms on one shaft eliminates the need for a second rocker-arm shaft, so the valve mechanism can be lighter and more compact. To reduce friction, the rocker arms feature tips with roller followers.
The compact valvetrain allows for a desirable narrow angle (30-degrees) between the intake and exhaust valves, which allows for compact combustion chambers. The intake ports create a swirl effect in the cylinder chambers that promotes a well-balanced and even air/fuel mixture as it enters the engine. This optimizes the air/fuel mixture for cleaner, more efficient combustion.
The VCM allows the regenerative braking system to reclaim as much energy as possible during deceleration, while also allowing the electric motor to propel the vehicle in certain steady-state cruising situations.
Since the electric motor, which also acts as an electric generator, is attached directly to the crankshaft of the engine, the engine needs to provide as little resistance as possible during deceleration to allow the generator to produce the maximum level of electricity to charge the batteries. In a traditional engine, the pumping action of the cylinders provides a moderate amount of resistance, or "engine braking," during deceleration. VCM virtually eliminates that effect, allowing the electric generator to recapture energy and provide a convention "engine braking" feel for the driver.
"Intelligent" Dual & Sequential Ignition with Two Spark Plugs Per Cylinder
Twin spark plug sequential ignition control is part of the i-VTEC system and helps facilitate an intense and rapid combustion process in the engine. The ignition control has eight ignition coils that are independently controlled according to a dynamic engine map program. The benefits are more power, less fuel consumption and reduced emissions. The twin plug sequential control system is programmed to respond to engine rpm and load conditions. Since the system has eight individual ignition coils, it can manipulate the ignition timing of each iridium-tipped spark plug.
When the air/fuel mixture enters the combustion chamber, the first plug located near the intake port ignites. Shortly thereafter, the second plug located near the port ignites, accelerating the combustion process by forcing the flame to propagate more rapidly. The spark plugs can also ignite simultaneously under certain circumstances. This process results in more complete combustion compared to a single sparkplug system.
Civic Hybrid: Drive-by-Wire Throttle with Engine Speed (CVT) and Motor Control
An electronic Drive-by-Wire throttle system helps enhance the driving character of the Civic Hybrid. Smart electronics measure accelerator pedal position, then adjust the throttle-body butterfly valve for the intake manifold, the gear ratio in the CVT, and the operation of the IMA to best suit the driving conditions. To determine the current driving conditions, the system monitors pedal position, throttle position, vehicle speed, engine speed, calculated road slope and engine vacuum. With this information, the Drive-by-Wire throttle system controls motor and engine power to maximize the output of the new Lithium-Ion battery.
Civic Hybrid: ECON Mode
ECON mode improves the Civic Hybrid's fuel efficiency by changing or limiting the operation of certain systems. ECON widens the idle-stop system's operating window. In addition, the adjustable "gain" between the accelerator pedal, throttle butterfly, CVT and IMA changes to further enhance fuel efficiency. Drivers will also find that when cruise control is engaged, the car takes slightly longer to reach a set speed. However, as a safety feature, full torque output is restored when wide-open throttle is used.
When in Eco Mode, the maximum threshold for maintaining a set cabin temperature (when the A/C is on) is slightly increased when conditions warrant in order to minimize the activation of the compressors and contribute to enhanced fuel efficiency.
Civic Hybrid: Hybrid Dual-Scroll Air Conditioning Compressor
For 2012, an enlarged dual-scroll hybrid air conditioning system reduces the load on the gasoline engine by using a combination of engine power and an internal electric motor to drive two air conditioning compressors. These compressors can act independently or together as dictated by the cooling needs of the Civic Hybrid's automatic climate control system.
Civic Hybrid: IMA System
The fifth-generation IMA system used in the Civic Hybrid is the most powerful to come out of Honda's hybrid development program. As with previous versions, the IMA system consists of an ultra-thin DC brushless electric motor mounted between the gasoline engine and the continuously variable transmission, and an Intelligent Power Unit (IPU) that stores electric power in a compact battery box and controls the flow of electricity to and from the electric motor.
Civic Hybrid: IMA Electric Motor
Providing a supplemental power boost and giving the Civic Hybrid the capability to cruise on its electric motor alone in certain driving situations, the IMA's new, lighter and more powerful electric motor is designed to provide up to 23 additional horsepower (17 kW) to the Civic Hybrid's engine. Mounted between the engine and the CVT transmission, the IMA motor is an ultra-thin DC brushless design and provides a substantial amount of low-end torque to aid acceleration, while also assisting in steady-state cruising and hill climbing.
