CAPABILITY INSIDE FLEECE PERFORMANCE ENGINEERING’S NEW CUMMINS STREET HEAD
The trickle-down effect from the competition diesel segment has a unique way of impacting the rest of the industry. Although the parts and pieces on display at truck pulls and drag races are used to support obscene amounts of horsepower, they’re also engineered to stand up to extreme heat, pressure, and stress. After these components prove themselves in diesel’s harshest environments, it’s no wonder a lot of the same technology makes its way onto our daily drivers. With the cylinder heads they were building for their pulling and drag racing customers proving to be rock-solid reliable, the folks at Fleece Performance Engineering decided to bring the same proven components and techniques to the masses with the release of their new line of Cummins cylinder heads.
Coined its Freedom Series heads, two versions are available: Street or Performance. Each Street head is rated for 700 hp at the wheels, while the Performance version is good for 1,100 rwhp. This time, we’re walking you through the in-depth process that unfolds when you order a Street version for your ’07.5-present 6.7L Cummins. Using state-of-the-art equipment and processes, each unit is thoroughly inspected and deep-cleaned, and then it’s fitted with new valve guide liners, oversize valve seats, and fresh valve springs. After that, the factory weak links are permanently addressed and the head undergoes a series of validation tests before being allowed to leave the premises. Stay tuned for Part 2, where we’ll detail the extensive upgrades performed on Fleece’s Performance cylinder head.