New Propane Outboard

Many of you know I'm a fan of propane as a motor fuel. Until I retired I was a dealer for Lehr Propane Outboards. Now Tohatsu has gotten into the propane engine game. So far only a 5hp, but that is the size that sold best for me.

Tohatsu 5hp Propane LPG

I like propane engines too.

Had a 73 Buick 350 big block converted to propane. It was magic then (about 1990) and I never burned over $100 propane in a month. Even though I drove high milage. Fuel consumption is slightly more but very little difference. They even got better milage than some early emission controlled engines ... about 1980.

On rare occasions I could smell the propane but almost not at all. Started instantly and ran perfectly right off. The seamless Buick performance helped too. But seamless running is not the least bit unusual today thanks to efi.

But I wouldn’t buy a single cylinder 4 stroke OB as they shake like the devil.

Eric, I don't think you're going to find an outboard 6hp or less that has more than one cylinder. I've run a bunch of the Lehr 5hp and they really don't shake that much.

My fam had a 3 hp twin water cooled and folded in half too!

Same motor, just powered by LPG?
My 6hp single cyl gas Tohatsu has given 10 years of light but reliable use,a little harsh at idle but runs smoothly at speed. Years ago I had a 9hp Suzuki twin, amazingly quiet and smooth. From memory, identical with the 6hp version but somehow tweaked to produce more power.

I have a 4hp Johnson 2cyl 2cycle OB.
A few older ones came w the folding lower unit. They had a classy dedicated shaped case w a handle for carrying. I see them at times on CL.

These engines are very smooth and the newer ones w fibre glass covers were quiet too. Very quiet below 1/2 throttle and about like a 4 stroke OB at high speed. 34lbs.

Picture underway is at half throttle or less.

Pic #3 is a 3 1/2 hp version of the same engine on one of my canoes in Alaska.

BruceK said:

Same motor, just powered by LPG?
My 6hp single cyl gas Tohatsu has given 10 years of light but reliable use,a little harsh at idle but runs smoothly at speed. Years ago I had a 9hp Suzuki twin, amazingly quiet and smooth. From memory, identical with the 6hp version but somehow tweaked to produce more power.

Click to expand...

I read that it was the same as their gasoline engine except the head configuration was different and propane / air mixer instead of a carburetor.

The head is probably designed to give a higher compression ratio as propane has a higher octane rating than even High Test gasoline.

diver dave said:

My fam had a 3 hp twin water cooled and folded in half too!

Click to expand...

I remember those. Came with a carrying case. I think they were made by Evenrude. Usually Johnson and Evenrude made the same engines but I don't think Johnson made the folding engine. I may be wrong on that. It was a looong time ago.

I had the Johnson non-folding version of that.

I am wrong, Johnson made them as well.