July 17, 2019 – The NMRA/NMCA Technical Department addressed turbo modifications in 2019 class rule sets and again in a statement on March 26, 2019. Over the last few months, the NMRA/NMCA Technical Department have seen several turbochargers (not in competition) that feature modified turbine wheels. This type of modification is highly susceptible to failure due to the center hub being cut-down from its original design. This increase in potential failure can create a very hazardous scenario, something that has been observed at other non-NMRA/NMCA events this year. As a reminder, due to the safety risk, “Any modifications to compressor or turbine wheel, blades, hubs, cover, or housing, as originally manufactured is PROHIBITED.”
Here is an example of a standard exhaust wheel from a manufacturer.
Here is an example of a modified version and a modified wheel that experienced hub failure.