Honda Automobiles: Honda Civic Si

For a initial time in Civic Si history, an modernized turbocharged engine powers a Civic Si Coupe and Si Sedan. An extended chronicle of a 1.5-liter 16-valve DOHC direct-injected turbocharged powerplant that powers EX-T, EX-L and Touring Civics, a new Si engine pushes opening on mixed fronts. It’s rated during 205 hp during 5700 rpm and offers an considerable 192 lb-ft. of torque between 2100 and 5000 rpm. That’s an boost of 31 hp and 25 lb.-ft. of torque, as compared to other 1.5-liter turbocharged Civic models.

The new Si also outlines a confidant change in plan when compared to a prior era 2015 Civic Si. With a banishment rebate of 36-percent compared with a routinely aspirated 2.4-liter engine that powered a prior Si, a new 1.5-liter engine is lighter, some-more compress and some-more efficient. With a assistance of a sophisticated, electronically controlled, intercooled turbocharging system, a new Si offers a same rise 205 horsepower as a predecessor, yet during a lower, most some-more fast permitted rpm. More important, a new turbo engine offers a wilful rise torque advantage over a distant broader rpm range. The outcome is a rarely manageable powertrain that advances a Si’s fun-to-drive mission.

Of course, some things have not altered in a new Si. It is still offering exclusively with a 6-speed primer smoothness for a limit in motorist control and pleasing connection, yet a all-new gearbox offers a slicker change action—and revised ratios to fit a energy smoothness of a new turbocharged engine. And to assistance put energy to a ground, as in a past, a scrolled limited-slip front differential is standard.

The Civic Si engine is EPA Tier3/Bin125 and CARB LEV 3/ULEV125 emissions compliant. The new, some-more fit engine and transmission, along with softened aerodynamics and a vital rebate in using resistance, outcome in almost extended opening and fuel efficiency, compared to a prior era (2015) Civic Si 2.4-liter. EPA fuel economy ratings1 are adult opposite a board: 

  • +6 mpg City (+27%)
  • +7 mpg Highway (+23%)
  • +7 mpg Combined (+28%)

Key Powertrain Specifications Features

Turbocharged 1.5-liter, DOHC direct-injected inline-4 engine *  

  • Dual Variable Timing Control (VTC)
  • Low sluggishness mono corkscrew turbo with electronic rubbish gate* 
  • Computer-controlled Direct Injection (DI) with multi-hole fuel injectors*
  • 10.3:1 focus ratio
  • Lightweight, high acerbity steel crankshaft
  • Drive-by-Wire stifle system
  • Maintenance Minder™ complement optimizes use intervals
  • 100,000 +/- miles tune-up interval
  • 205 horsepower during 5700 rpm (SAE net) 
  • 192 lb-ft. torque during 2100-5000 rpm (SAE net) 
  • Premium Unleaded endorsed fuel

Emissions/Fuel Economy Ratings

  • EPA Tier3/Bin125 and CARB LEV 3/ULEV125 Emissions compliant
  • U.S. EPA fuel-economy ratings (city/highway/combined)
    • 28/38/32 mpg1


  • 6-speed Manual
  • Helical Limited-Slip Differential
  • * First for Civic Si

Engine Architecture and Features
Turbocharged 1.5-Liter In-Line 4 Cylinder
The Civic Si’s new DOHC 1.5-liter engine is a initial turbocharged engine ever to be offering in a Si model. Closely associated to a 1.5-liter turbocharged engine permitted in a 2017 Civic EX-T Coupe and Sedan, a Si powerplant is almost upgraded to broach an boost of 31 horsepower and 25 lb.-ft. of torque. With approach injection, low-inertia high-flow mono corkscrew turbo complement with electrical waste-gate and twin Variable Valve Timing Control (VTC), a turbocharged Civic Si powerplant develops a horsepower and torque of a most incomparable engine.

Compared to a significantly incomparable normally-aspirated 2.4-liter engine that was customary in a previous-generation Civic Si (model year 2015), a 2017 Si engine develops a same rise horsepower (205) yet during a most revoke and some-more fast permitted rpm (5700 rpm compared to 7000 rpm). The new Si also develops 18 lb.-ft. some-more rise torque (192), and delivers it over a distant larger engine speed range. In a new Si, rise torque hits during usually 2100 rpm—less than half a engine speed (4400 rpm) of a prior era 2.4-liter engine.

Specifically engineered for approach injection and turbocharging, a Si powerplant is designed to offer really high torque outlay from 2,100 rpm to 5,000 to maximize responsiveness and acceleration but a need for high engine revs. The Si’s rarely permitted energy smoothness is a pivotal underline of a evident energy smoothness and fun-to-drive nature.

