A bit About Vehicle Selection and Compliance
What is discussed below pertains to completing the engine swap by means of replacing the factory Mazda subframe with a tubular subframe.
This is necessary for RHD vehicles to gain additional clearance in the engine bay and around 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.
- NA MX-5 can be swapped and road registered
- NB MX-5 cannot be road registered but can be used as off-road (motorsport) vehicles
We intend to investigate options to have a road legal NB swap in 2022.
K20 vs K24
A K24 block is ~20mm taller than a K20 one and if you are considering doing this engine swap into a NA chassis, this is the difference between being able to 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.
It may be that the cost of K24a3 engines is cheaper than K20a2s, but the long motor cost is only a fraction of the total build cost, and the cost and time of organising a custom bonnet and/or modified valve cover also needs to be taken into account.
What we have done to date
We have completed the installation of a K20a2 into a right-hand drive 1991 Australian delivered Mazda MX-5.
We took on this project because we believe the Honda K-series engines to be the perfect modern power plant for the MX-5 chassis and were confident that with our understanding of chassis engineering we would be able to solve the issues specific to right-hand drive vehicles.
Our car is running, driving and tuned.
It made 127kwatw on the dyno and now drives like a far more balanced vehicle in terms of it’s acceleration and cornering performance.
Honed NA6
- 1991 Mazda MX-5 NA6
- Honda K20a2 Engine
- Mazda 6 Speed from NB
- Larger 1.8 differential
- NA non-power Steering Rack
- Haltech 1500 ECU
- Aluminium radiator
- Bespoke exhaust manifold
- 2.5″ cat-back exhaust
What is available today
- 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.
What are we Bringing to the Table?
- RHD specific subframe to suit S2000 engine mounts
- Engine-side mounting brackets to suit either K20 or K24
- S2000 engine mounts
With the plans that are currently in place, these items will be released in January/February of 2022.
The approximate cost of these combined will be between $2300-2900 AUD
What’s Coming Beyond That?
We are evaluating developing the following products to support MX-5 and other RWD K-Series swaps
- Cast aluminium water outlet housings
- Throttle cables
- Exhaust manifolds
This article will be continually updated,
If you have any specific questions you can contact us via email, our address is