An Accord engine in a track car makes a certain kind of sense. An Accord engine in a Subaru makes you stop and look. That’s the Honda K24’s appeal in miniature: a 2.4-liter four-cylinder built for everyday life that enthusiasts keep finding reasons to put somewhere else.
The ingredients are unusually tempting. There’s more displacement than the K20, Honda’s i-VTEC valvetrain, and an aftermarket that lets a build grow from a near-stock street engine into an all-motor project or a turbocharged track car. The K24 can play all those parts, but the version that spent its life in a CR-V has a different starting point from the one under a TSX hood.
To understand why this engine inspires so many swaps, it helps to follow both lives: the engine Honda built, and the engine enthusiasts made of it.
On this page
- The K24 story starts in the family car
- Honda K24 specs: what gives it its character?
- K20 vs. K24: revs, displacement, and the appeal of both
- Which cars have a K24, and which versions matter?
- K24 tuning: from bolt ons to an all motor build
- Turbocharging and supercharging the K24
- How the K24 escaped the Honda engine bay
- K24 reliability: the less glamorous part of the appeal
- Why the K24 still gets enthusiasts planning
The K24 story starts in the family car
The early K24 arrived with a practical brief. One of its first North American homes was the 2002 Honda CR-V, where Honda’s original specification sheet lists 160 hp and 162 lb-ft. Useful torque in a practical crossover was the assignment. The 2003 Accord followed with a 160-hp 2.4-liter i-VTEC four-cylinder, putting the same basic engine family into another everyday Honda.
That ordinary beginning became part of the K24’s attraction. Engines spread through family sedans and crossovers eventually become donor engines, and a performance project looks much more approachable when its starting point lives in a salvage yard.
The 2004 Acura TSX gave the story a sportier turn. Its K24A2 produced 200 hp and 166 lb-ft, with a six-speed manual available alongside the automatic. Here was a factory example of what the larger K-series could be when Honda aimed it at drivers who enjoyed using the rev range. Acura’s TSX launch announcement puts those figures in their original context.
The contrast still explains much of the family today. Honda used the K24 to move people and luggage; enthusiasts saw displacement, breathing potential, and a growing supply of parts. The TSX made the connection easier to see.
Honda K24 specs: what gives it its character?
The familiar K24A and K24Z engines have an aluminum block and cylinder head, with cast-iron cylinder liners. Dual overhead camshafts operate four valves per cylinder, and a timing chain drives the cams. The basic dimensions are 87 mm of bore and 99 mm of stroke, giving 2,354 cc of displacement. Acura’s four-cylinder TSX specifications document that core layout.
| Specification | K24 overview |
|---|---|
| Layout | Inline-four, aluminum block and cylinder head |
| Standard displacement | 2,354 cc, usually described as 2.4 liters |
| Bore x stroke | 87 mm x 99 mm |
| Valvetrain | DOHC, 16 valves, i-VTEC; operation varies by version |
| Camshaft drive | Timing chain |
| Fuel delivery | Port injection on K24A/K24Z; direct injection on the later U.S. Accord K24W |
| Representative factory power | 160 hp in the 2002 U.S. CR-V; 200 hp in the 2004 U.S. TSX |
Those dimensions tell you why the K24 is the larger-displacement member of the original K-series pairing. The head, cams, compression ratio, and calibration then shape where it makes its power. A family-wide redline or compression figure would hide the very differences that make some versions more interesting to builders.
i-VTEC is more than the moment the engine gets louder
VTEC changes valve operation using different cam profiles. Variable Timing Control, or VTC, adjusts intake cam timing as operating conditions change. Honda combines these ideas under the i-VTEC name, giving the engine more flexibility than a single fixed cam profile could provide.
For an enthusiast, the interesting part is the powerband: keeping the engine useful lower down while allowing it to breathe at higher rpm. The exact valvetrain strategy changes across K24 versions, which is why an i-VTEC badge alone won’t tell you how closely a donor resembles a TSX engine.
