IMSA rule change allows JDC-Miller's Porsche 963s to continue

On Monday, IMSA issued a technical bulletin to GTP competitors which will allow previous-spec versions of existing cars, or any car homologated before the 2026 season, to take part in the current WeatherTech SportsCar Championship.

This clarification allows Porsche customer team JDC-Miller MotorSports to use the 2025-spec Porsche 963 this season. While Porsche unveiled its new Evo ‘joker’ package featuring a new splitter, engine cover, and diffuser on the two factory Penske cars, JDC-Miller’s No. 85 Porsche 963 ran in the 2025 configuration.

Before Monday’s rule change, JDC-Miller, which has two Porsche 963 chassis in its Minnesota shop, would have been required to race with the latest homologation of the 963.

In a statement given to RACER, JDC-Miller MotorSports managing partner, John Church, said, "Updating two cars just wasn’t in the budget for 2026. We are very grateful to IMSA and Porsche for working with us. As you can see from yesterday’s rule change, this wasn’t a trivial thing for them to do. They recognize that this is the kind of thing that keeps a privateer team on the grid.

“It’s huge for us. They see it as ultimately good for the sport, and we truly appreciate that.”

Both variants of the Porsche 963 will use the same Balance of Performance parameters at the Rolex 24 At Daytona.

Technical Bulletin #26-17 reads: "IMSA, in its sole discretion, may permit a GTP Car Homologated prior to the 2026 Season to participate in the IMSA WeatherTech SportsCar Championship.

"Any such Car must comply, in its entirety, with the applicable Homologation Form and the most recent LMDh Technical Regulations under which the Car was originally Homologated. The Homologation specification applicable to such Car shall be considered frozen and not be partially or selectively updated.

"Notwithstanding the above, IMSA may, at its sole discretion, require a Car Homologated prior to the 2026 Season to comply with specific provisions of the 2026 LMDh Technical Regulations, as expressly designated by IMSA. Any such requirement shall be strictly limited to the provisions explicitly identified by IMSA and not be interpreted as permitting the selective adoption of 2026-Homologated components, specifications, systems, or configurations beyond those expressly mandated.

"Transition from one Homologation specification to another is permitted only with express IMSA approval and be implemented in full when the Car is entered for the applicable Event and subsequently the remainder of the Season.

"IMSA reserves the right, at any time, to approve such participation and to determine compliance, eligibility, and conformity with all applicable Technical Regulations, Homologation Forms, and Technical Bulletins.”