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TF-Works RWD L15 E30 Swap Kit

Posted by William on 19th Feb 2025

Introducing the TF-Works L15 E30 Swap Kit

We are excited to announce our all-new L15 E30 Swap Kit, designed to bring a lightweight, modern, and responsive powerplant to the classic E30 chassis. Our kit leverages the Honda L15 turbo engine and the ND2 Miata transmission to deliver a balanced and engaging driving experience. In this post, we will dive into the reasoning behind our choices, key features of our swap kit, and what makes the L15 such an exciting engine for this application.

Why the L15?

The Honda L15 is a modern 1.5L turbocharged, direct injection, high compression engine that provides a great mix of power, torque, and efficiency while maintaining a lightweight package. It’s an ideal choice for the E30 chassis due to its:

  • Low nose weight for improved handling
  • Excellent response and torque for its size
  • Great fuel economy due to modern engine design

A complete L15 setup—including engine, harness, engine mounts, turbo, downpipe, intake manifold, intake, transmission, clutch, flywheel, intercooler and piping, filled with fluids—weighs just 387 lbs!

l15-engine-weight-will-carrying.png 

This low engine and transmission weight allowed our full interior with subwoofer e30 to weigh just 2323lbs!  

e30-l15-weight.png

Power & Cost Breakdown:

  • Non-Si Engine (~$500 used): ~240whp / 260 ft-lbs (on E85)
  • Si Engine (~$3,000 used): ~265whp / 285 ft-lbs (on E85)

Why the ND2 Miata Transmission?

Our search for a lightweight transmission with great driver engagement led us to the ND2 Miata 6-speed manual. After testing one on track, we were convinced:

  • Price: ~$1500 used, lightweight and well-matched to the L15
  • Excellent shift feel and engagement
  • Affordable and widely available

With our adapter plate, the ND2 transmission bolts to the L15 with minimal hassle, retaining the OEM L15 starter. Using our billet flywheel and single-disc clutch, this setup delivers a smooth and fun driving experience while maintaining OEM Mazda reliability with the stock Miata slave cylinder.

Development of Our Swap Kit

1. Billet Oil Pan & Pickup

We applied our K-series swap oil pan experience to develop a billet, heavily baffled oil pan with a matching oil pickup for proper oil control in spirited driving.

2. Engine & Transmission Mounts

Our engine mounts are designed to work with OEM BMW E30 Rubber engine mounts, keeping NVH low while ensuring a proper fit. To secure the ND2 transmission, we designed a billet transmission mount, eliminating the Miata’s factory power plant frame mount.

3. Custom Coolant Housing

The OEM Honda rear coolant housing is bulky and would intrude into the firewall in a RWD application. To solve this, we developed a custom low-profile coolant housing that:

  • Simplifies radiator plumbing
  • Allows the engine to be closer to the firewall keeping weight rearward
  • Features bungs for bleeding and temperature sensors

4. Turbo Inlet & Outlet Housings

The stock turbo inlet and outlet are not ideal for swap applications. We designed a billet compressor inlet/outlet housing adapter to make intake and intercooler plumbing much simpler. Additionally, our 3D-printed swap-friendly MAF housings support higher-than-OEM airflow for both Si and non-Si engines.  The adapter also features a more common 2.5" and 2.0" to allow for anyone wanting to use this for other applications. OEM sizes are 2.3" and 1.85"

l15-e30-tf-parts.png

Additional L15 Platform Development

Beyond just the swap kit, we are investing in the L15 platform as a whole. One of the major weaknesses of the L15 is its OEM head gasket. To address this, we collaborated with P1 to develop a head stud kit to increase clamping pressure which alongside a Cometic 5-layer gasket vastly improves head gasket reliability issues in high-performance applications. Read more about it here.

What’s Next?

We are committed to making this the most complete swap kit possible. Here’s what we’re working on next:

  • Plug-and-play radiator package with hoses (including heater hoses)
  • Bolt-in intercooler kit with pre-made charge piping
  • Turbo-to-tip exhaust system, including a downpipe and full exhaust
  • Complete plug-and-play wiring harness, making the swap as seamless as possible. Simply plug into an OEM L15 Honda ECU, flash a Hondata Swap FlashPro tune, and hit the road!

The first parts are available now, and the rest will be rolling out over the coming months as we complete testing and ensure they meet our TF Works standard.

Get in Touch

If you have any questions about our L15 E30 Swap Kit, give us a call or send us an email. We’re excited to see what enthusiasts will build with this platform!