A 2008 Freightliner Cascadia with a Detroit Series 60 14L DDEC 6 engine recently underwent a significant overhaul. Along with six remanufactured injectors and a new injector harness, the turbocharger is being upgraded to a Garrett GT4708. This upgrade raises several important questions regarding compatibility and potential challenges.
The original turbocharger on the DDEC 6 engine utilizes a square-shaped flange, significantly smaller than the rectangular flange found on older engines using the Twin Turbo (T6) configuration. This difference in flange design is evident when comparing the new center section (Part Number 23537114) to the T6 divided gasket. The correct turbo gasket for the DDEC 6 is Part Number 23535457.
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The exhaust ports on the T6 turbo are considerably larger – at least 50% bigger – than those on the existing DDEC 6 manifold. This size discrepancy alone presents a compelling argument for upgrading to a turbocharger with a larger exhaust flow capacity. The increased airflow potential could lead to significant performance gains.
Further investigation revealed that the DDEC 5 exhaust manifold appears to have a T6 flange and an EGR opening, although the EGR configuration is different. The DDEC 5 manifold uses slip joints for connection, while the DDEC 6 manifold employs flanges and a flexible collar. This raises the question of whether a DDEC 5 exhaust manifold could be adapted to fit the DDEC 6 cylinder head.
A final consideration is the cooling system for the turbocharger. The original DDEC 6 turbo is both water and oil cooled, whereas the new Garrett GT4708 is oil-cooled only. This difference in cooling methods raises concerns about potential overheating issues and the long-term reliability of the oil-cooled turbo in a system originally designed for water and oil cooling. Understanding the implications of this change is crucial for a successful upgrade. Research into potential solutions, such as adding an external oil cooler, may be necessary to ensure optimal performance and longevity. Successfully navigating these challenges will be key to realizing the full potential of the Detroit Series 60 14l Turbo Upgrade.
