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Dry exhaust question

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Old 10-12-2007, 06:54 PM
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Default Dry exhaust question

Okay, I have a dumb question. All I know about dry exhaust is the riser runs dry to prevent reversion and increase power slightly. Correct? But I don't know HOW it does it.

In this pic it looks like the water is being directed out the riser and through the hull. Is this dry exhaust?
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Old 10-12-2007, 07:13 PM
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Maybe, If its dry it doesn't mix water with exhaust gas, everything coming out exhaust pipe is dry. generally water mixes in the tail pipe after the riser and comes out the back mixed.
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Old 10-12-2007, 07:15 PM
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Those look like Gil dry exhaust risers. The pipes are jacketed then run out a seperate port. See how the top connection runs out to the transom? That's the dump. They're jacketed to cool the exhaust pipes but dont acually mix with the exhaust itself.

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Old 10-12-2007, 07:20 PM
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Quote:
Originally Posted by thisistank View Post
Those look like Gil dry exhaust risers. The pipes are jacketed then run out a seperate port. See how the top connection runs out to the transom? That's the dump. They're jacketed to cool the exhaust manifolds but dont acually mix with the exhaust itself.

The bung connector that runs to the transom is what caught my eye. So, water runs through the jacketed manifold and riser but then instead of being mixed with the exhaust in the tailpipe it is re-routed and dumped?

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Old 10-12-2007, 07:25 PM
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Yes, most pipes will allow water out at the far end of the pipe and may have a separate dump to allow enough flow.
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Old 10-12-2007, 08:24 PM
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Dry pipes are bad azz! No doubt about it. Sound great and improve performance (a little) and wont cause reversion. However (as Jim can contest to I'm sure) the down side is that the exhaust is so hot its hard to run flaps, thus more likely hood of causing reversion from back wash.

Damned if you do, damned if you dont.

For example look at these exhaust tips. These are Stelling headers (not manifolds) but same concept. See the little tub at the top of the exhaust. Thats the dump for the water. It never mixes inside the exhast. It comes out after. The pic you posted does the same thing but diverted to a different area in the transom.
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Old 10-12-2007, 08:28 PM
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BTW, the riser does not increase power. It actually creates backpressure, and cuts power slightly. The riser is there purely to keep water from entering the exhaust pipes, and running right into the engine. It's effect of prevent reversion caused by large overlap cams is minimal. The engine manufacturers usually use the riser to introduce water into the exhaust to cool it so they can use inexpensive rubber hoses, except in the case of dry exhaust.

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Old 10-12-2007, 09:48 PM
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and really, really LOUD. You're going to get busted for sure. I got busted even when there weren't any noise restrictions...
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Old 10-12-2007, 10:06 PM
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For sure when marine police see dry exhaust they usually head toward you. I think dry exhaust may be illegal is some states. The exhaust companies dump water it tips to make it look wet. Boating in Maryland in the eighties marine police were already out with decibal meters. The first noise levels were so strict their own boats whalers with 115 were too load. CPBA was formed to fight legislation. Anyway just got carried away.
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Old 10-13-2007, 11:45 AM
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love dry pipes, sounds much more clear! Do you have any more pics or vids? Im thinking of converting my CMIs....
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