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Why convert a Jeep to Propane


Home Up Jeephead's Propane Burnin' Jeep Scrambler Jeephead Support Gear
Jeephead's Cleaning House! This page tells the tales of my '97 Jeep TJ
Why convert a Jeep to Propane



Why convert a Jeep to Propane?!?

I will try to keep this from turning into a soapbox/rant. Consider
this an open letter to anyone who cares to read it.

Each section is a grouping of thoughts, etc.

The quote that sums this all up: "if it wasn't important enough to do
something about it, it wasn't important at all" - Anon.

"We have too many high sounding words, and too few actions that
correspond with them" Abigail Adams (1744-1818), in a letter to John
Quincy Adams, 1774. (from quotationspage.com)

Something I should point out here: True out-of-the-box thinking can
only occur when you know where the box is. The end result we're
looking for is to get ourselves from point A to point B. The obvious
solution is a car (true, until transporters are perfected). Cars have
tires (something that is true, but does it need to be? Currently, yes -
air cushions do not provide for safe stopping distances). Now we need
some way of turning those tires. Currently, we use an internal
combustion engine (ICE), route it's power through a transmission, into
a differential into those tires. Keep in mind that while we accept
this as the most efficient means, it will not always be the case.

Remember also that every time we convert energy from one form to
another, we lose a percentage, usually to heat or friction. Sometimes a
great percentage, sometimes small. For example, burning propane would
make no sense if it's production required more energy and produced more
emissions than that of gasoline. Same with hydrogen, when used in an
ICE. Electricity is a much more flexible means of stored energy - less
heat production, easily converted from one form to another.
Unfortunately, converting it to motion is more difficult because we're
used to using ICE's, that's where the R&D money has gone for 100 years.

What's my point? A hydrogen-powered fuel cell vehicle is a STEP in the
right direction. Until we're using solar-charged electric vehicles,
we're making baby steps. Note that current technology for capturing
solar energy requires enormous amounts of panels and sunlight to get
enough energy for even the most miserly e-car. We won't see this as a
practical solution for many many years to come.

Here are my thoughts as I searched for an acceptable solution to my
propulsion question.

Functional specifications, Courses of Action and Technical
specifications

Discussion: In project management these three terms help us shape ideas
into action. The process of determining the two spec sheets has
everything to do with the decision making process, weighted and driven
by the functional specifications.

We first must identify what we want (our idea). These are the
functional specifications. For me, the list includes:

* able to run the Rubicon (off-road 4-wheeling for three days
straight). I almost ran out of gasoline at the Rubicon - too much
stress!
* be dependable and field-repairable - wouldn't want to be broke or
worse on the trail.
* be less environmentally damaging than my current setup - 10 MPG
makes way too much smog. Treading Lightly is very important, but let's
treat the air like we do the ground.
* fit within a fairly restrictive time/money/scope triple
constraint - I have a real job, real bills, and a family who doesn't
want to have me in the garage all day/night.

Next we identify the actual process we need to fit these functional
specifications. These become the technical specifications. In the
course of determining the technical specs, we have gone through a
course of action development, and decided which course of action best
fits our functional specs. The following courses of action were
considered, with a very brief note to it's rejection. Note that these
may not seem relevant or complete to someone else (you), because they
(you) will have different functional specifications. I can further
discuss my evaluation of each COA, if you'd like to email me.

COAs evaluated against the functional specifications, scored 1 to 5
(higher is better):

