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Old 04-14-2016, 09:12 PM   #61
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After 20 years now , done about '94, and about 3-4,000hr my bellows/accordion pieces seem to be doing fine still.
As for the flanges, on each bellows is a solid flange and on the other end is a rotating flange so line up is not a problem. Just need to use a good gasket. Support is also important so the bellows is not carrying the weight from the rest of the system.

This setup has outlasted the original exhaust setup which had a slider sleeve . Can't say, of course, that tomorrow I won't discover I have a problem.
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Old 04-14-2016, 09:31 PM   #62
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C lectric:

Yours sounds like a good one too. The ones I have had to repair did not have a swivel on the flange and for some reason two of them did not have the fixed flanges parallel which meant while bolting them together you put a bind on one side of the accordion part. Thus those did not last too long. The expansion joint NOT carrying the weight as you so correctly put it was probably the reason those did not last too long.

The "slider sleeve" ones I never had the opportunity to dismantle but I always assumed there was some form of packing involved.

One note on the Delfin's dry stack. The Ulysses is a sister and evidently had a dry stack at one time. The exhaust race is still evident, I imagine there was a story there at one time.
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Old 04-14-2016, 09:33 PM   #63
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I used to work for a rubber and gasket company. We made them in all kinds of configurations . I never thought about them being used for exhaust on boat , but I wasn't into boats back then . We would cut the bellows and the braid to length then put it all together and weld the braid to a ring and then weld that to the bellows then weld whatever coupling or flange to that . We also made them with bronze bellows and braid .
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Old 04-14-2016, 11:14 PM   #64
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I dunno, I kinda like the sound of my twin Perkins 4-236s with wet exhaust. Kinda mellow burble.

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Old 04-15-2016, 06:36 AM   #65
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An expensive Hospital Grade exhaust will be as loud as a Lincoln underway.

One time expense , then silence!
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Old 04-15-2016, 07:37 AM   #66
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Conall, thanks for replying about the manifolds. Could I bother you to send me some pictures of your set up? I also want this loop to feed a red dot bus heater to defrost my pilot house windows so it's getting complicated in my mind. Lol
My email is sjemery at gmail dot com.
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Old 04-15-2016, 08:10 AM   #67
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FF A "hospital grade exhaust will be as loud as a Lincoln underway" might be an understatement. Maybe one of those Chevy Volts might be more appropriate analogy. If I remember correctly it will reduce noise attenuation down to about 40dBA.

The drawbacks of course are weight and size. The dia. will be about 4X the pipe size and the weight can be substantial. If you have the room that would be the way to go if you want quiet. These days I do not even know if I can hear 40 dBA anymore. Too many years listening to a 5800 HP boat's engine.
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Old 04-15-2016, 08:31 AM   #68
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I always figured that the higher RPMs and higher exhaust flow when SF back down keep out water.
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Old 04-15-2016, 09:16 AM   #69
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Steve,

I'll get some pictures in the next day or so and send them your way.

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Old 04-15-2016, 11:39 AM   #70
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Thank you very much, it is greatly appreciated. Love your boat.
Steve
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Old 04-16-2016, 06:52 AM   #71
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"I also want this loop to feed a red dot bus heater to defrost my pilot house windows so it's getting complicated in my mind."

Not so,, most engines will have a few areas where hot water can be tapped and returned.

Worst would be a small centrifugal pump might be needed.

Do not series HW heater and box heaters , single valved circuits.

Worst case simply tap off of engine coolant before bypass thermostat to keel cooler , return it just before cooler return to thermostat.
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Old 04-17-2016, 08:49 AM   #72
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All I have to worry about is that the heat exchanger in the water heater, as well as a manifold and hoses that will feed it, should all be lower than the cap on my expansion tank...is that correct?
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Old 04-17-2016, 09:04 AM   #73
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Do all these dry exhausts use wet exhaust manifolds with coolant?

Or are the exhaust manifolds wrapped with insulation?

