wmtheflash

I'm thinking about installing a fuel pressure safety switch (Hobbs Switch) during an upcoming nitrous installation. I'm brand new to nitrous, but trying to do this install as safely as possible.

The nitrous system will only be activated between 3k - 6k RPM at at wide open throttle only via an NOS combination window and wide open throttle switch. I'll be running a 50 shot at first.

I'm thinking about a 30 psi fuel pressure safety switch (fpss) from Edelbrock.

Is 30 psi a reasonable safety cutoff or should it be set higher?

http://www.jegs.com/i/Edelbrock/350/72213/10002/-1

Where should I mount the switch? I've been reading a few instructions and it's amazing the variability between manufacturers.

Edelbrock and NOS say it's OK to mount at the fuel solenoid or at the Schrader Valve. That makes for a very simple installation.

Nitrous Express says exactly the opposite. They claim that mounting between the fuel pressure regulator and fuel solenoid will result in erractic nitrous peformance. They reason that when the nitrous is sprayed it will result in a momentary drop in fuel pressure, activating the switch. They recommend mounting the switch between the fuel pump and fuel pressure regulator.

What is considered the acceptable way to mount this switch?

157dB

I would think post-regulator mounting is the best.
You are actually monitoring the post-regulator pressure.
A fauly regulator could cause problemswitha pre-regulator mounted
safety pressure switch as it would not see a faulty regulator
that does not let any fuel or just a little fuel past.

Apost regulator mounted safety pressure switch would
be the best bet and the safest. Maybe put an orifice between the
post-regulator pressure and the pressure safety switch to absorb
the post-regulator fuel pressure drops when the solenoids are activated?