Runge Cars’ 5.3 L Flat-Eight on the Dyno

Runge Cars unveiled their 5.3 L flat-eight called “Hetzer” earlier this year. The air-cooled DOHC motor features a 102.7 mm bore, 80.4 mm stroke, 12:1 compression, and individual throttle bodies. Runge Cars designed the motor to fit in air-cooled 911 cars. The motor is within 2 mm tolerance of the “M64” flat-six engine and G-body mount points. Runge Cars completed assembly of prototype #01 motor and began dyno testing. The motor will run for 30 hours under different loads and then will be disassembled for inspection. If everything is ok they will assemble the motor and test it again on the dyno before being installed in a test mule. Runge Cars plant to release power and torque numbers in December 2026.

Source: Runge Cars FB page