Muffler/Exhaust - Freedom 39

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OldRover
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Muffler/Exhaust - Freedom 39

Post by OldRover »

What type of muffler did the Freedom 39 use? Looks like a straight one like a Vetus dempmp50 and a 45 degree elbow would work (not sure how a waterlock could fit and be routed unless maybe an nlph50)? Is the system 2 inch? I have what appears to be a fairly new mixer elbow and rubber hose through the bilge with nothing in between. Its been a while since I have seen a Perkins 4.108 and thought it uses a 2.5 inch or larger. Also, my exit is actually through the port side about 18 inches forward of the stern and seems close the the water line. The location doesn't bother me too much, but it drops to a 1 3/8 inches 'transom' connector. (I'm not sure why it would not be consistent, 2 inch, with the rest of system.) I guessing it is a replacement piece, or is it correct?
TIA
'82 F39 ph

Mike Holibar
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Re: Muffler/Exhaust - Freedom 39

Post by Mike Holibar »

Tia,
Fyne Spirit has a Perkins M50 Prima engine, similar in output to the 4108. Exhaust dia is a good 3 inches which would be barely adequate given the length of the run. I think we have a Vetus waterlock muffler which (I think) is located in the bilge space just aft of the keel. 2" fittings would suit a 20 hp motor but are far too small for the 4108. It is also important to make sure you have a good goose neck arrangement and some means of shutting off the exhaust at the thru hull to make sure you don't accidentally fill the engine with sea water.
Cheers,
Mike Holibar
S/V Fyne Spirit of Plymouth (Freedom 39PHS-1989)
Lyttelton
New Zealand

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THATBOATGUY
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Re: Muffler/Exhaust - Freedom 39

Post by THATBOATGUY »

I would have to respectfully disagree with Mike. I've had the 4-108's in several boats, including the boat I'm typing from, with 2 inch exhaust as standard. In any case it's 2 inch right at the manifold where it's still hot and once the exhaust hits the cool water stream at the mixing elbow it condenses a lot as the gas cools and would actually need *less* diameter of hose rather than more.

George
George and Kerri Huffman S/V Marquesa Freedom 40 CC CK Sail MarquesaImage

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OldRover
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Re: Muffler/Exhaust - Freedom 39

Post by OldRover »

Thanks for the replies. I thought I remembered the 4.108s using a larger exhaust, but also would hate to replace the long run since the hose does look fairly new. I plan on replacing the transom exit with a larger one with the check valve. I will be at the boat tomorrow and remove the mixer elbow and confirm the manifold exit diameter (it did appear larger than the elbow's 2" exit) and if its 2" I stick with the existing hose. I am going take a little more time to try and figure out how to place a waterlock and route hoses with least bends. Part of my confusion is due to what appears be the location for the waterlock is above the aft hose which would require a 180 degree out of waterlock top exit and then a 90 into aft hosing. Usually I can look at an empty space and 'see' component location and routing. But since this is an older boat and may have had repair/mods over the years and complicated by sitting on stands for close to a decade with a middle owner who knew nothing regarding marine, especially sailboat, design, I am having difficulty weeding out some things that are plain wrong versus just things that are strike me as odd but are acceptable.
Thanks again,
Dean
'82 F39 ph

Mike Holibar
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Re: Muffler/Exhaust - Freedom 39

Post by Mike Holibar »

Just responding to George's comments, with of course the greatest respect, in my years selling and commissioning Perkins engines I have seen many poorly installed ones and one of the most common errors is undersizing the exhaust. Being an older engine the 4.108 is a bit more tolerant of excessive back pressure than the newer engines but these days back pressure must not exceed manufacurer's guidelines. I recently installed a 20hp engine with 2" wet exhaust and it failed the commisioning due to slightly elevated back pressure. In this case I shortened the run from about 4 metres to 2.5 metres to solve the problem.
Perkins produce detailed specifications for exhaust systems that take into account length of run, number and type of bends and engine horse power. The longer the run and the more bends, the greater the diameter must be. Also specified is that wet exhaust must be greater diameter than dry. The correct diameter for the exhaust of a modern 50 hp engine with wet exhaust and a modest 4.0 metre run works out at about 2.75" , so if I was installing this engine and wanted to pass the commissioning I wouldn't go less than 3". As I mentioned, many of the older models are much more tolerant of high back pressure so as George says, a 2" exhaust shouldn't cause any mechanical problems with your engine, but it will be operating at less than optimum efficiency.
Cheers,
Mike Holibar
S/V Fyne Spirit of Plymouth (Freedom 39PHS-1989)
Lyttelton
New Zealand

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Michel
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Re: Muffler/Exhaust - Freedom 39

Post by Michel »

THATBOATGUY wrote:I would have to respectfully disagree with Mike. I've had the 4-108's in several boats, including the boat I'm typing from, with 2 inch exhaust as standard. In any case it's 2 inch right at the manifold where it's still hot and once the exhaust hits the cool water stream at the mixing elbow it condenses a lot as the gas cools and would actually need *less* diameter of hose rather than more.

