How many miles per $

[Bwana Don]

So how many $ to the mile are we talking here. Is this cheaper than gas/oil 2 strokes or the gas 4 strokes.

 

[GA_Boater]

Re: How many miles per $

Now that is a very good question, BD. I have no idea and I don't remember what I paid the last for the small cylinders.

 

[QC]

Re: How many miles per $

It takes approximately 5.8 Lbs of Propane to equal the energy in a gallon of gasoline. Propane engines typically equal their gasoline counterparts for efficiency, so that part would be a push. So you would need 6 of the small Camping 1lb canisters to go as far as a gasoline gallon. There's your comparison for the little canisters. Whatever those cans cost x 6 = a GGE (Gasoline Gallon Equivalent). Also it takes 1.4 gallons of propane to equal a gallon of gasoline's energy, so if you use the larger 5 gallon tanks of propane you can figure that price. Today in CA that would be $3.10 x 1.4 or $4.34 per GGE. So basically $1.00 more than gasoline for the same amount of go juice. Propane is always higher in the winter, so in this regard propane works in boaters favor. Low in Summer.

I can see that for convenience if the small OB was not used much it could be cool. My guess is that it would never make sense from an economic angle. And for emissions, NOx is very close if ignition timing is similar, particulates go slightly down. Greenhouse Gasses (GHGs) go down about 10%.

 

[Harritwo]

Re: How many miles per $

Back in the 70's and 80's, I ran propane on my trucks. The advantage was it was cheaper than gas. I had a dual fuel system meaning I could run gas or LPG and with Propane i got slightly less mpg and less power. 10 mpg gas, 7.5 mpg propane. It cost me $20.00 for a 100 gallons of propane vs $20.00 for 20 gallons of gas. I did an overhaul on the engine which had been on propane since new at 150,000 miles. The engine was clean as the day it came from the factory. Propane is also cleaner burning overall. In the winter, sometimes when it got down to freezing, i would have to start off vapor instead of liquid. With the Lehr, it is running vapor all time anyways. The power was noticable only when towing. Running empty the truck would do 0-60 in 15.4 seconds and on propane it was still under 17 seconds. Fast forward to 2012, the cost advantage is no longer there. States now enforce a prepay tax on propane for motor fuel based on mileage, the cost of a dual fuel system with computers is astronomically prohibitive for me. While this does not really compare to the Lehr, it does give some idea of the differences.

 

[tazrig]

Re: How many miles per $

Hank Hill of Strickland Propane would love you guys!

 

[Bamaman1]

Re: How many miles per $

2 stroke is a little cheaper to buy, and has less maintenance. But you've got to buy expensive outboard motor oil.
4 stroke is smoother running and will last longer. Yearly oil changes most often offset the cost of adding outboard motor oil.

A boat with the 4 stroke will pull a much better price on the used retail boat market.

If you run full throttle all the time, go 2 stroke. Few people run that way and a 4 stroke is better for most boaters.

 

[Bwana Don]

Re: How many miles per $

Great replies guys. I'm always looking for a cheaper energy source. For now I'll stick to my smokey old Johnson. lol

I've got this plan in the back of my mind to trade my 14' rowboat in for a 15' Starcraft aluminum. I'll power it with a 55 hp Homelite/Bearcat 4 stroke. This would be my early spring and late fall river fishing rig. I'll use the 3.0 mercruiser all summer. I hate spending money on gas!

Don

 

[fishrdan]

Re: How many miles per $

So you would need 6 of the small Camping 1lb canisters to go as far as a gasoline gallon.

I can see that for convenience if the small OB was not used much it could be cool.

I burned through 3 gallons of gas in my little 7.5 HP 2 stroke on a trip, so if it were a propane outboard, I would have needed 18 of those little cylinders rolling around the boat,,, and changing them out every mile or so,,, or a 20# tank. (Think I'll keep my ol' 2 stroke )

I do see the cool factor if you're just putting around and not going long distance, less than a mile or so.

 

[ENSIGN]

Re: How many miles per $

Or you could get a set of oars.

