Propane Injection

[Robert Harris]

First - thanks Greg for the info about Advance Adaptors.  Will be using their
O/D in front of my New Process 5 speed on the C-600 when I drop the new engine
in this summer.

On to Propane.  When the new engine goes in, will be using LPG as the second
and BI-Fuel.   Since its an "RV" and I'll be using a 60 gallon ASME tank, I
don't anticipate any problems - including not having to pay motor or road
tax's as this is a heating fuel tank - its just a largish tank to run the
reefer, stove, hot water etc right.  Nah - no connection to the motor - that's
what the gasoline tank is for.

Next, a small note about safety. Get Real. You sit in front of enough gasoline
to level a building, pumping a gallon or more at high pressure around a very
hot engine with lots of ignition sources for exposed raw fuel, with a couple
of pounds of Freon that if ever burned as in an accident would liberate enough
Phosgene to poison 84 Janet Reno Bar B Que ees, spinning enough metal in the
flywheel and clutch or TQ to saw your legs and the car in half if it let go -
which happens frequently enough to require special shields for racing and you
lecture that two pounds of LPG as a refrigerant might be dangerous?   If that
thought frightens you witless, you must absolutely be terrified being in the
same cage as orders of magnitude more quantities of  "explosive"  gasoline -
and BTW car fires happen all the time.

Sunday Morning  Rant Over - On to EFI.  As has been pointed out, that simply
knowing the tank temp allows one to calculate the flow thru an orifice and
control the fuel without hoking up the system with pumps.  Greg has observed
that if you can get the liquid propane into the cylinder, and you are
operating in a region where it can be vaporized prior to combustion, you can
get some nice benefits from liquid propane injection.  

The greater the air temperature is, the more beneficial charge cooling becomes
and also, the higher the effective octane of the fuel needed.  It is a happy
co-incidence that the same raise in air temp raises the pressure which
increase's the flow.

The new motor will run primarily on gasoline with propane as a sometimes
BI-Fuel - depending on load, price and availability.   The moving towards
prototype Dark Side EFI simply manages air and lets the drivers foot manage
fuel so is oblivious to fuel controls.   This allows a very simple binary
liquid propane injection to be used for the power region and nicely
de-complicates defecation.  BTW, there were extensive comments in the archives
about Propane and EFI.

This system will simply use a very high pressure nitrous ( tank pressure 1000+
psi) valve connected to the liquid propane outlet after the appropriate LPG
safety valve, running to a nitrous injection system with a calibrated nozzle
in each inlet port.  Remember that nitrous has the same problems - in spades -
(  -190f bp, 1000 psi pressure vs - 43~ and ~125 psi pressure ) of a high
pressure, very low boiling point, even distribution, getting liquid into the
intake port and not freezing up.  What works for nitrous will work very well
for liquid propane.

Replace the fuel side with another nitrous side, I can now have four flow
states.  Off- Off, Off - On, On - Off, and On ON.  If the two sides nozzle
orifices are binary related that gives me three even steps of liquid propane
being dumped right at the intake valve.  Adding a third nozzle in 1-2-4
relationship gives me 7 even steps - overkill for what I want.

On cool or cold days, wacking the throttle into the liquid LPG turn on region
results in much less cooling and octane boost than on hotter days with higher
tank pressure and greater flow.  Almost a perfect match for reality.  And it
can be implemented with a minimum of computational overhead.

For a total propane system, a number of fixed orifice nozzles could be used
for the liquid propane and a Ford IAC to variably control a modest amount of
vapor propane.   Since this is a solenoid valve, a very simple pulse width
modulator and a series of relays is all you would need to have a complete
propane system.  Just a thought.


1963 Ford C-600 Prison Bus Conversion "Home"
1971 Lincoln Continental 460 "Christine"
1972 "Whale" Mustang awaiting transplant
1978 Dodge Long Bed Peeek Up "Bundymobile"

Habaneros - not just for breakfast anymore