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- Porsche 991.1 Turbo 3.8L (520 Bhp) 2014-16
- Porsche 991.1 Turbo S 3.8L (560 Bhp) 2014-16
Intercooler to Cut-Off Valve Pressure Hoses
These intercooler to cut-off valve pressure
hoses are designed for the Porsche 991.1 Turbo and form an essential part of
the charge air system. They connect the intercooler to the cut-off (diverter)
valve, ensuring controlled airflow and pressure regulation within the turbo
system.
Fits:
- Porsche 991.1 Turbo 3.8L (520 Bhp) 2014-16
- Porsche 991.1 Turbo S 3.8L (560 Bhp) 2014-16
Diagram ref no 5 and 6
In a high-performance twin-turbo engine, managing boost pressure is critical. These hoses allow pressurised air to be routed correctly between components, supporting both performance and system protection.
What These Pressure Hoses Do
These hoses link the intercooler to the cut-off valve, which regulates excess boost pressure when the throttle closes.
They help:
• Maintain stable and controlled boost
pressure
• Allow excess pressure to be safely redirected via the cut-off valve
• Ensure smooth throttle transitions and turbo response
• Support efficient airflow within the charge air system
• Protect turbochargers from pressure surges
A properly functioning hose ensures the turbo system operates smoothly and efficiently.
Why Intercooler to Cut-Off Valve Hoses Fail
Due to their position within the turbo system, these hoses are exposed to high pressure, heat and constant airflow.
Common causes include:
Heat and pressure cycling
Repeated expansion and contraction weakens hose material.
Cracking or splitting
Rubber or reinforced sections can degrade over time.
Boost pressure stress
High boost levels place additional strain on hose walls.
Seal and connection wear
Clamps and joints may deteriorate, leading to leaks.
Symptoms of Failing Pressure Hoses
• Boost leaks or inconsistent turbo pressure
• Hissing noise during acceleration or gear changes
• Reduced engine performance
• Poor throttle response
• Engine warning lights related to boost control
• Increased turbo lag
Replacing worn hoses restores proper boost regulation and system efficiency.
Why You May Need to Replace These Hoses
Restore Boost Control
Ensures the cut-off valve operates correctly under all conditions.
Eliminate Boost Leaks
Prevents pressure loss within the charge air system.
Improve Throttle Response
Supports smooth transitions during acceleration and gear changes.
Protect Turbo Components
Prevents pressure spikes that can damage turbochargers.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99111023
The product you are viewing cross references to these numbers
- Porsche 996 C2 3.4L 1997-08/01
- Porsche 996 C4 3.4L 1997-08/01
- Porsche 996 C2 3.6L 09/01-2005
- Porsche 996 C4 3.6L 09/01-2005
- Porsche 996 C4S 3.6L 09/01-2005
To Fit:
Porsche 911 (996 Turbo), GT2 manual and auto 1999 to 2005
Significant advantages with do88's Porsche Performance Intercoolers & Silicone Hoses:
• Equivalent OEM numbers, 997.110.639.00, 997.110.640.00 (ref only)
• Core Volume: 6825 cm³ (4821 cm³), do88 41% larger!
• Lower post Intercooler Air Temperature at same conditions: OEM 50°C (122°F), do88 34°C (93°F)
• See enlarged images for test data results!
These Intercoolers are constructed to deliver the best cooling efficiency during tough conditions. Exclusively manufactured in aluminium with continuous welds, they guarantees reliability and endurance when you really need it. The increased core volume improves cooling efficiency and lowers the intake air temperature. Do88 have undergone thorough testing under severe and continuous conditions to ensure the absolute best performance! These Intercoolers are immensely optimized to allow the maximum core size in the given space without compromising on easy drop-in-fitment. This is the undoubted choice for the inspired enthusiast or the race car driver demanding reliability at the limit.
This package is supplied with everything you need for fitment, including Silicone Hoses, Screws, Brackets and Clamps.
The Boost Pressure Hoses included in this Kit are Silicone reinforced 4 ply polyester fabric for optimum airflow, performance and reliability!
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
ICM-200-996
The product you are viewing cross references to these numbers