Honda Automobiles: Honda Civic Si

Using the 10th-generation Civic EX-T chassis as a starting point, the 2017 Civic Si Coupe and Si Sedan add significant technological and operational bandwidth, creating a pair of new models that expand the Civic Coupe and Sedan’s dynamic envelope. The MacPherson strut front and multi-link rear suspension are upgraded with firmer settings and benefit from the first application of an Adaptive Damper System (ADS) to Civic. Integral to Civic Si’s driving mode system, ADS lets the driver select the damping characteristics of the suspension to suit their pleasure – smooth and easy city driving in NORMAL mode (the default setting whenever the Civic Si is started) or taut and direct handling response in SPORT mode.

Linked to the ADS function, when in SPORT mode the Civic Si’s steering function firms up the dual-pinion variable-ratio electric power-assisted rack-and-pinion steering (EPS), adding a higher level of feedback and feel for the driver. Larger front and rear disc brakes, Civic Si exclusive 18-inch aluminum alloy wheels and tenacious 235/40R18 tires (all-season standard with summer tires available) likewise expand the Si’s performance envelope. Shared with other 2017 Civic models are convenient Straight Driving Assist, Agile Handling Assist, an Electric Parking Brake (EPB) with Automatic Brake Hold, and more.

Key Chassis Features

Civic Si Coupe and Si Sedan

  • Specially tuned MacPherson strut front suspension
  • Specially tuned Multi-link rear suspension
  • Two-mode Adaptive Damper System (ADS)*
  • Specially tuned front and rear stabilizer bars
  • Solid suspension compliance bushings (front and rear)
  • 12.3-inch front, 11.1-inch rear power-assisted disc brakes*
  • 4-channel Anti-lock Braking System (ABS) with Brake Assist
  • Electronic Brake force Distribution (EBD)
  • Vehicle Stability Assist™ (VSA®) with Traction Control
  • Agile Handling Assist*
  • Dual-Pinion Variable-Ratio Electric Power-Assisted Steering (EPS)*
  • Straight Driving Assist*
  • Electric Parking Brake (EPB) with Automatic Brake Hold*
  • Hill Start Assist*
  • Indirect Tire Pressure Monitoring System (TPMS)
  • 18-inch alloy wheels
  • 235/40R18* all-season tires (summer tires available)

* First for Civic Si

Front and Rear Suspension
Specially equipped with an Adaptive Damper System (see below), the Civic Si front and rear suspension system provides inspired handling that puts the Civic Si at the top of its class, and in the league of benchmarked European competitors, on city streets as well as on the most challenging winding roads. Front MacPherson struts optimize component packaging and crash performance, while a rear multi-link system helps maximize second-row seating and cargo space – all while also providing inspired handling characteristics. Front and rear stabilizer bars improve turn-in response while reducing body roll during cornering. The stabilizer bars are bonded to their mounting bushings and use low-friction connecting links for smoother operation.

MacPherson Strut Front Suspension

The MacPherson strut front suspension is engineered to provide a highly responsive and engaging driving experience. Performance-calibrated geometry ensures a high degree of quickness, precision and stability. The lower suspension arms are connected to the subframe and to the body via solid compliance bushings, which provide the ideal combination of handling responsiveness and precision. All front suspension arms and the front hub carriers are steel, and both Civic Si models use a tubular front stabilizer bar.

 

Compared to the overall Civic model range, the new Civic Si front suspension has the following differences:

  • 7-percent stiffer spring rate
  • Adaptive Damper System (ADS)
  • 18-percent stiffer upper damper mounts
  • 7-percent stiffer stabilizer bar rate

Multi-Link Rear Suspension
The multi-link rear suspension includes stamped-steel arms, cast aluminum hub carriers and a stabilizer bar. Mounted on a rigid subframe, the rear suspension provides highly precise handling in city driving, sport driving and emergency maneuvers, together with a composed, flat ride. The trailing arms are located on the unibody using solid compliance bushings for optimum handling precision. A solid rear stabilizer bar helps provide crisp turn-in along with body roll control.

Compared to the overall Civic model range, the new Civic Si rear suspension has the following differences:

  • 32-percent stiffer spring rate
  • Solid front and rear compliance bushings (rear shared with Civic Type R)
  • Adaptive Damper System (ADS)
  • High-stiffness upper control arms – common with Civic Type R
  • 26-percent stiffer stabilizer bar rate

Adaptive Damper System (ADS)
The Civic Si has new Adaptive Dampers that are integrated into the driving mode functions. Similar in appearance to the standard Civic’s dampers, the Adaptive Dampers have electronically adjustable hydraulic damping that lets the driving mode automatically fine-tune ride and handling to driver preferences. A button on the center console allows the driver to choose between NORMAL and SPORT modes. As directed by the driving mode controller, an electric actuator integrated into each damper governs hydraulic fluid movement inside the unit. Damper settings are automatically calibrated to the driving mode setting to achieve the following benefits:

  • NORMAL – Provides an ideal everyday balance of ride and handling for a wide range of conditions.
  • SPORT – Firmer damper settings flatten and stabilize the vehicle body during rapid steering inputs and maneuvers, which noticeably improves tactile feel, handling precision and overall responsiveness.