The turbocharged Si 1.5-liter engine is designed to work on reward unleaded fuel and is rated during 205 horsepower during 5,700 rpm and 192 lb.-ft of torque between 2,100 and 5,000 rpm (SAE net). The Civic Si is rated by a EPA during 28/38/32 mpg1.

Cylinder Block and Crankshaft

The Civic Si’s new 1.5-liter inline 4 has a lightweight die-cast aluminum retard with particular reinforced categorical temperament caps to minimize weight. Cast-in iron cylinder liners yield long-lasting durability. Each biography on a lightweight forged-steel crankshaft is micropolished to revoke inner friction.

Pistons and Connecting Rods  
The 1.5-liter engine’s pistons assistance say fast explosion and minister to softened potency with “cavity-shaped” crowns. The lightweight pistons have a delicately optimized dress settlement to minimize reciprocating weight, that minimizes quivering and increases handling efficiency. The pistons are cooled by twin oil jets destined during a underside of any piston crown. A cooling gallery expel into a rim of any piston helps yield aloft feverishness resistance. Ion-plated piston rings assistance revoke attrition for larger handling efficiency. Lightweight, high-strength steel joining rods are heat-forged in one square and afterwards “crack separated” to emanate a lighter and stronger rod with an optimally propitious temperament cap.

Cylinder Head and Valvetrain
The direct-injected Civic Si 4-cylinder turbocharged engine has a lightweight DOHC cylinder conduct that is done of pressure-cast aluminum alloy. With empty pier expel directly into a cylinder head, a need for a normal apart empty plural is eliminated. Compared to other 1.5-liter Civic turbocharged engines, that have a 10.6:1 focus ratio, a Civic Si has a lowered 10.3:1 ratio to concede it to reliably work during a aloft limit boost vigour of 20.3 psi (16.5 psi on Civic EX-T).

A low-friction, silent-chain drives twin beyond cams and 4 valves per cylinder. The cam expostulate is upkeep giveaway around a life of a engine. To assistance serve revoke weight, thin-wall vale camshafts are used.

To advantage fuel efficiency, emissions and power, a turbo engine utilizes sodium-filled empty valves. A vale cover within a valve contains sodium that is cooled by a exhaust-port cooling jacket. As a cover reaches tighten to a valve head, a sodium helps to cold a whole valve. As a valve is internally cooled it doesn’t need a enriched fuel reduction that was generally used in turbo engines to assistance cold a empty valve. The following leaner reduction reduces emissions, increases fuel potency and helps boost power.

The cylinder conduct includes smaller M12 sparkplugs, down from a some-more common M14, to save space and weight. The conduct also includes direct-injection multi-hole fuel injectors with a tiny hole bore. Higher-pressure approach injection optimizes fuel atomization, permitting for some-more fit combustion. To yield a high-tumble intake assign that serve enhances explosion efficiency, both a intake pier and piston climax have special designs.

The Civic Si turbocharged engine facilities Variable Valve Timing Control (VTC) that can change a timing of both a intake and empty camshafts independently. With a turbo engine’s non-static cam timing, a cam timing can be optimized to fit a pushing conditions. Under light loads, valve overlie can be augmenting to revoke pumping waste and urge fuel efficiency. When engine speed is low and engine bucket is large, such as during initial acceleration, a volume of overlie is augmenting to boost a scavenging effect, that improves torque and responsiveness. When engine speed is high and engine bucket is also high, such as during full-throttle acceleration, a volume of valve overlie is reduced to boost engine outlay by improving both intake and scavenging.

Direct Injection System
The direct-injection complement enables augmenting torque opposite a engine’s full handling operation along with aloft fuel efficiency. The complement facilities a compact, high-pressure, direct-injection siphon that allows both high fuel upsurge and tapping suppression, while non-static vigour control optimizes injector operation. A multi-hole injector delivers fuel directly into any cylinder (not to a intake port, as in compulsory pier fuel injection designs), permitting for some-more fit combustion.

The multi-hole injectors can emanate a ideal stoichiometric fuel/air reduction in a cylinders for good emissions control. Theoretically, a stoichiometric reduction has usually adequate atmosphere to totally bake a permitted fuel. Based on a handling conditions, a direct-injection complement alters a duty for best performance. Upon cold engine startup, fuel is injected into a cylinders on a focus stroke. This creates a diseased stratified assign outcome that improves engine start-up and reduces empty emissions before a normal handling heat is reached.

Once a engine is entirely warmed up, fuel is injected during a intake cadence for limit energy and fuel efficiency. This helps emanate a some-more comparable fuel/air brew in a cylinder that is aided by a high-tumble intake pier design. This improves volumetric efficiency, and a cooling outcome of a incoming fuel improves anti-knock performance.