In addition to providing supplemental power, the IMA motor acts as a generator during deceleration and braking to recapture kinetic energy and recharge the IMA's battery pack during regenerative braking. For this fifth generation of IMA motor, an 8-pole design (instead of the previous 6-pole design) reduces heat. The new motor also operates in a lower voltage range (108-172V) compared to the previous motor (132-211V).
Civic Hybrid: IMA Intelligent Power Unit (IPU)
Power for the IMA system is controlled through the Civic Hybrid's Intelligent Power Unit. Located directly behind the rear seatback, the IPU consists of the Power Control Unit (PCU)— or the IMA's command center, a rechargeable lithium-ion battery module, and an integrated cooling unit.The Power Control Unit (PCU) electronically controls the flow of energy to and from the IMA's electric motor.
The battery pack stores electricity in a bank of lithium-ion cells. This bank of 40 individual 3.6-volt batteries stores up to 144 volts of electrical energy for the IMA motor. The new lithium-ion battery technology has approximately twice the energy density and about four times the output density of the previous nickel-metal-hydride batteries. Output is increased by 33 percent, volume is reduced by 36 percent, weight drops by 29 percent and the work capacity of the charging and discharging rates is approximately 3 times higher.
The Integrated Cooling Unit, mounted directly on the battery pack's outer box, controls the heat generated by the constant flow of electricity to and from the battery pack. Interior cabin air enters the Integrated Cooling Unit via a small vent placed on the left outboard seat bolster and is continually flowed over the battery pack and re-circulated.
Civic Hybrid: Cooperative Regenerative Brake System
Honda's hybrid-powered vehicles recapture kinetic energy via a unique regenerative braking system. The captured energy is stored as electricity in rechargeable battery packs. The Civic Hybrid uses its IMA electric motor as a generator that can recharge its battery pack during braking, steady cruising, gentle deceleration, or coasting.
Less reliance on the traditional braking system and reduced engine pumping losses translate into greater electrical regeneration and improved fuel efficiency due to the introduction of VCM system in the new Civic Hybrid engine. The Civic Hybrid's regenerative braking system intelligently apportions braking power between the hydraulic brakes and the electric motor to extract even more electricity from the vehicle's kinetic energy. During braking, a braking pressure sensor sends a signal to the Intelligent Power Unit (IPU), which maximizes the level of regenerative braking. At the same time, the CVT alters the gear ratio as needed to adjust the rpm of the engine and electric motor to achieve the maximum efficiency for energy regeneration.
Civic Hybrid: Continuously Variable Transmission
The Civic Hybrid's CVT offers smooth and predictable gear ratio transitions and excellent low-end acceleration matched with low-rpm cruising. To improve fuel economy with the new, larger engine, the Civic Hybrid's CVT now incorporates additional pressure and temperature sensors to allow more accurate control over the transmission's operation.
The transmission has also been upgraded to accommodate the greater torque of the new IMA system. By helping the engine and IMA motor stay in their most efficient operating range, the CVT provides a fuel efficiency benefit superior to that of a conventional automatic transmission with fixed ratio gears, and it allows for greater efficiency during regenerative braking by smoothing deceleration.
Civic Sedan, Coupe, HF and Natural Gas Powertrain
The Civic Sedan, Coupe, HF and Natural Gas benefit from an updated and refined version of the 1.8-liter engine that powered the previous generation Civic. While peak horsepower and torque figures of the gasoline versions carryover, the new engine has extensive changes that reduce friction, upgrade its emissions performance and increase its fuel economy.
For 2012, all Civic Sedan and Civic Coupe models, plus the HF (High Fuel Economy) and Natural Gas (Compressed Natural Gas) sedans are powered by a Single Overhead Cam (SOHC) 1.8-liter inline 4-cylinder design with 16 valves, i-VTEC, and a dual-stage intake manifold. In the Sedan, Coupe and HF, the engine produces 140 horsepower at 6500 rpm, 128 lb-ft. of torque at 4300 rpm and has a ULEV-2 emissions rating. All Civic DX, LX, EX and HF models with automatic transmission are PZEV-rated in states that adhere to California Air Resources Board (CARB) emissions standards. In the Civic Sedan and Coupe, the 1.8-liter engine has an EPA-estimated city/highway fuel economy rating of 28/39 miles per gallon when equipped with automatic transmission.
This same powertrain in the Civic HF achieves higher EPA city/highway fuel economy of 29/41 miles per gallon with the standard 5-speed automatic transmission, thanks to the HF model's reductions in aerodynamic drag and rolling resistance. See the Body and Chassis section for more info on the Civic HF.
