300+ BHP Abarth 500 Demo Build – Part 1
Prometeo LSD Installation & Gearbox Preparation
Welcome to Part 1 of our 300+ BHP Abarth 500 demo build series.
This car is being developed as the foundation for our next-generation TMC Motorsport turbo kits, moving beyond our long-established 285 BHP packages and into the 300+ BHP range.
Before adding more power, we’re focusing on something just as important.
Putting the power down properly.
Why We Started with the Differential
The factory open differential in the Abarth 500 / 595 / 695 platform works well at standard power levels. However, once torque increases significantly, the limitations become clear.
Inside wheel spin under load.
Reduced traction on corner exit.
Torque steer.
Inconsistent power delivery.
At 300+ BHP, traction is essential.
The first major mechanical upgrade in this build is the installation of a Prometeo Limited Slip Differential, fitted by our partners at ADEdmundson, who currently run the UK’s fastest 1.4 T-Jet.
Why We Chose Prometeo
There are several strong ATB differential options available. This decision was not about criticising other brands. It was about choosing the most complete solution for this specific build.
The main reason we selected Prometeo is simple.
The kit includes new bearings and seals within the purchase price.
When building a gearbox designed to handle significantly increased torque, refreshing all wearable components during installation is simply the correct engineering approach. Reusing old bearings on a high-stress build is not something we are prepared to do.
The exact unit fitted to this car can be found here:
Prometeo LSD Abarth 500 / 595 / 695 C510 (With Bearings and Seals)
https://www.abarthtuning.com/products/prometeo-lsd-abarth-500-595-695-c510-with-bearings-and-seals
The package includes the differential unit itself, along with new bearings and seals, allowing the gearbox to be built correctly from the outset.
No shortcuts.
Technical Overview – Prometeo ATB Differential
The Prometeo LSD is a helical gear, Automatic Torque Biasing differential.
Unlike plated differentials, it does not use clutch packs. Instead, it operates through helical gears to distribute torque mechanically to the wheel with the most grip.
This provides smoother, progressive torque transfer.
No friction plates to wear out.
No servicing intervals related to clutch packs.
Improved traction under acceleration.
Reduced inside wheel spin.
More stable front-end behaviour under load.
For a high-powered front-wheel-drive platform, this creates controlled and usable power delivery, especially as torque levels increase.
Installed by ADEdmundson
The installation was carried out by ADEdmundson, ensuring the gearbox was assembled to a standard capable of handling the next phase of this project.
With the differential fitted and the transmission refreshed internally, the car is now properly prepared for significant torque increases.
What’s Next?
This is only the beginning.
Over the coming weeks, we will be documenting internal engine upgrades, turbo system development, supporting hardware selection, mapping and testing, dyno results, and real-world performance analysis.
This demo car will form the backbone of our next-generation turbo range, and we are building it properly, step by step.
Stay tuned for Part 2.
