Of all the import vehicles and engine platforms out there today, no other brand can claim the import throne like Honda. The market for Honda is huge and the availability of their vehicles and engines has spread across the globe. In addition to being widespread, Honda engines are generally a cheaper option than many others and the aftermarket support for Honda has always been massive. There’s seemingly an endless supply of Honda cars and engines. Related Articles - A Twin-Turbo LT7 Engine Earmarks the New 2025 ZR1 Corvette - Volvo Penta’s D17 Industrial Engine - A Different Dyno Design
Most people don’t have the budget to buy a performance car and then dump another small fortune into modifying it for racing. A lot of people opt for buying entry-level, four-cylinder cars and then put money into making those vehicles race cars. gb t12221 valve china
That’s Honda’s stronghold on the market and its K-series engines (K20, K24 and the newer K20C1) stand out when it comes to building performance vehicles. We spoke with a few engine builders about these engines in terms of rebuilding them, making more horsepower and why they have ruled the import crowd for so long.
First things first, we are living in a day and age where engine builders are frequently asked to provide power levels that would have been considered extreme even just a decade ago. The age of the turbocharger is upon us and it has allowed the average racer to look for big power levels out of something they want to drive around town. As an engine builder, you know the questions you need to ask your customers, and some of the answers you get in return are unrealistic.
For instance, what is more important to you? Getting the absolute most power production from an engine living on the edge, or having some reliability to get you through a season or more? The answer to that question is often, “Yes, I’d like the most power possible and for it to be reliable.”
What rpm range is more important for us to optimize? Off corner acceleration from 4,000-6,000 rpm or the top end from 7,000-9,500 rpm? The answer is, “Yes, I’d like both of those, and if it’s not too much I’d like to run 11,000 rpm.”
That isn’t every customer’s expectations, but it is familiar to us all to have to bring a customer back down a couple notches to get them into a package that is going to win races. Engine building is often a challenge of figuring out what should be done over what could be done. These Honda K-series engines have become a motorsport staple due to their performance and aftermarket support. They are readily available and can produce big power per cubic inch without the aid of forced induction. In short, the Honda K-series is an engine builder’s playground.
These engines are common for various types of road racing, endurance events and even simple club track days. In all of those scenarios, longevity is a huge focus, and of course, everyone wants to stand on the podium at the end of the weekend.
First introduced in 2001, the Honda K-series engine is a four-cylinder, four-stroke engine that replaced Honda’s B series. The K-series engines are equipped with DOHC valvetrains and use roller rockers to reduce friction. The engines use a coil-on-plug, distributor-less ignition system with a coil for each spark plug. This system forgoes the use of a conventional distributor-based ignition timing system in favor of a computer-controlled system that allows the ECU to control ignition timing based on various sensor inputs. The cylinders have cast iron sleeves similar to the B-series engines.
Also like the B series, the K-series engines have two short blocks with the same design – a 2.0L and 2.4L variant. The K20-based engines are 86mm stroke x 86mm bore in an 8.350” deck height, and the K24-based engines are a 99mm stroke x 87mm bore in a 9.114” deck height.
Two versions of the Honda VTEC system can be found on K-series engines, and both versions can come with variable timing control (VTC) on the intake cam. The VTEC system on engines like the K20A3 only operate on the intake cam – at low rpm only one intake valve is fully opened, the other opening just slightly to create a swirl effect in the combustion chamber for improved fuel atomization. At high rpm, both intake valves open fully to improve engine breathing. In engines such as the K20A2 found in the Acura RSX Type-S, the VTEC system operates on both the intake and exhaust valves, allowing both to benefit from multiple cam profiles.
The Honda B and K-series engines are the two main Honda platforms for performance. As time has gone on, it’s started to push more in favor of the K series. That’s because the B series engines obviously aren’t in production anymore and they’re starting to become a little more scarce and harder to get ahold of.
According to many Honda engine builders, the K-series engines are pretty solid overall. The upgrades needed for high horsepower with this platform are primarily around connecting rods and pistons when it comes to the bottom end. Additionally, their sleeves are a little thicker, so they’re a little stronger in the block as well.
To beef up something like the K20 engine block, machine it and outfit it with new ductile iron sleeves. While the primary function is to allow builders to run different bore sizes for more displacement, it also provides a much more rigid cylinder that will last longer and take more abuse. There are a dozen companies that make sleeves for these engines and they all work. They all have different hardness, thickness and installation techniques. Try to use a thick sleeve for added rigidity.
