The Guide to the Honda K20 Supercharger Kit. The Honda K20 4-cylinder engine is one of the most well-known engines ever produced. It’s simple to see why, because Honda truly condensed the greatest components of their prior engines into a single, powerful package. Aside from the use of performance VTEC on a variety of K20 engine variants, each variant is also extremely resilient and can withstand an insane amount of power in comparison to its factory output. The K20 is well-known for its high-strung personality and capacity to rev to the moon and back. The K20 DOHC 4-Cylinder engine is so good that it is one of the most popular engine swap options aside from the legendary Chevy LS.
While the K20 is a fantastic engine out of the box, most people find that they want more power. This is where forced induction comes into play. The K20 is well-known for its ability to withstand a lot of boost and abuse. While some 2.0L K20 owners prefer turbochargers, others prefer superchargers for a more even and predictable power and torque curve. With only minor modifications, supercharged K20s may easily exceed the 300-horsepower mark.
In this post, we’ll go through what it takes to create your own supercharged K20. Some K20 engine variants handle superchargers better than others. However, the overall procedure is the same for all K20 variants.
What kind of power can a supercharged K20 handle?
The Honda 2.0L 4-Cylinder’s ability to tank boost is one of its most enticing features. While that may appear to be an exaggeration, it is true. In fact, most K20 models can reliably handle at least triple their factory horsepower figure. With the addition of forced induction from a supercharger, a K20 can comfortably run anywhere between 320 and 350 horsepower with outstanding reliability and stock internals. There are no upgrades necessary.
Of course, there are other factors that influence the peak horsepower statistic for a K20. While thinking about the absolute horsepower limit is always entertaining, that figure is only useful if the engine doesn’t blow up on the first drive. Perhaps the most important factor is the K20 supercharger tune you use. The piston ring lands, like most other cars, do not respond well to detonation, which is one of the K20’s key dependability flaws. That being said, if you intend to push a lot of power, you should consider a safe tune and fueling mods. You’ll almost probably need to improve your K20’s bottom end with forged internals if your power objectives are in the 370-500 horsepower area.
Turbo vs Supercharger on the Honda 2.0L 4-Cylinder
When it comes to forced induction on a K20, most folks are torn between a K20 turbo system and a supercharged K20 setup. While each method has advantages, supercharging a Honda 2.0L 4-cylinder is more cost-effective and easier to install. While supercharging may be the best option if cost and ease of installation are important, turbo K20 engines produce more power with slightly less boost.
The form of the power band is one of the most notable differences between the two types of K20 forced induction. Of course, with a K20 turbocharger, power will peak at a rev range that corresponds to the spool time of the turbo. Although smaller K20 turbos will reduce lag, there will still be a delay. Because K20 superchargers are belt driven, there is no power delivery delay. A supercharged K20 engine will generate power much more linearly than a turbocharged K20 engine. Some individuals love the anticipation of a turbocharger, while others prefer the predictability of a supercharger. It everything comes down to personal taste.
Aside from power delivery differences, there is also a power ceiling in terms of how much performance a K20 supercharger can produce. Most members of the K20 community believe that 400 horsepower is close to the highest amount of power that a supercharged K20 can produce. In comparison, turbocharged K20s with considerable modifications can produce close to four-digit horsepower. Price, power supply, and convenience of installation are all important factors to consider when selecting which path is best for you.
Supercharging the 2.0L Honda K20 Engine
Honda introduced the 2.0L 4-cylinder in four different variants with over 20 different sub-variants during the K20’s production. The most common K20 variations are the K20A, K20B, K20C, and K20Z. While all of the variants have a very similar overall construction, there are a few key differences that can affect supercharged K20 performance.
Compression ratios, for example, change widely amongst K20 variations and even within their own subvariants. Lower compression is often preferable for supercharged K20 applications since it reduces the possibility of internal detonation. Higher compression, on the other hand, is generally preferred for increased horsepower. Flow characteristics differ greatly amongst K20 variations as well, with some K20 cylinder heads having higher flow values than others.
