Race Cars

How Mazda, Roush and Mahle Worked To Make A Great Spec Engine — Part 1

Mazda Motorsports, Roush Performance and Mahle Motorsports have worked together to make the new 2020 Spec MX-5 v2 engine one of the best spec engines in club-level road racing. They set out to create an affordable engine, with good power and torque levels. The engine is currently available professionally assembled for $7240. The new engine package delivers about +15 horsepower over the stock NC MX-5 engine.

Another key goal, along with affordability and performance, was to make the new engine work well for spec racing. That means engines need to be as close to identical as possible, which further implies that cheating must be difficult. Mazda wanted to take three approaches to accomplishing this. The first is that the flow and combustion characteristics are optimized. This means that race shops or drivers trying to modify the engine will not have an easy time finding improvements.  Second, the already tight OEM tolerances are further tightened during the optimization process, with the result that sample-sample variation is low. Finally, a set of measurement tools are available to make it easy for sanctioning bodies to check if an engine has been modified.

The key spec racing features of the new Spec MX-5 engine are:

  • Strict port sizing
  • Tight tolerance port opening
  • 3d puck for testing port size and shape (inspection tool )
  • serialized CNC heads with documentation.
  • camber volume is spec for intake, exhaust and combustion.

Mazda chose not to create a sealed engine as a requirement for the series in order to take a further step toward affordability. If shops and drivers can build their own engines, they may save on assembly costs, reduce shipping costs and be better able to get cars back on the track quickly. Stock donor cars can be converted to the Roush head and Mahle pistons for slightly over $3000.


More information on the new engine, including ordering instructions is available here.

Information on buying a complete car is here.

Additional information on the design program is here:




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