Honda is one of the biggest names in the JDM enthusiast community. Sure, many people make fun of Honda vehicles because there are a lot of ricers out there with D-Series engines, but there are a lot of Hondas out there with powerful little engines.
Honda produced some of the most legendary four cylinders ever in the 90s, so there were high expectations when the world got its hands on the K20.
We designed this short article to get you up to speed on everything you need to know about the Honda K20 engine.
Honda K20: Engine Basics and Specifications
Initially introduced in 2001, the Honda K20 is the engine that ultimately replaced the B-Series engine. It was initially met with a lot of skepticism from Honda die-hards, as fears of it being worse than the B-Series were high at the start of the K20’s life.
Honda initially brought the K-Series to the US market in the 2002 RSX and Civic Si. It had a lot of big changes that made it different than any other Honda engine before it. Like the B-Series, Honda designed the K20 as a great daily driver engine and a great performance engine. Really, they designed the K20 for use in both daily-driven economy cars as well as high-performance cars.
Building a series of engines that has two different purposes is not new to Honda and definitely not exclusive to Honda, but it’s still a difficult task nonetheless.
What made the K20 so much different from the outgoing B-Series was its direct-fire ignition system, reverse layout, and clockwise rotation. Comparing the two engines side by side, the big thing that stands out is how the K20 has the intake side toward the front of the vehicle, while the B-Series has it toward the rear of the vehicle.
This clockwise rotating engine design was different than decades of counter-clockwise rotating Honda engines. Ultimately it helps improve emissions by improving catalytic converter performance. But having the intake manifold on the front of the head makes it a little more difficult to retrofit into older chassis than the B-Series.
The Magic of VTEC
What gave Honda the ability to create an engine that excelled at economy and performance was i-VTEC. In case you don’t know what iVTEC is, go watch our VTEC vs iVTEC video, which explains everything.
Basically, there are two kinds of iVTEC: one for economy and one for performance, both of which combine VTEC and VTC. The K20A3 uses the economy version of iVTEC, so be sure to buy the right K20 when it comes time for your engine swap.
With i-VTEC and an improved cylinder head design, the head of the K20 engine is far superior to any stock B-Series head flowing as much as 300cfm through the head. One of the cool parts of the K20 is the square displacement, which means the bore and stroke are equal in size. This helps the K20 produce a decent amount of torque while still jamming out upwards of 110 horsepower per liter in the performance versions.
- Production Run: 2001 – 2011
- Cylinder Block Material: Cast Aluminum
- Cylinder Head Material: Cast Aluminum
- Configuration: Inline 4-Cylinder
- Valvetrain: DOHC – Four Valves per Cylinder – i-VTEC
- Bore: 86mm
- Stroke: 86mm
- Deck: Open Deck
- Compression Ratio: 9.7:1 to 11.7:1
- Horsepower: 155hp to 212hp
- Torque: 131 ft-lbs to 159 ft-lbs
Vehicles That Came With The Honda K20 Series Engine
The Honda Civic Type R (JDM) and (EDM), Honda Integra, Honda Stream (RN4, AWD) all came with this engine from 2001 to 2006, while the Honda Accord Euro R came with the engine from 2002 to 2008.
Not too surprisingly, the Honda Integra Type R (AUDM/NZDM)and the Acura RSX Type S came equipped with the K20 from 2002 to 2004.
The Honda Civic Si, Civic SiR, and the Honda Civic Type S were stocked with the engine from 2002 to 2005, while the Honea Civic 2.0, Honda CR-V, and Honda Accord (EDM) all came equipped with the engine from 2003 to 2006 and the Honda Accord came equipped from 2003 to 2006.
- 2001 – 2006 and 2007 – 2011 Honda Civic Type R (JDM) – K20A
- 2001 – 2006 Honda Integra Type R (JDM) – K20A
- 2002 – 2008 Honda Accord Euro R (JDM) – K20A
- 2001 – 2006 Honda Stream – K20A1
- 2001 – 2006 Honda Civic Type R (EDM) – K20A2
- 2002 – 2004 Acura RSX Type S – K20A2
- 2002 – 2004 Honda Integra Type R (AUDM/NZDM) – K20A2
- 2002 – 2006 Acura RSX – K20A3
- 2002 – 2005 Honda Civic Si – K20A3
- 2002 – 2005 Honda Civic SiR – K20A3
- 2002 – 2005 Honda Civic Type S – K20A3
- 2002 – 2006 Honda CR-V – K20A4
- 2003 – 2007 Honda Accord – K20A4
- 2003 – 2006 Honda Accord (EDM) – K20A6
- 2003 – 2006 Honda Accord (ADM)</li
Of course, with all of these different variants of the K20, there were different horsepower and torque ratings.
Most of the power differences come from different compression ratios, tunes, and cylinder head designs. The cylinder head is the key to unlocking the power in any internal combustion engine.
In the case of the K20, the A2 variants use VTC and VTEC in one system (i-VTEC), while the A3 variants use VTC and VTEC-E. The A2’s version produces much more power, and the A3 version offers better efficiency. Strangely enough, they’re both labeled as “i-VTEC” even though they operate differently.
Honda K20: Performance Potential
Just like the B-Series, D-Series, H-Series, F-Series, and pretty much every Honda engine out there, the K20 has a pretty big aftermarket. Just like other Honda engines, the K20 has also been proven to be quite a good little motor. Of course, the typical intake and exhaust modifications will gain power, putting a K20A2 around 200whp. 200whp is pretty good, considering a naturally aspirated B-Series can have a difficult time reaching 200whp depending on the setup.
With a stroker bottom end, high compressions pistons, head work, and more, over 300whp is possible naturally aspirated. If you didn’t already know, producing 300whp from a naturally aspirated four-cylinder engine is almost unheard of. For reference, modern turbocharged four-cylinder engines such as the Ford 2.0L EcoBoost can barely make that much power without an upgraded turbo.
When it comes to forced induction, there is one big thing that holds this engine back, and that’s the transmission. Unfortunately, the 6-speed transmission attached to the K20 isn’t particularly strong and tends to explode around 400whp, but there are plenty of cases of it exploding at much lower higher power numbers, but you get the idea.
With forced induction, you can safely run about 300whp for an extended period of time on the stock bottom end. Yes, you can make more power on a dyno with a stock bottom end, but making big power on the dyno for a few pulls is vastly different from daily driving at the same power level.
With a built bottom end you push power upwards of 700-800whp before you need aftermarket sleeves in the block. With aftermarket sleeves, you can push upwards of 1,000whp. Again, these numbers are not concrete. Different builds make different amounts of power with or without issues. To put it simply, though, the K20 makes good power, both N/A and boosted.
Today the K20A is on its way out with the L15 1.5L Turbo replacing it. In high-performance applications, the K20 is being replaced by the K20C. The new K20C1 is the engine used in the FK8 Civic Type R, and it makes a lot of horsepower and a lot of torque.
The K20C has a different head design, direct injection, changes to the valvetrain, including no VTEC on the intake cam and obviously a turbocharger. The days of high-revving naturally aspirated VTEC engines are almost over. New turbocharged Honda engines are coming in, so enjoy the naturally aspirated K-Series engines while you still can.