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View Poll Results: What size is your exhaust system? Choose all that apply.
1 1/4" I.D. Hot section 55 58.51%
1 1/2" I.D. hot section 13 13.83%
2" I.D. hot section 5 5.32%
1 1/2" hose 12 12.77%
1 5/8" hose 26 27.66%
2" hose 10 10.64%
Don't know / other 9 9.57%
Multiple Choice Poll. Voters: 94. You may not vote on this poll

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  #26   IP: 64.231.81.231
Old 08-25-2010, 02:19 PM
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Quote:
Originally Posted by Kelly View Post
Hanley,

I'll have to measure when I get back down to the boat. If I were to guess at the inner pipe diameter (hot section), I would say 1 1/4". I'll get back to you...

67,

As drawn in your schematic, our exhaust systems are nearly identical, with only small differences in the angled connections. It would be interesting to know if someone removed the mixer (riser?) from your setup. This would, I assume, as in Russ' example, eliminate almost all back pressure.
This winter I plan to do maintainence in that area - once I pull off the insulation I will take some pictures. My copper-jacket exhaust extends almost to the rear of my cockpit - much longer than the blueprint.

There is a heck of a lot of water in it when I drain the thing for winter storage!
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  #27   IP: 216.115.121.253
Old 08-25-2010, 04:33 PM
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I'll try to do the same next month. We can revive this thread then.
I need more pics of my boat anyway as I do a lot of planning from far away.

Russ
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  #28   IP: 173.166.26.241
Old 10-12-2010, 10:23 AM
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Question

As this discussion moves on, (see also the thread "No more Fouled Plugs), I am beginning to form a hierarchy of system desirability in my mind. I believe it goes like this 1) jacket system, 2) the standpipe, and 3) the water lift. Is this thinking sound or all wet?
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  #29   IP: 72.71.243.195
Old 10-12-2010, 03:48 PM
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I think it is very difficult to put salt water into the engine by over cranking
with the standpipe system. I have never had to worry about this, although
I don't go out of my way to over crank it.


Art
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  #30   IP: 173.166.26.241
Old 10-12-2010, 05:13 PM
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Art - I certainly respect that feature of the standpipe but for me the overriding consideration is to minimize wasted engine energy. Regards, Hanley
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  #31   IP: 98.248.12.160
Old 01-30-2011, 03:07 PM
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exhaust system size

I just noticed a leak in my exhaust system, good time for a question. My Tartan 30 has the MM SS water lift muffler, works great. I have a horizontal 1 1/4 inch nipple out of the manifold followed by a 45 deg elbow down, then a water injection fitting then about 12 inches down to the water lift muffler. No riser and not much of a vertical drop but it work well, never had a problem. I want to replace the nipple with a 316L SS nipple from Mc Master Carr, pretty cheap at about $10 but they offer two wall thicknesses, sch. 40 and Sch. 80. The schl .80 should outlast me but I would suffer about 10% loss in area, is that a problem??
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  #32   IP: 24.152.131.220
Old 01-30-2011, 07:36 PM
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I have 2 observations:

  • The SS sch 40 nipple should outlast you as well provided it isn't from the orient. Examine it with a magnet. If there's attraction, send it back.
  • Your experience with your exhaust as designed has been flawless so why change?
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  #33   IP: 174.94.22.135
Old 01-31-2011, 02:35 PM
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316L (L = low carbon) is the standard for marine exhaust especially if the piece has to be welded.

My guess is the part you are going recieve from the supplier is a casting and will be made in China.

Nearly all of N/A's metals are made in China using scrap metal that we send to them via ocean going ships.

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  #34   IP: 174.94.22.135
Old 01-31-2011, 02:40 PM
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Quote:
Originally Posted by Kelly View Post
Russ and 67-

Do you have some sort of mixing chamber after the copper jacketed section? You can see in my set-up that the gases are mixed with the cooling water in what I call the mixer (for lack of a better term) which is tucked up under the deck as high as possible above the water line. From there, it's a straight shot out the transom after about 4-5 feet.

I like this system as apart from the iron hot section, it's all copper. And, it seems highly unlikely that water could ever "back up" with this design.
Kelly, there is no mixing of the water until it exits out the transom of my vessal.

The water surrounds the exhaust pipe and cools the surface of the hot pipe inside of the water jacket. Then it exits out the rear of the water jacket pipe and runs to the transom where it is plumbed back into the exhaust.

Makes me think there is quite a load on the water pump as the pump must move a fairly large weight (head) of water throughout the system without receiving any assist from the exhaust gases.

