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Old 03-12-2015, 01:29 PM   #41
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Xsbank;
Good interesting read in your "proof" post. The stress during the combustion cycle in any engine is massive; more than most people imagine. I for one, wasn't aware of the cavitation issue; only simple salt water corrosion. Perhaps cavitation was the demise of my old volvo. I didn't bother doing an autopsy.

As an off topic side note - I used to work for a power generation company which ran engines (mainly Caterpillar 3516's) fuelled by a variety of sources; landfill gas, coal seam gas etc. We found that the engines run from a fuel containing a high levels of inert gas such as CO2 ran for an incredible number of hours (up to 80,000 hours) at full load before needing major rebuilds.
This was due to the CO2 slowing down the combustion process, resulting in much lower peak cylinder pressures and less stress on rings, liners, bearings, & crankshafts. They still obtained the same power output.
So yes - the shock from combustion certainly does due some damage.
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Old 03-12-2015, 01:31 PM   #42
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Maybe at 120 hp and non turbo the B series would be a candidate. I dont know, never having done it. And apparently no one else has either. As for the smaller passages and diminished water flow, it doesnt take as much "raw" water to cool an engines flow wise as it does coolant due to the fact that there is no heat exchanger. Brass freeze plugs are not a problem or the SS waterpump impellor. Copper sheet head gasket would be easy. Looks like all the negatives could be addressed. Even the "air bubble" theory (only a problem on wet liner types) because any air would be pushed out by new water constantly.
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Old 03-12-2015, 03:30 PM   #43
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What is the "air bubble" theory?
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Old 03-12-2015, 04:00 PM   #44
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You would have far less maintenance, the oils would never get hotter than the coolant.
Xsbanks, as I see it, if the tranny oil is to be cooled by the engine coolant it would have to be hotter than the coolant. How much hotter I don't know but if it is 10º to 20º hotter then the tranny oil would be at around 200º which as posted above is too high.

(A transmission is probably only 90% to 95% efficient. With a 120 hp motor at say, half power, the tranny needs to dissipate almost 5 Kw. As such a 10º to 20º or more temperature difference in the heat exchanger would not seem unreasonable.)
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Old 03-12-2015, 04:08 PM   #45
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Gear coolers in the engine coolant circuit are usually placed somewhere near the discharge of the coolant heat exchanger, so the coolant temp is a good bit lower than the normal say 180F coming out of the engine.
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Old 03-12-2015, 04:18 PM   #46
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What is the "air bubble" theory?

I think he's talking about cavitation corrosion and why you should run astm d6210 coolant in wet liner engines. Avoiding silicate additives as well should you have a keel kooler.

Here's some stuff from Bob Senter on the subject.

Diesel Marinization - there's more to it than you'd think!

Let's clear up what "marinization" means. You start out with an Assembled block, cylinder head and fuel system, then
add the peripherals that make it a marine engine. This process often makes or breaks an otherwise perfectly good
diesel. There is a lot more to it than first meets the eye.

1. A larger, preferably heavily cast, oil pan is specified for maximum oil capacity, but it has to be shaped so that it doesn't
make the engine so tall it will be uncompetitive with other engines and difficult to install. It also needs provisions for
different dipstick locations and oil drains compatible with low bilge locations and tight stringers.

2. A different valve cover may be specified for additional oil vapor/mist separation, noise dampening and resistance to
rust and corrosion. Marine engines often require optional oil fill locations and crankcase breather choices.

3. A marine-specific exhaust manifold must be installed - something completely different from any other application. The
Coast Guard requires the manifold to be heat shielded so that if something flammable comes in contact with it, there's
no fire. This can be accomplished with very expensive insulation (space shuttle tile material) and heat shields. That
improves engine efficiency about 10%
compared to a water jacketed manifold because more heat is available to run the turbocharger. Turbochargers and
exhaust elbows must also be insulated or water jacketed. Again, water jacketing reduces efficiency but may present a
slightly cooler surface for decreased radiated heat to the engine room. Higher output engines absolutely REQUIRE
water jacketed exhaust system parts to absorb the thermal stresses - dry insulated manifolds crack under those
conditions. Needless to say, water jacketed parts in expensive diesels are cooled by the engine's antifreeze/coolant
mixture because sea water is too corrosive.

4. A marine specific intake manifold is generally required for packaging efficiency with the cooling and exhaust systems
that are completely different from land bound applications. In order to meet current NOX emission requirements,
turbochargers are almost universally required on any engine over 100 HP. Turbocharging raises the temperature of the
air going into the intake manifold, requiring some sort of cooler to keep it cool enough to allow the engine to meet Nox
emission laws. <<Nox is formed by high combustion chamber temps.>> That "aftercooler" component may be either
seawater cooled or jacket water cooled. If it is seawater cooled, there is a strong possibility that the engine will be
destroyed by a leak into the manifold - depending on how seriously the engine manufacturer considers this issue, it will
directly affect the cost of maintenance and life expectancy of the engine. Engineering this part is one of the most
expensive and critical parts of marinizing. It is VERY expensive and, not surprisingly, where many marine engines are
deficient. A jacket water cooled aftercooler is almost totally reliable, but maximum horsepower available is limited
because it can't cool as much as a seawater aftercooler.