George
I have the same setup as George in my Freedom 44 with Perkins 4.108. There is a 2" exhaust system. When searching for a new exhaust / injection elbow for the 4.108, I came across several versions of the elbow (depending on the exhaust flange) but they were all 2" ID.
Michel Capel, Freedom 44 #4 1981 'Alabama Queen', NED8188, cat ketch with wishbones, home port Enkhuizen, the Netherlands, 52*42.238'N 005*18.154'E.

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OldRover
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Re: Muffler/Exhaust - Freedom 39

Post by OldRover »

Thanks for the confirmation Michel, and I had read your mixing elbow post which is why I was happy to find mine is fairly new. Looks like I will keep the existing 2" hose, although at over a 20 foot run I'd think it should be larger. I was able to do some more investigation yesterday and found there is no gooseneck, but instead there is a 90 degree metal fitting with a 'cleanout' plug tucked up under the port cockpit seat. The hose then drops down to the exit which is less than 2" as mentioned above. Maybe this was functions as a gooseneck with less restriction.
I am still not sure where to place the waterlock and route hoses. Looks like there is a mounting pad port side of the transmission. It just seems a odd to me since it is above the bilge where the exit hose is located. Since most of the waterlocks I have seen exit on top I would have to use a 180 elbow, drop the hose into the bilge with a 90 elbow to mate with existing exit hose. Seems 'bendy' to me. Maybe I am just getting over excited since when doing automotive exhaust the game is always biggest, straightest, and shortest as possible. If others are running similar setups, let me know and I'll accept the magic of the wet exhaust makes up for the long and winding path.
Oops, forgot. Basically I am inline with Mike's numbers which is why I initially posted. Mike, what waterlock are you using? Is it located on that pad by the transmission? Would you happen to have a pic?
Thanks,
Dean
'82 F39 ph

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OldRover
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Re: Muffler/Exhaust - Freedom 39

Post by OldRover »

Yesterday I took a journey up to Rhode Island in search of a replacement main mast and had the opportunity to speak with Paul Dennis. He recalled that only a few Freedoms were built with Perkins (owner requests) and they did originally use a 3" exhaust hose due to length. He was not sure why the waterlock would be sitting on that pad and not below the exit hose (down lower in the bilge). So I'll dig around to see if there is room and/or if that pad by the tranny was added and can be removed to provide a lower mounting.
-Dean
'82 F39 ph

Mike Holibar
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Re: Muffler/Exhaust - Freedom 39

Post by Mike Holibar »

Dean,
I will try and take a pic next time I am out, hopefully next weekend. From memory the waterlock look like it might be vetus make, but I will check that out also.
Michel, your 2" id water mixing elbow would have to be pretty close to 3" outside diameter which would mean you would need a 3" hose. The injection elbow dimensions should not be taken as an indicator of the correct exhaust diameter. In the case of the 20hp engine I referred to earlier, the id of that elbow was 1" through a water injection sleeve of 1 3/4" od. Even stepped up to 2", the diameter was too small for the length of run making the back pressure too high. We shortened the run, but I could have tried reducing the raw water flow through the elbow with a valve which will also reduce back pressure.
Dean, your comment re biggest, straightest, shortest for automotive is very relavent to marine also, remembering that marine engine exhausts have to shift water as well as gas and that marine engines are subject to unremitting loads as opposed to intermittent loads for automotive applications.
Cheers,
Mike Holibar
S/V Fyne Spirit of Plymouth (Freedom 39PHS-1989)
Lyttelton
New Zealand

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Michel
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Re: Muffler/Exhaust - Freedom 39

Post by Michel »

Mike, good thinking about the ID and OD dimensions. I mistakenly wrote that the ID of the exhaust mixing elbow is 2". The OD must be 2", since the hose ID is 2". That was the original setup on the F44.
Michel Capel, Freedom 44 #4 1981 'Alabama Queen', NED8188, cat ketch with wishbones, home port Enkhuizen, the Netherlands, 52*42.238'N 005*18.154'E.

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