All the non-DYI-EFI crap I've put up here

[Robert Harris]

What I would like to do and am working out is correctly called a Bi-Fuel system
(i.e. using two fuels at the same time) rather than a Dual Fuel (using either
or system).

Fuel A  Timed port injection Vapor Propane.  A poster ran Methane on a 75 lb
per hour Alcohol Injector at 80 psi and got 19 lbs per hour.  Another mentioned
Big Block Chevy Injectors run 75 lbs per hour and handle reasonable pressure. 
Using a dry vapor regulator off the top of the tank (still looking - any clues)
will plumb the regulated vapor to the injectors.  Looking for 15 to 20 lbs per
hour. Getting info on any number of TPI EFI systems that can be used.  Start,
run, idle, low - mid range on Propane Vapor.

Fuel A prime.  Liquid Propane.  Think NOS spray bar or direct port.  Will run
line from bottom (liquid) line unregulated to NOS type Gas Solenoid at spray
bar. Sense RPM, throttle position and PW of injector (and other depending on
final EFI selection) to determine turnon.  Measure Tank Pressure and apply
curve for volume thru orifice correction.  Grossly adjust EFI - finely regulate
thru Oxygen.
EFI selected must run closed loop at WOT as with propane, richening past stoich
RAISES temp's to meltdown range - not runs cooler.  Got to error on lean side. 
Each spray bar step will be power of two flowed so step two flows twice of step
one and strep three flows twice of step two.  This gives me 8 points with the
step
approximately equal between the points.  May only wind up with 2 as this covers
a wide range with reasonable cost.

What I get at this point is an off the shelf injection system that is tweakable
by a Chris Johnson or other chip or programming package to be just happy fine
on Propane.  All the controllability of TPI with SIMPLE CIS for taking
advantage of the high latent heat of evaporation.

Fuel B will be unleaded pump gas to use as a cheap extender fuel.  Gasoline is
cheaper than propane in most parts of the country and as this system is going
on an RV, would like to take advantage of it.  Also, if you can avoid start,
idle, and very light load, you avoid most of the problems.  Plan is after
warm-up, and under cruise load, to switch the vapor injectors out and use
gasoline thru small injectors located near the port.  This will be an either/or
situation - not both. Sizing the propane and gasoline injectors flow similarly
and using the gasoline primarily to trim or light moderate load portion. May
delay liquid propane steps till later in the pulse width to allow more
gasoline. A hidden side benefit of gasoline this way is to extend engine life
even further.   The major wear point on a LPG/CNG engine is the uncooled and
unlubricated exhaust valve. Gasoline contains lubricants for the exhaust valve
and adding Instead of Lead would really eliminate the wear.  Could probably get
away with not using unobtainium exotic valves and seats.

I can now have a high torque, hi compression (efficiency goes up startlingly
with compressions over 9 to 1), very clean burning, very long life engine that
can pull heavy loads without detonating.  Gasoline has 20 percent more energy
per gallon (but less per pound) than Propane and using it in a propane
optimized engine gives even greater economy.  Since the fuel switches to higher
octane, much colder liquid propane under load, I can forget about gasoline
detonation limits on a high compression engine.  Also note that gasoline is a
major player only under light moderate cruise loads where the extra propane
advance and higher compression really kick in.  If I experience light ping, can
run a solenoid valve from the regulated vapor to a central intake point.  Set
the hole size to supply most of the fuel for idle.  Now will have a 112 octane
"trickle" that should kill the light ping dead like DI.

Fuel selection is Propane, or Both.  Limp home on gasoline risks the China
Syndrome or interstellar beginnings on a high compression big block.

As cost IS an object and Keep It Simple Stupid rules apply - I think I'm
nearing the point when I can get it done.  Please note - if both injectors flow
the same amount of fuel in Pounds per hour, the EFI should be well within trim
range for either fuel.  Also, by limiting the range of control for the timed
injectors, I keep the cost way down without sacrificing any performance or
economy.

Also looking for moderate priced wide range O2 sensor as propane Likes to run
lean - up to about 18 to one and runs COOLER leaner.  Thiminking about how to
do this.

Usual disclaimer - just my normal wild ass guessing and dreaming

"When some one gets something for nothing -
             some one else gets nothing for something "

If the first ingredient ain't Habanero, then the rest don't matter.
Robert Harris <bob at bobthecomputerguy.com>


----------
> From: Joe Chiasson <chiasson at hutchtel.net>
> To: diy_efi at coulomb.eng.ohio-state.edu
> Subject: Re: All the non-DYI-EFI crap I've put up here
> Date: Saturday, September 13, 1997 7:41 AM
> 
> Robert just being curious:
> 
> Multipoint gasoline with carbureted vapourous propane?
> Multipoint gasoline with port vapourous propane?
> Multipoint gasoline with multipoint vapourous propane?
> Multipoint gasoline with multipoint liquid propane?
> Port gasoline with multipoint liquid propane?
> Port gasoline with multipoint vapourous propane?
> Port gasoline with port vapourous propane?
> Carbureted gasoline with multipoint liquid propane?
> Carbureted gasoline with multipoint vapourous propane?
> Carbureted gasoline with port vapourous propane?
> Carbureted gasoline with carbureted propane ------ doubt it but.....
> 
> Are you going to use one computer to control the gasoline ( I guess I am
> just assuming that your other fuel is going to be gasoline, is it perhaps
> diesel?) then piggy back with a controller for propane. Then flip of a
> switch and your on the other fuel? Are you setting this up to be able to
> switch fuels on the fly.  In a system like this would it be better to shut
> the fuel supply off (when switching) back at the tank or nearest the fuel
> induction components? (i.e. can your computer system handle the mixing of
> the two fuels for however short or long it lasts, I know there really
> shouldn't be a problem there are dual-fueled systems that work quite well.)
> 
> Just one more question or statement as it may be : If the first ingredient
> is Habanero then you ain't got hemorrhoids!
> 
> J.
> 
> > From: Robert Harris <bob at bobthecomputerguy.com>
> > Terry, since I am working on a Bi-fuel (not dual fuel) system,
> > using propane as one of the fuels, and I firmly believe in 
> > better racing thru chemistry and cheating - let me know if you
> > find one.  Meanwhile, I'll lurk here and pick up bits and pieces
> > as I can.  Been able to mine a lot of information - Just need
> > one piece of un-obtanium to complete the basics.
> > 
> > "When some one gets something for nothing -
> >              some one else gets nothing for something "
> > 
> > If the first ingredient ain't Habanero, then the rest don't matter.
> > Robert Harris <bob at bobthecomputerguy.com>
>