You've seen it before-they did it in Japan and they did it in the US. But those were one-off cars. Who else but HASport would competently engineer the first readily available K-series engine swap for the new GD or Fit chassis?
Though it's been in Asia for some time as either the Jazz or the Fit, America just got the Fit for the 2007 model year as an attempt to compete with Scion and position beneath the ever-bloating Civic. While you might wish that the Fit weighs as little as it looks (so this would truly be a big engine in a small car), today's emissions and safety regs mean it's just not the case. The Fit weighs about 2450 pounds, right in the ballpark of the old EK chassis.
But it's new, has all that safety tech, looks like a trendy micro-car and, given the power levels tuners are achieving with the K-series engines, could really haul some ass with this swap.
Picking The Chassis
Not a whole lot to choose from here, the Fit is the Fit. There's a Sport model, but it's really a mild cosmetic and suspension change. You'll be starting with a fairly new car with lots of fancy sensors and electronics to sort through. You don't want to try this with a Fit that has the CVT (continuously variable transmission), since you'll need a proper shifter on the floor. Plus, it's cheaper-list price for a basic Fit is $13,850 at the time of writing.
Picking The Engine
The choices are endless since Honda has so many versions of the new K-series engine. For this particular swap, HASport used a K20Z3-the engine from the new 2006 Civic Si. It also used its six-speed tranny with its excellent ratios and factory limited-slip differential, something absolutely necessary for something with this much power and oddball weight distribution. But any 2.4-liter K-series from the Accord or TSX can be used-they'll all fit under the Fit's tall hood.
Keep in mind the good K-series engines are from the RSX-S, TSX and the 2006-up Si. Unfortunately, the other K-series don't have real iVTEC and make considerably less power. They are a good deal cheaper, though, and with new cams from companies like Brian Crower or Skunk2, it's possible to make credible power with these engines. You decide: budget or baller.
The transmission is a little more trouble, but one from the previous generation 2002 to 2005 EP3 Civic Si or 2002 to 2006 Acura RSX or RSX-S is cool. Right now, the TSX and all other K24 transmissions have a different housing so they aren't compatible with the bolt-in HASport kit. The 2006-up Si will also work, but, like the '05-up RSX, it uses a different speed sensor. The earlier one is easy to work with, the newer one is different and gives most gauges trouble.
Engine Removal
First, getting the shop manual from www.helminc.com is highly recommended and it's usually cheaper than from the dealer. Start by removing the bumper fascia, radiator, condenser and fans. Then, remove the lower subframe. Disconnect the lower suspension arms, then the front lower transmission mount, then the rear mount at the back of the subframe. There's no reason to remove the Electric Power Steering (EPS) from the car. Just unbolt the rack from the subframe so it stays on the chassis. Drop out the subframe and then remove the axles.
Next, discharge the A/C system, since at least one of the hard lines will need to come off. Do it the right way and evacuate it with the proper equipment. According to the Fit manual, you can use a hoist to support the engine from the top, but you can also support it from the bottom on a 10-inch or taller cart. Then instead of lowering the engine to the floor, the car can be raised off the engine. Test fitting is much easier this way and is how the swap is illustrated.
Wiring: The Fork In The Road
As with most modern engine swaps, electronics and wiring present the main problem. The Fit engine has uses a drive-by-wire (DBW) electronic throttle body and an SOHC VTEC system, not the DOHC iVTEC found on K-series engines. So modifying the stock ECU to run the new engine isn't even an option. Problem two, the Fit's dash, like most new Hondas, is controlled by CAN-bus communication via the ECU. But since each car has its own CAN protocol, a K-series ECU cannot just be plugged in and expected to run the Fit gauge cluster. The level of integration is so high that there's really no way of getting the Fit dash to work without the original ECU.
This is the fork in the road for the swap. Use a Hondata K-Pro ECU and run the engine, but have no gauges, or use the Fit's ECU and lose the iVTEC. The only way to have your cake and eat it is to do both. As a prototype for this swap only, Hondata and HASport have worked together to piggyback a K-Pro ECU onto the Fit's ECU. The K-Pro controls the engine in terms of fuel, ignition, closed loop operation and cams, while the Fit's ECU talks to the gauges, go pedal, e-throttle and the rest of the car. It requires a custom jumper harness, which the two companies are looking into selling, that lets the two computers coexist in relative harmony. Unfortunately, at this point there is no plan for Hondata to offer the wiring harness as a kit, since it's far from a plug-and-play affair, but customer demand might just change that.
