Im in the process of modifying the fuel lines on my 1984 RX7 for better flow.
Engine: 12A Turbo, Carbureted, street ported, 10psi boost, BMW Bosch fuel pump regulated @ 6-35psi.

Questions are:

1. How thick can the lines be?
2. Can I use alluminum lines?
3. Do both.... fuel line and return line have to be the same thickness?.... or does one have to be thicker than the other?

Thanks for your input.

 

with those specs and boost level running the stock fuel lines will be big enough..

 

Yeah, stock is enough. I ran my nikki setup at 16psi with the stock lines, no problem at all.

If your upgrading, I think the return should be as big or bigger than the feed. It's not seeing as much pressure so if it can't flow enough the extra fuel will pool up in the regulator and make it run way rich.

 

You see... Ive been told that the return line should be smaller. Who's right?

 

return line should be as big as possible (within reason)

 

I notice this today.....
On stock lines for 12A; the return line is smaller than the intake line.

 

yah, the return line is smaller on most cars....

again, your stock lines will be fine