A harder sleeve will help keep great ring seal over time as the engine ages. The kind of engine speeds seen on these engines is really hard on the cylinders, amongst other things. The sleeve design, material and installation becomes a critical point in engine longevity.
Depending on your application, a billet crankshaft could add value to the rotating assembly as well. However, Honda’s forged cranks are absolutely bulletproof and there are quite a few options for different strokes. Most of these are out of production, so in many cases engine builders will rely on aftermarket billet crankshafts. The billets give you a new crankshaft and more flexibility in sizing your engine, but they are in no way as strong as an OEM forged crank.
In speaking with engine builders familiar with the K-series engines, most have never seen a broken forged Honda crankshaft, even at 2,000+ horsepower. Everything around it can break, but it never starts at the crank.
The billets are not so forgiving. They are a little lighter, which rarely shows up on the dyno or in car acceleration data, but there are some really nice offerings available. You need to choose the application carefully because 7,500 rpm clutch drops, high rpm inline 4 harmonics, and massive vibrations and tire shake can take them out in a bad way.
The pistons in K-series engines are an area you’ll want to upgrade if desiring more horsepower. Many engine builders opt for a lightweight forging that balances strength and performance. Going with a custom piston allows you to move ring locations and sizes, change the skirt profile, and reshape the struts to provide more support around the wrist pin. You can opt to have pistons made in billet or from forgings. One thing to consider in your piston design is to ensure it doesn’t have a massive dome in an effort to promote efficient combustion and to also help keep the weight down.
If you upgrade the piston, you might as well also upgrade to a tool steel pin that is still lightweight, but strong enough to handle the stresses of a racing environment.
Connecting the dots between that piston and the crankshaft should be an upgraded connecting rod as well. In the Honda market, something like a Saenz 4340 I-beam connecting rod does the trick quite well, but there are plenty of options for a great rod that’ll handle horsepower.
While the bottom end is fairly stout, some of the valvetrain components of the K-series engines need to be upgraded in high-performance applications because these engines are often being pushed to 10,000-11,000 rpm. They were never designed to hold that in stock form, so upgrading the valvetrain is usually one of the first things you want to do.
The top end of this engine is what really dictates the power and behavior of the engine, and serious decisions have to be made with the variety of configurations that are available in the Honda platform. The question of “What rpm range would you like to focus on?” is a major contributor, and the answer people like to give you back isn’t practical. Honda uses the famous VTEC variable lift system in these engines to accommodate that desire for low end and high-end power. It provides the small docile camshaft lobe for idle and low engine speed below 6,000 rpm, then through a series of rocker pins and oil pressure provided by a solenoid valve, it switches you to a high lift race cam profile. It made Honda famous and it offers some amazing sounds and great power curves. It does, however, have its limitations.
The VTEC system has some substantial weight to it, so you really need to think about getting rid of it for engines that will see over 10,000 rpm. Can you run it there? Yes, but for how long? The considerations to move to a lighter rocker arm and dedicated race camshaft profile start to become more relevant as we approach 10,000 rpm. Using the VTEC assembly above 10,000 can be done for bursts and occasional trips into that realm, but long straightaways and extended time can fatigue the rockers and cause some valvetrain instability that not only cost you power, but fatigue the valvetrain components prematurely.
Additionally, these engines have variable cam timing allowing you to adjust the camshaft centerline. In a racing engine with larger camshaft lobes and often larger valves, you do not have the luxury of using that full range without valve contact, plus you don’t need it anyway. It is a place where DIY builders and tuners make their fatal mistakes, advancing the intake camshaft beyond what they have physical clearances to do. In a basic engine with restricted induction and exhaust, these engines will prefer a lot of camshaft advance. Once you optimize the engine and have it breathing properly, it will not want the same type of camshaft advance. In most cases, the engine will make the best power in the 103-110 centerline range, and that will vary as it sweeps through the usable rpm range.
That system is attractive and has become commonplace in all modern engines, but it too has its deficiencies in a pure racing engine. It is a heavy system and the more rpm you turn, the more valve spring pressure you have to run to control the valve. That extra valve spring pressure is hard on the variable camshaft hardware and can fail. You may have an ECU that can warn you of its failure to reach target, but as it resorts to a position of zero you will notice 30-40 hp go away and a noticeable ticking sound at idle. If you have worked on variable camshaft timing vehicles from any manufacturer, you know the sound of a failed variable cam gear. It doesn’t do you much good to know about it in the middle of the race, you simply lose power and play hard on the timing chain and valvetrain. The question to the customer of desired rpm range comes back, and you have to make decisions.
