adapter Genuine Porsche part 99111028203

Air Box Housing Lid Cover (with inlets).



Fits:
Porsche 991 / 991 S 2012>>
Porsche 991 GT3 3.8L 2014>>

Click 'Zoom in' for large parts diagram.
Diagram ref no 2

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99111021202

The product you are viewing cross references to these numbers

Air Box Housing Grill. Price is for each.



Fits:
Porsche 991 / 991 S 2012>>
Porsche 991 GT3 3.8L 2014>>

Click 'Zoom in' for large parts diagram.
Diagram ref no 6

Related reference numbers
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9GT129075

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Plastic cover for air filter housing. 

Fits:
Porsche 991-1 Carrera 2012-16
Porsche 991-1 GT3 2014-17 
Porsche 991-1 GT3 RS 2015-17
Porsche 991-1 GT3 R 2016

Porsche 991-2 GT3 2018-21
Porsche 991-2 GT3 RS 2018-21

NOTE: This cover is not suitable for 991-2 GT3 Touring models or the 991 Speedster. 

Diagram ref. 3.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99111023101

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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

Intercooler to Cut-Off Valve Pressure Hoses

These intercooler to cut-off valve pressure hoses are designed for the Porsche 991.2 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 991.2 Turbo Coupe 3.8L (540 Bhp) 2016-19
• Porsche 991.2 Turbo S Coupe 3.8L (580 Bhp) 2016-19
• Porsche 991.2 Turbo Cabriolet 3.8L (540 Bhp) 2016-19
• Porsche 991.2 Turbo S Cabriolet 3.8L (580 Bhp) 2016-19

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.

99111024

The product you are viewing cross references to these numbers

Intercooler to Cut-Off Valve Pressure Hoses

These intercooler to cut-off valve pressure hoses are designed for the Porsche 991.2 GT2 RS 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 991.2 GT2 RS 3.8L PDK (700 bhp) 2018-19       

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