K20 Swap Guide – What you need to swap a K20

K20 Swap Guide – What you need to swap a K20

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The Honda K series VTEC engine has certainly been met with mixed results from the enthusiast crowd, but from no fault of the engine or design. Many factors have contributed to the K series not being quite the smash success the B series DOHC VTEC engines of yesteryear.

We receive questions about the swap into an older Civic or Integra frequently, and to solve the litany of questions we receive on the subject, we’ve created the K20 Parts Guide. Looking for a How To Honda Swap Guide? Take a look at our What Fits What article here as well as Part 2 of our Honda Swap Guide.

K Series Engine / Transmission


 

There are several different options when it comes to sourcing the K series engine. One option is the K20A3 VTEC engine that’s in the seventh generation Honda Civic SI from the year ranges of 2002-2005.

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There’s also the Acura RSX from year ranges of 2002-2004 with the K20A2 powerplant.

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You can also opt for the larger 2.4 liter displacement K series engine found in the 2003-2006 4 cylinder Accord and other vehicles.

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Part one of our K20 Swap Guide will give you the engine and transmission choices and options you have for the K20 Swap.

You can opt for any size of K series Honda motor here, from the K20 to the K24 which would bring displacement to 2.4 liters. You will need a complete engine assembly, the complete transmission assembly, and the two harnesses required to operate the engine.

In typical Honda fashion, there are many variants of the K20 that you hear about. The K20A is the original DC5 ITR engine and is as rare and popular as that sounds. The K20A2 which is what’s generally plentiful here in the US is the RSX Type S 200 hp engine. There’s also the K20Z1 that’s a 210 horsepower derivative of the K20A2, and that’s just the RSX Integras.

For those on a budget the K20A3 is an excellent engine for the price. This is the Honda Civic SI motor found in the less popular EP3 from 2002-2005. This engine puts down 160 horsepower and is a fairly priced engine that’s plentiful with the 2002-2005 Civic SI owners swapping for bigger and better.

While a tad limited in horsepower, its cheaper and a lot more fun to drive around town due to a large torque band.

In addition to the Honda Accord K24 found in the later model Honda Accords and Honda CR-V’s, the 200 horsepower version can be found in the USDM Acura TSX. The TSX engine is a great find and isn’t hard to find, or you could put together your own Frankenstein K series engine for your K swap.

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This consists of the K series engine harness from a EP3 Honda Civic or the engine harness from a Acura RSX Type S or Base model. It’s best to stick to the year range of 2002-2004 for these harnesses, which will eliminate a lot of the unnecessary wiring. You will also need the charging harness from the same engine in order to connect to your vehicle and to the K series alternator.

There are several services available for the harness conversion that you will need to convert your K series harness to fit into your Civic or Integra.

Engine Accessories


 

If you are swapping a K20A2 from a RSX into your vehicle, you will need the starter and alternator for this engine.


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The alternator for the K20A2 is part number 31100-PRB-003 and it can also be found under 31100-PRB-013. If you are swapping the K24, the alternator part number will be 31100-RAA-A01 or 31100-RAA-A03, and this alternator can also be found under 31100-RAA-A05 or 31100-RTA-023. The aftermarket interchange part number for this alternator is CSC29 or CSD73, and if you need the alternator bolts, the part number is 90008-PNA-000.

The starter for the K series engine must also be sourced if your K engine swap does not come with it.

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The part number for the K20A2 or the Acura RSX is 31200-PRB-A01, while the 2.4 liter version will be part number 31200-RAA-A61. The starter will most likely have to be swapped, unless you purchased your entire donor swap as a whole. If you need replacement starter bolts, the part numbers are 95701-12085-08 x 2 for the bolts to the transmission housing. The long starter bolt is part number 90027-PND-A00.

Engine Control Unit


Engine control can be the most difficult part of our K20 Swap Guide, so make sure to choose wisely. Don’t be afraid to plan ahead for future mods when selecting the engine management of your choice.

The ECU required to run your K series engine swap can be easy depending on what your end goals are. For most people the simple choice of a PRB ECU from a Acura RSX will do the trick, if you are looking for the ultimate in performance, you can choose the Hondata K-Pro or a JDM version of the same PRB ECU.

The part number for the Kpro is HAD-K-PRO and it’s basically the end game for your computer tuning needs. Check out our Kpro install and dyno tune on a Honda GD Fit here.

Intake Options


 

In what could be the biggest decision for your K series swap, what throttle body / intake manifold combination? If you are intent on retaining the drive by wire feature and stock throttle body options, you can select the RSX Type S throttle body or the Accord throttle body depending on your engine or intake manifold.

