exaust turn downs
 

has anyone tried the turn down exaust extensions that come off the back of the boat, and direct the exaust underwater until on plane. If so what size, and how well did it work reducing noice?

Have not tried them on a Nordic but from what I have seen they seem to work very well.

I have a set of turn downs on my Heat. This is FTM (Bob's) old boat. They work great for mine. You can actually talk between one another without shouting! Its great when you have the family and dog out. Shoot me an email and I can send you a [email protected]

I just put a set on my new Flame. They made a huge difference in cockpit noise. I just bought 4" 90 degree SS bends and cut the ends at an angle so they don't hang down. Clamped them on with a short piece of hose. They look good and were not too expensive. They are submerged at idle so it's really quiet. There is room to insert mufflers into them also. For the record I ran my boat on the prop shaft dyno and put some muffler inserts in. It lost 2 HP! This is with 496 Mags. I had previously tested the inserts on a 600HP 540 and they cost about 5 hp. You can buy the Gibson turn downs that clamp on. Just cut the down turn length to whatever you want.

what was the total height, top to bottom of the extensions?
Also when you say you lost HP, was that with muffler inserts, or just the turn downs.
Love to see any pics anyone has installed.
Had some neighbors last year that did not enjoy the sound of the boat as much as I did, need to keep the peace.

Here's a picture. I'm going to cut them a little shorter though.

The HP loss was from the mufflers. Turn downs don't affect the HP.

Did it quite it any while running?

Tremendously inside the boat. Don't know about outside, probably not much. It did away with all the resonance so all you hear is a nice exhaust tone. This boat just had the tips with external flappers to begin with. If you have longer tips it may not make as much difference.

I might try them. I had (3) 22foot Pachanga's. They had the fiberglass mufflers that still gave them some rumble but much more quite. It had a 454, 330HP. I put a 496 old style with Imco exhaust, and it ran great. After a friend saw them and told me they were too restricted. I had Imco make a new set of elbow tops in them to the tune of 2K and I gained 1 mph, maybe 2 at best. It gets tough on twins finding the space in the center of the boat.
Noise is good until you want to listen to some music going down the river.

Bob,
Your set-up looks great. I tried to install a set of Gibson's on my Flame a couple of years ago, but they were too long and wouldn't fit around my external steering. Looking at your pic, looks like you got around that problem by attaching them with 4" wet exhaust hose. What is that hose lenght? Are the turndowns angle cut on the bottom, like the Gibson's? I think the angle cut was to prevent reversion when in reverse. What length did you end-up cutting them @? Have you tried them yet? I'm really interested in doing this on our Flame, if you could give some details, I would greatly appriecate it. Presently, all I have on our boat is internal flappers and Salibury external flappers.

Thanks,
Dean

BTW, SWEEEEET Looking Flame, what speeds are you seeing with her? I bet whatever speeds she's running, it's only a matter of time, til you start tunning her up!

I've got about 4 hrs running time with the tips. I cut them straight across at the bottom, but I'm going to recut them at more of an angle. Right now they actually tuck under slightly, so if I were to lose power while running at speed water could conceivably be forced in the exhaust. They do quiten it down a bunch.

I tried a set of labbed 30" props this weekend and was able to get 76.6 MPH(gps) at 4700 RPM. It was running 73.6 with stock 28's before with approximately the same load and weather. So, I need to find a set of labbed 30's. Keep in mind this boat has the 496 Mags, not HO's.

Almost 77MPH with stock MAG's in a 35 is very impressive!

Bob,
Thanks it was great talking with you yesterday. Thanks for sharing some of your wisdom.
Dean