Ya, it a pretty free-flowing system for the exhaust gases I guess.

I am starting to think the MMI Tartan standpipe with a North-Sea exhaust might be just the ticket for my old girl!

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  #35   IP: 193.253.220.149
Old 02-02-2011, 04:15 AM
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Hmmm...I hadn't really thought about the "weight" of all the water as it fills the jacketed exhaust and works its way up to the horizontal run. The water pump seems to be up to the task though given the numerable years of service.
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  #36   IP: 173.166.26.241
Old 02-02-2011, 09:43 AM
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67 - The engine/electric driven water pump is much more capable of driving water uphill than exhaust gases are.
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  #37   IP: 174.94.22.135
Old 02-05-2011, 03:12 PM
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Hanley...what do you think of the "North Sea" exhaust system, either with a standpipe or with a waterlift type of exhaust?

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  #38   IP: 173.166.26.241
Old 02-05-2011, 03:27 PM
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67 - The "North Sea" idea seems a little complicated for our purposes. I really respect your quest for exhaust system improvement, and I believe in trying new things, but I keep coming back to the fact that you already have the best system in the fleet.
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  #39   IP: 174.94.27.44
Old 05-13-2011, 05:00 PM
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Quote:
Originally Posted by hanleyclifford View Post
Neil - I guess you knew that I would be among the first to respond to this new thread. I like the way you have framed the issue. Let me begin by saying that I have been using 2" ID pipes and hoses all the way to the transom for several years. But your discussion about "diminishing returns" is sound and should give reason for pause about going any larger. The engine must always be able to expel the water. This requirement of course is going to vary with each boat's configuration. The greater the "head" against which the engine is working, the more dangerous larger wet sections would be potentially. All this of course needs to be quantified. Just one final thought for now: the manifold exit diameter is 1 1/2" - comments on why the manufacturer would reduce immediately to 1 1/4"?



Hanley...I'm thinking that 1 1/4" shedule 40 pipe was the largest inside diamter Universal could machine threads in the manifold pipe bracket without having to recast a much larger part that would accomadate a Schedule 40 1 1/2" (or larger?) pipe.

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  #40   IP: 174.94.27.44
Old 05-13-2011, 05:06 PM
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Quote:
Originally Posted by hanleyclifford View Post
67 - That exhaust system you have could very well be the least restrictive of all. It appears to eliminate the need for a riser and all the 90 degree bends associated with most systems. Can you give us the ID numbers from engine to transom? Also, do you have any sort of muffler or waterlock anywhere in the system? Regards, Hanley
1 1/4" Schedule 40 bronze pipe from stem to stern Hanley...soon to have a MMI waterlift in the transom with a 2" bronze check valve installed in the 2" line from the MMI waterlift to the new 2" transom exit thru-hull.

I am keeping the water-jacket for the moment but in time will likely go with the set-up Rigsy has in his 27 C&C (which looks almost identical to my boat) when the copper-jacket pipe starts to deteriorate.

Cheers!

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  #41   IP: 173.9.105.253
Old 05-13-2011, 06:52 PM
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Quote:
Originally Posted by 67c&ccorv View Post
[/B]


Hanley...I'm thinking that 1 1/4" shedule 40 pipe was the largest inside diamter Universal could machine threads in the manifold pipe bracket without having to recast a much larger part that would accomadate a Schedule 40 1 1/2" (or larger?) pipe.

I opened up a stock flange to 1 1/2" NPT and ran it to Florida and back twice before I made my own custom unit out of 1" steel. The performance improvement was notable. I have never understood why Universal would take a manifold with a 1 1/2" outlet and immediately chop off a third of the exhaust flow by going to a 1 1/4" flange. Does not compute in my limited mind.

Last edited by hanleyclifford; 05-17-2011 at 01:11 PM.
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  #42   IP: 174.94.27.44
Old 05-18-2011, 01:28 PM
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Spent some time at the boat yesterday cutting out the aft section of my Corvette's exhaust system.

It was a 10' section of 1 1/4" bronze pipe with all connections and changes of direction welded!

Old school engineering done very well...probably should have left it in except it was very heavy and took up a lot of space. No provision (other than an upward bend in the pipe at the transom) to keep following seas from flooding the system.

It also appeared to be very sound with little or no deterioration in the I/D of the pipe...except for the soot which is all over me and the boat now!

Now I have a MMI waterlift at the transom with a 2" bronze swing checkvalve in the outlet line.

Pics to follow when I get a chance.