The OEM Honda cylinder head casting is a solid platform to work off of for most applications. It’s merely a balancing act of matching the port size and air speed to the type of driving, fuel and rpm range you need to work within.
The exhaust ports on these cylinder heads are already very large, so you do not want to go crazy in just opening them up just for the sake of opening them. Instead, you’ll want to straighten the walls out to improve cfm, but take as little material as possible. It makes for what some would consider an odd looking, but very effective exhaust port. Clamp the head back on the block using an upgraded ARP head stud to provide huge improvements in clamping force.
The camshaft choice is one that has to be made carefully. It is easy to fall into the trap of wanting to see peak dyno numbers that are pleasing to the eye, but you really have to look at the entire rpm range and what will play nice with the valve spring and other valvetrain components.
More often than not, the valve spring in these engines is not up to the task. For many years, the offerings on the market simply were not stiff enough to control the valve weight and rpm range where consumers were running the engines. Lightweight beehive springs were popular at that time, and you’d see lots of valve-related failures as they couldn’t control the valve. That has changed in the past 10 years, and we’ve seen the standard market offerings improve.
Normally, you’d like to have more spring pressure than required rather than not enough, but given the use of the variable cam timing in this engine, it does narrow the window that you are allowed to work in. Just as important as the spring pressure is the wire purity of that spring and how nicely it fits with the spring seat, retainer and valve lock. This is all critical to controlling the valve motion, which you will see right away in regards to power, and later down the road in regards to service life. In these engines, you can have 6-8 hp variances in a valve spring alone, all other things being equal.
If you opt for upgraded valves, you’ll also want to look at the valve seats. In many applications, this engine gets a pretty standard 45-degree seat for longevity purposes and to make sure it is easily serviceable with off-the-shelf valvetrain components.
The timing chain system is an Achilles heel in these engines, so some engine builders bulletproof them by replacing the two-piece OEM chain guides with a one-piece guide. The guide has deep channels to direct the chain and the shape is changed for a smoother motion and to eliminate areas where slack can form. You can run them for many seasons and they look as if they were not operated when you take the engine apart. The chain and tensioner see limited wear with these guides in place, as opposed to an OEM guide that will stretch and eventually come apart, requiring frequent chain and tensioner service.
Streetwise, a lot of guys usually shoot for 500 horsepower, which is super easy with K-series Honda engines. Built up, they’re similar to the B series and guys are making anywhere from 900-1,400 horsepower, but 2,000+ horsepower is also possible. To accomplish that, you’ll be using a turbo application, which the K series is great for. But, where the K series really shines is if you’re considering an all-motor application. Either way, the K series has effectively taken over where the B series left off. Civic Type R (K20C1 Engine)
One of those newer K-series engines is the K20C1 seen in the new Civic Type R. There’s real potential behind this powerplant and many engine builders in the Honda space have been putting resources into its further development.
While the familiar “K” remains in this new engine’s name, these engines are not merely an evolution, but rather a completely new design. They’re pretty big engines from the factory, capable of bending rods at 400 horsepower, which is unlike Hondas in the past. It’s the Honda engine that builders will be working with for the next 20 years.
The K20C1 is a direct injected, turbocharged, 2.0L engine that produces 306 hp and 295 lb.-ft. of torque from the factory. This engine is not only being utilized in on-road Honda Civics, but also purpose-built racecars, including F4 and F3 feeder series for the climb to IndyCar, British Touring car, IMSA, and many other forms of endurance racing.
Engine builders are making the K20C1 engine stronger and setting them up for higher output. The stock turbo can produce 400 lb.-ft. of torque at low rpm and over 400 hp. Two of the differences between the Civic Type R engine and Honda engines of the past are direct injection and a tumble port design in the cylinder head.
Honda’s of the past 20 years have flown 300 cfm. This engine’s head flows 150-160 cfm, but it’s a tumble port design, so it’s got a big sharp point right before the valve – like the EcoBoost – to create tumble so they can get an efficient fuel burn in the chamber. However, that really kills flow. One thing Honda did differently is they gave this head a large race port where the EcoBoost and some of these other engines are tiny, little ports going into a little sheer before the valve to tumble the air.
