Honda brought the K24A to life in 2002, about one year after the launch of the K20A. The reason they developed the K24 was to use it in their larger vehicles because the only real downside to the K20A was the lack of low-end torque. So, they took the K20A design and simply made it bigger, because bigger engines are going to make more torque and at the time Honda wasn’t really making turbocharged engines, so the only option was to just increase displacement.
The K24 engine from Honda is last in the K-Series. Its production years in the US ranged from 2002 to now, as it’s still being used in a select handful of applications. As with many of the company’s engines, it has a reputation for running smoothly and efficiently for a long time. In fact, cars equipped with these engines can easily reach six digits on the odometer, surpassing other brands for reliability and performance.
Honda K24: Cylinder Head
As with any engine family, there are changes from one variant to another. While the Honda K24 is pretty consistent across all models, there are a few major changes in the cylinder heads. To put it simply, there are two main types of cylinder heads you’ll find on any K24: the TSX Type S head and the CRV head.
Without getting into too much detail the TSX Type S has a way better head design and flows much better than the CRV/Accord/Element heads. The major improvements on the A2/A3 TSX/Accord head include the larger intake valves and a more aggressive intake cam. What’s particularly interesting about K24 heads is the different kinds of VTEC honda used for different variants.
Basically, there are two kinds of iVTEC: one for economy driving and one for performance, both of which combine VTEC and VTC. The VTEC part of the system has two different camshaft profiles, one for low RPMs, and one for high RPM. The VTC part of the system allows valve overlap to be adjusted at any moment, resulting in much greater efficiency and slightly better performance.
The performance version of iVTEC uses VTEC and VTC, whereas the economy version of iVTEC combines VTEC-E and VTC. To make this really easy to understand, the A1, A4, and A8 variants of the K24 use the economy version of iVTEC and the A2 and A3 variants use the performance version of iVTEC.
- Cast aluminum
- DOHC – 4V per cylinder
- iVTEC / VTC
Honda K24: Bottom End
On the bottom end, the K24 is very similar to its smaller brother, the K20. The big difference between the two is the difference in displacement. The K24 uses an 87mm bore and 99mm stroke, which is quite a bit under square. Typically with under square engines, you’re gaining low-end power but sacrificing max RPM speed and peak power. This is true with the K24A in stock form, where the redline is limited to 6500rpm to 7600rpm depending on the specific variant.
Of course, with some minor modifications and tuning you can get a K24A rev over 8k RPM, but in totally stock form that’s not the case. One of the inherent problems with all four-cylinder engines is vibration, but this problem can be quite a bit worse for larger four-cylinder engines like the K24. For this reason, the K24 uses balance shafts. Well, technically not all K24 variants use balance shafts, and eliminating them is something most tuners do, especially if your plan is to your engine at higher RPM for extended periods of time, such as on a track.
The rods are 152mm in length and depending on the K24 you’re looking at, they’re a bit on the weak side. You can definitely use the stock rods in a boosted application, but don’t expect to get some insane power figure before they break. A lot of people are finding the limits of the stock rods to be around 300whp. They have a 9.6 to 10.5:1 compression depending on the variant.
One of the problems that come up when boosting a K24 is the thickness of the stock sleeves and to put it simply, the OEM sleeves are pretty thin and typically don’t play nice with forged pistons. This is why you’ll see many boosted K24s run stock pistons because running forged pistons is much more likely to end up with a cracked cylinder sleeve.
For those of you who want to make crazy amounts of power, aftermarket sleeves are a must-have modification, because the stock sleeves just aren’t that strong. There are people who have pushed the stock sleeves upwards of 700whp, but if you want a long-term reliable high-horsepower K24, you’re going to have to replace the OEM sleeves.
That brings us to the deck, where the K24 uses an open deck design. As we’ve discussed in other videos, open deck blocks are typically weaker than closed deck blocks, but there are ways to fix that issue. Really, the open deck on the K24 isn’t going to be much of an issue until you’re talking about forced induction where power levels are 3 to 5x higher than stock.
Honda K24: Applications
While Honda offers a wide range of vehicles, the K24 was really meant for its larger sedans and smaller SUVs. It was meant to provide more torque than the K20 and help push around heavier applications, however, you can The 24-series engines are found in the following vehicles:
- Odyssey Absolute
Honda K24: Common Problems
Despite the fact that this engine is tough and long-lasting, it is not without problems. One main component of the engine that can fail is the timing chain sensor.
The problem started to develop when the company switched timing belts to connect the crankshafts with the camshafts. Closing the gap of the piston by bringing it closer to the chain by a single tooth is the easiest solution to the problem, but it might not be a permanent solution.
Other issues with this engine include that the camshaft can wear out easily and the idle is sometimes rough. Leaking engine oil has also been reported, which makes keeping up with regular oil changes essential to maintaining the proper health of the Honda K24.
Some owners have also noted hearing engine noise upon starting the car, which can signal a deterioration (and necessitate replacement) for the engine’s VTC gear.
Honda K24: Basic Specs
- Production years: 2002
- Power output: 160 HP
- Torque: 162 LB-FT
- Redline: 6,500 RPM
- Compression ratio: 9.6:1
- Block deck height: 231.55 mm
- Production years: 2002-2008
- Power output: 197-205 HP
- Torque: 171-164 LB-FT
- Redline: 7,100 RPM
- Compression ratio: 10.5:1
- Production years: 2003-2007
- Power output: 197 HP
- Torque: 171 LB-FT
- Redline: 7,200 RPM
- Compression ratio: 10.5:1
- Production years: 2003-2006
- Power output: 160 HP
- Torque: 161 LB-FT
- Redline: 6,800 RPM
- Compression ratio: 9.7:1
- Production years: 2006-2014
- Power output: 166-180 HP
- Torque: 160-161 HP
- Redline: 6,800 RPM
- Compression ratio: 9.7:1-10.5:1
Honda K24: Tuning Potential
The stock power output for the engine can reach 205 HP. With the addition of a turbocharger that power increases to 400HP+. Other performance parts can increase the engine’s power potential to the upper 200s and even 300 HP.
Of course, many vehicles equipped with a K24 engine stick with a naturally aspirated engine setup. For N/A vehicles, an intake, full exhaust, throttle body, and quality tune can push the engine to near 300whp.
Another recommendation for modification is replacing the head of the K24 with that of the K20. The advantage of using the K20’s head is that it is built better than the one in the Honda K24.
It also has higher-quality valve springs and camshafts. Modification recommendations include replacing the K24’s water pump with a K20 water pump to accommodate the new oil cooler and coolant fluid.
Honda K20 vs K24: Which is Better?
Production of the K20 engine precedes that of the K24. Overall, the K20-series engines are simpler and less expensive to replace. They also generally have fewer problems.
The transmissions of the K20 series are better than those in the K24 family. However, K24-series engines have a larger capacity of 2.4L and provide more torque. They are easy to modify and are a great platform for enhancing sports cars, notably the Formula 3 series.
The K24-family engines are easier to modify than the K20-series and respond better to modifications. Since the K24 engines have camshafts that lack a high lift, they are better for street racing instead of regular driving when tuned.
As a whole, they are better in stock form than the K20 series when tuned.
Most components can be swapped out between engines. However, there are parts that cannot be interchanged between the two engines:
- Timing chain and timing chain cover
- Head gasket
Both the K20 and K24 have strengths in stock form. The K20 has slightly fewer problems, a better timing chain, and more displacement. However, the K24 offers good power output.
It is a larger engine and has more torque, too. The K24 is also easier and less expensive to tune.
There are a number of tuning mechanisms available for the K20, however, and it is a more common engine with more readily available parts.