Fuel System
Luckily for us, Honda's streamlining process means that both the L15 and the K20 use similar quick-disconnect system fuel lines and connectors. With hardly any adjustment, the Fit's fuel line will snap right onto the K20 returnless system fuel line.
The final step is wiring. For this install, Hondata and HASport have made jumper harness t
Tuners have found the RSX's fuel pump will support up to about 400 wheel-hp, but the Fit's pump is an unknown. Anyone going turbo or using large injectors may want to replace the stock fuel pump. For a mostly stock K-series, the Fit pump will work fine.
Intake And Exhaust System
For an intake, any of the aftermarket RSX short ram units work well. For true cold air, though, you'll need to make one. The exhaust is a bit more complicated, because the Fit has a flat floor with the gas tank under the front seats. Jackson Racing has come to the rescue and will be manufacturing headers that will clear the EPS, the subframe and then terminate just before the exhaust, making a sharp right turn to go down the side.
The header seen here is the prototype for the Jackson Racing unit and should be nearly identical to a production version. Jackson Racing is also working on an exhaust, including a version that should flow well enough to support forced induction.
Measure Twice, Cut Once
This is a complicated swap. The electronics and wiring make it a real challenge. Bending the brake lines gently and getting some new A/C lines, plus cutting and reinforcing a frame rail, means you need to be a competent mechanic.
And there you have it. A short ram intake for an RSX will work just fine. HASport went the
Any K-series engine will work, but the best is one from an EP3 Si or an RSX. If the engine is still in the car, here's a check list of what the junkyard needs to pull out: engine, transmission, shifter cables, shifter box, primary O2 sensor, ECU, alternator, engine harness, battery/starter/ charging harness and, if you want A/C, the compressor and suction hose. If the engine doesn't have the RBB or RBC manifold, it'll also need one of those.
Decide up front if you're going to do this with just a K-Pro or hope HASport or Hondata makes the harness that lets you keep the Fit's ECU so it can run the dash and a few other creature features.
| K-Series Engine Codes & Chassis |
| Engine | Year | Model |
| K20A | 2001-up | Euro/JDM ITR and CTR, JDM Accord Euro-R |
| K20A2 | 2002-2004 | RSX-S |
| K20A3 | 2002-2005 | USDM Civic Si, |
| | 2002-2006 | RSX |
| K20Z1 | 2005-2006 | RSX-S |
| K20Z2 | 2006-up | Acura CSX (Canada), |
| | 2006-up | JDM Civic |
| | 2006-up | Euro Accord |
| K20Z3 | 2006-up | USDM Civic Si |
| | 2007-up | Acura CSX Type-S (Canada) |
| K23A1 | 2007-up | RSX |
| K24A1 | 2002-2006 | CR-V |
| K24A2 | 2003-up | TSX |
| K24A3 | 2003-2006 | Accord (Japan, Europe & Australia) |
| K24A4 | 2003-2005 | Accord & Element |
| K24A8 | 2006-up | Accord |
The Basics
*Use any K-series engine
*Only RSX (all models) and EP3 transmission
*Requires Hondata K-Pro
*Fit's dash will not work without Fit ECU, requires lots of gauges
*Hondata or HASport may have harnesses for both K-*Pro and modified Fit ECU, which allows Fit dash to function
*Custom axles and specific half-shaft
*Custom header and exhaust (Jackson Racing-supplied)
*RBB or RBC intake manifold required
*EP3 idler pulley assembly
*Minor cutting, welding and fabrication required