Committee) SMX Single Source Engine
#38524 from Spec Mazda (SM/SMX · Member feedback requested · Minutes (2025-07 Fastrack)
SMX Racers,
The Spec MX-5 (SMX) class was founded in 2019 on four key pillars: Reliability, Techability, Affordability, and Fun to Drive. Now
in its second year as an SCCA national class, SMX continues to thrive.
However, we have observed increasing engine development that begins to drift from these core pillars. To address this, SMX is
evaluating the possibility of transitioning to Roush as a single-source engine provider, beginning with the 2027 Hoosier Super
Tour season.
Continued development and innovation can unintentionally add cost, reduce reliability, and create performance disparities
among competitors. These factors can compromise the long-term health of the class. Moving to a single-source engine supplier
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helps ensure parity while staying true to the founding principles of Spec MX-5.
Under the proposed Roush single-source model, all engines would be run-in on an SAE-certified dyno cell with break-in oil, and
additional power pulls would be conducted to verify output and ensure class compliance. Roush currently maintains an SAE-
certified dyno tolerance of approximately 1.5%, which keeps the field as competitive as possible while managing costs. A 2-3
year price freeze and some version of an exchange/rebuild program would also be part of this plan.
We value your input on this important decision. Please share your comments and connection to SMX (Driver, Crew, build in
progress, etc).
Thank you for your continued support of the Spec MX-5 class.