In the Civic Natural Gas, which is powered by Compressed Natural Gas (CNG), the engine develops 110 horsepower and 106 lb-ft of torque. Though its targeted peak figures are slightly lower than those of the previous generation (113 horsepower and 109 lb-ft of torque), torque output below 4000 rpm has been increased for greater drivability. The Natural Gas has a targeted EPA-estimated city/highway fuel economy of 27/38 miles per gallon and is equipped with an automatic transmission as standard equipment.
Civic Powertrain at-a-Glance
- High rigidity aluminum cylinder block with low friction internal components
- i-VTEC "intelligent" valve control system
- Composite dual-stage intake manifold
- Drive-by-Wire throttle control system
- Programmed Fuel Injection (PGM-FI)
Emissions / Fuel Economy
- EPA-estimated fuel economy of 28/39 city/highway (Sedan, Coupe with automatic transmission)
- Estimated EPA fuel economy of 28/36 city/highway (Sedan, Coupe with manual transmission)
- EPA-estimated fuel economy of 29/41 city/highway (HF with automatic transmission)*
- Preliminary EPA-estimated fuel economy of 27/38 city/highway (Natural Gas)*
- Ultra Low Emissions Vehicle-2 (ULEV-2) (Sedan, Coupe, HF)
- Partial-Zero Emissions Vehicle (PZEV) (automatic transmission equipped Sedan, Coupe, HF in CARB states)
- Advanced Technology Partial-Zero Emissions Vehicle (AT-PZEV) (Natural Gas in CARB states)
- 5-speed manual transmission (standard in Sedan DX, LX; Coupe DX, LX, EX)
- 5-speed automatic transmission (available on Civic Sedan and Coupe; standard on HF, Natural Gas, EX Sedan, EX w/navi, EX-L)
Civic: High Rigidity Aluminum Block and Low Friction Engine Design
Compact, rigid, lightweight and low friction describes the end result of engine technology that helps to enable the Civic to achieve high power and high fuel economy. 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 unusually compact, allowing for excellent packaging efficiency. To make the engine highly rigid, extensive analysis was used to create reinforced areas in the aluminum block construction. Furthermore, a lightweight and very 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 adds to rigidity. The high rigidity block design helps reduce noise output and friction.
The Civic's 4-cylinder engine now makes use of new friction reducing technologies designed to improve engine efficiency. The outer skirts of lightweight aluminum pistons now feature a molybdenum coating applied in a unique dot-pattern application. The result is reduced overall friction as the pistons move within the cylinder bores. A new plateau honing technique lowers the friction level between the pistons and the cylinders by creating an ultra smooth surface. Plateau honing is a 2-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. Ion-plated piston rings and low viscosity oil (0W-20) are also used to reduce friction.
Civic: Cracked Connecting Rods
High-strength crack-separated connecting rods are used to minimize weight and size, while also increasing connecting rod rigidity and long-term durability. A "cracked" connection means that the rod and cap are forged as a single unit during the manufacturing process, and then are cracked apart to create a custom fit between the two matching surfaces.
This unique 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.
Civic: i-VTEC Valve Control System
To achieve strong performance and excellent fuel economy, the Civic's 1.8-liter engine uses a variation of the innovative i-VTEC system. Valve timing specs have been revised for 2012, and this variation of i-VTEC includes single intake valve operation. At low engine speeds, just one intake valve in each cylinder operates, while the second intake valve remains closed. Single intake valve operation is a significant factor in the engine's excellent emissions performance during cold start-up on PZEV-rated models. At high engine speeds, the i-VTEC system locks together both sides of the rocker arm to allow both intake valves to open at the same time. The Civic's i-VTEC system is able to switch valve timing duration using a hydraulic actuator.
Torque output has been optimized in the most frequently used 2,000 to 4,000 rpm engine speed range. To this end, the switchover from the low-speed timing to the high-speed valve timing is set between 1,200 rpm and 3,500 rpm depending on engine load. Furthermore, a shutter valve operating the variable intake switches tract length from long to short at approximately 5,000 rpm to best match the more aggressive high-speed valve timing.
This Civic's i-VTEC valve timing reacts to driving conditions related to throttle opening, vehicle speed, engine rpm and gear selection. A sophisticated Drive-by-Wire throttle control system, air flow meter, knock sensor and dual-stage air intake allow the Powertrain Control Module (PCM) to create seamless transitions between the two modes of i-VTEC operation.
In theory, intake ports should be designed as straight as possible to promote more complete filling of the cylinders. However, with the objective of promoting the mixing of fuel with the incoming air, Honda has devised a curved intake port for the Civic. This strategic curve not only promotes improved air-fuel mixture, but it is also designed to better concentrate the mixture around the spark plug. This allows for an even more efficient combustion process and further increased fuel efficiency.
