Ultimate-Honda-k24-engine-guide

Ultimate Honda K24 Engine Guide

Austin Parsons

Meet Austin

Austin holds a technical writing degree and has 5 years of experience working as a Technical Product Specialist at BMW. He is an avid car enthusiast who is constantly watching F1, consuming automotive content, racing on his simulator, and working on his Toyota’s and BMW’s. Austin’s technical writing skills, extensive automotive knowledge, and hands-on experience make him an excellent resource for our readers.

Honda is one of the first manufacturers that comes to mind when it comes to all-star 4-cylinder engines. While earlier Honda 4-cylinder engine families, like the B-Series, have a strong aftermarket following, the later K-Series is just as established. While the K20 gets most of the K-Series love, the 2.4L K24 engine can be just as, if not more, capable than the baby-K. 

Honda-k24-engine
Credit: Hatsukari715/Wiki

Over the years, the K24 engine proved itself to be very reliable and solid, with only a few common problems and issues. In addition, it has proven as a favorite to modify, with countless cylinder head swaps and bolt-on modifications available for it. Let’s take a look at one of Honda’s most celebrated engine series, the K24.

Make sure to check out our other Honda engine content, including our Honda K20 vs K24 Engine Guide, Ultimate Honda K20 Engine Guide, and Best Honda Engines of All Time Article.

Specs

EngineHonda K24 Engine
ConfigurationInline-4 Cylinder
Displacement2.4 Liters (143.6 cu in)
AspirationNaturally Aspirated
ValvetrainDOHC i-VTEC
Block/HeadAluminum/Aluminum
Bore x Stroke83.0mm x 99mm
Compression Ratio9.6:1 – 11.0:1
WeightLong Block ≈ 283lbs
Horsepower158-206 hp
Torque (lb-ft)160-182lb-ft

K20 vs K24

As part of the Honda K-Series, both the K20 and K24 have made a name for themselves for many of the same reasons. The overall engine architecture and structure of both the K20 and K24 are remarkably similar, with only a few key differences separating the two engine families. The most obvious and significant difference between the two engine families is displacement. 

Honda-k20-vs-k24

The Honda K20 is the 2.0L variant of the K-Series. The K20 features an 8.3” deck height with an 86.0mm x 86mm bore and stroke, creating 2.0 liters of displacement. In contrast, the K24 features a taller 9.1” deck height with an 87.0 mm x 99.0 mm bore and stroke, allowing for an additional 0.4 liters of displacement. The K24’s longer stroke also changes the engine’s characteristics slightly. 

Since the K24 is an undersquare (or long-stroke) engine, meaning that its stroke is longer than its cylinder bore, it produces higher torque than square engines, like the K20, especially at low-rpms. That is certainly true of the K24 and a solid argument in favor of the K24 for certain applications. However, the K24’s higher low-end torque comes at the expense of high-rpm power. In comparison to the K20, the K24 has a notably lower redline which puts some enthusiasts off.

Outside of the obvious displacement difference between the two engines, there isn’t much to note outside of that. It is important to note that the K20 and K24 feature different intake manifolds, and use slightly different camshafts, springs, and spring retainers. However, it is popular in the community to mix and match K20 and K24 parts. 

For more information about the similarities and differences between them, take a look at our dedicated Honda K20 vs K24 Engine Guide.

Variants

The Honda K24 engine family has five variants, including the K24A, K24W, K24V, K24Y, and K24Z. Like the K20’s variants, each K24 variant also has sub-variants.

The most common and sought-after K24 variant is the K24A, specifically the K24A2. The K24A2 features Honda’s performance version of i-VTEC, with VTEC applied to the exhaust and intake sides of the engine. The K24A2 also has the highest stock horsepower figure of the K24 range (outside of the more modern K24W7). Like the K20, each K24 variant differed a bit in terms of compression, ranging from 9.7:1 to 11.0:1 for performance models.

Earlier K24A variants are generally preferred by the community, as most of the later K24 variants focused primarily on fuel efficiency and emissions requirements. Variants like the K24Z1 and Z2 are reworked versions of earlier K24A variants. K24Z variants feature different intake manifolds, throttle body design, reworked catalytic converters, and updated fuel injectors compared to K24A engines. 

Reliability and Common Problems

  • Front Crankshaft Seal Leaks
  • Exhaust Camshaft Lobe Wear
  • Timing Chain Tensioner Failure

As with almost every Honda engine ever created, the K24 has a pretty stellar reputation for reliability. Even high mileage K24 engines are known to hold up well over time. In most cases, if you stay on top of regular maintenance and engine care, you can expect to blow past 200,000 miles with ease. For that reason, it wouldn’t be fair to say that any of the problems that I am about to discuss are truly common. These are simply the problems that you can most expect.