To keep it simple, a K-Pro, an E plug to add some inputs and outputs that aren't in the stock engine harness plugs, and a rack of gauges is all that's required, just as we've seen in previous K24 swaps. You will need a speedo, engine temp, check engine indicator, tach and fuel level, at a minimum. For about $750, Racepak's 250-DS-UDXSR street dash has all the above, plus oil temp and pressure, high beam, odometer, brake and turn signals.
Going this route means a lot of re-wiring. Hondata has K-Series swap wiring listed on www.hondata.com/images/k20awiring.gif. The Fit factory service manual is needed to build a subharness that integrates with the cabin harness. The harness needs a starter signal, then power for the main relay, fuel pump relay, O2 sensor relay and ECU. With a dash like the Racepak, a lot of the connections are available from the ECU. Just add the missing sensors. Lots to do, but possible.
Which way you go determines what you will use as an engine harness. The Hondata way uses the original engine harness. Add another cam sensor and wiring, wires for the VTC cam actuator and stretching it here and there is all that needs to be done. If you're going K-Pro only, use the K20's engine harness. Slight modifications and the cabin subharness are needed as mentioned above.
It's also rare to find a K20 engine with the starter and alternator harness. For some reason, these are on a separate harness that also connects to the battery. If you have it, great, modify it to, um, fit. If not, strip the four alternator wires, starter wire and charging wire from the stock harness and integrate them to the engine harness you have. Don't forget the K-series uses a wideband primary O2 sensor. If you didn't get it with your swap, you'll need to buy one.
If all this sounds too complicated, HASport is working on the solution. It will offer a complete harness made from the K20 and L15 engine harnesses along with all that's needed to connect to the Fit's cabin harness, including the O2 sensor connection (but not the sensor).
Engine Mounting
This is probably one of the hairiest engine shoehorn swaps we've done. Although the drive configuration is similar, the stock L15 Fit engine is narrow, and so the engine bay is narrow, even though it has plenty of height. The K20 and trans, on the other hand, is pretty wide. To make the fit, a number of things need to be moved around and the left-side frame rail needs a circular hole cut into it. Other than that, the HASport kit uses the stock mounts resourcefully, with new brackets. In the future, replacement mounts will be offered for less engine movement or even getting racy with the stock engine.
The first thing to do is move the brake lines along the passenger side and back of the engine bay. They will need to come out of the white locator clips and be gently bent by hand to hug the firewall and move along the wheel well above the frame rail. This, in conjunction with removing the hard A/C lines, opens up the right side of the engine bay completely.
While you're there, do the same type of operation to the ABS modulator. It needs to be much closer to the headlight to make room for the idler pulley of the K-series and a HASport bracket. It will take modifying the stock hold-down brackets to reposition the modulator securely.
Moving to the driver side of the engine bay, clearance needs to be made on the chassis frame rail for the transmission case. Measure 10.5 inches back from the bulkhead and cut a notch 2.5 inches in diameter. A hole-saw is recommended. Double-check the notch by lowering the car on top of the engine and checking the clearance. The notch should only be about 0.25 to 0.375 inches deep. Make sure to reinforce the frame rail after removing the material.
Double-check the notching again, this time with the mount in place. This will give you an idea of how much material to remove from one edge of the notch for clearance. Under acceleration, the engine will move forward and up an inch or more. Make sure there is room for that, because when aluminum from the transmission case comes into contact with the steel of the frame rail, steel wins.
The last place to make some room is out front. The radiator core support needs to be trimmed just a bit to clear the intake manifold. Again, lowering the car to the engine will show the amount to remove. Allow at least an inch of clearance, because the stock mounts let the engine move under hard acceleration.
Now the engine bay of your squeaky-new Fit has been hacked into a work of modern industrial art, there's another problem. The only intake manifold that works with this swap is from the 2002 to 2006 RSX Type-S, EP3 Si or JDM Civic or Integra Type-R. They have the large flat front and the letters RBB or RBC cast into them. The longer Euro R, TSX or 2006-up Si manifolds stick out farther and will hit the radiator. The RBB and RBC manifolds will interfere with the alternators from the Accord, TSX and 2006 to 2007 Civic Si. An alternator from a 2002 to 2005 EP3 Si, any RSX or CR-V can be substituted. In addition, on some heads (mostly K24), you will need to plumb the thermostat bypass passage in the head, just to the side of the number one intake runner, back into the coolant system. HASport makes an adaptor plate for this. Don't just block it off, as this is a coolant passage.
Now clean up the K-series engine and take off all the accessories. If you have an engine with power steering, you'll need to replace it with an idler pulley and bracket from an EP3 Si, since the Fit has EPS. To retain the A/C, use the compressor from the EP3 or RSX, because it has a single wire control for the clutch like the Fit. Most K24s have a three-wire setup, not compatible with the Fit. You'll also need to redo the suction and receiver hoses.
