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Purpose
 

Fuel rails are exposed to engine radiated heat.  Under some operating conditions, fuel may begin to vaporize when it becomes too hot for the prevailing fuel pressure conditions.  To minimize that, Porsche insulated fuel rails.  However, OEM material degrades with time and is useless after some time. 


Method
 

To address this issue, I have followed the example set forth by John Pirtle - thank You John.  I have used John's idea of employing a  pipe insulation over the fuel rails.   However,  to assure that the thermal properties of materials used will not degrade through out the entire range of engine compartment operating temperatures, I have decided to use materials rated for continues operation at or above 300°F.  
 

Components
 

The following are the materials I have identified for this application:

• Armacell HT Armaflex high temp pipe insulation and HT 625 adhesive - see spec data,
  
• McMaster Harsh-Environment Cable Ties - see spec data, and
• Heat Shield Aluminum Foil Tape.

Construction

• Fuel rails are wrapped with Heat Shield Aluminum Foil Tape:

 

• It can be seen in above picture that 1/5" ID is a bit too small for this application,
• after insulation is cut open along the pipe are wrapped around the rail there is about 1/5" gap that cannot be closed,
  
• I have used the excess length to fill the gap and bond it with Arnmacell's HT625 Adhesive.
• Completed rail was wrapped with Heat Shield Aluminum Foil Tape:
  

 

• McMaster's Harsh-Environment Cable Ties were used to zip tie completed thermal insulation;
  

 

 

Installation:
 

• The following pictures show installed fuel rails after approximately 2 years of operation (approx. 10 K miles):

 

 

 

 

 

 

 

• This close up picture shown that the insulation foam is as new (no thermal damage effects) and is as soft to a touch as it was before installation (as expected since all components are rated above 300°F):

 

 

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