Steam Car Engine Suitability ?

[JonRiley56]

Hi,

Has anyone used a steam car engine in a boat ? I happened across one from the early 1900s. It appears they were set up to mesh directly into the differential from a drive gear in the middle of the shaft. There is no fly wheel or excess shaft so drivng auxillairies may be a challenge. They are set up with stephenson type reversing mechanisms.

Opinions

jon

[fredrosse]

Many steam launches have used this type of engine, typically a two cylinder double acting simple engine, with sprocket chain drive or spur gear drive to the automobile differential. Having 4 power strokes per revolution, these engines are self starting, and put out fairly constant torque, so they can be run without much of a flywheel.

Some automobiles used compound engines, all the better for steam economy.

[JonRiley56]

Hi Fred,

I just sent a pm.

jon

[Maltelec]

Some steam cars worked on much higher pressure than your average boat would.

Whats the cylinder bore and piston stroke?

Most steam car engines were designed with much more power in mind for their size than your average boat engine, and it is quite possible that a 25HP car engine could be run at 5HP in the boat and be quite suited.

[JonRiley56]

Hi,

I measured the engine tonight. The bore is 2.5" and the stroke is 3.5". With that information, what would you estimate the horsepower to be assuming 100psi and 600 rpm ?

jon

[fredrosse]

2.5 x 3.5 two cylinder, double acting
600 RPM, 100 PSIG Steam, Atmospheric Exhaust
Engine with cutoff at 50-60% of stroke, about 7.5 IHP, 7 SHP
Net plant output, allowing 10 % for auxiliaries, 6.3 HP
Estimated steam consumption, 360 PPH
Boiler Output 383,000 BTU/hr
Boiler Fuel Input @ 70% efficiency 550,000 BTU/hr
Burning Oil, about 4 US Gallons per Hour
Burning Good Coal, about 42 PPH

[JonRiley56]

Thanks !!!! WOW !!! That is a lot of steam in pph requirement. I was running on a 5gph per hp assumption using 6hp and thinking I would need 30 gph of steam or ~ 250 pph. Based on that I was pondering a 30 to 35 sq ft watertube set up.

If I need 360 pph that puts me 43 gph. Does taht mean I need a larger heating surface or am I just going to move water through the system faster. If it is moving through faster, should I go larger anyway so that it is not as sensitive ?

jon

[fredrosse]

The numbers I quoted are very approximate, and your engine may be capable of satisfactory service with the lower boiler output. 6 actual horsepower continuously is more than most of us need. For example, with the above mentioned setup, at 90% of maximum speed you will only need 73% power, at 80% speed you only need 52% power. Pushing the machine at maximum power continuously is probably not necessary.