Not all K20 models include performance VTEC. “Performance VTEC” refers to Honda’s variable valve timing technology, which operates on both the intake and exhaust sides of the engine. While some K20 variants have VTEC performance, others only have VTEC on the intake cam. The combination of performance VTEC and supercharger will undoubtedly deliver the optimum performance. However, you must use the correct cylinder head for it.
Finally, all of these factors are directly related to their cylinder head. Because the bottom end of each K20 variant is identical, you can swap in a cylinder head from a more desirable K20 engine to improve performance. The improved 2.4L Honda K24 engine’s cylinder heads can easily be placed onto a K20 bottom end.
K20A2 supercharged / K20Z1 supercharged
While any of the 2.0L engines can be supercharged, the K20A2 is arguably the best to supercharge right out of the gate due to its widespread availability in the US, use of performance VTEC, and high-flowing cylinder head. While the JDM K20A is the holy grail of the K20 engine family, finding one in the United States can be difficult. The K20A2 engine is the closest thing to the high-performance K20A engine available in the United States.
You may however argue that the K20A2 is the superior option in any case because to its lower compression ratio of 11.0:1. The Honda K20A2 engine is used in Acura RSX Type S vehicles sold in the United States. Because of its widespread availability, the K20A2 engine is a relatively inexpensive engine to obtain. If you own another K20 version, such as a K20A3, you may easily switch a K20A2 head onto the bottom end.
When it comes to the best K20 variation to supercharge, the K20Z1 is a close second. The Z1 engine is nearly comparable to the K20A2 seen in the previous Acura RSX Type S; the K20Z1 merely has somewhat more aggressive cams. The variation in cams is responsible for the 10 horsepower difference between the A2 and Z1. Overall, the K20Z1 may be the more gratifying supercharged engine. They are, however, frequently substantially more expensive to purchase than a Honda K20A2 engine.
Considerations for the Supercharged K20 Engine
When it comes to forced induction, the Honda K20 engine is rather simple when compared to many other engines. While some engines require a complete internal rebuild before a sustainable supercharger build can be obtained, the K20 can be left alone for the most part. In many ways, supercharging a Honda K20 is by far the most straightforward route to forced induction. The majority of the suggestions for a supercharged K20 build focus around exhaust modifications to assist the 2.0L 4-cylinder engine breathe better under load. Even so, the alterations aren’t necessary.
Honda K20 Supercharged Exhaust Modifications
Headers and a corresponding exhaust are two of the most typical modifications recommended to K20 owners wishing to supercharge their Honda. The exhaust manifold houses the majority of the exhaust restrictions found on K20-equipped Hondas and Acuras. When combined with forced induction, K20 headers designed to boost exhaust flow and increase exhaust pulse velocity can be game changers.
In the supercharged K-series community, 4-2-1 headers are the most popular option. That simply means that four primary tubes are combined into two central tubes, which are then combined into a single collector. 4-1 headers appear to be less popular. However, if top-end power is your primary concern, they may be the better choice. On a naturally aspirated engine, headers could result in a 15-20 horsepower increase. When combined with a supercharger, they can provide 20-25 horsepower.
Similarly, as backpressure may rob horsepower and impair performance, a less restrictive exhaust system can considerably improve the performance of your supercharged K20. While there is some debate about the best diameter exhaust to pair with a supercharged K-series, most people settle on 2.5″ or 3.” As long as the engine can breathe better than it did with the stock exhaust, either size should work fine.
Transmission modifications are a key consideration in addition to exhaust enhancements. K-series transmissions are generally rather tough and can sustain a significant amount of abuse. In most cases, a K-series gearbox breakdown is caused by how the automobile is driven rather than the amount of power or torque it produces. Due to its superior gearing, many supercharged K20 owners prefer the 6-speed manual gearbox from a 2002-2006 Acura RSX Type S. The 6-speed gearbox can often withstand more power and torque than the 5-speed seen in Civics from 2002 to 2005.
