Hello Bill, Below is an interesting quote from the Aeroquip Performance
 Products catalog JC125C. The hose elastomers in this catalog are either

AQP

 or Teflon.

 "A caution about fuel injection. All hose listed in this catalog is

suitable

 for use with leaded and unleaded fuel. However, caution must be used in

fuel

 injection systems that recirculate fuel. This causes fuel to oxidize which
 can attack the hose inner tube. To increase service life, keep the time of
 exposure to the oxidized fuel to a minimum. Drain hose line or flush with
 original fuel or other suitable material."

 Not very encouraging to people who are using engines such as the TCM

IO-240B

 which at times are recirculating almost as much fuel as the engine is
 burning. On the other hand maybe the engine is giving better performance
 because it is burning oxygenated fuel.

 'OC' Baker,  Builder of KIS TR-1 #116 4/14/97 - ?/?/?

This statement by Aeroquip puzzles me -- it is not clear to me how
circulating the fuel from the tank, through a fuel pump, up to a fuel rail,
and back to the tank "oxidizes" the fuel.

First of all, oxidation of the fuel means that it is combining with oxygen,
which is what we do when we burn it in the engine.  The only oxygen available
to oxidize the fuel is the air space in the tank, and at least 'some' of the
time we will be flying with the return line covered, at the most you would
have only the first bay of the wing tank airspace to worry about. The amount
of fuel that could be oxidized by this much air must be miniscule.

I am wondering if the effect that they are seeing is one of 'erosion' of the
inner tube wall, due to the higher flow going through the tube 'all the time'
while the fuel pump is running?  As you indicated -- fuel injected engines
may have 2x flow over a dead-ended engine.

Bear in mind, I believe that Aeroquip must have seen a problem, but I
question whether it is because of oxidation of the fuel by circulation
through the system.

With respect to performance, oxygenated fuel does NOT give better performance
in an engine. It reduces the total energy content of the tank, and
'supposedly' helps on tailpipe emissions, although I think 90% of the effect
is a political effect to help the ethanol lobby.

Bill Schertz
KIS Cruiser #4045

 
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