Suspension Bushings
In front, the lower control arms pivot uses solid bushings to provide the exacting precision required for sharp, nimble handling. For the front suspension only, a specially ventilated under-cover allows airflow to cool the bushings, ensuring more consistent performance in all ambient temperature conditions, as well as enhanced long-term durability.

An additional duct, located near the middle of the aluminum front under-panel, cools the engine’s torque rod bushing, reducing operating temperatures and ensuring greater durability.

Dual-Pinion Variable-Ratio Electric Power-Assisted Rack-and-Pinion Steering
The Electric Power Steering (EPS) incorporates dual-pinion gears and a variable gear ratio for outstanding steering feel and handling performance. Compared to a traditional single-pinion steering system, the dual-pinion EPS utilizes the physical steering input from the driver as well as from a supplemental electric motor. A non-contact torque sensor measures the driver’s steering effort and an ECU determines how much electric motor assist to add, with the result being seamless, natural feeling steering in all situations.

The steering ratio is variable over a 17-percent range with a final full off-center ratio of 10.93:1. This provides a quick 2.11 turns lock-to-lock, which minimizes hand movement and steering effort when turning, parking or maneuvering. High steering-mount stiffness and a robust 30mm steering column diameter further enhance steering precision and feel.

The Civic Si models have a larger electric motor and unique EPS tuning in comparison to the other Civic models. In NORMAL mode, the Civic Si’s EPS delivers a smooth, natural turning and handling response, which transforms to a noticeably more direct and linear feel when the driving mode is set to SPORT. (See the Powertrain section for more information.)

An integral part of the Civic Si’s standard driving mode system, the Electric Power Steering automatically firms up when the mode is changed to “SPORT” from “NORMAL.” The benefit for the Civic Si driver is firmer steering effort and substantially more direct feeling through the wheel.

Straight Driving Assist
Straight Driving Assist reduces the steering effort required when driving on a sloped or crowned road. When the Straight Driving Assist system detects that continuous steering effort is being applied to keep the car driving along a slope, the Electric Power Steering system applies motor assist to reduce driver steering effort to the same level as is required on a flat road.

4-wheel Disc Brakes with ABS, EBD and Brake Assist
Both Civic Si models are equipped with 4-wheel disc brakes with 4-channel ABS, Electronic Brake Distribution (EBD) and Brake Assist. The system provides a comfortable and refined feel at low speeds, predictable and easy operation on the highway, a sporty, fun-to-drive feel on winding roads, and a reassuring high-performance stopping in emergency situations.

The braking system incorporates larger discs than the standard Civic – 12.3-inch diameter ventilated front rotors (1-inch thickness) clamped by single-piston calipers, and 11.1-inch diameter solid rear rotors (0.4-inch thickness) paired with single-piston calipers. Optimized master cylinder and brake-caliper piston diameters contribute to a short, firm pedal stroke and excellent feel, while also helping to maintaining the power of the braking system. The low-friction design of the brake calipers reduces energy losses when the brakes are not in use, directly improving fuel efficiency.

The 4-channel Anti-lock Braking System (ABS) independently modulates braking power at each wheel to help the driver retain steering control during heavy braking. The Brake Assist system recognizes emergency or heavy braking situations and almost instantly applies full braking force when appropriate to help shorten braking distance. (See the Safety and Driver Assistive section for more information.)

Vehicle Stability Assist™ (VSA®) with Traction Control
Vehicle Stability Assist™ (VSA®) is an Electronic Stability Control system that works in conjunction with the Civic Si’s Drive-by-Wire™ throttle and its 4-channel ABS systems to enhance control capability while the vehicle is accelerating, braking, cornering or when the driver makes a sudden maneuver.

In conjunction with the Civic Si’s helical limited-slip differential, VSA provides an additional limited-slip effect for the driving wheels by applying braking force to a slipping wheel, thereby redirecting driving force to the wheel with more traction.

The driver can reduce the traction control effectiveness to allow more wheel slip by pressing the VSA button should the vehicle become stuck; ABS remains fully operational at all times. (See the Safety and Driver Assistive section for more information.)

Agile Handling Assist
Standard on both Civic Si models, Agile Handling Assist selectively uses the vehicle’s brakes to improve initial turning response and overall cornering ability. Agile Handling Assist utilizes brake vectoring to improve corner traceability and confident handling feel. By applying braking force to the inside wheels during cornering at high lateral G, the system creates a yaw moment, thus generating more turning force and reducing understeer.