How exactly are the systems configured?
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Old 04-17-2016, 09:23 AM   #74
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I'm trying to educate myself as well . I just googled images on keel cool dry exhaust .it helped me get a better idea .
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Old 04-17-2016, 09:49 AM   #75
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Yes, dry exhaust piping is insulated usually with a blanket wrap. Basically a "wet exhaust" allows for a raw water engine driven pump to supply water from outside the boat then through a heat exchange that cools the coolant in the engine which also circulates. The raw water then mixes with the exhaust and goes out with the exhaust. In a dry exhaust system just like your car the exhaust goes through a silencer (muffler) then out usually through a high stack. The exhaust is not cooled as that is not necessary. The engine is cooled by circulating the coolant through a pipe external to the boat in a closed loop type arrangement. If you can imagine, your radiator in your car uses a closed system too that circulates the engine coolant through the radiator. The radiator uses air flow to cool the water in the case of the boat system the external pipe (keel cooler) operates by cooling the engine water by means of the ambient water temperature surrounding the boat rather than air.
As mentioned above, both systems have their advantages and disadvantages.
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Old 04-17-2016, 10:16 AM   #76
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Originally Posted by sdowney717 View Post
Do all these dry exhausts use wet exhaust manifolds with coolant?

Or are the exhaust manifolds wrapped with insulation?

How exactly are the systems configured?
Some use manifolds with cooling jackets, some the manifolds are not cooled, but insulated. Most purpose built marine engines, even if intended for keel cooling will use a cooled manifold. Mostly to limit fire risk and to keep engine room temps down.

Many keel cooled engines are sourced from industrial or road engines, and those usually have "dry" manifolds.

In the case of keel cooling with dry stack, the engine does not "know" it is in a boat. It has no interface with sea water like a normal "wet" engine. So an industrial engine can simply be dropped in and hooked up with minimal changes, including exh manifold.
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Old 04-17-2016, 10:59 AM   #77
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On a largely non variable waterline recreational vessel why is a dry stack used? To have fun, be different and appear working trawler like are the credible answers I've heard. No doubt they work just fine if one is accepting of the downsides. And your boat and neighbors don't mind soot.
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Old 04-17-2016, 11:10 AM   #78
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On a largely non variable waterline recreational vessel why is a dry stack used? To have fun, be different and appear working trawler like are the credible answers I've heard. No doubt they work just fine if one is accepting of the downsides. And your boat and neighbors don't mind soot.
It seems about half the problems on marine engines come from sea water pumps, wet exhaust reversion and corrosion, sea water leaks on coolers, and things corroding where sea water contacts engine stuff.

Keel cool with dry stack has none of these issues.

Downside is noise, soot, heat issues and corrosion issues in the dry pipe/muffler rig. Dry also probably more expensive and eats up interior space.

I think they type of boat where dry is best is pretty rare. And that's what we see in the fleet. Mostly wet.

I do like the "coolness" factor of dry, though.
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Old 04-17-2016, 11:14 AM   #79
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Some use manifolds with cooling jackets, some the manifolds are not cooled, but insulated. Most purpose built marine engines, even if intended for keel cooling will use a cooled manifold. Mostly to limit fire risk and to keep engine room temps down.

Many keel cooled engines are sourced from industrial or road engines, and those usually have "dry" manifolds.

In the case of keel cooling with dry stack, the engine does not "know" it is in a boat. It has no interface with sea water like a normal "wet" engine. So an industrial engine can simply be dropped in and hooked up with minimal changes, including exh manifold.
How well would a simple wrapping of the exhaust manifold work and how thick would must it be for a decent reduction in heat if you used this, versus some kind of blanket this company also sells.
https://www.heatshieldproducts.com/m...e-exhaust-wrap

Or is this not the appropriate usage for a manifold?



Advertises a tighter weave versus their normal weave product, any thoughts?

This other one has higher rating, think it could fit on an exhaust log type manifold?
As in cut around the port connectors to the head.
https://www.heatshieldproducts.com/m...ust-insulation

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The inner ceramic liner makes it capable of withstanding 1800F continuous, which allows this heat shield to be placed directly on turbo manifolds, down pipes, and exhaust pipes.
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Old 04-17-2016, 11:21 AM   #80
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How well would a simple wrapping of the exhaust manifold work and how thick would must it be for a decent reduction in heat if you used this, versus some kind of blanket this company also sells.
https://www.heatshieldproducts.com/m...e-exhaust-wrap

Or is this not the appropriate usage for a manifold?



Advertises a tighter weave versus their normal weave product, any thoughts?
Depends on the manifold shape. Some are very hard to wrap, some easy. Fabricated sheet metal shaped to fit is another way, blocks the radiative heat transfer. Look at how the QSM11 dry manifold/turbo is insulated.
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