* (21) Fuel injected internal combustion piston engine
o (4) Rubicon non-stop
+ Others do, probably could, assumes improvement in gas
mileage so not a 5.
o (4) Dependable/repairable
+ very reliable on the highway, just ensure a
well-built system
+ repairs could include the engine control module,
sensors, high pressure fuel lines, hoses, pump or injectors lots more
spare parts and special tools to carry and they are expensive, but may
be on the trail in other f.i. rigs
o (3) Environmentally better
+ Replacing the engine/transmission eliminates leaks,
better efficiency reduces emissions w/ added cat. converter.
+ Still burning gasoline, polluting the same but less.
o (2,3,5) Triple constraint
+ Time
# Another powertrain swap, this time with a
computer. Not scared, but not retired yet either.
+ Money
# $2,000 if I use a Jeep motor/tranny
+ Scope
# Fairly straight-forward swap, not very
challenging for me technically.
* (13) Rotary internal combustion engine
o (3) Rubicon non-stop
+ Probably could, assumes improvement in gas mileage
+ No basis to estimate - complete guess
o (3) Dependable/repairable
+ Rotaries are very dependable, few moving parts to
wear/break/replace
+ Power output will need other mechanical compensation
+ Repair parts are not common to anyone else on the
trail
o (3) Environmentally better
+ Reduced emissions as with f.i.
o (1,2,1) Triple constraint
+ Time
# Planning and executing will be very time
consuming.
+ Money
# Cost of engine, computer, etc. plus potential
for custom machining of adapters $$$
+ Scope
# This will be a challenge getting the drivetrain
to play well together, not to mention strenuous testing to validate
design before use at the Rubicon.
* (7) Turbine engine
o (1) Rubicon non-stop
+ Probably not, the turbines I use at work are much
less efficient than their piston-powered brothers
o (2) Dependable/repairable
+ Great until it breaks, then call a helicopter
mechanic!
+ Turbines generate high RPMs and high temperatures
o (1) Environmentally better
+ Not likely, can't think of a single benefit
o (1,1,1) Triple constraint
+ Time - this is a full-time job and then some
+ Money - not without a grant from Lycoming or somebody
+ Scope - I'm drooling at the engineering challenges
here

* (16) Electric vehicle
o (3) Rubicon non-stop
+ Probably not on one charge, given current battery
technology
+ To my knowledge, no one has done it yet - see the "5"
score in Env. Better below.
+ Would need a recharging capability on board, charging
either while driving or at night
# add a small gasoline powered generator (noisy,
polluting and expensive)
o (4) Dependable/repairable
+ EVs have been on the road for decades. People drag
race with them. The right components can do the job right.
+ Special tools and parts needed. Not very many parts
to this COA (motor, batteries, controller), but they are critical and
expensive.
o (5/3) Environmentally better
+ I must admit there is some personal drive for
selecting this COA, so it's a 5, but the use of a generator to recharge
will reduce yet not eliminate the pollution produced by this COA, so
it's a 3.
o (2,1,5) Triple constraint
+ Time
# Takes longer than an FI, but less than the
other COAs above.
+ Money
# Motor: $2000; Controller: $2500; Batteries:
$2750; Adaptor: $650 plus another $1K in misc parts.
+ Scope
# Not too bad, there are two EV businesses here
and a local EV club. Plenty of conversion info to draw from. Must
also add in the coolness factor of the first EV on the Rubicon being a
Scrambler.
* (15) Hybrid vehicle - not to be confused with an EV with an
on-board charger. This one needs the generator portion to function
properly - the above one does not.
o (4) Rubicon non-stop
+ Probably could, assumes cargo space for fuel (the
batteries will take up a lot of room too)
+ No basis for estimation - complete guess
o (4) Dependable/repairable
+ Special parts, tools. If donor is a current hybrid,
taken completely, should do fine as long as it can handle the heat and
vibration and dust.
+ It breaks, you're towed.
o (4) Environmentally better
+ As much as a hybrid is better than a regular car,
still burns gas, those pollutants are still there.
+ The generator will be more efficient than the small
generator of the EV, so it scores higher.
o (1,1,1) Triple constraint
+ Time
# Find a crashed hybrid, tear it apart and graft
it into the Jeep.
# This is building an EV plus the hybrid teardown
part.
+ Money
# Probably $10K for a crashed hybrid
# Custom machining for adaptors
+ Scope
# Not as bad as a turbine, worse than the rotary
:(
* (0) Fuel cell vehicle - I'd be better off trying to wheel in
Santa's sleigh.
* (30) Alternative fuels: CNG, LPG, Hydrogen
o (5) Rubicon non-stop
+ Probably could, assuming I could find a CNG tank that
fits and is big enough
+ LPG tanks are plentiful
# Two types, vapor and liquid service
# I've located a liquid LPG tank that will fit
and extend range over the 15 gallon CJ tank
# There's a guy in the Pirates of the Rubicon
club that's running Propane too.
+ Hydrogen tanks are hand-in-hand with fuel cells, so
we'll stop there with Hydrogen.
o (5) Dependable/repairable
+ CNG and LPG carbs are simple, almost no moving parts.
+ Not victim of altitude changes, off-camber or "bad
gas", can be further tuned using an O2 sensor and a flow control
computer, Autotronics makes an entire line of them.
+ Extra hoses, fittings, filter & lockoff and a fuel
metering rod - it will all fit in a tackle box.
o (5) Environmentally better
+ The only emissions from CNG or LPG are NOx gasses.
# These are present because we're burning air
which has Nitrogen in it.
# These gasses burn hotter than gasoline, so they
make more than gasoline.
# Catalytic converters can remove this.
# Time to be part of the solution, not part of
the problem.
+ The chemical mix for LPG is 23.82 or 16.7 depending
on what you read, the mix for gasoline is 14.7 so we're already up on
the efficiency side
o (5,5,5) Triple constraint
+ Time
# Conversion is incredibly easy! Even better than
FI.
+ Money
# If you buy new parts, it's about $1300; I found
used parts on ebay and in Canada for less than $400!
+ Scope
# Some documentation is available, as well as
books which are mostly out of print.
# There are still some people out there who know
stuff about this and are willing to help. (It seems that the bottom
fell out of the gasoline-to-propane conversion market about 5 years
ago.)
o Which gas: CNG or Propane? CNG is harder to find, so are
the tanks. Propane is plentiful (but not always at a "fair" price.
You can also use a BBQ tank as a "gas can." Propane wins.

