177 Horsepower 2.4-liter Inline 4-cylinder Engine (LX, LX-P Sedan)

2.4-liter 2.4-liter i-VTEC 4-cylinder engine

2.4-liter i-VTEC internal components

Engine Block and Crankshaft
2.4-liter i-VTEC 4-cylinder engine Accord's 2.4-liter engine has a die-cast aluminum block with a single main-bearing cradle design that creates a rigid assembly to help minimize noise and vibration. Centrifugal spin cast iron cylinder liners provide long lasting durability. Each journal on the forged-steel crankshaft is micropolished to reduce internal friction.

Cylinder Head and Valvetrain
The Accord four-cylinder engine has a lightweight cylinder head that is made of pressure-cast aluminum alloy. A silent-chain drives dual overhead cams and four valves per cylinder. The cam drive is maintenance free throughout the life of the engine. 2.4-liter i-VTEC internal components

i-VTEC Valve Control System
The Accord's 2.4-liter, DOHC, 16-valve i-VTEC engine uses an advanced valve-control system to combine high power output with high fuel efficiency and low emissions. The Accord system combines Variable Timing Control (VTC), which continuously adjusts the intake camshaft phase, with Variable Valve Timing and Lift Electronic Control (VTEC), which changes valve lift, timing and duration of the intake valves.

At low rpm, the VTEC intake valve timing and lift are optimized for rapid swirl-pattern cylinder filling. As engine rpm builds past 5000 rpm, the VTEC system transitions to a high-lift, long-duration intake cam profile for superior high-rpm engine power.

The "intelligent" portion of the system is its ability to continuously vary the timing of the intake cam relative to that of the exhaust camshaft. This helps boost power and also provides a smoother idle (allowing idle speed to be reduced). The intake cam timing is varied based on input from sensors that monitor rpm, timing, throttle opening, cam position and exhaust air-fuel ratio. The result is increased fuel economy and lower NOx emissions.

PZEV Version
A PZEV version of the 177- and 190-horsepower four-cylinder engines is sold in California, Connecticut, Maine, Massachusetts, New York, Pennsylvania, Rhode Island and Vermont. The principal differences between the PZEV Accord and the ULEV-2 version sold in all states are single exhaust valve operation at low rpm, special dual-probe spark plugs and remapped Powertrain Control Module (PCM) programming, in addition to the near-zero evaporative emissions equipment. The horsepower, torque and EPA-estimated fuel economy of the PZEV and ULEV-2 engines are identical.

Single Exhaust Valve Operation
The Accord's 2.4-liter DOHC i-VTEC PZEV-compliant engine has two modes of exhaust valve operation. Below 2500 rpm, only one exhaust valve operates, creating a strong rotational flow in the exhaust gases that creates a "thermal reactor" effect to reduce hydrocarbon emissions. Above 2500 rpm where exhaust flow increases, a hydraulically actuated pin locks the rockers for both exhaust valves together so they operate in unison, following a single cam profile.

190 Horsepower 2.4-liter Inline 4-Cylinder Engine (EX, EX-L Sedan; All Coupes)

Overview
The 2.4-liter inline four-cylinder engine that powers the EX, EX-L Sedan and LX-S, EX and EX-L Coupe is closely related to the engine in the LX Sedan and LX-P Sedan. The 190-horsepower inline four-cylinder meets ULEV-2 in all states, and PZEV (AT only) emissions standards in select states. Like the 177-horsepower engine, the 190-horsepower engine's PZEV variant has single exhaust valve operation at low rpm, dual-probe electrode spark plugs and special PCM mapping.

The key feature that allows this engine to make an additional 13 horsepower and 1 lb-ft. of torque compared to the 177-horsepower four-cylinder engine is a special exhaust system with larger diameter tubing and a variable-valve silencer design that nets a 31% increase in flow relative to the previous generation Accord four-cylinder system. Despite its performance advantage, this engine delivers the same EPA-estimated 21/31¹ City/Highway fuel economy (Sedan AT) as its less powerful counterpart. Inside the interior of 190-horsepower Accord models, an Active Noise Control system (ANC) helps reduce certain undesirable sound frequencies for greater passenger comfort. (Please see the Interior tab for more information.)