The K-series swap is the most documented engine swap in the Honda enthusiast world. Whether you're building a track Civic, a quick daily EK, or a purpose-built EP3, the K-swap offers modern power in a well-understood package. This guide covers engine selection, supporting parts, and what the full build actually costs. For the K20A vs K24A head-to-head, see our dedicated K20A vs K24A comparison.
Which K-series engine for your build?
| Engine | Best application | Price (our stock) | Character |
|---|---|---|---|
| K20A (JDM Type R) | Performance builds, time attack, spirited street | $749–$1,749 | High-revving, peak power at ~7,000+ RPM |
| K24A | Torquey street builds, daily driving, budget hybrid | $849–$1,749 | More low-end torque, broader powerband |
The most popular choice for performance-oriented EG/EK swaps is the JDM K20A — not the USDM K20A2 (from the RSX Type-S) but the genuine JDM K20A from the JDM Civic Type R (EP3) or Integra Type R (DC5). The cam profiles and compression ratio are different from the USDM version, and that difference is measurable on the dyno.
For street-biased builds or builds that prioritize torque over peak power, the K24A from a CR-V, Accord, or Element provides more displacement and better low-RPM pull at a similar price point. Some builders do a "K24/K20 hybrid" — K24 block with K20 head — to get the displacement advantage of the 2.4L with the higher-flowing head from the Type R. See our K20A vs K24A guide for the full hybrid breakdown.
Chassis compatibility: which Civic platforms K-swap
- EG chassis (1992–1995): K-swap requires mounts, transmission, axles, and wiring. High-clearance firewall sometimes needed for K24 headers. Most popular lightweight K-swap platform.
- EK chassis (1996–2000): similar to EG; slightly more engine bay clearance in some variants. Also very popular.
- EP3 (2002–2005, Civic Si): the EP3 actually came with a USDM K20A2; the JDM K20A is a direct-spec swap (same mount points) needing ECU work and a tune.
- DC2/DC5 Integra: the DC5 RSX chassis is K-series native (K20A2 from factory); JDM K20A is a spec upgrade.
Supporting parts list for a Civic EG/EK K-swap
- K-swap mount kit: Hasport, Innovative, or equivalent. ~$300–$500 depending on configuration.
- Transmission: K20 or K24 gearbox (cable or hydraulic depending on chassis). Budget $300–$600.
- Axles: chassis-specific K-swap axles (EG or EK). Don't assume OEM axles fit. ~$150–$300 for the pair.
- Wiring harness adapter or conversion harness: OBD1 (EG) or OBD2 (EK) to K-series ECU pinout. $150–$300.
- ECU: JDM K20A ECU (if importing JDM management), or aftermarket standalone (Hondata KPro is the most common). KPro: ~$700–$900 new.
- Shifter linkage: OEM or short-throw aftermarket. $80–$200.
- Supporting ancillaries: power steering elimination or conversion if applicable; alternator brackets for accessories from your donor engine.
Total K-swap cost estimate
Engine only ($749–$1,749) + supporting parts ($1,200–$2,000 for a budget EG/EK build with KPro ECU) + labor if not DIY ($800–$2,000 at a shop familiar with K-swaps). All-in range for a complete street K-swap: $2,800–$5,700 depending on spec level and labor situation.
Frequently asked questions
Do I need to tune a K-swap after installation?
Yes. A K20A or K24A running a foreign ECU or base map needs a proper tune to run safely and make correct power. The Hondata KPro on a JDM K20A is the most common solution — it allows precise calibration for your specific injectors, intake, exhaust, and VTEC parameters. Don't skip the tune.
What K transmission should I use in an EG swap?
The most common choice is the K20A2 transmission from an RSX Type-S (6-speed, close ratio) or the K24 transmission from a Accord/Element for more gear spread and torque handling. Confirm the transmission input shaft matches your chosen engine before ordering axles.
Is a K-swap worth it over a B-series in an EG/EK?
For a modern build targeting 200+ hp, yes — the K-series head flow, modern engine management options, and broader displacement range make it the better long-term investment. The B-series is simpler for a budget build or for preserving a period-correct build, but the K-series is the current default for modern Honda performance builds.
Shop K-series engines
Browse K20A engines, K24A engines, and our full Honda engine lineup. See the full JDM engine inventory.