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You can either choose to run the RSX Type S throttle body (shown above) with the matching intake manifold, or switch to a TSX or Accord setup from a K24. You can of course always choose aftermarket routes, which would require a RBC and throttle body adapter at the very least.


Mount Kit


 

There are many mount kit choices available, from Hasport to other copycat companies, many kits give you a complete turnkey solution. Most of these kits are made for the 1992-2000 Honda Civic or 1994-2001 Acura Integra, but other choices do exist.

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Other mounts you may require if you are not going the normal Hasport mount kit route, but you may need a Honda CR-V K24A1 passenger side engine mount. The Honda CRV passenger side mount is part number 50840-S7C-980 and is required if you are putting your mount kit together separately.


Exhaust


 

Because the K series exhaust faces towards the vehicle firewall, you have a few options here when it comes to aftermarket support. Many popular aftermarket choices are solid for header selection, from DC Sports to SSR or R-crew.

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Once you have the header and catalytic converter choice sorted out, you can merely choose the catback of your choice that will fit your chassis.

Sensors required in our K20 Swap Guide


 

The Knock Sensor is an important part of your K series engine swap starting, and for good reason. Without the signal the knock sensor provides, your ECU will not know when predetonation or engine knock occurs in your engine.

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This sensor is basically a microphone that allows the ECU to realize when the engine is encountering dangerous operation. This sensor will notify the ECU which will then pull ignition timing to attempt to stave off engine knock, or go into limp mode.

The part number for the K20A2 Knock sensor is 30530-PRB-A01, and is connected to the K series shortblock.

RSX Oxygen Sensor ( PRIMARY )

You’ll need just the upstream 02 sensor, unless you are intent on CARB legalizing your K series engine swap. The primary oxygen sensor on the K20A2 is found in the header B pipe, towards the rear of the engine.

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The primary 02 sensor for the K20A2 is part number 36532-PRB-A01, you can also opt for a universal style four wire 02 sensor and simply wire it to the oxygen sensor connector.

Drivetrain K Swap Components


Because you are installing the K series engine into a different vehicle, you will need new axles and the proper halfshaft if you want to use OE Honda parts. For a 1992-1995 Honda Civic swap, you’ll be using the RSX Type-S halfshaft with a combination of outer or inner axle components from your target vehicle.

For example to swap a K series into a 1992-1995 Honda Civic EG, you will need the Type S halfshaft, with the RSX base model axles. The base model axles will need you to swap the inner joints and U joint with the EG versions to fit. For 1994-2001 Acura Integras, you can use the Type-S Axles with GSR outer axle components.


The best possible option however is to purchase a driveshaft shop axle kit or a premade axle kit made to the lengths you need. If you have any questions about fitment, please let us know in the comments below.

You should also locate and purchase a new set of clutch bolts and flywheel bolts with the appropriate anti-seize. The K series flywheel bolts are part number 90011-PNA-B00, you will need eight of these. The clutch bolts that button the clutch plate and disc to the K series flywheel are part number 90034-P10-A01, of which you need six.

If you are using an aftermarket clutch or a specialized dual or triple plate clutch, the throwout bearing that is to be used should be supplied. Always service your pilot bearing as well, the part number is 22103-PNA-003 for the K series pilot bearing.

Shifter Components


Because you will be leaving the world of rod actuated transmissions behind, you will need a shifter mounting kit to mount the new K series shifter box and cables. There’s quite a few options for the shifter mounting kit, we prefer the units from Karcepts which feature everything you need for install.

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You will also need a RSX Type S shifter box and shifter cables required to mount and install your shifter cables. Because this shifter box assembly requires some serious modification, make sure you can shift into all gears before finalizing the mounting process.

Clutch Slave Cylinder


The Acura RSX Type S Clutch slave cylinder is what’s needed here if you are converting to a six speed transmission. Because you are using the K series transmission, part of the K20 Swap Guide is converting the slave cylinder as well. The part number for the cylinder is 46930-S7C-E01, and you will also need a clutch line to go from your master to the new K series slave cylinder.

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Power Steering

To retain power steering in your new K series swap, you will need a K20A power steering pump and the high pressure hose from a 2002-2004 Acura RSX. It’s also a good idea to run a power steering cooler to help keep your power steering fluid from breaking down.

To complete the install of power steering in your K swap, you will need a pulley kit like the one from Jackson Racing part number 052-154. This pulley mount will help the power steering pulley and belt clear most hoods and engine bays.

If you are not retaining power steering, you will need the Honda Civic SI EP3 idler pulley and bracket. On the K20 the serpentine drive belt will be 50.5 inches long and the K24 will use a 52″ serpentine drive belt.