 

[angus63]

Re: How many miles per $

I can see a real market for smaller sail boats that already use cylinders/tanks for the galley stove, fridge, and/or heater.

 

[phillnjack2]

Re: How many miles per $

I think too many people are not seeing that the lpg is infact more economical especially in 4 strokes.

I used to own a Range Rover 3.5 litre Fuel injected v8 4x4.
On petrol the engine was kicking out 150 bhp at 5,000rpm and on average i got 12 miles per imperial gallon(4.54 litres).

I got a lpg kit fitted and the negine produced 145 bhp but from 3,500 rpm upto and including 5,000rpm.
The lower down power from 1200 to 2000 rpm was far supeior and the torque was almost 75% gain.
The reason being is that the propane(lpg) is a lot higher octane. average was around 115 octane compared to 90 petrol and
no silly additives to destroy the potential power of the fuel.

Now if you dont alter the timming then you dont see much gain at all,infact a bit lower on power, but when you change from
8 degree BTDC to 18 degree BTDC you see massive gains in pull away and top end performance.
I was getting on average 11 to 11.5 miles per imperial gallon, but the propane (lpg) is half the price of petrol.
Engine maintainance is a little less and the wear factor is far less than on petrol. like siad above the internals are always
cleaner and the oil dont seem to blacken at all.
The engines run far cleaner than petrol and give around 50% less total emmisions.

This is the reason that most cars in europe that are running on lpg get a massive tax reduction and are allowed to
use roads that petrol vehicles are limited to.

In wharehouses lpg forklifts are allowed where diesel or petrol engines are not allowed due to pollution and general health.
The lpg forklifts also cost half to run compared to petrol.

Now diesel engines can also be converted to run on lpg and then the gains are massive, you get diesel economy
and power but with the smoothness of petrol. But it is more expensive to convert the diesels !!!!!!!!!.

A huge company in the uk is marks and spencer stores, they have been running 44 ton lorries on lpg for a long time now
well over 15 years, and they still buy new diesel lorries that are capable of running on both diesel and lpg.
needless to say the diesel pumps at marks and spencer dont get much use .

For a boat we need low down torque, this is where lpg gains come in to play even more than in a car.

Now i understand from what ive been reading here that people buy very small bottles of the propane.
why not buy bigger tanks that can be refilled like the tank sizes for camping etc.
Then you can see the prices drop,because buying bigger amounts always cost less.
Just remember that you need a tank with a internal pipe that sucks from the bottom of the tank and
not just get the gas from the top as in a normal cooker or burner, .
what you are after is the lpg liquified petroleum gas (propane in the liquid form).

if you go to a wharehouse where they use lpg forklifts youl see the tanks on the forklifts hold around 10 gallons
and have a arrow on the bottom of the tank.
to fill one of these bottles is around half the price of petrol in the uk. and a lot cheaper in other countries.
you can buy fittings to just take these to ptrol stations that sell lpg and just simply fill them up from the pump.
its even cheaper than going to camping shops.
if we in the uk go to a boat fueling station its even cheaper, and the cheapest is the hot air ballon tanks.
they pay around 20p per litre for the gas, petrol in the uk is around 8 times this price per litre !!!!!!!!!!!

also the household heating propane is the same stuff as well, so if you have this in big tanks you can fill your
little tanks from that at a small price per litre.

I do not know about prices in the united states, but in the uk we can run cars for under half price of petrol on
LPG (propane) and the cars run a lot cleaner and greener all round..

I cannot see any reason why any 4 stroke outboard cannot run on this fuel, and any 2 stroke could also be
converted but would need a oil injection system for the 2 stroke oil.



phill

 

[QC]

Re: How many miles per $

We pay $4 per US Gallon for gasoline here. Half of what you do. That's why this is a struggle for us (US and Canada). LP is NOT a suitable fuel for diesels. You can absolutely do it, but the fact is you can maybe get to 30% of the total fuel, and although power goes up, there is no reduction in the diesel use. More total fuel equals more power, but that does not equal efficiency and usually doesn't result in better economy. I am unaware of any successful LPG 44 Tonners anywhere worldwide. Certainly none that actually save money. And there are none available new.