Tuning can also change the transition. In its 2004-2005 TSX reflash documentation, Hondata describes lowering the VTEC crossover and smoothing torque delivery. A dramatic kick isn’t the only way to make a Honda entertaining; a fuller pull through the middle of the tachometer can be the more useful result.
K20 vs. K24: revs, displacement, and the appeal of both
The naturally aspirated K20 and K24 appeal to slightly different Honda instincts. The performance K20 is associated with chasing the top end; the K24 adds displacement that builders can use to fill out the torque curve. In a light Civic, that extra capacity is a large part of the temptation.
The choice is about the complete engine, though. A performance K20 and an economy-oriented K24 have different heads and cams as well as different capacities. A performance K20 can be the better fit when you want to retain that engine’s high-rpm character; a K24 is appealing when a broader torque curve is the goal.
There’s also a mechanical tradeoff. At the same rpm, the K24’s longer stroke means its pistons travel farther per revolution. Building one to rev higher brings the rotating assembly, valvetrain, and oil system into the conversation together. A higher limiter is only useful while the engine is still making power and the hardware can support it.
This is where Honda enthusiasts found a particularly appealing third option: keep the K24’s displacement and pair it with selected K20 hardware. We’ll come back to that combination once the donor codes make sense.
Which cars have a K24, and which versions matter?
Accords, CR-Vs, Elements, TSXs, Civic Sis, and ILXs all appear in the K24 story. The useful distinction is what each version brings to a project. These are representative applications, with North American models as the main reference point.
| Version | Familiar factory home | Its place in the K24 story |
|---|---|---|
| K24A1 | 2002-2006 Honda CR-V | An early utility-oriented K24 donor. |
| K24A2 | 2004-2008 Acura TSX | The performance-oriented U.S. starting point that anchors many naturally aspirated builds. |
| K24A3 | European Accord and Australian Accord Euro | Another early performance-oriented branch, with market-specific specifications. |
| K24A4 / K24A8 | Early- and mid-2000s Accord and Element, depending on year | Everyday-car donors that become more interesting when a build already includes internal changes. |
| K24Z family | Later CR-V, Accord, and second-generation TSX, depending on code | Revised heads, exhaust arrangements, and electronics change the swap recipe. |
| K24Z7 | 2012-2015 Civic Si and 2013-2015 ILX 2.4 | The later port-injected performance branch. |
| K24W | U.S. 2013-2017 Accord four-cylinder | Earth Dreams direct injection takes the family in a different direction. |
K24A2: why the TSX engine gets the attention
For a naturally aspirated project that will retain much of the factory engine, the K24A2 is our first shortlist candidate. It starts with a performance-oriented combination, so the money buys more than a block to rebuild.
The later first-generation TSX engines deserve attention, too. Acura rated the 2006 TSX at 205 hp and 164 lb-ft, following engine revisions. Acura also notes the revised SAE rating method, so comparing that number with the original 200-hp rating isn’t a clean before-and-after dyno test.
A less expensive A4 or A8 becomes more appealing when the plan already includes pistons, rods, and cylinder-head work. Much of the A2’s factory advantage would be replaced anyway. That makes the best donor a question of how much original engine the finished build will actually keep.
JDM K24A and K24A3: the overseas branches
Imported engines add another layer to the search. Japanese-market K24A listings and the K24A3 found in overseas Accords belong in the discussion, but their names aren’t interchangeable with a U.S. TSX specification.
Honda’s 2002 Japanese Accord launch information lists a 2.4-liter version rated at 200 PS. PS and SAE horsepower use different units and rating conventions, and Japanese applications include configurations outside the U.S. lineup. With an import, the donor model and head identification are more useful than a seller’s “JDM K24” headline.
K24Z and K24W: the story keeps moving
The K24Z7 brought 2.4-liter power to the ninth-generation Civic Si. Honda’s 2012 Canadian Civic brochure lists 201 hp and 170 lb-ft for the Si. The larger engine gave that generation its own identity within a model line closely associated with high-revving 2.0-liter engines.
