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Old 07-27-2012, 04:51 PM   #21
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Originally Posted by Forkliftt View Post
But it produces less BTU's than gasoline not great. Less power. Never really noticeable on a forift but on a high reving outboard??
Propane contains about 30 percent less energy per unit of volume than gasoline. That doesn't mean you can't get the same power from burning it, you just need to burn more to get it.
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Old 07-27-2012, 05:07 PM   #22
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you must remember that there are a lot more moving parts in a 4 stroke then there are in a 2 stroke that can go wrong???????
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Old 07-27-2012, 05:18 PM   #23
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That's true. That's why it pays to buy a reputable brand of four-stroke which is why there are only two brands of outboard we would ever consider buying. More moving parts does not inherently mean more operational failures and less reliability. It might mean more frequent service intervals or a lower tolerance of lousy maintanance and abusive operation, however.

A 4-stroke engine made by a mediocre manufacturer may have reduced reliability compared to a 2-stroke made by the same mediocre manufacturer for the reason you state. But I believe that if you buy a 4 stroke made by a top-notch manufacturer there's no reason it can't be as reliable as a 2- stroke made by the same top notch manufacturer.
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Old 07-27-2012, 05:22 PM   #24
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...which is why there are only two brands of outboard we would ever consider buying...
And they are?
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Old 07-27-2012, 05:32 PM   #25
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Yamaha and Honda.
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Old 07-27-2012, 09:13 PM   #26
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Forklift, you're right about the lower BTU's and the higher octane (110 I think, one of us should look it up!) but an engine designed to put out 5 hp on propane has just as much power as an engine designed to put out 5 hp on gasoline. You only lose power if you convert an engine designed to run on gasoline to propane. You could also make up a lot of that loss by installing higher compression pistons to take advantage of propanes higher octane rating.
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Old 07-28-2012, 09:09 AM   #27
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I guess our assistance towing boats will start carrying the small propane tanks used for camp stoves/grills just like we carry gas/diesel and spare oil.
Will be no big deal if that's what out customers need/want.
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Old 07-28-2012, 02:27 PM   #28
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I don't have a predjudice against the E-tech technology, I have a predjudice against Evinrude motors (and Johnson and Mercury). If Yamaha or Honda were using this technology and it had a proven track record we'd probably consider it if the weight advantage made a significant difference.

The 17' Arima Sea Ranger is rated for more than 100 hp. I've seen them with 115 and 120 hp motors (2-stroke) although the most common power over the years has been 70 and 90. So I think our boat would do fine with the 100 hp 4-stroke Yamaha in terms of weight. I've seen a fair number of them so it seems to be a popular engine for that boat.

We have not yet looked into what Honda has on offer in our power range.
I've read several posts on the forums that cater to smaller boats where owners have replaced two stroke engines with heavier four stroke engines and are now asking how to correct weight distributin problems as a result of the replacement.

What you might want to do is add temporary weight to the stern to simulate the additional weight of the replacement engine before investing several thousand dollars.

Or not, your choice.
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Old 07-28-2012, 02:34 PM   #29
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Marin we have an 18' OB w a 60hp and it does fine as long as it's not over loaded and one shouldn't do that anyway.
If you were to be time traveled to 1965 or so you'd be say'in the same thing except that the only OBs you would buy would be OMCs or Mercurys.
Generally speaking propane engines (not motors) will produce about 5% less power than gasoline in cars that aren't emission controlled but w some or many emission controlled car engines 5 to 10% more power may be had.
Many house boat rentals have been propane powered for at least 30 years. With the old FP Bearcat 4 stroke.
With oil injection I don't see why any old (or new) two stroke couldn't be converted to propane.
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Old 07-28-2012, 02:39 PM   #30
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I've read several posts on the forums that cater to smaller boats where owners have replaced two stroke engines with heavier four stroke engines and are now asking how to correct weight distribution problems as a result of the replacement.
Our current engine only has about 300 hours on it. The problems it's had have had more to do with long periods of disuse than actual motor problems. In fact the only actual motor problem we've ever had was the partial failure of the stator last year. So for now we will continue to use the 90 hp Yamaha 2-stroke.

However this engine is now 25 years old and it's pretty inefficient to say nothing of polluting, so I foresee the need (or desire) to change it at some point down the road here a bit. It will depend on how much we continue to use the boat. But while the Yamaha 100 hp 4-stroke is, IIRC, about 100 pounds heavier than the equivalent Evinrude E-Tech 2-stroke, the additional weight does not seem to be an issue for the model of Arima we have.