Civic: Composite Plastic Dual-Stage Intake Manifold
A composite plastic dual-stage intake manifold utilizes two intake runners for each cylinder— with one runner longer than the other. Below 5,000 rpm, only the longer of the two runners delivers air to the cylinder—taking advantage of an inertia effect of the long intake path. Above 5,000 rpm, however, a shutter valve in the bore of the short runner opens to allow the passage of additional air to the cylinder. This has the effect of boosting midrange and high-rpm power by utilizing the inertia effect at both low and high rpm.
Civic: Drive-by-Wire Throttle Control
An electronic Drive-by-Wire throttle system helps enhance the driving character of the Civic. With smart electronics connecting the throttle pedal to the throttle butterfly valve in the intake system, the engine response can be optimized to suit the driving conditions and to better match the driver's expectations. Combined with the dual-stage intake manifold, the Drive-by-Wire throttle system is an important component to the i-VTEC system that makes switching between the engine's low pumping loss mode and the high performance mode seamless to the driver. By eliminating the direct throttle cable connection to the engine, the ratio between pedal movement and throttle butterfly movement can be continuously optimized. This adjustable "gain" between throttle and engine is a significant benefit to drivability. A highly responsive DC motor moves the throttle butterfly position in the intake system to change actual throttle position. To establish the current driving conditions, the system monitors pedal position, throttle valve opening position, vehicle speed, engine speed, and engine vacuum. This information is then used to define the throttle control sensitivity.
The throttle system also works to enhance the available 5-speed automatic transmission's ability to make shifts faster and smoother. By coordinating the throttle opening with the transmission's shifting functions, engine power can be precisely tailored to the needs of the transmission at every point during the shifting process. That means less shift shock and delay, no matter the driving situation.
Civic: ECON Mode
All Civic models (except Si models) have as standard a driver-selectable "ECON" driving mode that alters the Drive-by-Wire throttle system response curve in the range from about 25 percent of pedal movement to 90 percent. With less gain, the throttle opening in this range increases more gradually, for better fuel efficiency. ECON mode also alters shift timing (when equipped with automatic transmission), and alters the operation of the air conditioning system (see the Interior section for more information).
Civic: Programmed Fuel Injection (PGM-FI)
The Civic engine features Programmed Fuel Injection (PGM-FI) that 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 (altitude), air flow, along with the position of the crankshaft and camshafts. A new high-performance air/fuel sensor contributes to the engine's enhanced emission performance. Special multi-hole fuel injectors mounted in the lower intake manifold spray directly toward the intake ports. The multi-hole injector design means that fuel droplet size is reduced for better fuel atomization, resulting in improved cold weather start-up, better fuel efficiency and higher horsepower.
Civic: Direct Ignition System and Detonation Knock Control
A strong ignition spark is critical to improve power and reduce emissions. The 1.8L I-4 features a direct ignition system that uses individual coil units positioned directly above each spark plug. The Powertrain Control Module (PCM) continually monitors several engine parameters to determine optimum spark timing based on specific driving conditions.
Additionally, a block-mounted acoustic detonation (knock) sensor sends information per each rotation, so that the engine can analyze each frequency with high precision. This signal is sent to the PCM, which then controls ignition timing as needed to help prevent damage.
Civic: Exhaust System
The Civic is equipped with a stainless-steel, low heat-mass exhaust system integrated into the cylinder head that eliminates the need for a separate exhaust manifold, helping contribute to the engine's compact design and light weight. The system employs a new high-density low precious metal catalytic converter for improved light-off performance along with reduced hydrocarbons and NOx. For improved emissions performance, the catalytic converter bolts directly to the cylinder head, resulting in faster light-off and more complete conversion of the exhaust gases.
Civic: Maintenance Minder and Tune-Up Intervals
The Civic'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 PCM) 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. Under normal usage, a tune-up is not required until approximately 100,000 miles (only routine inspections and fluid changes are required up to this point). Credit for this longevity goes to long-wearing double-tipped spark plugs, a long-life timing chain, and careful engineering of the precisely manufactured SOHC valvetrain— which reliably maintains proper valve tappet clearances until the first tune-up.
Civic Natural Gas Engine
The Civic Natural Gas, previously known as Civic GX, is powered by a variant of the same 1.8-liter engine found in all Civic models, with the exception of the Civic Hybrid and Civic Si. First introduced in 1998, the Civic GX has been marketed primarily to fleet customers nationwide, but with the arrival of the 2012 Civic Natural Gas, it is now being made available at select dealers across the country.
