Honda Gasoline Engine Series Collection, Part Sixteen: Inline-4 K-Series

Honda Gasoline Engine Series Collection, Part Sixteen: Inline-4 K-Series
Original Author: Honda誌 日系車迷誌
Updated: November 21, 2024
In previous articles, we introduced several inline-4 engines from the "90s generation." This time, we will begin introducing three "2000s generation" inline-4 engines.

🌟 Hello, my friend...�Welcome to a hidden gem—OLD FISHER DISCOUNT, your one-stop online shop with 7,000+ unique finds waiting for you. 🎉
🛒 Explore a World of Discoveries�Dive into our collection and uncover special treasures that will delight and inspire.
🔗 Start Your Journey Here: www.fisherdiscount.com
Come and see why we’re more than just a shop; we’re a place of endless possibilities! ✨

Before discussing the K-Series, let’s review their lineage. The K-Series engines represent the high-end segment of Honda's four-cylinder lineup. These engines replaced earlier B-Series, H-Series, and certain high-end F-Series products such as the B18C Spec R, H22A, H23A, F20B, F20C, and F22C1 high-power naturally aspirated engines. Their roles were succeeded by the K20A and K20Z. Similarly, standard-performance engines such as the H22A, H23A, B20B, F22A, and F23A were replaced by the less powerful 2.0L and 2.4L K-Series engines.
Another defining feature of the K-Series is its counterclockwise crankshaft rotation, with the engine placed on the right side in the forward direction. Additionally, traditional ignition systems comprising distributors and high-tension wires have been replaced by an integrated electronic ignition system using coil-on-plug spark plugs. In this system, the ECU collects data from various sensors to control ignition timing, eliminating the distributor.

Like the B-Series engines, the K-Series features two different block heights: the K20 has a height of 212mm, while the K23 and K24 have a height of 231.5mm.
The K-Series engine was first released on October 26, 2000, and made its debut in the 2001 Integra Type R (DC5). In 2015, the K20C1 was introduced, powering the ninth-generation Civic Type R (FK2). Production of K-Series engines continues to this day.

The K-Series’ Notable Evolution
The first model of the K-Series was the K20A, equipped with Honda’s renowned DOHC i-VTEC system. Its iconic red valve cover speaks volumes about its capabilities. Without achieving 100 hp/L, it wouldn't deserve such a design.
The most famous feature of the K-Series is undoubtedly its i-VTEC system, which is a progression of Honda’s exclusive DOHC VTEC technology. Over time, advancements in environmental and engine management systems allowed for more precise control of valve timing, making the system more efficient. Consequently, a Variable Timing Control (VTC) mechanism was added to the drive gear of the intake camshaft. This VTC mechanism, installed at one end of the intake camshaft, adjusts intake valve timing by ±30 degrees.

This marks yet another evolution in VTEC’s journey since its introduction in 1988, which saw further iterations such as SOHC VTEC, three-stage VTEC, and VTEC-E. The 2003 i-VTEC system expanded into the J-Series engines with the Variable Cylinder Management (VCM) system, while in 2004, it integrated direct injection technology to create the i-VTEC i system (K20B). In 2006, the system evolved into AVTEC with continuously variable valve lift and control, and more recently, it combined with turbocharging to give rise to the VTEC Turbo series engines.
However, it’s important to note that not all K-Series engines feature VTEC on both the intake and exhaust camshafts. High-performance versions typically include i-VTEC on both, while most lower-performance versions only have VTEC on the intake side. In low-speed conditions, the two valves are operated independently: one valve with minimal lift for creating a swirl effect to improve fuel atomization, and the other operating normally. This essentially turns the engine into a 12V setup. At high speeds, the valve rockers are linked, and the normal-shaped camshaft drives both valves, restoring 16V operation.

For example, the K20A3 represents this setup, while turbocharged models like the K20C only have VTEC on the exhaust camshaft.
A Closer Look at the K20A
The K20A cylinder head features VTEC structures on both intake and exhaust camshafts, signifying its high-performance naturally aspirated design. The Japan Domestic Market (JDM) version of the K20A boasts the highest performance levels. For example, the K20A in the Integra Type R (DC5) is tuned to outperform the K20A in the UK-built Civic Type R (EP3).

K-Series Engine Variants
The K-Series engines are divided into three displacement variants:
K20 Series (2.0L): The most widely used and largest group of the K-Series engines.
K23A1: A unique turbocharged model.
K24 Series (2.4L): Commonly found in larger Honda vehicles such as the Accord and CR-V.
Notable Models:
K20A: The first K-Series engine launched in 2000, created a sensation upon release. It became a global benchmark, overshadowing even the F20C engine in the S2000.
K20A2: Export-oriented high-performance version with 200 hp.
K20B (2003): Introduced i-VTEC i technology with direct injection, achieving ultra-lean combustion (65:1).

K20Z (2005): Export-oriented, with versions ranging from 153 hp (low-performance K20Z2) to 210 hp (high-performance K20Z1).
K23A1: Honda’s First Turbocharged K-Series Engine
The K23A1 is a unique model in the K-Series lineup and represents Honda’s first foray into turbocharging. Debuting in 2007, it featured Mitsubishi’s TD04HL variable-geometry turbocharger, producing 240 hp and 350 Nm of torque at approximately 1.1 Bar. This engine powered the Acura RDX.
K24 Series: Meeting the Needs of Larger Vehicles

The K24 engines were designed for larger vehicles such as the Accord, CR-V, and Odyssey. With an 87mm bore and 99mm stroke, the K24A2, for instance, delivered 200 hp in the JDM Odyssey Absolute and 205 hp in the US Acura TSX.
K20C: The Latest Evolution
The newest K-Series engine, the K20C, was introduced in the FK2 ninth-generation Civic Type R. Starting production in 2015 in Honda’s Ohio plant, it combines direct injection with turbocharging for maximum efficiency.

While the K20C1 powers the Type R with 272 hp, the naturally aspirated K20C2 delivers 158 hp for the US-spec Civic and Formula 4 race cars.
End of Production for Older K-Series Models
K20A: Discontinued in 2011.
K20B: Phased out in 2006.
K20Z: Production ended in 2015.
K23: Ceased in 2012.
K24 Series: Currently, only K24V, W, and Y remain in production, gradually being replaced by smaller L-Series engines.