[Diy_efi] Propane injection (KISS)

[Ray Drouillard]

Commercial propane systems use a fuel pump.

There are several problems with trying to use the tank pressure.

1) If the tank is cooler than the engine compartment, the pressure from the
tank will not keep the propane in a liquid state.

2) Even if that wasn't a problem, you would have calibration problems due to
the wide variation of pressures due to ambient conditions.  In fact, in
extreme arctic conditions, the tank pressure will be about one atmosphere.
In other words, if it's cold enough (we're talking about the arctic circle
in the winter), you can carry liquid propane around in an open bucket.


Ray Drouillard


----- Original Message -----
From: <A70Duster at aol.com>
To: <diy_efi at diy-efi.org>
Sent: Thursday, April 17, 2003 10:55 AM
Subject: [Diy_efi] Propane injection (KISS)


I have some extra low-impedance injectors that I first applied 120 PSI
compressed air to and the injectors operated correctly.

Then I plumbed liquid propane (from a propane tank with the valve on the
bottom) to the injector and pulsed it.  Again the injector was working
correctly.

The problem was that a mix of liquid and vapor came out of the injector,
even
after a minute of pulsing the injector.  My guess is that the liquid propane
is boiling in the transfer tube.  How does one stop this while keeping
things
simple?!?!  Insulate the line can help with heat intrusion and maybe a
liquid/vapor separator.

I don't want to add a fuel pump and regulator, I can live with tank pressure
at the injector, but should find out the pressure that the injector doesn't
open at.  And I want to inject liquid propane.  Phase change cools the air
drawn in and I can deliver A LOT more liquid propane than vapor propane.

Why do I do this?  With propane at 110 octane and I can get it for $1.30 a
gallon, I could run on 87 octane gas for cruise and then kick in some liquid
propane under heavy loads/WOT conditions.  This would first be applied to a
turbo 4 banger, then who knows what is next..>:-)

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