The Civic Natural Gas operates on compressed natural gas and has as standard a 5-speed automatic transmission. The Natural Gas has a Honda-targeted EPA-estimated city/highway fuel economy of 27/38 miles per gallon (gasoline equivalent). Compared to the previous generation, city fuel economy is improved by 12.5 percent, and highway fuel economy is increased by 5.6 percent.
To allow the engine to operate exclusively on natural gas, it incorporates a range of unique features. The compression ratio is increased to 12.7:1 (compared to 10:6 in regular gasoline-powered engines) to improve performance with the gaseous fuel. Since CNG fuel is non-lubricating, the engine has exclusive intake and exhaust valves and different valve seats to reduce wear. Special, stronger connecting rods are used to handle the extra load generated by the higher compression ratio. To control the flow of CNG into the engine, a single-stage pressure regulator is located on the right side of the engine compartment. Special fuel injectors deliver precisely metered amounts of CNG into each cylinder's intake tract.
Civic Natural Gas: Emissions
The Civic Natural Gas GX is certified to the Federal Tier II, Bin 2 emission level, and is also certified as a Super Ultra Low Emission Vehicle (SULEV) by the California Air Resources Board (CARB). It complies with AT PZEV, (Advanced Technology, Partial Zero Emission Vehicle) criterion established by CARB, allowing the Civic Natural Gas credits toward the California Zero Emission Vehicle mandate. It is recognized as a PZEV by meeting SULEV standards and maintaining its emissions durability for at least 150,000 miles or 15 years. SULEV requirements are the most rigorous in the world, calling for a reduction in hydrocarbon emissions of 96 percent from federal Tier-1 passenger car levels, and an 86 percent reduction compared to the California Low Emission Vehicle (LEV) standard. Since it operates exclusively on natural gas with no provision for gasoline, the Federal EPA categorizes the Civic Natural Gas as an ILEV (Inherently Low Emission Vehicle) recognizing its sealed fuel system emits zero evaporative emissions. Due to its efficiency and emissions performance, in many states the Civic Natural Gas has been granted carpool lane access— a major benefit for solo commuters.
Civic Natural Gas: Fuel Tank
The Civic Natural Gas has a cylindrical fuel tank for compressed natural gas located behind the rear seatback. The composite tank has an aluminum liner and can contain the gasoline-gallon equivalent of approximately 8.0 gallons when pressurized to 3600 p.s.i.
Civic: 5-Speed Manual Transmission
The 5-speed manual transmission is a lightweight and compact unit that minimizes power-robbing rotating mass and has a rotating selector link for quick and direct gear changes. Additional features include a low-friction design with single cone synchronizers and high capacity bearings throughout. From a performance standpoint, the manual transmission has a high torque capacity and a short, firm and direct shift feel.
Civic: 5-Speed Automatic Transmission
The Civic Sedan and Civic Coupe are available with an electronically controlled 5-speed automatic transmission. The computer-controlled transmission provides amazingly smooth shifts, and has gear ratios that are closely matched to the output of the engine help extract maximum performance. For 2012, the transmission incorporates refinements that enhance fuel economy, reduce noise and save weight. It now incorporates an automatic transmission fluid (ATF) warmer/cooler that uses the engine coolant to alter the temperature of the ATF. This helps reduce ATF viscosity more quickly when starting from cold with a consequent reduction in friction and related reduction in fuel consumption. Conversely, when transmission oil temperature rises above engine coolant temperature, the system helps reduce the temperature of the transmission.
The 5-speed automatic transmission uses a wide variety of technologies to help provide smooth shifting as well as minimal friction for enhanced efficiency. These technologies include a low-friction clutch and a special super-thin torque converter, now with greater capacity. The thin torque converter results in a compact transmission unit. Other space-saving measures include a double-row idle gear and a tightly packaged second-gear clutch.
To improve powertrain smoothness and reduce gear "hunting" on steep grades, the 5-speed automatic transmission is also equipped as standard with a Grade Logic Control system. Using sensors that monitor throttle position, vehicle speed, and acceleration/deceleration and then comparing these inputs with a map stored in the transmission computer, the system is able to determine when the vehicle is on an incline and adjust the shift schedule for improved climbing power or downhill engine braking.
To improve fuel economy while maintaining a high level of drivability, the 5-speed automatic transmission includes an active lock-up torque converter. With the precise control afforded by a linear solenoid, the system expands the speed and throttle setting range in which lock-up can be automatically engaged.
*Fuel economy values determined from manufacturer test results. Official 2012 EPA mileage estimates not available at time of publication. Mileage figures shown for comparison purposes only. Actual mileage will vary.