 

43 COMMENTS

  1. Very good guide noob proof, hahaha, i’m swapping a k20a to a 1995 civic coupe b16, the cuestion is, where is the second part of the guide?
    And which sway bar kit do you recomend and which turbo kit? I have a edelbrock in mind
    Thank you!

    • Hi Marco, thanks for commenting, part 2 is coming up shortly so stay tuned!

      As for turbo kits, we’d recommend putting together your own kit to save on money. The Edelbrock kits are nice but if you dont care about emissions, cheaper kits can be had!

  2. Hello I have a 2003 rsx type s shell. I’m putting in a k24 engine from a 2005 honda accord, It’s from a automatic car. My question is what parts do I need to get to get it up & running?and also have a ep3 5speed tranns that I’ll be putting on it!

    • Hi Darrion, thanks for reading.

      You will at the very least need the right starter combination as well as the shifter linkage, have you figured out your ECU situation? sounds like a great project, let us know how it turns out!

      Thanks for commenting!

  3. Hi I want to install a k20a into my 1999 honda civic si and knowing how the motor faces would I be able to install an air/heater conditioning system that would fit my em1?

    • Hi Issac, thanks for reading.

      You can get this done, however it’s going to be a tight squeeze. What you will need is both sets of air compressor lines, and a reputable hose and fitting shop or company that will fab you the distance and fab it correctly. Bracketry will be required to mount the right compressor, but we’ve seen more than our share of nice setups here in California.

      Thanks for commenting!

  4. Hi me again. My question is once I install the k20a engine what would be the best type of speedometer to put in the dash.

  5. Hi there I jus recently bought a 2003 type s but the engine block was blown threw a rod and I found a k20z1 and was wondering if it would be a direct fit or it there’s modifications needed to fit my stock a2 trans

  6. I have a 2003 rsx-s and I lm trying to swap the k20a2 for a k20z1. Does anyone know if it would be a direct swap or would I need to change harnesses,ecu or anything like that?

      • So would I need to swap the speed from the k20z1 over to my k20a2 trans? And would I also need an 05 rsx-s dash? And would I need to make some hoses fit to the k20z1 imrc or would the hoses from my k20a2 work?
        Sorry for asking so many questions I just want things to go smoothly and not make any costly mistakes

  7. Hi great info… Im thinking of swaping my k20a3 for a k20a2 on my rsx base … Will i need k20a2 ecu and harnes?

  8. example lets say I have A Rsx Acura type s with k20a2 complete car
    and i have my eg 92 Civic hatch ready for the swap
    what parts of the acura can i use besides the Engine and tranny?
    can i use the acura rsx ecu for my eg k20 swap?

  9. Hey so i was looking at a K20A3 to drop into my 2000 Civic Ex Auto and the motor i was looking at came with the power steering, ECU, and Alternator. would i be able to use these in the swap or would i have to run a different ECU and Alternator? Also in the process of converting from and Auto D16y8 to a manual K20A3 would there be a significant difference in that other than the fact that i would need a clutch pedal and master cylinder?

    • Hi Julian, thanks for commenting

      Going to a K20A3 in your EK is a great swap but you’ll have to pick up a few conversion parts to make it fit, namely the power steering. You will also need to eliminate the security, or choose a standalone ECU for your swap.

      As far as the manual swap, opt for the EK Honda civic pedal assembly and the master cylinder. You’ll need to modify the shifter area to fit the shift kit box and cable assembly, because you’ll need the RSX shifter.

      Sounds like a great swap! Let us know how it turns out!

  10. What axles should I run if I have a type S halfshaft and what axles should I run if I have a base model halfshaft this is for a 92-95 eg running a k24 bottom and type s head. I seem to be having an issue with the passenger side axle fitting.

  11. Hello, I’m Ahmet.
    I have a 95 Honda Civic sedan and I got a k20 that I want to install in it but I don’t know what are the necessary stuff I’m going to need to swap it.
    The k swap come with everything tranny, Ecu, harness, alternator, radiator, I mean everything from ep3. I just little advice before I do the swap.
    Thank you. Hope to hear from you soon.

    • Hi Ahmet, you will need the motor mount kit as well as the shifter modifications that we went over in this guide above.. you will also need an immobilizer kill or a standalone ECU to get past the factory Honda security. Sounds like a great setup! Thanks for commenting!

  12. I am thinking of putting a k20a in my 1983 honda civic 1500 dx. It’s auto right now and I want to change it to standard. So my question is what will I need to do the swap.

