Propane outboard?

[rmhxruss]

Have heard that the propane fuel system tends to leak. very expensive parts.

[20mercman]

lotec, I think you hit the nail on the head! I first noticed this trend in the ice drills up here in the northern areas. These would sit all summer, and then the guy would try to get it started on the lake, and he could have drilled the hole by hand as fast. The ethanol gummed up carburetors are a real problem. Fuel storage is another. The stuff stays ready and safe in a pressure can, nothing to spill out in the trunk of a car. For ice drills, I think it is a big win, but as you and others have pointed out, there is almost no reason that you can’t make a 50’s-60’s magneto motor as reliable and serviceable today as the day it was built. These new motors are almost disposable. Take a look at string trimmers and how difficult it is to service the fuel systems on them. Almost are compelled to throw the carburetors away and start over with another piece of junk!

Steve

[cookjer24]

propane is 110 octane,burns clean,produces less carbons,they should start making conversion kits for vehicles,your motor will last longer than the body lol.

[boxcar]

Here is what I can tell you about propane powered conversions.
Propane is not higher octane than gasoline.
I’m not sure where the 100 to 110 octane level referred to in an earlier post came from . I’d guess from someone trying to sell conversion kits.
It is closer to 75 – 80 octane .
It also burns colder.
It produces lower power than gasoline but burns much cleaner.
Generally propane powered vehicles require much less maintenance.
It’s not available at most fueling stations.
It hates altitude and cold weather.
When it leaks it settles in the bilge and can produce a rather nasty surprise.
It tends to strip the oil from the cylinder walls witch is not good on higher revving engines.
A pressurized propane tank is nothing I want in my boat unless it’s housed in a proper blast cabinet that is vented over the side.
And lastly, at least in Oregon , marina fuel is non ethanol…… Stop running pump gas . Buy at the marina or start using marine stable.
I’d pass on the propane outboard.

[jerry-ahrens]

Taking a quick look online, I see the 15 hp Lehr propane outboard is about the same price as a new 15 Mercury 4 stroke. Somewhere in the neighborhood of $2,500 to $2,700 dollars. While I sure wouldn’t pay that for either one, they are competitively priced. Maybe a propane outboard is way out there for some, but with the problems I see on most 4 stroke carburetors, it may be a way to avoid fuel system problems. I see this stuff all the time at my shop. People come in with carburetors overflowing, or the motor simply will not start. In my humble opinion,Marine Stabil is not a cure for using ethanol. In, fact, I don’t know of any ”magic” additive that will eliminate all carburetor problems. Of course we all know that proper lay up for storage and using good fuel, etc, etc. will eliminate most problems. Trouble is, the average outboard owner doesn’t understand this, and always ends up with the hassles and repair bills. As I stated earlier in this thread, I own a Generac propane generator. I bought it just for this reason… I don’t want the hassles of storing gasoline, keeping it rotated so as to always have a fresh supply on hand in case of power outages. I start my propane generator once or twice a year, and let it run for a bit, as stated in the owners manual. It always starts right up, with no problems. I have a 100lb. cylinder, along with a couple BBQ cylinders full and ready if needed. Seems to have worked out well. I’m not saying to toos your old OMC Light Twin and buy a Lehr… but for some part time boaters it might be a good choice. Heck, even my propane suppliers brand new tank truck is propane powered.

[boxcar]

I use marine stable in my expedition rig . I have had no problems in several years.
Personally. I wouldn’t own a 4 stroke outboard. Most are built poorly , have short life expectancies , have poor performance and are just to damn heavy.
I also have no need to fish in California………..

[cookjer24]

Propane has a higher octane rating than gasoline (104 to 112 compared with 87 to 92 for gasoline) and potentially more horsepower, but its lower British thermal unit (Btu) rating per gallon results in lower fuel economy. However, the price per gallon can quickly offset the lower fuel economy.and i am not trying to sell conversion kit’s lol.

[boxcar]

I have been running propane and converting vehicles to propane for many years.
I build off road ( 4×4 ) rigs. Propane makes sense on these rigs as a propane powered Jeep will run nearly upside down.
I have never found that it adds hp or economy. It does the exact opposite . Lower economy and a marked reduction in HP.
All of this means nothing in an off road rig where gearing overcomes all deficiency’s.
As stated earlier, your octane ratings are a mystery. I would guess the alternative fuel data center .
A green bio fuel advocate. Who’s data should be scrutinized. They use words like " comparable , and similar " often, rather than just stating that the fuel is just not as efficient .
They also advocate propane’s use in cold weather climates stating that it cold starts better than gasoline engines .
This is true . What they don’t and won’t talk about is its tendency to freeze up and turn the carburetor into a large chunk of ice in cold weather.
Or it’s rather dramatic loss of efficiency above 3000 ft altitude.
Octane ratings for propane run the gambit from claimed 75 up to 115 octane.
I tend to believe the lower numbers. Call me a pessimist….
I never stated that you were trying to sell kits . Rather that you got your Octane information from someone who was trying to sell kits.
The hard fact is that in a boat , propane is a known hazard. It always has been and always will be.

LPG (Liquefied Petroleum Gas) is kept under pressure as a liquid
and when released, becomes a highly flammable gas that is much
heavier than air. The gas industry also knows it as one of the most
searching of gases, that is, it can escape through gaps that would
hold water and other gases.

On boats, the Liquefied Petroleum Gases in common use are,
‘commercial butane’, and ‘commercial propane’. They exist as gases
at normal temperatures, but become a liquid under moderate
pressure. Propane turns into gas at a lower temperature than
butane, so the storage pressure for liquid propane is slightly higher
than butane.
One volume of liquid butane or propane produces approximately 250
volumes of gas and thus a leak of liquid is a grave hazard, especially on
a boat. Since LPG vapor is denser than air, leaked LPG vapor will fall
and flow along cockpit floors, bilges, etc and the vapor may travel
some distance. The LPG will build up in low-lying parts of your boat and
it may persist for some time.
It only needs concentrations of 2–10% LPG in air to make a flammable
mix. In a boat, a flammable mix will explode if ignited. It is also possible
for gas/air mixtures from leaks or other causes to be ignited some
distance from the point of leakage and the flames travel back to the
source before exploding. In extreme cases, if the cylinder is lying on its
side; if the cylinder valve is faulty; or if the exposure to the fire is
extended, the cylinder may rupture leading to a violent explosion.
Alternatively, the point could be reached where the pressure-relief valve
releases LPG, causing a significant jet of burning gas.
To help prevent incidents, a stenching agent is added to give LPG a
strong odour, which most people can smell long before the gas reaches
dangerous concentrations.
[Based on information from the LP Gas Association]

[Anonymous]

quote boxcar:

Octane ratings for propane run the gambit from claimed 75 up to 115 octane.
I tend to believe the lower numbers. Call me a pessimist….
……
Rather that you got your Octane information from someone who was trying to sell kits.

I thought higher Octane rated fuel prevented knock (premature detonation) in high compression engines as opposed to containing more energy.

https://en.wikipedia.org/wiki/Octane_rating says:

quote :

Octane ratings are not indicators of the energy content of fuels. (See Effects below and Heat of combustion). They are only a measure of the fuel’s tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where the octane number is raised by blending in ethanol, energy content per volume is reduced.

That page also quotes the 1999 Johnson Operation and Maintenance Manual for Octane for "requirement for a typical two-stroke outboard motor" as US 67 Octane.

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