Compatibility Guide for RX8 K Swaps
We get asked about K swapping the RX8 platform almost daily here at KPower. The firewall of the RX8 needs to be cut to fit a K series, so this has kept us from building a complete RX8 swap package. However, we've worked with some of our do-it-yourself RX8 swap customers to check compatibility of many KPower products, and we're excited to share our findings.
If you need some assistance planning your project, do not hesitate to reach out to Dustin, our build advisor, by calling 847-865-5739 or clicking this link to schedule a 15 minute phone call.
From our K24 NC MX5 catalog, we know that the KPower NC subframe is a direct replacement unit. When combined with our KPower engine mounts and either the factory NC Miata engine mounts or our KPower-spec AWR engine mounts, you can bolt the engine into place.
Our engine placement location is nearly identical to the currently performed K swap builds, the benefit is our subframe does not require steering rack spacers to be used with NC Steering rack. Just like any other K swap, you should expect extensive firewall modifications that will certainly require cutting and welding. The ABS system may need to be massaged as well, which we understand is common on K swap RX8 builds.
From here, you have the option to retain power steering in a few ways. Our KPower NC Power Steering kit allows you to plug and play a complete NC steering rack and hydraulic system into the RX8, providing an opportunity to ditch the CANBUS EPS system. If you prefer electric steering, we offer a full standalone Electric Power Steering system for the RX8.
Our NC Air Conditioning kit can also be used; simply mount a stock NC AC compressor and have your favorite local AC shop build the AC lines for you.
We provide the best bang-for-buck, dyno tested, reliable, and efficient intake manifold on the market: the KPower Cast Intake Manifold. Pair this with a 74mm drive-by-wire Bosch throttle body and a 3D-printed vibration-absorbing adapter plate and you'll be able to retain drive-by-wire functionality. When fitting our intake manifold to the engine, we are told all of the mounting bolts need to be removed to slip the manifold into place.
We offer two fantastic OEM oil pan options that fit the tubular subframe, both modified by Unit2 Fabrications to include baffling and trap doors. These options are compatible with both the RBB balance shaft oil pump and the popular K20 PRB oil pump. Do not forget to purchase a K20 PRB oil pump conversion, or if you already have the OEM parts you'll just need our Modified K20 PRB oil pump, we have you taken care of!
KPower offers many in-house designed, produced, and tested transmission adapter plates and flywheels. Our NC transmission adapter plate and flywheel allow the use of the factory 2006-2015 Miata transmission. We also offer adapter plates and flywheels for BMW ZF5 or ZF6 which can be found in E36/E46 2.8L and larger vehicles, the BMW G260, and Toyota/Subaru 86 adapter plate and flywheel for those interested in alternative transmission options (we recommend the Verus Clutch fork for the 86 transmissions). We offer the clutches you need for any of those solutions on our Clutch Collection page.
For coolant hoses, assuming you are running a K24A RBB long block, you'll need to run an intake manifold side upper coolant hose configuration. Our NC upper coolant neck is the answer.
For electronics and wiring, we recommend a Haltech Elite 1500 ECU, and our new Haltech Elite 1500 drive-by-wire universal engine harness that fits perfectly around our intake manifold and supporting parts. This harness will pair with the Haltech Elite 1500 ECU, Haltech CAN WBO2, and the Bosch Oil Temp & Pressure Combo sensor. Given the GR86 CAN code has not been cracked, you will need to run a Haltech iC-7 or uC-10 Dash display. If you are getting deep into wiring, you can utilize the Haltech PD16 PDM system and Keypad options too! This route will get the engine running in a racecar build. Factory CAN electronic functionality will need to be sorted by the car builder, however we have heard if the factory engine harness is connected (including the ground cable), many of the OEM electronics will remain functional.
For fueling, a solid build starts with the KPower Fuel rail. We realize the stock K series injectors are likely clogged or have a deteriorated spray pattern, so instead of spending money on cleaning injectors that will be at 90% duty with simple bolt-ons, its always best to future proof! Get a better spray pattern and trust the best injector in the industry with some ID1050XDS injectors, or if you are shooting for turbo power to opt for the ID1300XDS injectors.
To dress up the engine bay, we always recommend our properly modified KPower Powder Coated Valve Cover that cleans up the engine bay while relocating a breather port to the most ideal location possible, on top of the valve cover and above the factory baffle plate. This gives plenty of space between the valve cover and firewall as well. To compliment the valve cover we recommend the Radium Vent To Atmosphere catch can as it is twin inlet from both ports on the engine, and vents out the top.
We recommend a motorsport grade fuel filter on any build, so the ID F750 fuel filter or Radium Canister style fuel filter will get the job done. To regulate your fuel, we recommend the often overlooked Radium Fuel Pressure Regulator with built-in damper to keep erratic fuel pressure readings at bay. A solid second option is the Fuelab FPR.
These product recommendations are the basis to a solid RX8 build! Again, please let us know if we can be of assistance as you plan out your project.