On your petrol vehicle, you are aware that some emission components go up with LPG? Also, that some emission components go up when timing is advanced. LPG is not a magic fuel. Trust me, we have tried. The biggest downside to LP (primarily Propane) is that vapors are heavier than air, and that it is generally a byproduct of Petroleum refineries. The upside is that it is easy to store and transport. Not as good as petrol and diesel, but easier than methane (natural gas). The benefit of Methane is that it is even higher Octane (140ish) and is available in MEGA quantities worldwide. The downside is you need to either liquefy at cryogenic levels, compress highly or use a pipeline for transport.

 

[DirtyOldBoat]

Re: How many miles per $

Propane engines typically equal their gasoline counterparts for efficiency, so that part would be a push.

I'm gonna have to disagree with this. Propane engines can have higher compression and more advanced timing, this also makes them more efficient. Also, since they burn so clean, they stay running in good order longer than a gas engine would. I can't imagine trying to run any engine on those little green propane bottles, even a weed wacker! When you buy those you're paying more for the container than the fuel inside. You can refill them, but you'd need to bring a BUNCH with you in the boat! I think this is why Lehr's propane lawnmowers have disappeared.

If you buy your propane at the gas station, I think your fuel cost would be about the same as gas. If you have access to bulk propane, you can save a lot of money over gasoline. It's usually $1-2/gallon less than propane at a gas station. I've been wanting to convert my truck to propane (8mpg on premium!) and I was quoted just $1.61/gallon delivered for propane less than a year ago. Unfortunately I don't have a place to store a 1000+ gallon propane tank. Currently I can get propane at the gas station for $2.29, with premium gas being real close to $4...you really have to shop around.

For engines as small as the Lehr outboards, I don't think it's going to be much of a difference either way. You won't save enough to buy a beer. But, you have all the other advantages of propane - cleaner, better engine life, doesn't go bad, and you can't get water in your fuel. Another advantage is that propane prices are a lot more stable, it doesn't go up $1 overnight because there is a holiday weekend coming or somebody farted in Nigeria.

 

[jimbo_jwc]

Re: How many miles per $

How about Tri toon house boat with Reinforced Fiberglass High Press Natural Gas tanks inside of aluminum ones ? Alot of people in my neck of woods are switching their trucks / small ones and go to their wellhead only fill to 450# and run 100miles with tank that fills 1/3 of bed .They only had cost of tank,regulator ,and valve to run back on gasoline

Question for Moderators . Is spell check copiewrited ABC ?

 

[JB]

Re: How many miles per $

The little tanks can be refilled from your big propane tank for the house. Brings the cost down a lot.

 

[QC]

Re: How many miles per $

I'm gonna have to disagree with this. Propane engines can have higher compression and more advanced timing, this also makes them more efficient.

Agree, but probably a very small increment. Also, despite all the hype for gaseous fuel emission benefits, a more advanced timing will have higher NOx emissions and may not be legal regardless of the fuel. Unless they are running a catalyst that could be dramatically higher NOx, so needs to be qualified. In my business we usually refer to efficiency at the same NOx levels. Needs to be clarified when discussing. Agree that Propane engines burn cleaner, but in the grand scheme gasoline engines are very clean. Especially modern automotive engines with a three way cat. In this discussion all that matters is data. For propane to gasoline in automotive it is pretty easy to find. Remember to check on the author's biases

Also, "can have higher compression" and do have are different things. Almost all [gasoline] LPG products are conversions and would have the same compression ratio as the base engine. Not sure in this particular case.

Edit: somewhat major typo. changed out gasoline for LPG in second to last sentence.

 

[DirtyOldBoat]

Re: How many miles per $

The little tanks can be refilled from your big propane tank for the house. Brings the cost down a lot.

Even with a full one, you've only got the equivalent of less than a quart of gasoline. I can't imagine trying to power a boat with that! I think an aluminum forklift tank would be really nice, or maybe one of those clear fiberglass tanks...

 

[JB]

Re: How many miles per $

For low HP putters on a canoe or a small jon the equivalent of a quart is plenty.

