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From: "Giffen A Marr" <gamarr@charter.net>
To: "'Rotary motors in aircraft'" <flyrotary@lancaironline.net>
Subject: Fuel system pressures
Date: Sun, 13 Mar 2005 20:29:44 -0600
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 I have the Haynes Mazda RX-7 86-91 repair manual. I am a little confused on
the specifications for the fuel system pressures. I am planning on using a
20B/turbo, but there are no manuals available for that engine, unless you
can read Japanese.

The Mazda book calls or the following for the 86-91 Mazda models above:
Fuel system pressure 34.1 to 39.8 psi
Fuel system hold pressure 18 psi (whatever that is)
Fuel pump pressure EGI 64 to 85.3 psi; Turbo 71.1 to 92.4 psi
Fuel pump hold pressure 57 psi (whatever that is)


The questions I have are: 

What fuel pressure do you want from the fuel pump to the fuel rails for a
20B/turbo? I recognize that you need a fuel pressure regulator to maintain a
constant pressure differential for the injectors. 

What is the pressure range for the fuel pressure regulator?

I have taken my fuel system design from Marv. Installing GM fuel filters
before the pumps, pressure relief valves, before the fuel selector, to
divert the fuel flow after you turn on the pump but before you select that
system, the fuel selector, fuel flow transducer, 10 micron filter, fuel
rails, pressure regulator, return flow transducer and fuel return. 

Giff Marr
LIVP/20B 30%