Then we decide how to implement the action.

Since LPG had the highest score, I went with that system.

The technical specifications for a propane system is quite
simple. Liquid service tank, a filter/lockout valve (for safety,
vacuum or electric), 350psi + capable hose, a converter (expands the
liquid to a gas), and a mixer carburator. See? Easy. Go to the build
up page to see how I put it together.

Technical superiority as an internal combustion engine fuel:
propane has a few other peculiarities that I like:
* 104 Octane rating (can run up to 14:1 compression in the engine
and more advanced ignition; must run jet fuel to find a similar liquid
which is $10/gallon, now the $2/gal propane (here) isn't so bad, is
it?)
* 90% less reactive therefore less damaging to the ozone layer when
vented to the atmosphere
* Boils at -44 degrees F, so IF you managed to overcome the greater
thickness of the tank (several times thicker than your gasoline tank)
and the superior strength of the cylinder's shape (think about VW's
commercials about the dome), it would be gone long before gasoline
would - less available for accidental ignition

Understanding the national and global economy and market as I do,
I can hardly fault the automakers. Here is why I say this: have we,
the consumers, decided that fuel economy is our number one requirement?
Are we more willing to sacrifice other features (and more money) for a
less polluting vehicle? No. Ask someone on the street about an
alternative fuel vehicle. They start whining about range, convenience,
cost of repairs, blah blah blah. Until the customers decide it's
important and "put their money where their mouth is" Detroit (and
Tokyo) won't either. Major advances like fuel cells and better
batteries cost serious cash, something no company has much of these
days. If we won't pay for the next technological advance, why should
they? So I guess it's up to the Government to pay for it ... so I
guess we will pay for it after all, won't we?

By the way, above I mentioned looking at the smog and wanting to
do something about it. Have you ever been to Detroit? No smog.
Everybody drives a 4x4 because it might be 50 degrees and clear when
you drive to work but snowing sideways when it's time to go home. The
engineers and decision makers don't see the smog (as much), don't sit
in traffic (as much), don't get to think about it as much as I do.
Gasoline doesn't cost $4/gal like it can in Canada, Australia and
England, which is why other countries are much more interested in this
stuff than we are.

So the bottom line here is: don't blame the automakers. Think
back to the last time you bought a car, what were you looking for and
why? If you didn't tell your dealer that fuel economy was your number
one constraint, you now understand why no one else is too worried about
it either.

When it's all done, there will be a smog sniff and dyno test to
see just how right it is.