> "Del Johnson, North Point Solutions, Inc" wrote:
 >
 >> I'm in the process of building injector bosses that will weld onto the
 >> intake runners.  I'm considering moving (and possibly replacing) the fuel
 >> pressure relief valve back to the firewall where the return fuel hose
 >> assembly connects to the solid fuel return lines that are plumbed back to
 >> the wings.  First of all, are there any drawbacks to this approach. Also,
 >> what pipe/hose ID should be used for the gas feed?  and is there a pressure
 >>  relief valve available that has NPT connnections that can be substituted
 >> for the Mazda relief valves?
 >>
 >> Thanks in advance!
 >>
 >> Delbert Johnson

It probably won't make any noticable difference moving it a couple of feet away
from the injectors, but regulators are usually placed at the 'load' so that the
design pressure is maintained where it matters.

Charlie England

Del and Charlie,
This may be a really good idea.  The most common fuel leak has been in the fuel line vibration damper that attaches to the fuel rail.  We know that we can eliminate this piece, so the next most likely item to fail would seem to be the fuel regulator (is this a true statement - I can't say that I have ever heard of one of these leaking?), which of course must be used if using Tracy's FI.  If the fuel rail and injectors are on the 'hot' side of the engine a potential leak could be avoided by moving the regulator to the 'cold' side of the engine and away from the exhaust.  Sorta makes me wonder if the regulator could be placed in the wing root in an installation like Tracy's?  Of course, this 'safety' item could be introducing more danger by adding more joints to the fuel system (looks like 2 extra fittings would be required).  The other side of this coin is that if I can't make 2 extra leak proof joints then maybe I shouldn't be building an airplane.

Ken Powell

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