Low Inertia Mono Scroll High-Flow Turbo System with Electronic Wastegate

The turbocharged Civic Si engine employs a singular high-flow, high ability turbo for limit responsiveness. The Mono corkscrew housing settlement helps a turbo build boost even during comparatively tiny stifle openings and low rpm. The electrically actuated wastegate allows boost vigour to be precisely controlled. With a revoke focus ratio, a Civic Si’s limit boost vigour has been towering to 20.3 psi (from 16.5 psi in Civic EX-T), almost augmenting limit horsepower and torque.

A vast atmosphere low-restriction intercooler is positioned low in a front of a automobile where it receives unrestricted airflow when a automobile is in motion. Intake atmosphere travels from a atmosphere filter, to a turbo compressor, on to a intercooler, afterwards to a engine’s intake ports. The intercooler helps revoke a heat of atmosphere entering a engine, creation it denser for larger performance. To revoke weight, a turbo complement is plumbed with rigid, lightweight creosote combination estuary pipes to lift intake atmosphere to and from a intercooler.

Friction Reducing Technology
The Civic Si’s engine creates use of friction-reducing technologies designed to urge engine efficiency. The outdoor skirts of lightweight aluminum pistons underline a low-friction cloaking practical in a singular settlement application. The outcome is reduced altogether attrition as a pistons pierce within a cylinder bores. Plateau honing serve lowers a attrition turn between a pistons and a cylinders by formulating an ultra-smooth surface. Plateau honing is a 2-stage machining routine that uses dual harsh processes instead of a some-more compulsory singular honing process. This also enhances a long-term wear characteristics of a engine. Low flexibility oil (0W-20) also reduces friction. Other contributors to altogether handling potency are a special two-stage oil siphon use valve, low-friction oil seals, special low-drag piston ring design, low-friction cam sequence and a lightweight crankshaft.

Drive-by-Wire Throttle System
The Civic Si’s Drive-by-Wire stifle complement replaces a compulsory stifle wire with intelligent wiring that “connect” a accelerator pedal to a stifle valve inside a stifle body. The outcome is reduction under-hood confusion and revoke weight, as good as quicker and some-more accurate stifle actuation. Plus, a specifically automatic “gain” rate between a stifle pedal and engine offers softened drivability and optimized engine response to fit specific pushing conditions.

Honda’s Drive-by-Wire stifle complement evaluates a stream pushing conditions by monitoring stifle pedal position, stifle valve position, engine speed (rpm) and highway speed. This information is used to conclude a stifle control attraction that gives a Civic Si’s stifle pedal a predicted and manageable feel that meets motorist expectations.

With a Civic Si’s expostulate mode selector positioned on a core console, a motorist can select between NORMAL and SPORT modes. In SPORT mode, a Si’s Drive-by-Wire stifle complement has a some-more assertive form targeted during opening driving.

Emissions Control
The Civic Si’s engine meets a tough EPA Tier3/Bin125 and CARB LEV 3/ULEV125 emissions standards, and is approved to this turn of emissions opening for 150,000 miles.

100,000+/- Mile Tune-up Intervals
The Civic Si’s powerplant requires no scheduled upkeep for 100,000+/- miles or more, other than periodic inspections and normal liquid and filter replacements. The initial tune-up includes H2O siphon inspection, valve adjustment, and a designation of new hint plugs.

Maintenance Minder™ System
To discharge nonessential use stops while ensuring that a automobile is scrupulously maintained, a Civic Si has a Maintenance Minder™ complement that ceaselessly monitors a vehicle’s handling condition. When upkeep is required, a motorist is alerted around a summary on a Driver Information Interface (DII). (See a Interior Section for some-more information.)

6-Speed Manual Transmission
In gripping with a Si’s fan motorist tradition, usually one smoothness is available, a quick-shifting 6-speed primer smoothness (6MT). The territory offers well-spoken and accurate change feel and good efficiency. Compared to a closely associated 6-speed primer smoothness offering in a Civic EX-T, a Si smoothness has some-more firm joint mounts to compare a engine’s aloft horsepower and torque. Refinements to a change linkage and selector resource furnish a accurate and well-spoken rigging push change movement while shortening cadence by 10 percent.

The 10th-generation Civic 6-speed primer smoothness has been delicately engineered to broach state-of-the-art opening and change action, with reduced inner friction, tighter inner tolerances and softened synchronizers. The smoothness also has a some-more firm aluminum extraneous case, higher-capacity round bearings, stiffer rigging shafts, and larger torque ability – compared to a prior Civic Si transmission. A constant-mesh scrolled retreat rigging resource significantly reduces sound when retreat is selected. A retreat lockout underline prevents a smoothness from incidentally being shifted into retreat while a automobile is relocating forward.

Manual Transmission Gear Ratio Comparison

Powertrain Feature Comparison

Fuel Economy and Emissions Ratings

(See a Specifications and Features territory for all data.)

1Based on 2017 EPA fuel-economy ratings. Use for comparison functions only. Your mileage will change depending on how we expostulate and say your vehicle, pushing conditions and other factors.