Elementary Aftermarket Fuel Delivery/Rail questions

[freds]

This is my first rodeo with detailed attention to fuel injection. So be kind!

1. Why are the aftermarket rail to distribution block return hoses so large a diameter?
The return to tank outlet from the regulator is so small by comparison. Which makes sense.

2. If the spec is for, say,45 psi fuel rail pressure, controlled by the regulator: What is the purpose of the vacuum hose connection to the regulator? Does it over-ride the "normal" and open the regulator when the manifold vacuum is high?

3.Is the small port in the distribution block for a pressure gauge?

Thanks

[JeromeS13]

2. The regulator is a rising rate 1:1 unit. So, for ever 1 psi of boost, the regulator increases fuel pressure 1 psi.

[freds]

2. The regulator is a rising rate 1:1 unit. So, for ever 1 psi of boost, the regulator increases fuel pressure 1 psi.

Thanks Jerome...."got it" that's one question down, and makes perfect sense. (This is also my first turbo rodeo)

fred

[Mechie3]

Small port is likely for a gauge. Diameter isn't that big. Return hose is metal and is thin wall, the kit hoses are rubber and thick wall.