Vehicle Selection and Compliance
In order to install a K20 engine in a Mazda Miata/MX-5 the factory Mazda subframe must be replaced by a tubular subframe.
However, the left-hand drive kits available are not suitable for right-hand drive due to the location of the steering rack and input shaft.
Vehicles registered after 1995 cannot be road registered with an aftermarket subframe due to more stringent crash and safety regulations.
As such, only the original NA-series model is able to be swapped and road registered, but the NB-series can still be swapped for motorsport use.
K20 vs K24
If you are considering K-swap, the most important difference is a K24 block is ~20mm taller than a K20 and this will dictate whether you can close a stock bonnet or not.
We found that even with the K20, it was necessary to modify the front of the valve cover in order to have sufficient clearance to the bonnet.
While a K24a3 may be cheaper than a K20a2s, the long motor is only a fraction of the total build cost, especially when taking into account the cost and time of organising a custom bonnet and/or modified valve cover.
Honed’s K20 MX-5 project
We have completed the installation of a K20a2 into an Australian-delivered, right-hand drive 1991 Mazda MX-5.
We took on this project because we believe the Honda K-series to be the perfect modern engine for the MX-5 chassis and were confident that our understanding of chassis engineering would be able to solve the issues specific to right-hand drive vehicles.
Our K20 MX-5 made 127kW at the rear whels on the dyno and now drives like a far more balanced vehicle in terms of its acceleration and cornering performance.
In addition to the K20 swap, the following upgrades were made:
- Six-speed gearbox from NB MX-5
- Larger differential from the 1.8
- NA non-power steering rack
- Haltech 1500 ECU
- Aluminium radiator
- Bespoke exhaust manifold
- 2.5-inch cat-back exhaust
Available K-swap parts
- Kpower K20/24 Intake Manifolds
- Kpower Throttle Bodies
- Kpower Transmission Adapter
- Kpower Flywheel
- Kpower Oil Pump Adapter
- Kpower Aluminium Sump
- RWD Coolant Outlet
You can find the retail pricing for these items here:
https://honeddevelopments.com/honed-kmiata-landing/
If your build was to feature all of the available Kpower products, the approximate cost of these is $4500-5000 AUD.
This article will be continually updated,
If you have any specific questions you can contact us via email, our address is