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Old 02-13-2018, 10:52 PM   #11
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Great discussion and great links. The engine would power another mahogany boat. I feel better about small water jackets now and I like the thermostat idea. Lots more drawing to go.

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Old 02-14-2018, 04:33 AM   #12
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In my mind, a fresh water cooling jacket should be more on the generous side rather than the thin side. Thin jackets will foul more quickly if the water clarity is poor. An intake water strainer might also be advisable.

Set up your engine running at the design load and RPM with a summer pond temp intake water supply. Adjust the flow or pump speed to get a 9-12 degree F differential temperature across the engine cooling system. This will provide an optimum coolant flow to cool your engine under the warmest expected operating conditions. A bypass thermostat would be ideal, but I have never seen one for small scale use.

Another issue is that a smooth running 360 degree crankshaft twin cylinder engine will create significant crankcase pressure pulsations and require a check valve type crankcase vent. This will likely trap blow-by moisture in the crankcase making the oil milky. It gets a little better as the rings seat, but doesn’t completely go away. Design for easy crankcase oil draining and flushing with WD-40 after use. A good hot running engine will combat the moisture build-up and gasoline produces a little less moisture in the combustion gases than propane.


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Old 02-14-2018, 12:57 PM   #13
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Originally Posted by BaronJ View Post
Hello Al,

I was never great at spelling Its way over 50 years since I did anything like this, so that gives you an idea of how little I remembered from what was then Chemistry / Physics... I'm glad I went for Electrickery
Hi Baron,

You picked an unlucky word to mis-spell, adsorption is a confusingly similar, but physically quite different process and can be easily confused with absorption, which is why I mentioned it.

I have exactly the opposite problem to you, I'm hopeless with electricity (as evidenced by my occasional self inflicted shocks) but seeing as I'm a physicist, physics and thermodynamics is right in my wheelhouse... each to his own I guess. Have a good one.
I'd like to be a perfectionist, but I lack the patience...not to mention the skill...
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Old 02-14-2018, 11:32 PM   #14
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Jeff, I received your PM. I sent you two replies but can't verify if they were posted. The web site seems to be having a problem.

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