There are also many differing perspectives on how much torque a stock K-series clutch can handle before sliding. Most K20a forum members agree that a fresh K-series clutch may perform well under difficult conditions. According to some accounts, a new factory K20 clutch can withstand 250-270 lb-ft of torque and 350 horsepower. Above that point, you’ll probably want an upgraded aftermarket clutch. The Competition Stage 2 Clutch is a popular choice for K20s with more than 400 horsepower.
One of the most important considerations when supercharging a K20 is keeping the IATs low. A lower intake air temperature not only improves overall performance, but it also protects your K20 from detonation. If IATs get too high, long-term harm can occur. One of the simplest solutions is to use high-octane petrol such as E85 or methanol. E85 and methanol both contribute to lower combustion temperatures by burning more effectively than regular pump petrol.
E85 and E85 blends are often the better options for greater performance. It has a 108 octane rating and helps the engine operate cooler internally by reducing the chance of detonation. Even with a low E85 blend, power increases can be substantial. The disadvantage is that E85 is less fuel efficient and puts more strain on the fuel system. Having said that, E85 is not the best solution for engine safety. Methanol injection wins this prize.
Methanol injection minimises the likelihood of detonation or knock, making high horsepower builds much safer and more reliable. This is also true for supercharged K-series engines. Methanol is a good strategy to lower internal temperatures in Honda K20 engines because they rev so high. Methanol injection becomes critical for high horsepower builds that require a lot of boost.
K20 Supercharger Kits That Work
Because superchargers are such a popular modification for the K-series platform, it’s no surprise that there are a plethora of K-series supercharger kits available. K20 supercharger packages, like any other aftermarket system, can cost anywhere from $3,000 to $8,000. Of course, if you’re not aiming to build a 600+ horsepower K-swapped Integra for a weekend warrior, you probably won’t need to go that far.
Higher price points are typically associated with greater power potential. It is also indicative of the build quality and type of supercharger included in the kit. Some kits, such as the TVS supercharger kit, use a roots-style supercharger, but others use a centrifugal supercharger design.
1) Supercharger Kit MercRacing K20
One of the most popular kits on the market is the MercRacing K20 supercharger kit. The Eaton twin vortices-style supercharger has a high power potential and can perform at a high level. In compared to previous Rotrex-style K20 supercharger modifications, the MercRacing TVS kit maximises the amount of horsepower that a supercharged K20 can produce without sacrificing daily drivability.
As previously said, this kit will most likely deliver the most linear powerband of any supercharger choice on our list. Twin vortices superchargers have the most consistent power delivery of any K20 supercharger option. This means that power and torque are available at the majority of revs. The MercRacing MR2300 K20 supercharger kit can produce up to 500 horsepower with the right tune and fueling modifications. The K20 TVS supercharger has a lower blower rpm speed than other supercharger designs, which keeps IATs and internal strain minimal. Because of this, the MercRacing roots supercharger kit is one of the most dependable kits on the market.
While the MercRacing kit is undeniably one of the best K20 supercharger kits on the market, there are a few other factors to consider before making the purchase. While the kit includes an air-to-air manifold, an intercooler must be purchased separately. Furthermore, MercRacing states that the 2300 kit produces too much torque for a stock K20 gearbox. The TVS system requires a custom gearbox and an improved clutch.
2) CT Engineering Supercharger Kit K20
The CT Engineering K20 supercharger kit, like the MercRacing kit mentioned above, employs an Eaton-style supercharger. As a result, the CT Engineering K-series supercharger kit performs identically to the MercRacing kit. Both have identical power delivery and boost characteristics. Having said that, the CT Engineering package lacks the power potential of the MercRacing kit. This is mostly due to CT Engineering’s lesser capacity supercharger.
