4.1 Limited Pro Stock Turbo for 2026
FOR IMMEDIATE RELEASE
October 28, 2026
OTTPA Announces Turbocharger Rule Update for 2026 Limited Pro Stock Tractor Class
The Outlaw Truck and Tractor Pulling Association (OTTPA) has announced an important update for the 2026 pulling season regarding the Limited Pro Stock Tractor class. Beginning in 2026, all vehicles competing in this class will be required to run the 4.1 box turbocharger from Harts Diesel.
OTTPA has seen strong success with standardized turbocharger programs in other divisions including the Wimer box turbo in the 5.0 Pro Stock class and the box turbo currently used in the Super Farm class. After careful review and conversations with multiple suppliers, three proposals were received, and the Harts Diesel 4.1 smooth-bore box turbocharger was selected.
A key objective of this rule change is to ensure fairness and equal performance across the class. To eliminate any perception of favoritism, Harts Diesel will produce all turbos and ship pallets of turbos to three designated distribution locations. Pullers will have the opportunity to personally select their turbo from these pallets, ensuring complete transparency in the distribution process.
The Limited Pro Stock Tractor class originally launched using a box turbocharger, which contributed to large, competitive fields with over 20 tractors at many events. Over time, the number of competitors has declined due to increased costs and component failures. This rule change is designed to reduce breakage, control costs, and help rebuild participation within the class ensuring the long-term strength of the class and continued value for our promoters.
OTTPA remains committed to supporting fair, competitive, and sustainable pulling classes for all members and fans.