Accessory belt size varies, depending on several factors. For K24s and the K20A3, you can use the EP3 (2002 to 2005 Civic Si) belt. On a K20A2, Z1, Z3 or any of the K20A Type-R engines, the crank pulley is smaller, so a shorter belt than the EP3 is required. No A/C? Start with a belt about 1.5 inches smaller than an EP3 and go from there.
If the engine harness is not on, install it. Install the half-shaft from an EP3 Si or RSX, which have 6MN, S5T30 or SNG30 stamped on them. These are the only Honda axles with the proper length and mounting flange pattern. Bolt the HASport right-hand engine bracket to the block using two of the stock bolts and one of the HASport-supplied bolts. With the engine and transmission on the support stand, lower the car over it. Keep a close watch on the VTEC solenoid on the rear of the engine, the clutch actuator fork, and the slave cylinder on the front of the transmission. You may need to twist the engine while lowering the car to avoid contact. This is a two-man job.
Once the car has been lowered and the engine is within a few inches of where the mounts are, install the left-hand transmission bracket using the HASport hardware. Then place a spacer under the bracket on the outside rear mount hole, so the bracket mounts flush. Leave the bolts finger-tight at this time. Continue to lower the car until you can bolt the transmission bracket to the mount. Use the stock bolt and HASport-supplied nylon lock nut.
The Fit's left-hand upper engine mount will need to be modified for clearance. Grind down the small nub on the top, near the upright stud. Notch the mount on the left inside edge to clear the engine-mounted HASport bracket. Put a couple bolts in the right-hand mount (passenger side) and check for clearance (0.25 inches).
Leaving those bolts loose, attach the HASport top bracket with the supplied two bolts. If the hole on the mount end doesn't match up, try moving the engine around until it does. Torque the two HASport brackets to spec and finger-tighten the factory nut at the top of the Fit's right-side mount. Finger-tighten all three factory mount bolts. If nothing looks bound up, torque the top nut on the Fit mount to spec and then do the same for the three bolts around its base. Go to the right side and torque all those fasteners as specified in the HASport directions.
Drivetrain Hook-Up & Engine Accessories
Attaching the two side mounts will hold the engine for now. The swap needs custom-length driveshafts. HASport and the Driveshaft Shop plan to have these available. Install the driveshafts and then attach the lower subframe. After that, the lower control arms can be bolted to the knuckles.
Bolt the steering rack and gearbox back to the subframe. Finger-tighten the Fit's rear mount to the HASport bracket, using the stock rear mount bolt and HASport-provided nylon lock nut. Install the bracket and mount into the subframe together as a unit. You may need to lift the front of the engine to make room for both parts to be installed and line up properly. Install the rear mount using the factory hardware. Don't tighten yet.
Next, bolt the HASport rear bracket to the engine and transmission. The front hole will use the stock bolt you removed earlier from the transmission. The other two holes will use the HASport-provided hardware. Once all three bolts are in, torque the mount and bracket to HASport installation manual specs.
The Fit's radiator fans will no longer work, but the car needs at least one 12-inch electric pusher fan (two, if you keep A/C) on the front of the radiator. Connect it to the stock harness, so the K-Pro can control it. A lower GSR radiator hose, properly cut, will connect both the top and the bottom of the Fit's radiator.
Attach the alternator, connecting it to the alternator/starter-specific harness. Bolt on the EP3 idler pulley and bracket and, whether or not you're using A/C, install it along with the correct belt and new lines.
If you plan to keep the e-throttle (like the HASport Fit), install the HASport adaptor plate and the throttle body (the TSX unit is the largest at 2.44 inches). Most won't be doing this, so the Fit must be converted to drive-by-cable. The pedal assembly will need to get swapped with something from another Honda or custom-fabricated. It will also take some experimentation to find the right length of throttle cable.
Because HASport had a 2006 Si at its disposal, it used the car's K20Z3 engine and transmission. If, by some enormous amount of luck, you can find one of these gearboxes, you can use the Fit's shifter assembly with shortened 2003-up Accord shifter cables. For the rest of us, only a tranny from an EP3 Si or any RSX will work. For these gearboxes, you also need the original shifter cables and shifter box from the chassis. TSX, Accord and other gearboxes have different casings and the HASport mounts won't line up.
The Fit's shifter box won't work because the way it operates the cables is the reverse of the EP3 Si or any RSX gearbox. That's why you'll need the cables and shifter box that match your tranny. The shifter box will also need to be modified. The center tunnel has a big bump that will need working around. But once installed, simply pass the cables through the floor in the stock location.
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.
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.
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
Photo Gallery: 2007 Honda Fit K20 Install - Sport Compact Car Magazine
No comments:
Post a Comment