Runge Engineering Tested Bespoke Flat-Eight Engine
The new 5.3-liter power plant is designed for installation in classic Porsche 911 sports cars.
Updated on Oct. 11, 2026 in Performance Vehicles
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Minnesota-based Runge Engineering has successfully completed dyno testing on a custom air-cooled flat-eight crate engine. The high-performance unit is engineered to fit directly into 1974 to 1989 Porsche 911 chassis without firewall modifications.
Why it matters
This engine allows owners of classic Porsche 911 vehicles to adopt a flat-eight configuration, a layout the manufacturer never offered for production road cars. The architecture draws inspiration from the historic Porsche 917 racing engine design.
The engine features a 32-valve configuration, dual overhead cams per bank, and a 12:1 compression ratio. While past bespoke engine projects from similar workshops have reached costs around $250,000, official pricing for this model remains pending.
The players
Runge Engineering
A Minnesota-based automotive workshop specializing in bespoke engine design and custom vehicle fabrication.
Porsche 911
A legendary German sports car platform known for its rear-engine, air-cooled performance heritage.
The details
The bespoke engine bolts into existing engine bays to maintain the structural integrity of the vehicle. It utilizes a design referencing the power plants that propelled the Porsche 917 to victory at the Le Mans endurance race in 1970 and 1971.
Timeline
1970 and 1971: Porsche 917 models won the Le Mans endurance race.
1974 to 1989: The original production years for the Porsche 911 G-body chassis.
December 2026: The expected release date for horsepower, torque, and pricing figures.
Roadmap
This development represents a niche evolution in the air-cooled performance market, bridging the gap between historical racing technology and vintage road car restoration. It signals a continued trend of high-end engineering firms enhancing the output of legacy chassis rather than replacing them with modern electric drivetrains.
Owners of 1974 to 1989 Porsche 911 models will be able to upgrade their engine bay with a flat-eight unit without needing to modify the vehicle's firewall. This provides a plug-and-play option for those seeking racing-inspired power while preserving the original chassis design.
The takeaway
Engine enthusiasts looking to upgrade vintage Porsche 911s now have a new path to install flat-eight power in a street-legal format. This project highlights how bespoke engineering firms continue to push the performance limits of air-cooled engine architectures.
What happens next
Performance figures and pricing for the new flat-eight engine are scheduled to be released in December 2026.
Further reading
For more on high-performance retrofits and custom builds, explore our Performance Vehicles section.
Live Poll
Would you pay a premium price for a custom, performance-focused engine swap for your classic car?
