LONG-HAUL DURABILITY, 700-HP CAPABILITY
INSIDE FLEECE PERFORMANCE ENGINEERING’S NEW CUMMINS STREET HEAD
BY MIKE MCGLOTHLIN
With a core program that brings in all kinds of different candidates, some heads show up looking like this—reason enough to justify why a thorough cleaning takes place before each unit can be properly evaluated. A core charge of $700 is incurred by the customer with the purchase of Fleece’s Street head (the head itself running $1,836.45), but is fully refunded once the unit they’ve sent back passes inspection.
Once a core cylinder head has been stripped, cleaned, and qualified as reusable, the remanufacturing process begins. Here, three pallets of heads (approximately 30 units) are about to begin circulating around Freedom Racing Engines (the machine shop and engine building side of Fleece’s Indianapolis area operation), where they will either be transformed into a Street or Performance version of their former self.
The day we sat in on the machining and assembly process, our guides were the head of Freedom Racing Engines’ Cummins cylinder head program, John Benshoof, and machinist and assembler, Brandon Smith. To initiate the Street head build, Smith placed the usable core head in Freedom’s Haas VF-4SS vertical machining center to be decked. During resurfacing, between 0.003 and 0.005-inches worth of material is removed—a number that varies depending on how untrue the head is to begin with.
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.