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 # ,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: 00; Controller: 00; Batteries: 50; Adaptor: 0 plus another K 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 K 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 00; I found used parts on ebay and in Canada for less than 0! + 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.