Best K-Series Engine by Honda (K20, K24) — Our Choice and Explanation

For a petrolhead or anyone just beginning their car-swapping journey, choosing the best K-powered block from Honda can be confusing.

For a company with longstanding credibility of manufacturing reliable power engines plus an immeasurable enthusiasm for motorsports, creating an all-in-one technology solution that has been sought-after for over two decades and counting is not only a milestone but also a legacy.

Talking about the K-series- we can only imagine the unthinkable possibilities to improve car performance and efficiency, plus a handful of chances to revive classic cars. The K-series has been a favorite go-to of engine builders and enthusiasts.

With over forty variants, anyone would switch heads from left and right because of confusion between K20 and K24 engines. Many enthusiasts would still be confused between these two commonly used K-powered engine ranges because of their similarities.

And even though we had to enumerate their differences, deciding who wins is a matter of preference and a few considerations. Whether you go after the swapping potential, the amount of money you are ready to shell out, or the performance, it would surely affect which K-motor stands out.

Key features and my opinion about the K20 engine

• Production years:2001-now
• Average lifespan of K20:180,000-220,000
• Fuel supply type:port injection (later - direct injection)
• Power range:153-320 hp
• Fuel efficiency:average
• Engine block material:aluminum
• Engine reliability score:medium
• The most common problems:exhaust camshafts are weak, no lifters, throttle contamination, oil leaks, engine mounts problems.

Key features and my opinion about the K24 engine

• Production years:2001-now
• Average lifespan of K24:210,000-240,000
• Fuel supply type:port injection (later - direct injection)
• Power range:160-206 hp
• Fuel efficiency:average
• Engine block material:aluminum
• Engine reliability score:medium
• The most common problems:exhaust camshafts are weak, no lifters, throttle contamination, oil leaks, engine mounts problems.

What Do You Need to Know About Honda's K-Series Engines?

K-series has been out since 2001. It's a range of four-stroke four-cylinder with all-aluminum construction and cast iron sleeves. The dual overhead camshafts (DOHC) were an inherent feature of D-series engines, and the roller rockers on the cylinder head that minimize friction are distinct on F-powered engines. K-engines utilize a direct ignition system instead of using a distributor. Another distinct feature of K-powered motors is the intelligent Variable Valve Timing & Lift Electronic Control (iVTEC).

K-series is most-loved for being an all-in-one engine swapping solution for different chassis. You can swap the K-engine for Odyssey, Accord, CR-V SUV, Civics, and Integra. And not only that, K-engines would challenge your swapping abilities to drop in it to the craziest rare bodies and still find it doable since most parts are easier to find and more affordable.

For this reason, Honda has gained quite a massive aftermarket support that made the parts industries competitive, providing enthusiasts and builders more choices at more affordable prices.

The K-series has been favorable to engine tuners because one can adjust the compression ratio and rotating assembly. Enthusiasts can customize and optimize their cars according to their preference: to make their units supercharged or turbocharged. Moreover, VTEC has been very useful for power and fuel economy optimization.

K-series has acquired the most-loved features from D, B, and F series engines into one robust interchangeable engine standard.

• Dual overhead camshafts
• All-aluminum built
• Forged crankshaft
• Direct ignition
• Chain-driven camshafts
• Roller rockers
• Chain-driven oil pumps

Distinct from the K-series is the reversed engine assembly, making it possible to rotate clockwise. This assembly places the intake ports on the front, enabling exhaust routing and modification easier.

And since these technologies are both present in the commonly-swapped K20 and K24, the battle for the best K is still a long debate. In the next parts of this write-up, we will discuss what makes each one different and who does it better.

What is the Best K-Series from Honda?

Each K-series offers uniqueness suited for its applications. Let's start with the obvious displacement of K20 of 2.0 liters and K24's displacement of 2.4 liters.

Because of this, K24 engines have added bore and stroke of 87 mm (3.4252 in) x 99 mm (3.8976 in), and K20 measures 86 mm (3.386 in)  x 86 mm (3.386 in). Also, a K20 is a long block with 275 lbs weight, and a K24 would have 300 lbs weight.

K20 has four variants with their subvariants: K20A, K20B, K20C, and K20Z. K24 has five of them: K24A, K24W, K24V, K24Y, and K224Z.

1) The K20 Engine

K20 is the first-produced engine among the K-series, named the variant K20A. If you're a long-time engine builder, you can agree that the latest release is not always the best option.

K20 took the first blows of criticisms from the B-series lovers. And over time, K20 has gone through a lot of changes. With all the pressure from B-series enthusiasts, K20 has justified its existence. It was the start of a new era for Honda.

The launch of K20 is Honda's participation in the worldwide movement of improving fuel economy and producing greener emissions. It is the era where every player tries to make further steps in boosting performance and unleashing more tuning potential to their own.

Over time, K20 developed over 20 variants for different applications. Its initial launch was found on the bodies of a Honda Stream JDM, followed by high-performance Type R of Honda Civics and Integra equipped with i-VTEC technology. Back then, JDM runs at 154 hp at 6500 RPM. K20 has gone a long way since then.

Going through the high-powered K20s produced, a high-performance engine from K20A could run at 221 hp at 8000 RPM with torque peaking at  159 lbs-ft at 6100 RPM. Even so, K20C1 could run up to 316 hp at 6500 RPM and torque peaking at 295 lbs-ft at 2500 RPM.