It is also important to mention that while these issues affect all variants of the Honda K24, some variants might be more prone to these issues than others. If you are interested in learning about Honda K24 engine problems in more detail, take a look at our dedicated guide on the subject here.

Front Crankshaft Seal Leaks

Like most aging engines, the K24 is prone to leaking from several places as various gaskets and seals become brittle and crack. The front crankshaft seal is one of those pesky oil leak locations. On the Honda K24, the front crank seal seals the end of the crankshaft with the timing cover. While it is a simple component, it is a vital one, as it keeps oil from streaming out of the front of the engine while also keeping the crankshaft sufficiently lubricated. You might also have heard people refer to the front crankshaft seal simply as the “front main seal,” but the two terms can be used interchangeably.

There isn’t anything inherently wrong with the design of the front main seal on the K24, instead, like on any other engine, the rubber seals simply degrade and crack over time. At this point in the K24’s lifecycle, it’s likely that most K24 front mains are leaking at least a little if they haven’t undergone replacement. Luckily, replacing the front main seal on the K24 is a relatively straightforward job, especially compared to the rear main seal. Most repair centers will charge in the ballpark of $400-$500 for the repair, including parts and labor.

Exhaust Camshaft Lobe Wear

Camshafts are one of the most crucial elements of an engine’s top end. They are responsible for opening and closing the intake and exhaust valves, allowing fuel, air, and exhaust in and out of the engine. In the case of the K24, there have been a number of reports of the exhaust camshaft wearing prematurely. The wear is usually in the form of pitting or galling, which means that the surface of the camshaft lobes becomes uneven or rough over time. 

There is quite a bit of speculation as to the actual cause of K24 camshaft galling. The most common explanation is that the cams aren’t sufficiently lubricated, leading to excess friction that can cause the material to weld or connect to the contact point where the excess friction occurs. It may also cause cracking or roughening of surfaces. Many Honda enthusiasts also believe that improper casting methods and subpar build materials are to blame as well.

Most of the time, there aren’t any truly apparent symptoms of camshaft galling in the beginning. As the problem continues to get worse, some owners who have experienced the problem say that they have heard a clicking noise coming from under the valve cover. A loss of engine performance typically follows. Unfortunately, it isn’t cheap or easy to replace a K24 exhaust camshaft, leading to a ballpark repair cost of around $800-$1,500. 

Timing Chain Tensioner Failure

Following along similar lines to the camshaft wear issue, the K24 is also prone to some other serious oiling problems. One of the most common K24 problems caused by poor oiling is timing chain tensioner failure. The timing chain tensioner plays a vital role in ensuring that there is no slack in the timing chain and maintaining that engine timing stays correct. While we won’t go into detail here about how timing chain tensioners work, but if you’re interested, here is an article that goes into the K-Series tensioner design in detail.

The K24’s timing chain tensioner issue is caused by the internal spring that has a tendency to fail to keep tension on the timing chain before oil pressurizes the tensioner’s internal chamber. If the spring fails, it can do damage to other parts of the tensioner, preventing it from functioning properly. Over time, the bad tensioner allows slack to build up in the timing chain, leading to engine damage from the pistons making contact with the valves. 

Honda-k24-timing-chain-tensioner

Timing chain tensioner issues are tricky, as there isn’t a way to monitor the tensioner’s health before it fails. If the problem just started, there might be some indicators that the timing chain itself is gathering slack. You’ll likely notice a rattling or rumbling noise when the chain develops too much slack. The check engine light may illuminate due to improper timing. That can also cause issues with starting the car or the K24 stalling. Depending on whether or not you plan on replacing the timing chain itself while you’re having the tensioner replaced (which is recommended), you can expect to pay between $800-$1,200 for the repair.

Performance Mods

Honda’s K-series is a fantastic platform for modifications. The K24 earns its reputation for its unparalleled build construction and its ability to withstand huge amounts of horsepower with relative ease. While it is possible to dip into sizable horsepower numbers with any K-series engine, some are easier and more worthwhile to modify than others. 

In general, the performance K24 variants are more receptive to modification than the more economy-focused variants. With so many block/head combinations possible with the K24, it is best to start with a good bottom end and shop around for cylinder head options. The best K24 variants to modify include the K24A1, and K24A2.

K24 engines are said to be able to handle 280-300 horsepower reliably with stock internals. While there are tons of examples of stock K-series pushing far more horsepower than that, 300whp is about the highest safe figure. With that being said, K24s are highly receptive to simple bolt-on mods. Let’s jump in and talk about the most popular K24 engine mods including the following:

  • Cylinder head swaps
  • Headers
  • Tuning

Cylinder Head Swap

One of the most celebrated traits of the Honda K24, and the entire K-Series in general, is its interchangeability. Almost every K-Series engine can loan parts to any other K-Series engine, meaning that there is a nearly endless amount of customizability available between K20 and K24 engines. That is especially good news for those who own a K24 variant that lacks performance VTEC. The K24A2 is the only K24 variant that comes with performance VTEC with three lobes per cam on both the intake and exhaust cams. All other variants only have VTEC on the intake camshaft.

