I am very surprised Merc designed it so the exhaust has to be routed so oddly low. It would have been nice to have it installed on the stock Bravo exhaust cutout spot (so to speak) Then it could have been added on easily to existing apps or removed easily if you didn't like it. The way it is now you need to re-route the exhaust to an unusual place and hope you're happy. It also adds two unwanted bends. If you want to remove it, you need to re-route again and fill big holes under the waterline. Silly.

That is a good point! I agree...

I believe the box on the outside of the boat has exhaust/water entering from the bottom, then up into any of 3 holes/tubes plumbed into the second section (There's a baffle in the center). The second section then exits at the bottom of the box.

The 3 tubes are tuned (possibly to a specific engine offering - 700sci, in this case) to somewhat cancel out the noise when running on plane. When the boat is idling, the box is mostly under water, so noise suppression is easy there.

In this case, I suppose it would be possible to have another direction turn in the box, or just start from the normal bravo position. Defintiely nice having a common location for exhaust exit. The problem with 3 turns in the box is you would need to have water drain from each baffle of the box (eventually). Also the box just got bigger.

Maybe they are not after the aftermarket, just new, very expensive installs....

Of course they're not after the aftermarket, they want to sell new motors!! They've finally realized that they the engine manufacturer are the ones responsible for meeting the decibel limits, not the boat builder. And if they want to continue selling motors they'll have to conform. Steve

Ron,
Make a 90* turn in the first chamber using 4.5" tubing and extend it almost to the bottom. Then then have tubes above it, or along each side of the down tube crossing over to the second chamber. A small hole in the first chamber to drain the water??

And what was the name of that magazine??
Thanks
Dick

Dick,

I believe the magazine was performance boat magazine. I'll double check later. They don't have a working website. The article did not explain very well what exactly happens, and because they painted the boxes black, it's almost impossible to see what's happening from the pictures... figures, huh?

I agree with your idea of entering from the top to avoid having lower holes cut into the transom... I was also thinking for a trial run, I'd use a valve to drain water first, and control cooling.

For me it's a little tougher having exhaust exiting above the swim platform - so I may be trying this without the platform or with a second set of holes like mercury.

By the way, we ran the boat for the first time this year on Macatawa last Thursday... the imco lowers are definitely helping my prop slip numbers. A little harder to get on plane, but not a big deal with tabs. Handling is perfect, no porpoising or chine walking - haven't punched it yet, but I hit mid 80's on the last pass with more left and some trimming to do. I also am still running stock props. It was getting pretty late, so I didn't go for more... that and I'd rather not go that fast inland

Thanks!
Jeff

I just checked, the magazine is Performance Boats - it was their premier issue:

www.performanceboats.com

Not too bad compared to powerboat and hotboat... but it was their pilot issue, so who knows how it has been since.

Their article had interviewed Fred Kiekhaefer, but it's pretty short and the pictures aren't too great.

Thanks Jeff! I will take a peak!