  13. My only question because I didn’t see it i have a totaled rsx type s with a a3 motor I’ve got mounts,header,shifter already ordered from k-tuned for my 92 eg hatch. Only issue I haven’t found is what to do about the clutch master cylinder. Do I just take the master out of the rsx? Does it mount up to the eg firewall where that stock clutch master would be? I’m ordering a k tuned master clutch cylinder but want to make sure it will go right in. Also the cables are they the same or do I need swap cables? Hope you can answer my questions. I also already ordered the k-tuned swap harness.

    • Hi Robert! thanks for reading!

      You can rock the EK clutch master cylinder, but I’d recommend stepping up to a larger bore CMC from the Honda S2000. You can see this part here : http://prostreetonline.com/products/blox-s2000-clutch-master-cylinder. You can use an adapter to make this a plug and play affair in your engine bay, and you can then adapt your clutch line or convert to a fully hydraulic brake line, depending on the transmission slave cylinder you are using.

      If you are using a K20Z1 or K20Z3 clutch slave cylinder, the size should be 8th inch NPT banjo. If you are using the K20A/A2/A3 slave cylinder it’s a different size however. Whichever method you choose to go in your K series swap, it’s best to try and keep as much hard line as possible. That will keep your clutch “slippable” and easy to modulate.

      Thanks for commenting! Sounds like an awesome swap! let us know how it turns out!

  14. Hello,
    I am swapping into my 2007 Civic Si Fa5 a k20a1 Integra R motor and transmission. It is a full assembly (engine, tranny, ecu, alternator, starter, shift cables, manifolds etc..) What else would I need to make this swap complete? Will the stock motor mounts work? Will any combination of throttle body/air intake work? Will any other modifications need to be made since its simply swapping my k20z3 for the k20a? Are there any upgrades you would strongly suggest before installing the type r k20 (clutch/flywheel, timing chain tensioner etc..?) Thanks!

    • Hi Brandon! Sounds like an awesome swap there and yes if you have a K series Type R engine you are ready to go! I would suggest:

      Tuning your ECU
      Changing your timing belt
      Water pump

      Let us know how your K series engine swap turns out! Sounds awesome!

  15. Thanks for the guide! I have a 97 civic ex with a D16a and I’m doing a swap for a k20a3. I had before an ep3 so i mostly have all the parts from her. Im just woundering what more I’ll need and and if most of the parts of the ep3 will fit?

    Thanks and have a nice day!

    • Janbo, if you have an EP3 donor more than half of the work is already done!! Just pick a good engine mount set and make sure to buy the right axles! Sounds like a great project!

  16. Hi there. I plan on swapping an auto k24a2, out of an accord/tsx, in my auto 2000 civic sedan which currently has a d16y5 motor. Since its going to be an auto to auto swap it will save me the manual tranny issues. The engine comes with complete wiring harness, sensors, ecu, tcm, alternator, ps and the axles as well. ive seen many write ups on the manual k20a2 swap but nothing on the k24 auto swap. i will try not to get the drive by wire motor for lesser electronic issues. i understand no swap is easy but would love some tips on what parts can i use from the accord and what other do i need to source. also ive seen guides mentioning the ep3 subframe which isnt mentioned in your guide. really looking forward to your valuable advice on this swap.

    Thanks in advance.

    • Hi Taha, you won’t need the subframe for your K series Honda swap, however you will need a customized auto transmission side mount. You will also need to source / measure / have your automatic axles customized. If you are ditching the drive by wire, you will be faced with the issue of your TCM/TCU being confused or not being able to shift.

      In short if you are swapping in an auto, you need to keep everything as you have it. This allows you to retain the automatic K series transmission ECU, and the functionality of the automatic transmission. You will also need to figure out the shift cables, as the throw is definitely not the same between your Ek civic and your K series engine / transmission swap.

      Best of luck to you! Sounds like an awesome swap. Let us know how it turns out!

  17. I currently own a 2003 EM2 4 door and looking to do the swap how do i know where to start and what parts i should be buying in order to get going with the swap I’m looking at doing ITR JDM K20 . and i was also wondering once the swap done is possible to convert from 4 bolt to a 5 bolt hub

  18. Looking for some help, please. I put a K20A into My 06 Acura Rsx Type S, running it with an RBC intake manifold, with the Karcepts adopter and a Weapon R ram intake, long tube headers and exhaust. From My understanding I could use the ecu off of the K20Z1… everything is installed now, except that the car doesn’t want to stay on. It turns on but it turns off after giving it some gas. Would you have any idea what it could be???

    • Hi Julian, have you used an OBDII scanner to read the real time values from your ECU? I would start there and begin with the basics.

      Check TPS voltage
      Check MAP voltage

      and go from there! Thanks for commenting!

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