That is where cylinder head swaps come into play for the K24 variants that lack true performance VTEC. It is possible to swap the cylinder head from a performance-VTEC-equipped K20 or K24A2 engine onto a K24 variant with a VTEC-E head. And, in most cases, it is a very straightforward swap. If you have either a K24A1 or K24A2 block, the head swaps are plug-and-play. If you are starting with either a K24A3 or K24A4 block, you’ll need to swap to shorter pistons in order for the head swap to work. It is also important to note that all of the high-flow K20 cylinder heads are only a direct swap onto K20A variants and not the newer K24Z or K24Y variants.

K20A2, K20A Euro R, and KA20A Type R cylinder heads provide the best flow while also using performance VTEC, these are the best heads to couple with a K24 block. In addition to the higher flow and improved camshafts, K20 heads also have more robust valve springs that can withstand higher RPMs. With one of these head swaps, you can pick up between 40-60 horsepower with a quality tune. 

Headers

One of the most popular K24 upgrades is a set of performance 4-2-1 headers. 4-2-1 headers, or tri-y headers, get their name from their appearance. They feature four primary tubes that merge into two further down the runners. They then merge into a single tube. Overall, 4-2-1 headers have better flow characteristics to promote low to mid-range power. 

Since the K24 has plenty of top-end oomph, most people choose to go with 4-2-1 headers to help with boosing low-rpm performance. It is a debated subject though, as some Honda enthusiasts choose to run 4-1 headers, which promote high-rpm performance. The benefit of 4-1 headers is that it makes VTEC activation a bit more fun due to the added “go” up top. 

Overall, the 4-2-1 header option is better for street applications where you won’t consistently be in high revs. A 4-1 header choice is better for performance driving and track applications, where you have the opportunity to use the entire tachometer. 

Regardless of your choice, there are tons of reputable options out there. Some of the most trusted Honda performance header manufacturers include Skunk2 and Toda. They both provide 4-2-1 and 4-1 header options, so the choice is up to you. You can generally expect around a 8-15 horsepower bump from a set of quality headers alone and around 20-25 horsepower when paired with a tune.

Tuning

Tuning is unquestionably the most important aspect of modifying a K24 engine. A Hondata FlashPro is widely considered the best mod that you can get for your K24-equipped Honda. The FlashPro allows you to make tuning adjustments to your vehicle’s ECU, with a wide range of customizability and adjustability for many engine functions. It connects directly to your vehicle’s OBDII port and allows you to adjust your vehicle’s ECU via a laptop through a USB connection. FlashPro works using its own proprietary software called FlashProManager and does not require any kind of ECU modification to function.

A Hondata FlashPro is truly a necessary modification to get the most out of your other upgraded performance parts. For example, the other engine upgrades that we have mentioned in this article typically require some kind of engine tuning to reap full benefits. With a FlashPro, you can install premade maps for common performance upgrades, or have a tuner custom build a tune based on your parts and their expertise. In addition to all of the modification options and capabilities, the Hondata also comes with a datalog function to ensure that everything is running smoothly after you make changes to the base tune. 

If you are planning on introducing forced induction to your K24, a FlashPro is a requirement. It allows you to customize fuel, ignition, and cam angle tables, which is a must for any turbo or supercharger application. 

The Honda K24 is the King K-Series

While the Honda K20 engine is often celebrated as the worthy replacement for the famous B-Series, the K24 is truly the most capable and potent K-Series entry. We all know the saying “there’s no replacement for more displacement,” and that is a saying that the K24 takes literally. With an additional 0.4 liters of displacement over the K20, there’s more potential hiding in the K24’s bottom end. 

As with most of Honda’s engines, the most common K24 engine problems aren’t common at all. In fact, most K24 owners won’t even experience a hiccup until well beyond the 200,000-mile mark. As far as reliability goes, it doesn’t get much better than that. Front crankshaft seal leaks are the result of aging rubber as opposed to a design defect. While the K24 is known to have exhaust cam galling problems, they are often the result of neglect and improper oil maintenance. Timing chain tensioner failure is truly the only common and design-related failure on the K24 that can be remedied relatively easily. 

Performance modifications are the K24’s strong suit. With one of the biggest aftermarket communities of any engine under the sun, there is an endless number of performance upgrades under the sun. Not only does the K24 respond very well to aftermarket bolt-on mods, but most other K-Series parts are interchangeable on the K24’s bottom end.

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