 

[HT32BSX115]

Re: How many miles per $

Howdy y'all,

The number of miles per gallon is really an automotive number since we frequently BUY fuel on a dollar PER gallon basis.

If you're going to buy 1lb cyls, you're basically buying them on a Dollar PER lb basis.

If you want to compare apples to apples, the you really have to figure out how many dollars per POUND you're going to practically spend using either fuel to decide which is more economical, THEN decide if it's practical or convenient or a hassle, etc.

That requires a bit of simple dimensional analysis.

Gasoline is rated at about 114,000 BTU per GALLON and weighs about 6.25LBS per gallon.

LPG (propane) is rated at about 92,000 BTU per (liquid) gallon and that gallon weighs (approx) 4.25 lbs



It's interesting to note that Propane's energy density (BTU/lb) is actually HIGHER than gasoline.....(but NOT by volume)

Propane 4.25lb/gal-- approx 21,560 BTU/lb

Gasoline 6.25lb/gal-- approx 18,240 BTU/lb (this includes all grades of AVGAS too and really is UNAFFECTED BY OCTANE NUMBER)

[Diesel 7.2lb/gal by the way has approx 138,000 btu/gal or 19,166 btu/lb]


If a propane fueled , spark-ignition engine CAN have higher compression and more ignition advance, it COULD approach the same (or maybe exceed slightly) the efficiency of a gasoline (petrol) fueled engine.



So then one would want to know the approx price PER LB of the fuels so you decide if you want to hassle with the different storage problems.

The current price for gasoline around here is approx $3.60-4.00 per gallon ( Which IS $0.58 -- $0.64 PER LB )

Propane purchased by the 1 lb container:
I checked Walmart and Home depot locally. Walmart, $5.37 + tax for (2) = $5.85 OR $2.92 PER LB
Home depot was $3.25 + tax PER POUND!

Most of us would conclude that using propane by purchasing 1lb containers, is NOT cost efficient by ANY STANDARD!






Ok, so suppose you go to your local propane supplier (assuming you DO NOT HAVE a 500 or 1000 gallon home propane fuel tank)

The local CENEX supplier told me that they charge $2.19 (cash) per gallon to fill a 5 gallon (20lb) container. (they didn't say if tax was included or not) NOTE: they will only put about 4 gallons in a 5 gallon container +/-

This calculates out to $0.51 PER POUND

So the REAL difference ............. $0.51 per lb[LPG] vs $0.58--$0.64 per lb [PETROL/gasoline]



A "20lb" LP tank weighs about 19lbs..........ADD approx 4.1 gallons of liquid propane and you add approx 18-19lbs for a total of 38lbs to lug around and place in your boat!

A standard 6 gallon (plastic) fuel tank only weighs a few lbs empty and with 6 gallons would weigh approx the same.

I also found a company that makes aluminum forklift tanks. 5, 8 and 10 gallon tanks. The 8 gallon tank filled to 6 gallons LPG would weigh nearly 50lbs.


So, considering approx the same efficiency, (which is probably a "stretch") I would probably still choose the petrol fueled 4-stroke cycle engine)

[QC....check my math!! ]


ymmv.......



Rick

 

[QC]

Re: How many miles per $

QC....check my math!!

I would only say that "efficiency" is hp out vs. btu in, so I would not compare efficiency by pound or $. Just btu's consumed. BTU/Hp/hr I think . . . Brake Specific Energy Consumption (BSEC). What you did was Brake Specific Fuel Consumption (BSFC) which is lb/hp/hr. If BSEC is the measure (it is) then the propane engine can potentially achieve better efficiency if the compression ratio was raised and timing advanced. But this also needs to be at the same NOx level to be a fair comparison. This is what Detroit and Stuttgart care about.

I like to think of fuel economy as miles per dollar which is exactly the thread title We often use economy and efficiency interchangeably and they really aren't. One is the use of the inherent energy in the fuel (efficiency) and the other is the burning of money. You can have an inefficient engine that gives outstanding economy if the fuel is cheap enough