How does the K24 NC stack up to the original KMiata swap?

Feb 6, 2024

To say that we're excited about the K24 NC swap package is an understatement. Production is well underway, and we are targeting to have NC swap components in stock and ready to ship in the first half of 2024.

K swapping Miatas was our original claim to fame, and the nature of the NC chassis has given us some really cool opportunities to build the most refined KMiata swap yet.

Not sure which chassis to choose for a K swap? The NA and NB chassis are absolute performance bargains with a ton of potential (look no further than our turbo K24 NB race car). However, the NC chassis allows us to eliminate every complexity or minor compromise from the older swaps, and the end result is a beautiful thing. Let's compare the NA and NB swaps with the new NC swap and highlight the unique features of the NC.

 

Engine Bay Packaging Differences

For starters, the NC chassis allows for easy, factory-like exhaust routing. Our NC header fits in the same location as the stock header does. The entire header and 3" exhaust are tucked nicely into place above all undertrays and bracing, achieving factory ground clearance.

Secondly, the engine is tucked farther back in the engine bay compared to the NA/NB. This allows us to fit a stock K24 steel oil pan completely behind the stock steering rack and sway bar just by swapping to a roomier tubular subframe. No custom oil pan required!

 

 

NVH Levels (Noise, Vibration, and Harshness)

For the NA and NB swaps (and all other cars we support), a K20 oil pump with deleted balance shafts has always been a requirement. Thanks to the engine position and stock oil pan, we're able to retain the complete K24 oil pump and balance shafts. 

Additionally, the engine bay packaging allows us to retain OEM rubber NC engine mounts. With these two combined, the car feels stock, with zero NVH increase. Of course, dedicated race cars can still swap in a K20 pump or upgrade to stiffer mounts if desired.

If you're looking for a refined K swapped street car, the NC is tough to beat. Best of all, we datalogged oil pressures on our K24 NC test car during many track days and found that as long as there is enough oil in the engine, there is consistent oil pressure for track use.

 

Air Conditioning and Power Steering Solutions

Thanks to the inherent design of the NC, we were able to take a unique approach to the power steering and air conditioning systems on this car. The NA/NB platform requires an aftermarket A/C compressor and an electric power steering kit. However, on the NC, both of these systems function exactly like stock because we've adapted the stock NC power steering pump and A/C compressors to the K24!

Not only does this result in 100% OEM functionality, but it also lowers costs for the end user. We created a bracket that allows the factory NC power steering pump to mount above the K24 water pump housing, and the stock reservoir and lines are all retained in the stock locations, and steering feels exactly like it did from the factory.

We took a similar approach with A/C, but had to get even more creative. Since the K24 compressor won't clear the steering column, we mounted the stock NC compressor to the passenger/exhaust side of the engine with a custom-machined mount. The NC idler pulley is also reused for this application. Just two custom A/C hoses are needed, but otherwise, every component of the K24 NC air conditioning is unchanged and works exactly the same as a stock car.

 

Wiring Differences Between Generations

Each generation of Miata is easier to wire than the previous one. The NA is a bit challenging since the engine harness is integrated into the cabin harness and can't just be removed. Thankfully, the NB has a detachable engine harness, but even a Haltech-equipped NB with our All-In-One swap harness requires wiring to enter the cabin, and a few splices need to be made.

The NC's stock ECU is under the hood, so for this car, we were able to build a 100% plug and play engine harness that adapts the K24 and Haltech ECU to the chassis without even passing wiring through the firewall. The Haltech Elite 1500 and CAN wideband controller mount neatly on the passenger-side firewall. Two connectors mate the engine harness to the OEM cabin harness, and you're done!

 

 

Drive-by-Wire Functionality

Speaking of the Elite 1500, we've been really enjoying the drive-by-wire (DBW) throttle upgrade on our NA and NB swaps thanks to our new Haltech electronics package.

Converting these cable-driven cars to DBW gives us a ton more functionality, and the engine startup, idle control, throttle tip-in, and driveability are amazing. We can also take advantage of cool, performance-enhancing features such as auto blip downshifts, no lift upshifts, and traction control.

Thankfully, the more modern NC chassis came with DBW from the factory, so all of these perks are built into every K swapped NC without any extra expense.

 

Conclusion

Overall, the NC K swap takes everything we love about the classic NA/NB KMiata swap and adds a level of simplicity, refinement, and ease of installation to an already fantastic concept. We hope this post answers some of your questions while comparing the different swaps, and feel free to email us at info@kpower.industries if there's anything else we can do to help!