Hill Start Assist
The Hill Start Assist function helps to prevent the vehicle from rolling backwards when the driver switches from the brake pedal to the accelerator pedal while the vehicle is stopped on a hill. Hill Start Assist automatically activates when the vehicle senses a certain incline and is fully stopped in any forward gear when facing up hill or reverse gear when facing downhill. The system uses a longitudinal G-sensor along with a wheel speed sensor to control the hydraulic brake modulator. Hill Start Assist, when activated, will release the brakes when the driver depresses the throttle or if the driver doesn’t press the accelerator after a few seconds.

Electric Parking Brake (EPB)
The standard Electric Parking Brake (EPB) is simpler, more convenient and comfortable to use than a traditional parking brake. The EPB also frees up center console space, allowing a higher console and an extended armrest length.

Automatic Brake Hold 
When activated, Automatic Brake Hold retains brake pressure when the vehicle comes to a stop such as at a traffic light or in heavy traffic. This frees the driver from continually pressing the brake pedal to maintain the vehicle in a stopped position, a significant improvement in driving enjoyment.

Operating the system requires two simple actions from the driver:

  • Activating/deactivating the system via a switch on the center console
  • Pressing on the brake pedal until the vehicle comes to a stop

Releasing the clutch pedal while the transmission is in gear releases the brake pressure.

Wheels and Tires
The Civic Si Coupe and Si Sedan ride on P235/40R18 tires – the widest and lowest-profile rubber ever fitted to a production Civic Si – mounted to 18 x 8.0-inch aluminum-alloy wheels. The tires are 20mm wider, and the wheels are one-inch larger in diameter and one-inch wider, than the Civic EX-T models upon which the Civic Si models are based.

The standard tires carry an all-season M+S rating, making them suitable for year-round use in all weather and conditions. The standard Civic Si tire is a Goodyear Eagle Sport All-Season, developed cooperatively with Honda engineers and the tire company. Despite being wider, the tires maintain a low rolling resistance while also helping to reduce road noise and vibration. Available Goodyear Eagle F1 summer tires offer superior handling performance in dry conditions.

Wheel Design
The Civic Si’s 18 x 8.0-inch aluminum alloy wheels feature a split 5-spoke design. The wheels are asymmetrical, with their aerodynamically designed spokes uniquely matching the left and right sides of the vehicle for a dynamic, windswept look. The wheels feature a painted gloss black finish with machined silver spoke edges for a high-contrast, dramatic appearance.

A summary of the 2017 Civic Si Coupe and Si Sedan’s wheel and tire sizes includes:

Civic Si Coupe

  • 18-inch alloy wheels
  • 235/40R18 all-season tires
  • Available 235/40R18 summer tires

Civic Si Sedan

  • 18-inch aluminum wheels
  • 235/40R18 all-season tires
  • Available 235/40R18 summer tires

Tire Repair Kit
The Civic Si features an easy-to-use tire repair kit in lieu of a spare tire. This reduces weight and increases trunk volume, and simplifies temporary repairs in the event of a flat tire. Honda Roadside Assistance supports tire repairs. In addition, a T125/70R17 space- and weight-saving temporary spare tire is available.

Low-Friction Wheel Bearings
Civic Si wheel hubs feature low-friction bearings that measurably reduces rolling resistance, which directly contributes to fuel-efficiency for all models.

Exhaust
The Civic Si uses a dedicated exhaust system. Twin rear-mounted silencers and a single center exhaust outlet improves gas flow, helping to enable the higher power output of the turbocharged engine, while also creating a more powerful exhaust sound in mid- and high-rpm ranges. A bright finisher adds visual appeal at the rear of the vehicle. (See the Powertrain section for more information.)

Fuel Tank
The 12.4-gallon fuel tank and fuel lines are molded of high-density polyethylene for low weight, freedom from corrosion, impact resistance and resistance to fuel vapor losses. The tank and filler pipe are formed as a single unit, reducing weight and complexity, while further improving safety in the event of a collision. Additionally, the tank is positioned ahead of the rear wheels to help guard against collision damage. A high-efficiency fuel pump is housed inside the tank, and the fuel filter is a lifetime design that never needs replacement. An integrated baffle system positioned inside the tank reduces the sound of fuel sloshing.

Tire Pressure Monitoring System (TPMS)
Both 2017 Civic Si models use an indirect Tire Pressure Monitoring System (TPMS), which uses the ABS wheel-speed sensors to continually monitor the rotational speed of each wheel. Because a tire with low pressure rotates more quickly than one with a higher pressure, by comparing these values with a specifically designed computer algorithm, indirect TPMS can determine when a tire is low on pressure. When this occurs, a symbol illuminates on the instrument panel warns the driver. Special logic included in the TPMS processor is designed to eliminate false warnings.

Chassis Features

(See the Specifications and Features section for all data.)