To get the cylinder head of a K20C1 setup to handle increased horsepower, builders will remove some of the tumble port design for fuel economy and to increase airflow by 140 cfm without drastically increasing the port volume. This brings the power in a couple hundred rpm sooner and allows for around 20 hp in gains on the stock turbo, but at lower boost pressure.
They will also relieve some of the back pressure with the exhaust port, which becomes important when upgrading to larger turbos that will exceed 600 horsepower. Exhaust Gas Temperature (EGT) can be pretty high in these as well with the way they are being used in endurance racing, and that is something that needs to be controlled to get the engines to last. It’s advised to replace the stock valves with Ferrea Competition Plus Super Alloy valves to handle the extra exhaust heat, and use a higher pressure PAC valve spring and titanium retainer for rpm use over the factory head, which runs out of steam before 7,000 rpm.
According to many engine builders, the market interested in these engines is going to be really, really excited about 400 horsepower, but most builders aren’t stopping there. Instead, they are adding a MoTeC ECU to the stock car and turning it up. This makes it easy to add 120 horsepower without touching any part of the car, other than putting a computer in it and about 30 percent ethanol in it. It’ll also deliver well over 400 ft.-lbs. of torque.
The K20C1 engine also has an offset crank in relation to the bore so that the piston is straight up and down when it’s on a power stroke. For this reason, and to protect against the environment that comes from added horsepower, engine builders will replace the rather fragile OEM connecting rod with something stronger such as a Saenz I-beam rod that is rated at over 800 hp. These upgraded rods are also lighter than the OEM rod.
The stock pistons are also replaced by upgraded aftermarket options such as a JE forged piston, which has a thicker top, thicker pin boss area and a tool steel wrist pin. Many engine builders will also offer replacing the OEM sleeve with a ductile iron sleeve for larger bore size and use an o-ring for additional cylinder sealing. The goal is designing the engine to be able to handle about 800 horsepower, even if the engine never sees all of it.
Designing an engine for a specific purpose can be a big challenge and one of the most rewarding pieces of the profession. Just as important as it is to maximize the potential of the engine on the dyno, you really have to recognize the component of engine building that is understanding the customer and what their true needs and desires are. What is going bring them back? What is going to make them happy enough to tell their story? When it comes to the K-series Honda engine, there are people out there willing to race hard and put trophies on the shelf at any cost and through any adversity, but there are a lot more who want to enjoy the whole process with as few bumps in the road as possible. Recognizing those customers and knowing when to pull the reins is what will add value to your name and give you staying power in the racing industry. EB
Many of the biggest names in motorsports have built and used the 2JZ in their own racing machines, proving that the engine platform can be competitive in various formats.
When it comes to iconic import engines in the automotive world, few can match the reputation and cult following of Toyota’s 2JZ. Originally introduced in the early 1990s as part of the Toyota Supra’s fourth generation, this inline-six engine quickly became a legend thanks to its impressive power output, bulletproof reliability and potential for modification.
In today’s world of supply chain disruptions, it is a big benefit to be able to source an entire engine system and not have to wait for that last back-ordered component to arrive.
They’re the pinnacle of drag racing, and the engine builders, crew chiefs and teams who make these cars function at peak performance all season long are looking at every single area of the engine and the car to make it down the track as fast as possible.
Find out what it takes to build a formidable marine engine.
One of the most important aspects of engine building has nothing to do with the engine at all. You have to understand the customer and what they are trying to achieve.
Take your Honda B series engine to another level with Plazmaman’s billet intake manifold featuring either four or eight injector options.
Check out the B18c BoostLine Connecting Rods for power adder Honda applications. These are 1,000+ hp capable.
As we’ve mentioned in other Sick Week interviews, there aren’t tons of import cars at the annual drag-and-drive event in Florida, so when we see something like RC Flint’s Honda S2000, we take notice. Upon further investigation, RC opted to forgo the 4-cylinder for a 414 cid L8T engine, and we got the full scoop
Following a fire with his Honda S2000 in December 2023, RC Flint spent five weeks in a mad dash to get his turbocharged L8T engine and the car back together in time for Sick Week 2024. Even with the setback, the S2000 had lofty goals. Check it out!
din 3356 globe valve Content for engine professionals and enthusiasts