2) The K24 Engine

K24 is much-favored for its reliability and high-performance potential. Like K20, you can build it with Front Wheel Drive and Rear Wheel Drive bodies. And if you have long been assembling RWDs, you can agree that K24 is the best choice for it.

In reality, K24 has made it to rare engine builds like drifters and mid-engine racing builds. And if you are going for the V8 swap, K24 would be the other route to save a few more bucks. Not only because of the high-power potential and reliability, but a K24 could also stand forced induction.

Like K20, K24 has gone through a lot and produced over 20 subvariants. But what we love about K24 is the variety of choices when making off-the-shelf upgrades. A popular build is the K24A block with a K20A2 head, or you can build it with K20A Type R or K20 A Euro R heads.

And with more effort, you can surely build a K24 engine that goes up to 300 hp.

Design

When it comes to design, these two don't have much difference as most of their parts are interchangeable. K20 is shorter, having a deck height of 8.3 inches. K24 has a deck height of 9.1 inches. Because of this, K24 would have more advantages since the stroke is higher.

If there's any more difference, that would be the size of the intake ports and intake manifolds used. A K20 has larger intake ports, which makes it lower torqued compared to the K24. Also, most K20 engines use PRB or RBC intake manifolds, while K24 utilizes RBB or RAA intake manifolds.

Another difference is they use different springs, spring retainers, and camshafts. The K24 camshafts would have bigger primary lobes than the K20s, producing higher lifts and suitable for low or midrange power. K20 camshafts have more pronounced primary lobes that work better with higher RPM.

For this reason, interchanging a K20 camshaft with a K24 engine can be more stressful on the valvetrain.

Tuning

Both K-series are highly receptive to modifications. We advise you to use high-performance K-engines for your power requirement.

For K20s, go for K20A, K20A2 (this would be our best choice), K20Z1, and K20Z4. These engines are truly remarkable when it comes to modifications. Try bolting in an RRC manifold, cold air intake, FD2 throttle body, upgraded exhaust, and ECU, it would run up to 230 hp.

For higher power, you can upgrade the intake manifolds, camshafts, gears, bigger throttle bodies, a bigger exhaust, and larger fuel injectors. A popular build was K20A or K20A2 heads into a K24A2 cylinder block. The added 2.4 liters displacement is perfect for larger pistons. You can increase the compression ratio from 12 to 13.0:1.

For K24, choose between K24A2 or K24A3. We recommend K24A2 for more flexibility. K24 mods can increase your engine performance to 500 hp and more. You can use any of these K20 heads for a K24A cylinder: K20A, K20A Type R, or K20A Euro R. These heads do not fit right for a K24Z.

Additionally, K20's camshafts and valvetrain are better than K24s. If you want to use them, make sure you also use K20's oil pump. Without forced induction in mind, you only have to upgrade the throttle body and manifold and add some internal porting, including camshafts and valvetrains. Your K24 can reach 300 hp.

So when it comes to modification potential, we would always go for the K20 engine.

Engine Swaps

Both K20 and K24 are capable of ridiculously exciting engine swaps.

But with the long existence of the K20, Honda made all the possibilities when it comes to engine swaps. Imagine a K20 fitting into a Mercedes C240. When we saw a Porsche turbocharged K20 at the 2018 SEMA Show, it left us all in awe. We've also seen how a Metro 6R4 took a supercharged K20. The car throttled at 320 bhp. And the vehicle turned out light as 800kg.

Other insane swaps made an Acura NSX superpowered by a 1000 hp K20.

K24 has a fair share of crazy engine swaps too. Think about these units powered with K24: Mazda Miata, Toyota MR2, Nissan 240SX, Lotus Exige, Ferrari 308, and Bisimoto Wagovan. Crazy, right?

Forced Induction

When it comes to forced induction, both engines can handle well over 300 hp. As you can see, both of them respond to the supercharger and turbocharger. But even so, a much more effective route is to turbocharge your K-engine, as supercharging may be less efficient.

In this case, a K20A2 is a better option for forced induction. But if you must go over 400hp, you better make a transmission upgrade, as your stock internals could blow up in these figures even if they could handle them. According to many Honda enthusiasts, the EP3 5-speed transmission is your best upgrade.

Reliability & Usual Issues

Both engines are reliable when it comes to performance and construction. Added that both engines utilize the iVTEC technology, it's also easy to source parts and components.

Here are some issues you might experience with K24:

• Timing chain sensor failure
• Oil seal leaks
• Worn-out exhaust camshafts
• VTC gear may deteriorate

Here are the common issues with K20:

• Wearing of exhaust camshafts
• Elongated timing chain
• Front seal oil leaks
• Overheating the fourth cylinder

Although these problems occur, you can avoid them with regular maintenance.

K20 vs. K24: Which is the Best K-series?

Honestly, both engines will deliver and never disappoint. Both blocks have gained aftermarket support, and you can easily find parts. With the extra 0.4 liters, you can only first see their difference in displacement. K24 creates a longer stroke but is a bit heavier. This means the K24 could drive smoothly with more power but lower gears.

But K20 has a fair advantage too. K20 is much easier to swap for many chassis and generally cheaper. However, K24 has a disadvantage with its heads. A lot of enthusiasts have been using a K24 bottom with a K20 engine, which addresses the head issues of the K24.

If you are still undecided, think about your budget and how much you are willing to shell out of your pocket. If you are on a tight budget but don't want to compromise the quality of your build, go for K20. If you are after the performance potential and budget is not an issue, go for a K24.

In reality, comparing these two engines could be an endless battle. But you surely would never go wrong with a K-series.