While CT Engineering claims that their K-series supercharger kit adds 60-70 horsepower while remaining extremely reliable, some K20 owners have used the kit to extract 400 horsepower from an engine. Those are obviously extreme cases, with most CT Engineering kit owners aiming for 300 horsepower. CT Engineering sells their K-series supercharger kit in two stages: stage 1 and stage 2. At 5-6 psi, the stage 1 kit produces roughly 240-260 horsepower. The stage 2 kit includes a larger 3.15″ pulley and high-performance injectors that boost horsepower to around 280-295.
One of the kit’s strong points is its low cost. At $4,195.00, the CT Engineering K-series supercharger kit is unquestionably the best value on this list. Despite its cheaper price, the kit does not compromise on construction quality or dependability. The CT Racing package includes cast aluminium supercharger manifolds, all of the necessary mounting brackets, and all of the necessary hardware to install the system, in addition to the Eaton-style supercharged head unit. The CT kit is essentially a plug-and-play alternative that is almost ready to use straight out of the box. Of course, you’ll also need a tune. A HONDATA KPro or a HONDATA reflashed ECU are two proposed options.
3) Supercharger Kit Kraftwerks K20 Rotrex
Moving away from roots-style blowers and towards a more modern K-series supercharger solution, the Kraftwerks K20 Rotrex supercharger kit is centrifugal in design and belt driven. A K20 centrifugal supercharger functions similarly to a turbocharger, as opposed to a roots design. They use an impeller to compress intake air before forcing it into the engine. Because a K20 Rotrex supercharger operates via a belt, performance is directly proportional to engine speed. As a result, kits such as the Kraftwerks K20 Rotrex don’t produce as much power at low revs as they do at high revs.
This has a direct effect on power supply as well. Centrifugal K20 superchargers typically have a peaky power and torque curve as engine speed increases. This is similar to how a turbocharger generates power. Some people, like those who use turbochargers, prefer having power come on in a direct manner high in the rev range. It can be additional entertaining when teamed with an engine like the K20. The high-rpm supercharged performance complements the start of VTEC at the top of the rev range. Due to the power delivery, a TVS-style supercharger is typically your best pick for a track-focused project. A Rotrex K20 supercharger, on the other hand, can be a terrific alternative for the drag strip.
The majority of the K20 Rotrex supercharger systems, including the Kraftwerks K20 supercharger kit, are built around a C30-94 Rotrex head unit, which offers some substantial power potential. The Kraftwerks kit will deliver you close to 400 horsepower with the appropriate tune, fueling adjustments, and exhaust enhancements.
Summary of the Honda K20 Supercharger Kit
The Honda K-series engine is one of the most popular 4-cylinder engines ever produced. Even in factory form, the high-revving, VTEC-equipped 2.0L engine is an extremely impressive engine. It is apparent that the K20 was created with strength and reliability in mind. That is obvious given that they can withstand twice their factory horsepower figure with stock internals. The K20 is the excellent platform for forced induction as a result. The linear power delivery that a supercharger may provide is a prominent argument for many. Superchargers are typically less expensive and easier to install on a Honda K20.
Before you install a supercharger on your Honda K-series, you should think about the additional modifications that will be required. In comparison to a host of other engines, the K20 barely needs any additional work. That is unless you are going for exceptionally high horsepower figures. K20 exhaust adjustments aren’t always necessary. Having said that, performance headers and an improved exhaust will boost engine breathability and horsepower. You’ll also undoubtedly require improved engine management, with the HONDATA KPro being the most common option. While K-series transmissions can handle up to 300 horsepower, you may need to replace the OEM clutch around that point.
The K-series supercharger kit market is dominated by three contenders, each with its own set of advantages. The MercRacing Eaton-style supercharger kit is unquestionably the best option if high horsepower is the goal. The CT Engineering kit is a wonderful low-cost option for another twin vortex type K20 supercharger kit. Finally, one of the most popular K20 centrifugal supercharger kits on the market is the Kraftwerks Rotrex supercharger kit. Whatever kit you choose, a supercharged Honda K20 will almost certainly not disappoint.