For swaps, the Z-series needs its own plan. Exhaust layouts and other hardware differ by application, so an early K24A header-and-mount recipe isn’t a shopping list for every later engine.
The K24W moved further toward efficiency with Earth Dreams technology. Honda introduced direct injection for the U.S. 2013 Accord’s 2.4-liter engine, adding high-pressure fueling and a newer control system. That branch belongs in the K24 family tree, while the earlier port-injected engines remain the focus of the swap paths discussed here.
K24 tuning: from bolt-ons to an all-motor build
A naturally aspirated K24 has an appeal that’s easy to understand: throttle response, an induction note that changes as the revs climb, and power delivered without waiting for boost. There is room to enjoy that character before opening the engine.
An intake, a suitable exhaust header and exhaust system, and calibration are the familiar first steps on a K24A2. The aim is to improve breathing and make the fuel, ignition, cam timing, and VTEC crossover work with the hardware. Hondata’s TSX testing is a useful example because it shows how gains within the rev range can matter more than the change in peak horsepower.
Beyond bolt-ons, the project becomes a combination of camshafts, valve springs, compression, head work, and intake design. Individual throttle bodies can become part of that plan, bringing their own induction character and packaging demands. Runner dimensions and calibration shape the powerband, making them part of the same decision as the cams and cylinder head.
The K20/K24 “Frankenstein” engine
The classic hybrid uses a K24A block with a selected K20 cylinder head, often a performance version such as the K20A2. Hybrid Racing’s build guide documents this early-engine route. Its appeal is the combination of larger displacement with a head and valvetrain chosen for the intended airflow and rpm range.
A healthy K24A2 head can also remain part of a performance build, saving the cost of another head when it suits the target. Once different heads, pistons, and cams enter the picture, piston-to-valve clearance, compression ratio, and cam travel have to be worked out for that exact assembly.
That includes the much-discussed VTC gear and oil-pump conversions. More available cam advance gives the tuner another tool, but usable advance is limited by mechanical clearance. A K20 oil-pump conversion likewise involves the matching installation hardware and engine preparation. These changes belong in the engine build plan, alongside the sump and oil control needed for sustained cornering.
How much horsepower can a K24 make?
Factory ratings around 160-205 hp describe the examples above. Modified output spans a much wider range, but the useful number comes with a parts list and a measurement method.
For a concrete example of the all-motor end, 4 Piston Racing advertises its K24-K340 engine at 340 hp. Its listed combination includes forged rods and pistons, 12.5:1 compression, a CNC-machined cylinder head, aftermarket cams, and an upgraded oiling package. That’s a builder’s advertised complete-engine figure, not a ThinkTuning test or a promise of wheel horsepower from bolt-ons.
It also shows how far the idea has traveled from a donor engine. A complete performance crate engine buys a developed combination; a salvage-yard long block buys a starting point. Comparing their prices without comparing what’s inside misses most of the story.
Turbocharging and supercharging the K24
Boost opens another route: keeping the displacement and feeding the engine more air than atmospheric pressure alone can supply. A turbocharger offers considerable freedom to shape the power target through turbo sizing and boost control. A supercharger offers a belt-driven alternative, with delivery that depends on the type of compressor and its drive ratio.
Either way, the build expands beyond the engine itself. Injectors and fuel supply must match the fuel and airflow demand; charge cooling and calibration manage the conditions inside the cylinders. As torque rises, the clutch, gearbox, and traction become part of the result you can actually use.
There isn’t one defensible “safe stock-internal horsepower” number for every K24. Engine version, fuel, torque curve, knock control, and how long the engine spends under load all affect the risk. A drag pass, a dyno pull, and repeated circuit sessions ask different things of the same parts.
For a substantial boost build, forged rods and pistons let the builder choose strength and compression deliberately. More demanding combinations can extend to cylinder sleeves and further block work. Set the target around the car’s job, then build the engine and drivetrain together.
Reflashed Honda ECU or standalone?
