i replaced all my system with 2" hose ...new muffler ...new hose to the outside and a new through hull exhaust fitting all 2"...but you still have the small out let to the outside of the boat...i think centex makes an adapter/reducer for that...you will get better performance if you up grade to a 2 " in and out muffler and a 2"... long hose....the way it stands now you are sort of smothering that 2gm20f engine by having the 1 1/2 inch system but you can get byJust back from the boat. I had to use a Dremel with a cut-off wheel to cut the wire-reinforced host from the outlet on the lift muffler (that was pretty smoky/smelly!). I measured the inside of the hose and the outside of the outlet and both look to be 1 1/2". No problem there; however, I noticed that the inlet side of the muffler had a piece of exhaust hose still on it, despite my pulling that hose off without cutting it. Apparently, a short piece of hose was put on the inlet to bring it up to the 2" ID of the Yanmar's exhaust. I suspect that isn't up to ABYC standards!
Is there another/better way to bring the 2" hose down to the 1 1/2" inlet? I didn't immediately find a source for a new muffler with a 2" inlet and 1 1/2" outlet.
Thanks.
John
Yep. I thought you'd say that. I don't suppose I can change the opening exiting the hull to 2" with the boat in the water. I can probably trim the cut part of the old 1 1/2" hose and get it to work temporarily, then do the muffler and 2" hose when I next have the boat hauled, probably next summer.i replaced all my system with 2" hose ...new muffler ...new hose to the outside and a new through hull exhaust fitting all 2"...but you still have the small out let to the outside of the boat...i think centex makes an adapter/reducer for that...you will get better performance if you up grade to a 2 " in and out muffler and a 2"... long hose....the way it stands now you are sort of smothering that 2gm20f engine by having the 1 1/2 inch system but you can get by
i put my new bronze outlet in the boot stripe on the rear and closed up the hole with glass and epoxy i am sending you a pmI checked and I can get a Centek 2" to 1 1/2" reducer for about $25. So, I'll probably go ahead and order that, the 2" x 2" lifting muffler, and all 2" hose. That'll do it until I can get the boat hauled. I will check with a local fiberglass guy and see if he wants to put the 2" hull outlet in with the boat in the water, but I suspect not.
John
in the first place that is what is recommended by Yanmar and your 12 cylinder auto is not restricted by a water lift muffler and i suspect that the exhaust mixing elbow is less prone to clogging with the larger size pipe and we know how aggravating that can be....and also i have to wonder why the big mercruiser inboards all seem to have 5 inch diameter pipes or larger and it only cost a nickel more to do it correct while he is in there ...you don't mess with propulsion when it comes to boating neither the engine or the sails do it right or you may spend some very disparaging days and nights on the water from short changing your self i am sure there are more reasons than what i have posted.....a good example of short changing one self is i recommended to a friend about 2 years ago to change the power steering belts on his Caterpillar powered motor home he didn't do that and he called me from some place in VA on the way back from NY he had lost steering and had to call the truck repair guy out to get him going$$$$$$$ dahI have to say that I just can't believe that a two inch exhaust is going to smother a piddling little 2 cylinder 20 hp diesel. There is a 2 inch exhaust on every car I own and some make 300 hp and some have 12 cylinders!
not a problem bob theses little engines need all the help they can getWell, one Jag XJS with a V12, a 73 Charger with a a 340, a 64 Dart with a 273, a BMW 328 and my 06 Tundra. So one V12 at the moment and perhaps two with 300 hp. Sorry Woody but I just can't see, viewing engines as air pumps, that a 25-30% increase in capacity is going to be a strain, but it is probably a deal breaker on a new engine warranty. Just a PITA to change the hole in the hull needless to say.