Re: 1989 Wellcraft Monte Carlo ?'s and build
Hi Kevin, really enjoying this thread. I noticed that you asked over and over about the dual muffler setup on the genny. What I have found is that replacing the stock muffler with a much larger muffler from a motor 3-8 hp larger is usually the max noise reduction you can get in the exhaust of an air cooled motor. If the genny is air cooled, then the rest of the noise is vibration and sound emanating directly through the cooling fin area, because there is no water jacket to help quiet the motor like in a car. Plus the whir of the generator itself is rather loud. If possible, additional sound BLOCKING can be done with simple 1/2" plywood panels around the genny, with generous open space to allow for air flow. The ply will block the sound. But you have to be sure it will not cause heat buildup too.
What I learned from trying to quiet my B&S 10 hp 5500 watt Coleman home generator:
- Replacing that small 3" x 6" muffler with a B&S 4" x 13" tube shape muffler reduced the sound of the exhaust about as much as can be, without impacting performance. At least a 1" in and out on the muffler matches the block threads.
- After a big muffler is added, the sound of the genny changes. It is no longer the roar of the exhaust, but instead the roar of the generator. Surprising how much noise a spinning generator makes. It has a cooling fan, along with other parts (brushes?) that makes me think that is why the actual generator suddenly becomes so loud. Kill one noise, and the next loudest comes out!
- The motor is air cooled on my generator, so it needs a good supply of fresh air. But that same air cooled motor is ringing out every compression stroke right through the aluminum finned block. No dampening at all. Will talk more about this later.
- The generator.... Sucker is spinning at about 3000 - 3600 rpm, depending on model. It is loud. It gets hot. It has cooling fans built in. It is noisy. Best plan of attack is to put a plywood sound barrier on one or two sides that face the interior of the boat, so that it still has good air flow, but sound is blocked in your direction.
- If you really want to get nit-picky, pull of the air shrouds from the motor, along with the starter housing, etc, Line them with same material sold at the stereo shops for the "boom boom" stereo systems kids put in their cars. This is the cheapest heavy duty sound deadener, and it should make a difference. I must warn you, I have only used this product inside outboard motor covers to reduce sound. It works very well. Not sure how well it will work that close to a heat source. The stuff is only about 1/4" thick. Maybe put it on the outside of the cooling tins???
Hope that helps.
Not sure if your genny is water cooled or not, could not tell from the pics. But if it is , then go with a single larger muffler that will afford the silencing you want, but not cause the back pressure that can burn valves and shorten spark plug life.
Just my experience. Your mileage may vary....
