[Diy_efi] Propane injection (KISS)

[Eck, Joel (Houston)]

I would think that exposing the injector to a liquid at those =
temperatures would end up killing it somehow, eventually... but then =
again, i don't know what temperature propane at that pressure is... but =
I would believe you are right, the propane is changing phase in the =
tubing. use tubing that is less capable of transferring heat, then =
insulate it - stainless transfers heat slower than mild steel, and a =
bunch slower than aluminum, you could then maybe coat it in rubber or =
sandwich layers of insulating material... but maybe some other material =
would be better than stainless.=20

the other thing to consider is this, the pressure drops slightly in the =
fuel line when the injector opens, so it may be dropping enough pressure =
to allow the propane to vaporize, rather than allow sufficient heat in =
through the tubing to allow it to phase change.

or maybe more correctly, a combination of both?


-----Original Message-----
From: Mark Linder [mailto:mark.linder at verizon.net]
Sent: Thursday, April 24, 2003 12:08 PM
To: 'List for general do-it-yourself EFI talk'
Subject: RE: [Diy_efi] Propane injection (KISS)


I may be wrong, but it was my understanding that you NEVER wanted to
inject liquid propane.  From everything that I have read, only vapor
should be injected.

Mark



-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]
On Behalf Of A70Duster at aol.com
Sent: Thursday, April 17, 2003 7:56 AM
To: diy_efi at diy-efi.org
Subject: [Diy_efi] Propane injection (KISS)


I have some extra low-impedance injectors that I first applied 120 PSI=20
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=20
correctly.

The problem was that a mix of liquid and vapor came out of the injector,
even=20
after a minute of pulsing the injector.  My guess is that the liquid
propane=20
is boiling in the transfer tube.  How does one stop this while keeping
things=20
simple?!?!  Insulate the line can help with heat intrusion and maybe a=20
liquid/vapor separator.

I don't want to add a fuel pump and regulator, I can live with tank
pressure=20
at the injector, but should find out the pressure that the injector
doesn't=20
open at.  And I want to inject liquid propane.  Phase change cools the
air=20
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=20
gallon, I could run on 87 octane gas for cruise and then kick in some
liquid=20
propane under heavy loads/WOT conditions.  This would first be applied
to a=20
turbo 4 banger, then who knows what is next..>:-)

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