Re: Cryo-Treated Alpha 1 + 383 Stroker: Thoughts, Q&A?
I would suggest that Cap Pointless do some research on marine closed cooling systems. It's obvious from his statements about thermostats, raw water in the block, etc, that he has no idea how a marine closed cooling system works.
The reason boats with closed cooling systems use water-to-water heat exchangers instead of water-to-air heat exchangers is because water-to-water is much more efficient. You have all that free water there anyway, why not use it? A rough calculation should show the difference.
The thermal conductivity of water is about .6, air is about .025. So water is 24 times more efficient than air at removing heat. That means with air you need 24 times the equivalent MASS of water to remove the same amount of heat.
Density of air is .08 lb/cubic foot, density of water is 62.4 lb/cubic foot. So to get the equivalent mass of 1 cubic foot of water I have to move 62.4/.08 = 780 cubic feet of air.
Since the water is 24 times more efficient, you need to move 780*24 = 18,720 cubic feet of air to get the equivalent cooling of 1 cubic foot of water.
Maybe that's the reason the radiator on my 300 HP Suburban is about 4 feet long and 3 feet high, while the radiator on my closed-cooling 425 HP boat is about 4 inches in diameter and 1 foot long .....
No reason you can't run straight exhaust with a closed cooling system and just dump the cooling water overboard. Depends on the design of your engine bay, exhaust heat will definitely be a problem.
Another problem to consider with your air cooled-radiator is that the exit area MUST be bigger than the entrance area. Air expands as it absorbs heat. An automobile has the entire open area under the engine compartment for the heated air to expand into and escape. There were lots of overheating problems on early high HP WW2 aircraft (both liquid and air cooled) before they figured that out. Hard to imagine how you will do it on a boat without just sticking the radiator up in the air (like on an airboat). In that case you're adding a huge amount of unnecessary drag if you hope to get any speed out of your boat.
It's not impossible, there's lots of things you can do with flush mounted radiators and ducting, etc. The question is why? You're adding extra complexity, weight, drag, and expense to gain exactly nothing. If you want to do it just to be different, nothing wrong with that. Kind of like putting square tires on your car. People figured out a long time ago that round is better, but hey, it's your money and time!
When you get to the outdrive, you'll spend $1200 on an SEI Alpha, then another couple of thousand getting it cryo-treated and put back together. I'm not familiar with the stress levels in an Alpha so no way to say how much cryo-treating will gain you. Then you'll get to kluge together some kind of cooling system to feed your radiator for your Alpha. Why do you think you fill an Alpha through the lower drain hole? The oil passage between the upper and lower is about 1/8" in diameter. Can you say "no oil flow"? You going to run external plumbing to move the oil from the lower to the upper?
So you'll have at least $3000 in an Alpha that MIGHT stay together for a while if you're careful and lucky. Or you could buy a brand new Bravo for $5000, hang a $100 drive shower on it and be happy for the rest of your life. Again, your call, if you like square tires, go for it!