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  #43   IP: 173.10.248.102
Old 05-18-2011, 03:41 PM
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Cool copper jacket

my bristol has a copper jacketed pipe 11/4 id for the exhaust, the water doesnt enter the system till the very end at the down turn of the pipe to the fitting in the transom. no water back up problems at all just can't figure out how they put the bends in the two pipes and still leave a space between them for the water to run
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  #44   IP: 173.10.248.102
Old 05-18-2011, 03:44 PM
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Cool copper jacket

my bristol has a copper jacketed pipe 11/4 id for the exhaust, the water doesnt enter the system till the very end at the down turn of the pipe to the fitting in the transom. no water back up problems at all just can't figure out how they put the bends in the two pipes and still leave a space between them for the water to run
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  #45   IP: 216.115.121.253
Old 05-18-2011, 06:21 PM
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The old post with a graphic of my exhaust is here:

http://www.moyermarine.com/forums/sh...45&postcount=4
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  #46   IP: 174.94.23.187
Old 09-14-2011, 10:43 PM
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Quote:
Originally Posted by 67c&ccorv View Post
Spent some time at the boat yesterday cutting out the aft section of my Corvette's exhaust system.

It was a 10' section of 1 1/4" bronze pipe with all connections and changes of direction welded!

Old school engineering done very well...probably should have left it in except it was very heavy and took up a lot of space. No provision (other than an upward bend in the pipe at the transom) to keep following seas from flooding the system.

It also appeared to be very sound with little or no deterioration in the I/D of the pipe...except for the soot which is all over me and the boat now!

Now I have a MMI waterlift at the transom with a 2" bronze swing checkvalve in the outlet line.

Pics to follow when I get a chance.

Hope these pics can help you understand my exhaust system - now if only I had a proper video cam to show the exhaust batching and initial startup with little water coming out the transom!

1.) from the exhaust manifold end showing the initial cooling water inlet into the water jacket exhaust;

2.) the business end of the water jacket showing the cooling water exit which follows along top of the exhaust gas 1 5/8" line to the transom;

3.) looking down on the exhaust gas and cooling water lines which enter the MMI S/S waterlift muffler under the lazarette and then exit through 2" swinging check valve and overboard at the transom;

4.) 2" line from the check valve to overboard at the transom;

5.) transom view of 2" S/S thru-hull.

Cheers!
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  #47   IP: 71.253.202.232
Old 03-26-2012, 07:24 AM
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I really don't see needing a large exhaust exit from the manifold as of yet.
a 2,000 max rpm average rate engine that is only making upwards of teens of HP at that point, and is 6 to 1 compression and 60 cubic inches,
there is small amount of spent gases sent through this manifold.
Many a old car from the 60's-70's had single 2" inch exhaust pipe on a v-8 engine that may have been 300+ cubic inches that could rev to over 5,500 rpms. and make over 250hp (did they breath better larger and dual? YES) But they still made plenty of power to move a car.
With water in the pipe and great lengths you may need more diameter along the way, but right at the engine, there is no water leaving the flange and only a limited amount of air.
I placed my hand over my exhaust on the stern, expecting it to quickly blow my hand away from pressure like a car can do...
Well, other than build up water thats all the happened, it just keep running pressurizing the pipe, and not enough restriction to kill the motor.
This was at no load @1,500 rpms.
But I also run no muffler just about a 7 foot shot of 1 5/8" hose.
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  #48   IP: 173.166.26.241
Old 06-12-2012, 08:36 PM
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Daniel - Have you run a pressure test of your hot section? Also, remember the car system does not have to deal with water being injected which must subsequently be lifted and expelled. IMO back pressure is the enemy of engine efficiency.
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Old 06-13-2012, 01:37 AM
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Quote:
Originally Posted by hanleyclifford View Post
I opened up a stock flange to 1 1/2" NPT and ran it to Florida and back twice before I made my own custom unit out of 1" steel. The performance improvement was notable. I have never understood why Universal would take a manifold with a 1 1/2" outlet and immediately chop off a third of the exhaust flow by going to a 1 1/4" flange. Does not compute in my limited mind.
Can you tell us about the performance improvement?
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Old 06-13-2012, 08:20 AM
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Quote:
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Can you tell us about the performance improvement?
Sorry to say I have no quantified proof. My exhaust hot section back pressure is 1 psi or less and the hesitation on throttling up disappeared. MM sells a lift with 2" output, so I reason why not increase the input side of the lift as well? It's the "batching" issue that limits output size, and I still have slight batching at cruise. I suppose I should have documented my journey from 1 1/4" thru 1 1/2" to 2", but I didn't.
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