5. A marine-specific cooling package must be engineered and installed. The cooling package must include a heat
exchanger, coolant surge tank, Seawater pump and plumbing, a transmission oil cooler and engine lube oil cooler.
Engines that already incorporate jacket water engine oil coolers are very easy to adapt to keel cooling, although keel
cooled engines require ENORMOUS transmission oil coolers because the return water from the keel cooler is only 15 -
20 degrees cooler than the what came from the engine.

6. Marine grade, moisture resistant starters and alternators are specified. To make the engine's packaging dimensions
more compatible with a boat engine compartment, the locations of the starter and alternator are often re-engineered,
requiring new brackets and different flywheel housings. The entire electrical wiring, circuit protection, harness and
connector system and instrumentation must be re-engineered for marine requirements.

7. Marine engine mounting engineering and mounts must allow maximum flexibility for installing the engine with its
centerline over, under, parallel with or at an angle to the stringers. Then you have to be able to reach the bolts.

8. Additional accessory drive capability must be added to allow for the installation of extra alternators, emergency fire or
bilge pumps, hydraulic pumps, or refrigeration compressors.

9. Belt guards compatible with accessory drives must be installed.

To the degree that a particular marine engine builder addresses these issues, they acquire a better or worse reputation
for their engines. That assumes they started with a good engine to begin with.

The best marine engines utilize heavy-duty industrial base engines, typically used in agriculture and construction
industries. These engines all have replaceable wet liners and very robust construction that allows very long life (typically
40,000+ hours) and economical rebuilds - this is vitally important to commercial customers who will accumulate over
8000 hours per year of running time if their application runs 24/7. <That type of construction is completely unimportant
and needlessly expensive in a pleasure boat application that is lucky to run over 200 hours a year.







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Old 03-12-2015, 05:27 PM   #47
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My foggy memory of the 50s says that the only pleasure boats that had FWC were 50 footers or thereabouts. Most engines were flathead gasoline and SWC.

In my 1953 Motor Boating magazine there is a full page ad for Crysler's "Crown" engine. It may be the straight eight because they talk about it's smoothness in the very extensive text .. but no mention of FWC.
Hi Eric
The Chrysler Crown engine was based on the 6 cylinder T120 block.
The Chrysler Royal was a straight 8 cylinder, I don't know the block model.
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Old 03-12-2015, 06:51 PM   #48
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Lots of years experience in this thread. What was the norm in the old days is definitely outdated now.

Engines gas or diesel that could run on SW cooling then are not able to now, (unless you find an old dinosaur in the bone yard) since on modern engines the differences in turbos, aftercoolers, intercoolers and different metals in the blocks preclude salt water and minerals. If you have an 'old' diesel it is possible to run straight salt water through for cooling. But any newer tier 2,3,4 diesels with after, inter or turbo cooling with aluminum coolers must have high efficiency coolers. In addition, These MUST have the high performance antifreeze, coolants used in the fresh water side. Salt water has way too many particulates that generate slime and growth almost immediately which degrade the heat transmission rate.
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Old 03-12-2015, 07:44 PM   #49
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Keep in mind that the raw water cooled oil heat exchangers are an integral part of the overall engine cooling. The oil cooler sees the coldest water and takes a lot of heat out of the engine. Changing that to engine coolant cooled would likely raise the overall oil temp and likely necessitate a larger main heat exchanger. My BW manual states 190 max oil temp. My BW oil temps run 150 normally. My Lehman 135's spec oil temps of 165-220 and they run at 190. These temps are easily checked and at the temps I'm seeing I can be confident that they are where they should be for long life.

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Old 03-13-2015, 06:18 AM   #50
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Keep in mind that the raw water cooled oil heat exchangers are an integral part of the overall engine cooling. The oil cooler sees the coldest water and takes a lot of heat out of the engine. Changing that to engine coolant cooled would likely raise the overall oil temp and likely necessitate a larger main heat exchanger. My BW manual states 190 max oil temp. My BW oil temps run 150 normally. My Lehman 135's spec oil temps of 165-220 and they run at 190. These temps are easily checked and at the temps I'm seeing I can be confident that they are where they should be for long life.

Ken
Yep.
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Old 03-13-2015, 08:33 AM   #51
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Keep in mind that the raw water cooled oil heat exchangers are an integral part of the overall engine cooling. The oil cooler sees the coldest water and takes a lot of heat out of the engine Ken
Ken

I don't know the exact timing, but a decade or more ago some marine engines started going to jacket water engine oil coolers. This eliminates the chance of salt water entering the engine oil. Also it keeps the oil temps in the 190F degree range even at low RPMs, which hastens burning off volatiles, condensation and helps to permit 400 hour book oil change intervals.
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Old 03-13-2015, 03:33 PM   #52
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Ken

I don't know the exact timing, but a decade or more ago some marine engines started going to jacket water engine oil coolers. This eliminates the chance of salt water entering the engine oil. Also it keeps the oil temps in the 190F degree range even at low RPMs, which hastens burning off volatiles, condensation and helps to permit 400 hour book oil change intervals.
Interesting. Where can I read up on those?

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Old 03-13-2015, 08:13 PM   #53
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Interesting. Where can I read up on those?

Ken
Rainda Industries makes them (plate HXers) for various engine builders. My Perkins Sabre engines have them as does the Cat 3056. These have been in use for a long time. I seem to recall seeing them (or similar) on Deutz and MAN engines.
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