Slip-In Silencer

[Hudsteve]

Has anyone used a slip in silencer to help reduce the noise?

Or any better ideas to help quiet our crusader 454's?

thanks

Steve 1990 carver montego

[km1125]

Not sure exactly what you're referring to. Have a link or picture?

A LONG time ago I tried some things called "dappers". They were a 4" tube with some baffles inside. I put them in the 4" exhaust hose headed out to the transom. It was tough to do a before/after comparison because I did it over the winter. Anybody who had taken a trip the prior year couldn't tell that it was any quieter with them on. I ended up removing them and didn't notice an increase in sound either. This is on 350HP 7.4L Crusaders.

One thing I DO think makes a difference (other than, obviously, a real muffler), is to make sure your raw water pumps are flowing all the water they're supposed to flowing. At over 1000 hours on my original pumps, they were still pumping plenty to keep the engines cool, but I ended up rebuilding them as part of PM. The new cams were quite a bit thicker than the old worn cams (I have pics somewhere). The increased flow make a noticeable reduction in engine noise. Not as much as mufflers would, but certainly noticeable.

[Hudsteve]

Here's a link to what I was looking at

https://www.hardin-marine.com/p-12622-4 ... aspx#video

Thanks

[Viper]

I doubt you'll get any meaningful reduction in noise with those units. I've dealt with Hardin in the past for other more substantial units that are about 2 feet long and even they can't compare to a good muffler.

What kind of muffler do you currently have?

[Hudsteve]

It looks similar to this one

https://www.greatlakesskipper.com/maste ... uffler-kit

I will get the exact pic this weekend

what do you recommend?

[vineyardgray]

Those look too small. My 454's have centek mufflers on them - larger, barrel shaped. If you search for centek on that same greatlakesskipper.com site something similar comes up for carver boats.

[Viper]

I find "lift" mufflers to be the quietest design but there are good horizontal designs too. There are also a few things that can reduce a muffler's ability to reduce noise. Horizontal designs need to be mounted pretty level which isn't always the case. An internal failure such as a broken tube or baffle will basically render it useless as far as reducing noise. A poor running engine will also change the acoustics.

If you have room and cash and really want to get it as quiet as possible, I'd retrofit with Lift mufflers from Centek known as the Vernalift. Here is a common design but there are other base mounted horizontal types... https://www.bing.com/images/search?q=ce ... HoverTitle

Another option is to contact Hardin and ask them about their exhaust system inserts. These units are installed inside your exhaust hose by the engine but you need a long straight run that will accommodate them. Unless things have changed, they build them based on your application. What you have to be careful with here is that you don't introduce excessive back pressure in the exhaust system.

What is it that is concerning you about the noise? Is it really noisy when you run it at the dock and you're concerned about your neighbours? Are you in an open or covered slip? Sometimes the acoustics at the dock in a covered slip can be amplified by the surrounding structure.

[RobGunn]

I wondering if you simply add a angled elbow at the exhaust exit that would force the exhaust down into the water? Let he water muffle the sound?

[km1125]

QR_BBPOST I wondering if you simply add a angled elbow at the exhaust exit that would force the exhaust down into the water? Let he water muffle the sound?

I have seen boats do that, and I considered it myself on the 3607. If you do though, make SURE you provide a small relief port so that air can get in and water doesn't get sucked up into the exhaust when it cools down. This solution would work great around the dock and at no-wake speeds, but would do little up on plane unless you extend them further down below the hull. That could be a lot more work though, as the drag would be substantial.

[bud37]

Not to derail this but this is interesting never the less as some Carvers had this installed with no internal muffler.....28 Mariners for example.

http://www.google.com/patents/US3291252