DD 8-92 Wet vs. Dry Exhaust

[Passages]

Is one preferred over the other?

If so, why?

 

[SKYCHENEY]

I would say dry is preferable for any boat in that you have less chance of fire due to loss of water flow. You also have more options for cooling such as a keel cooler. And, you don't have as much risk of sinking from the giant tubes going out the stern at the waterline. But, you do have to deal with dry exhaust temps and materials that are near it and the soot that can land on your deck and make a mess.

Maybe I misunderstood the question. Do you mean wet-vs-dry exhaust or wet-vs-dry turbo jackets?

 

[Genesis]

If you're talking about the risers if you have the wet ones get them out of there right now!

These have a history of leaking and when they do they will RELIABLY destroy the engine.

There are some Detroits out there that had this design and they're BAD NEWS. This is not to be confused with the manifolds which are fresh-water cooled and not a problem.

Dry cladded (or blanketed) risers are not an option IMHO.

Now for the sweep pipes (horizontal) I prefer dry cladded as well for the same reason; there a leak may not hose you into the engine but it will destroy your turbocharger and those cost money too.

IMHO the best design is a manifold cooled off the fresh water circuit, dry to the showerhead (cladded) and then of course you have your water injection elbow which faces DOWNWARD. If that leaks there's no harm done.

 

[DLCameron2]

Hi:

If your question is wet turbo or dry turbo; Genesis and I are on the same page. (Sky as well I think.) The wet turbo application has some problems and is not quite as "popular" as the dry turbo version. My mechanic; who worked for the DD factory for 30 years says if possible stay away from the wet turbos.

Let us know what you find out.

DC

 

[Boss Lady]

I have water jacket cooled turbos on my 8v92 and stainless risers. Here is a link on this subject. http://www.marinesurvey.com/yacht/exhaust_risers_2.htm

 

[krush]

Wait, did I read water cooled exhaust manifolds into the turbo...that is RETARDED!

 

[luckydave215]

"Wait, did I read water cooled exhaust manifolds into the turbo...that is RETARDED!"

For power/fuel efficiency, yes. For preventing getting the hell burned out of you in the engine room, no.

 

[Mike36c]

If you're talking about the risers if you have the wet ones get them out of there right now!

IMHO the best design is a manifold cooled off the fresh water circuit, dry to the showerhead (cladded) and then of course you have your water injection elbow which faces DOWNWARD. If that leaks there's no harm done.

The other nice advantage to these risers is that when the showerhead fails your marine exhaust shop can cut it off and replace just the showerhead saving $$$. If you purchase from a good shop (Marine Exhaust Systems) they will have your drawings on file eliminating any guesswork years down the road.

 

[captddis]

Two different issues. Dry exhaust RISERS are the way to go. WET turbos is the way to go. Almost every marine engine manufacturer uses wet turbos.
Much safer and cooler outside the jacket. No blankets or risk of nearby items igniting, much more stable temp and the flange warping and exhaust leakage is not a issue. no blankets to deal with either. The exhaust risers/elbows come apart without much trouble and are held in with bolts and tabs. No Marmon clamps to break. The turbos even last longer.

 

[SKYCHENEY]

Sorry. I thought the original question was wet exhaust (pleasure craft) vs dry exhaust (work boat). I was somehow thinking of the entire exhaust system not just about risers and manifolds. Who knows, maybe he was thinking about buying an old steel tug to convert or something.

 

[Passages]

My original question was prompted by a call from a broker regarding a 1983 boat with 8-92's. I know little about the reliability of 8-92's. I do recall some earlier chatter regarding wet vs dry exhaust and wanted some clarification on what to avoid.

 

[captddis]

The 8V 92 is a very good engine. I much prefer a 92 to a 71. The only two models to avoid are the JT 750 HP single turbo engine and the S+S back to back twin turbo engine that was 710 HP.