Engine management helped make all these combinations practical. Hondata K-Pro, supported factory-ECU reflashes, and standalone systems provide different routes, with compatibility determined by the ECU, engine, and chassis.
A supported factory ECU can suit a Honda street car or an appropriately wired swap. Hondata’s K-series swap guidance explains why the wiring must match the ECU architecture. A standalone becomes appealing when the car needs custom integration, extra sensors, or motorsport functions. Choose the control system before the harness so the finished car’s electronics work as one package.
How the K24 escaped the Honda engine bay
Older Civics and Integras give the K24 an obvious home: a light chassis, an established Honda swap community, and plenty of reasons to want more displacement. Rear-wheel-drive conversions take the same appeal somewhere different. KPower’s installation library documents K24 projects for Miatas as well as the BRZ/FR-S/86 platform.
This is the part of the story that makes a commuter engine interesting even to people who have never wanted an Accord. Turn it longitudinally, solve the transmission and sump packaging, and the K24 becomes an option for a completely different kind of car.
The hardware outside the long block explains much of a swap’s cost: mounts, oil pan, transmission adaptation, exhaust, cooling, wiring, and working chassis electronics. A supported conversion gathers many of those answers into a package. A one-off build leaves more of them to the fabricator.
The K24 also gets compared with an LS V8 for rear-wheel-drive projects. The appeal is different: the LS brings much greater displacement, while the K24 preserves the character of a smaller four-cylinder and offers both naturally aspirated and boosted build paths. Chassis support and the desired torque delivery make a more useful comparison than a universal claim that one swap is cheaper.
Yes, K24-swapped Subarus are part of the story
The BRZ is the clearest Subaru connection. KPower documented its first-generation BRZ/FR-S/86 conversion development in 2021, following work on its own shop vehicles. Its development story covers the mechanical package and integration of functions such as the gauges and air conditioning. It’s a concrete example of the K24 moving into a Subaru-developed sports-car platform.
For a BRZ enthusiast, the attraction is keeping the rear-wheel-drive coupe while giving it Honda engine character and access to K-series build options. The swap replaces the original flat-four with an inline-four, so packaging and electronics are central to the conversion. Our Subaru FA20 guide covers the engine the first-generation car started with.
That BRZ example is specific to the rear-wheel-drive platform. An all-wheel-drive Impreza or WRX brings a different transmission and front-driveline layout into the project, so the BRZ conversion doesn’t establish a ready-made route for those cars.
K24 reliability: the less glamorous part of the appeal
The K24’s everyday origins remain relevant long after the first swap. Factory engines were designed to start in traffic, idle with accessories running, and cover ordinary road miles. A lightly modified build can preserve much of that usability. As rpm, cylinder pressure, and track loads rise, the oiling, cooling, and internal hardware need to follow.
There are documented factory concerns worth knowing. Honda’s 2012 revision of bulletin 09-010 identifies a defective VTC actuator as the cause of an approximately two-second cold-start rattle on 2008 four-cylinder Accords and specified 2009 Accord VIN ranges. A persistent rattle outside that start-up pattern needs its own diagnosis.
Oil consumption has its own application-specific history. A Honda CR-V product-update notice describes how cold-start injector and VTC timing could contribute to deposits on oil-control rings. It is a different issue from the Accord actuator rattle, with a different cause and service response.
For a used engine, a true cold start, evidence of oil consumption, and compression or leakdown results tell a more useful story than a mileage boast. With a modified K24, add the build sheet and calibration history. Those few details can separate a promising next project from somebody else’s unfinished experiment.
Why the K24 still gets enthusiasts planning
The K24’s appeal is the distance between where it started and where it can go. An engine intended for a family Honda can become the centerpiece of a light Civic, an all-motor build, or a Subaru coupe with an unexpected voice under the hood.
For a mostly factory naturally aspirated project, start by looking at the K24A2. For a build that replaces the internals, compare the cost of the completed combination. And for a non-Honda swap, find the transmission, packaging, and electronics solution before buying the engine.
Honda gave the K24 a place in the family car. The next engine bay is up to you.