Whether you adore it or abhor it, the formidable Acura RSX Type S engine, or the Honda K20 engine, has undeniably endured the test of time. Renowned for its exceptional reliability and vast tuning capabilities, it’s no wonder why it remains a favored option among enthusiasts. Nearly two decades have passed since Honda first introduced its K-series engine lineup, and throughout the years, numerous revisions and updates have been implemented, making it somewhat challenging to keep track. Fortunately, we’ve succinctly outlined these changes in our history section.

By now, you’re likely aware that not all K20 engines are created equal. Choosing the wrong one could leave you wishing you stuck with the B-series. The Acura RSX Type S engine (K20A2) stands out as the most venerable among the K-series engines, featuring an all-aluminum block, DOHC configuration, and a 16-valve cylinder head. In contrast to the economy-focused K20A3, the K20A2 boasts upgraded intake and exhaust camshafts, a PRB intake manifold, and larger intake and exhaust ports.

With a slightly lower compression ratio of 11.0:1, the i-VTEC system kicks in at 5,800rpm, delivering 200 horsepower at 7,400rpm and 142 lb-ft of torque, courtesy of 310cc OEM injectors.

Since the K20’s inception nearly two decades ago, significant changes have occurred. In a world increasingly prioritizing emissions reduction and fuel efficiency over raw performance and tuning capabilities, opting for the latest powerplant may not always be the wisest choice.

The K-series saga commenced towards the end of 2000, as the world emerged unscathed from the ‘millennium bug’ scare, with Honda poised to unveil its groundbreaking innovation to the world.

Acura RSX Type S engine specs

The Acura RSX Type S, particularly the model with the K20A2 engine, is a highly regarded performance vehicle known for its engine capabilities and overall driving experience. Here are some details about the K20A2 engine:

1. Engine Type: The K20A2 is a 2.0-liter inline-four cylinder engine produced by Honda. It’s part of the K-series engines, known for their high-revving nature and performance-oriented design.
2. VTEC Technology: Like many Honda engines, the K20A2 features Variable Valve Timing and Lift Electronic Control (VTEC) technology. VTEC allows for different camshaft profiles and valve timing to optimize both low-end torque and high-end power.
3. Power Output: The K20A2 engine in the Acura RSX Type S produces around 200 horsepower and 142 lb-ft of torque. However, these numbers can vary slightly depending on factors like tuning and condition of the engine.
4. High-Revving: One of the standout features of the K20A2 engine is its ability to rev high. The redline typically sits around 8,000 to 8,200 rpm, allowing drivers to enjoy a thrilling driving experience with plenty of power available throughout the rev range.
5. Performance Upgrades: Due to its popularity among enthusiasts and the robust aftermarket support, there is a wide range of performance upgrades available for the K20A2 engine. This includes aftermarket intake systems, exhaust systems, engine management systems, and even forced induction setups for those seeking even more power.
6. Reliability: Honda engines, including the K20A2, are known for their reliability and durability when properly maintained. With regular maintenance and proper care, the engine can provide many miles of trouble-free operation. Owners of the Acura RSX Type S engine have mentioned their car crossing easily over 200,000 miles, some even had mentioned it reaching 300,000 miles.
7. Transmission: The K20A2 engine is often paired with a close-ratio 6-speed manual transmission in the Acura RSX Type S, enhancing the driving experience and allowing drivers to make the most of the engine’s performance characteristics.

Overall, the K20A2 engine in the Acura RSX Type S is highly regarded among enthusiasts for its combination of power, high-revving nature, and reliability, making it a popular choice for those seeking a spirited driving experience.

Whats the difference between the K20A2 vs K20Z1 engine

The Acura RSX Type S engine did indeed change between the 2002-2004 model years and the 2005-2006 model years.

Here are the differences in performance between the two engine variants. The 2002-2004 Acura RSX Type S models were equipped with the K20A2 engine. The 2005-2006 Acura RSX Type S models were equipped with the K20Z1 engine.

The K20Z1 and K20A2 are both variants of the Honda K20 engine series, and they share many similarities, but there are also some key differences between them. Here’s a breakdown of the main distinctions:

1. Valve Train: While both engines utilize Honda’s VTEC (Variable Valve Timing and Lift Electronic Control) technology, the K20Z1 features an upgraded camshaft profiles that use the same K20A Type R cams from the JDM DC5 Type R, the Japanese version of the Acura RSX.
2. Power Output: The K20Z1 generally produces slightly more power than the K20A2. In the Acura RSX Type-S, for example, the K20Z1 engine is rated at around 210 horsepower and 143 lb-ft of torque, whereas the K20A2 engine produces around 200 horsepower and 142 lb-ft of torque. These figures can vary slightly depending on factors like tuning and condition.
3. Engine Block: While both engines share the same basic engine block design, there may be slight variations in materials or manufacturing processes between the K20Z1 and K20A2 engines. However, little is known if there are true differences, the K20Z1 does use a slightly smaller harmonic balancer similar to the Type R engine as well.

Importance areas to notice of the K20a2 engine

The K20A and K20A2 share the same casting for the head and block (PRB). It is in the K20A’s internals where it is differentiated from the K20A2. Camshafts, intake manifold and pistons are PRC on the K20A only where as the crankshaft and connecting rods are PRB on both K20A and K20A2. The K20A2 engine with a lower compression ratio of 11.0:1 compared to the 11.5:1 DC5r compression ratio is primary because it’s made the the US market and the lower octane that’s offered in the States (91 octane, sometimes 93).

The Acura RSX Type S engine comes in a silver top valve cover with an Acura “A” emblem plastic black top spark plug cover, while the Honda Integra DC5 Type R engine comes in the iconic red top valve cover with a silver spark plug cover that reveals the etched “Honda”.

The PRB intake manifold creates high flow to the k20a2 head and is popular amongst enthusiast that modify. Often times, you’ll find people that take the k20a2 head and place in with a k24a bottom end / short block from a TSX K series engine. The PRB manifold is very similar to the PRC manifold on the Type S in shape, but has slightly port differences and more EVAP system attachments to it for US based emissions. While this is better than the k20a3 engine seen on the Acura RSX base model car, many people will get rid of this and opt in for an aftermarket upgrade like the Skunk2 manifold or even go with the RBC intake manifold from 06+ USDM Civic Si  models which is known to create high end HP and torque at higher RPM range.

The PRB manifold is good across the entire band including low to mid RPMs

Overall, the Acura RSX Type engine engine is very iconic and highly sought after even after 20 years. While the K20Z1 and K20A2 engines are closely related and share many similarities, the K20Z1 tends to offer slightly higher performance potential and may feature some power enhancements over the K20A2.