I haven't looked into what Honda has in the 80-100 hp range so there may be an option there, too. But regardless there is no way we'd ever put an Evinrude motor on the boat anyway so the E-Tech issue is sort of moot.

And we have no interest whatsoever in converting our current engine to propane. Be like converting a Model-T to propane--- it might run okay on propane but it'd still be a Model T.
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Old 07-29-2012, 07:21 AM   #31
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Size matters.

With propane in a tank that is not an easy fill the smaller OB will be the best conversion

10hp costs a Gal of gas , even with a modern propane setup that might come close that is a bunch of fuel for a large engine.

A yachtty's 4 or 6 hp run at modest rpm will go thru a 20lb (4.2 gal) cylinder nice and slowly.

A 50 might empty it in a single hour.

One huge advantage of propane is the fuel is so clean that the gas engines (at least in noisemakers) get diesel service hours before needing replacement/rebuild.

Due to the lubrication issue , I would think a 4 stroke would be required.
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Old 07-29-2012, 12:42 PM   #32
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FF,
Why would oil injection not get the job done? And how would propane adversely effect the 2stroke engine?
Seems to me ther'e must be a reason they don't do it. Must have todo w emission problems.
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Old 07-29-2012, 08:25 PM   #33
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two strokes have only 105 to 125 LBS of compression, may that why they wont burn it??????? its somthing to think about,4 strke has a lot more compression
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Old 07-30-2012, 06:16 AM   #34
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Oil injection would be fine , but on a 4 hp engine?

In theory it would be possible to use the high octaine rating of propane , with a higher compression ratio , but then it would ONLY be a propane engine.

Propane emissions are fine , that's why fork lifts and floor buffers work so well in occupied buildings.
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Old 07-30-2012, 03:11 PM   #35
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Good thoughts all. I've seen oil injection on very small motorcycles. Hadn't thought of the lower compression though. Rick B should be able to clear the air on that one.
I think all the little propane OBs will run on the camp stove canisters. So running out w a small engine should'nt be a problem.
Perhaps we'll see propane 2 stroke OBs soon?
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Old 10-24-2012, 12:45 AM   #36
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Over the weekend I got to play with one of the Lehr 5hp Propane Outboards. I took it out of the box, put a pint of oil in it, screwed a canister of gas in and two pulls later it was running. One pull starts the rest of the day. They should have a 9.5 out by the end of the year.
I'm going to get one of the 2.5HP motors for my canoe and Avon.

I should tell you that I have a financial interest in these motors as I am now a stocking dealer.

That said I'll now tell you the bad things.

The owners manual wasn't in the box but I was able to down load it off Lehr's website. The motor did come with a set of tools and a spare spark plug.

The cover latches were a little fiddly to get back on. The cover has to be aligned just right.

The steering tension screw was a little stiff.
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Old 10-24-2012, 08:50 AM   #37
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One big advantage to propane is when the engine is not in use the gas will evaporate from the carb.

No deposits of varnish to clear after sitting a year.

This , and diesel life , is probably why it is used for so many RV's and in dirt house emergency systems that may not be run for a year or more.

Its a great fuel, tho more costly per hour than gas or diesel.

The TOTAL cost over the years in hassle and money may be far lower than gas or diesel.

IF you need 24/7 go diesel, otherwise propane might make sense.
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Old 10-24-2012, 12:13 PM   #38
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When my 27 year old two-stroke 2.5 HP Mariner finally goes to that marina in the sky, I'll think about Lehr. The propane part is alright but the increase in weight could be an issue.
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Old 10-27-2012, 11:27 PM   #39
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I worked in the Lehr Outboard booth at the Ft. Lauderdale Boat Show today. I must have started one twenty five or thirty times. It started on the first pull every time but three. Two of those times I forgot to crack the throttle and the third was just a weak pull.

They were showing the 9.9 hp motor for the first time but I didn't get to run it. The people there who had run it said it was very quiet.

I got to talk to the owner of the company about the efficency of the motors. He said that because propane mixes so well with the air and the fact that propane has a higher octtane than gasoline you get a much more complete burn of the fuel compared to small carburator gasoline motors.
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Old 10-28-2012, 05:50 PM   #40
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........... I got to talk to the owner of the company about the efficency of the motors. He said that because propane mixes so well with the air and the fact that propane has a higher octtane than gasoline you get a much more complete burn of the fuel compared to small carburator gasoline motors.
You expected him to say something bad about his product?

Propane may turn out to be a great fuel for boats. I just worry about being on the leading (bleeding) edge. Since I bought a new 2 HP outboard this year, I am probably good for many years before I have to buy another one.
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