fuel hose Id ?

[cabc26b]

Getting ready to replumb - need to tap into the knowledgebase - What is the optimal fuel hose ID ? - for my race car I have used -6 hose with electric pumps , i remember my hose from the tank to the mechanical pump on my last street car being smaller than that( maybe -4?/) . my plan is to use AN- bulkhead fittings between the lenght that runs inside the spine of the chassis ( with braided hose) and the rest with non overbraid auroquip and barb fittings -

I guess the real question is about the mechanical pump's compatability with -6 hose

[steveww]

On my S4 the fuel lines are 6mm id

[cabc26b]

Thanks - 1/4 inch sounds about right for the stock set up - It occured to me after my post that the flow may be determined by the tank pick up as much as anything , and -4 will suffice.