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Exhaust through the transom below the water line?
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I am rigging a 32 classic and was wondering if anyone has ever had the exhaust exit through the transom and not the deck. Biggest reason is to have the exhaust below the water line at idle to keep me legal with the noise police. Hole on each side of the six drive would work nice I think.
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Isn't that what Nor-Tech is doing now?
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Brad...I thought you were a Mti man????:D ....32 skates are hot.
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Lightening Jcks has their exaust holes for the 525s in the transom
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I am keeping my canopy MTI for Poker Runs and Lake Michigan. I just bought this 32 as a crusier for our local Chain-O-Lakes. I have 525's with the sweep headers and I am worried about reversion if the tailpipes go up and out the deck holes. Plus having the exit under water at idle keeps me legal with the noise police.
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What about those donkey dong extentions that go beneth the waterline at idle? You would need some custom pipe at the current exhause holes- but then you wouldn't need to cut the transom.
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B'yond Reason as a crusier?? SAY IT AINT SO!!!!
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Originally Posted by vtec
(Post 2043113)
What about those donkey dong extentions that go beneth the waterline at idle? You would need some custom pipe at the current exhause holes- but then you wouldn't need to cut the transom.
Keep in mind it will be a 120mph cruiser. :D We live on some smaller lakes and this will be perfect. If I get bored I know a good enigne builder. Ateco. |
we had them below the rub rail on our 36 classic, no problems here
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120 for a Sunday cruise. That should work!!
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I had this exact setup on my boat. It used to be at the top of the transom but you need 14" of drop so you don't get reversion so we relocated through mid transom. The exhaust gas just "knips" at the waterline, it is very cool, it is not actually submursed with thru-transom exhause tips. With external mufflers (Gibson) they were completly underwater at idle, once on plane, they were above the water.
I took the mufflers off because I hated the way it looked, performance was fine either way Gregg Reichman |
Brad, Have you done any more with the tail pipes ?
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The tails came from CMi and I just cut the transom holes. I will take a few pictures Monday. I think this is going to work real nicely. Exhaust should be 4" below the waterline at idle.
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Notice the angle of the tails. Standard Sweep CMI headers and it works perfect for the tailpipes. Just waiting the transom tips that will be down turned and with baffles (water flaps for reversion)
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The old exhaust holes are covered with a hinged aluminum flap to relieve the air pressure like a vent. I got the idea from an Outerlimits boat that had them. They are primer grey now but will be painted to match the PPG Harelquin paint that changes from green to purple. I also need to paint the new hatches with the scoops from Skater. The other hatches were cut out for the massive Superchargers. The paint is $5,100 a gallon. Hopefully just a quart will do. :eek:
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Originally Posted by vtec
(Post 2043113)
What about those donkey dong extentions that go beneth the waterline at idle? You would need some custom pipe at the current exhause holes- but then you wouldn't need to cut the transom.
Gregg Reichman |
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CMI make downturns and they work great on my MTI. I think they look rather nice.
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Worlds Quietest Nortech...........
Here's the thread and the info on how they did it. http://www.offshoreonly.com/forums/s...d.php?t=117884 Cougarman |
Brad, For verification, are the tails wet or dry ? Transom integrity ? One inch vent hose as on Nor-Tech tails ? Do you have any idea for the splash date ?
The total project looks super sanitary---nice work !!! |
Not worried about the transom. There are knee braces right next to the drives. No need for relief vents like the Nortech as I am not as deep in the water. The exhaust is wet at the tip of the tailpipe. That is a full 18" below the header exit not including the angle of the boat floating. This really is no different in concept than my MTI with the exhaust exiting underwater at idle. The MTI has nearly triple the horsepower with big cams and blower surge with zero reversion issues. If we ever get out of this 40 degree cold front I will splash the boat.
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What are the tip baffles for ?
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Rubber flaps like the inboards boats use with the ehaust below the water line. I went with turndown tips with no flaps instead.
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Brad, I plan on using a variation of your design and would like to have your input and opinion.
I would prefer to have the tip double wall ( two pipes )through the transom. The tail pipe would connect to the tip with a rubber collar and double clamps on each end of the collar. A typical dry tail pipe jumper would connect the tail pipe to the tip. The tip would be turned down and wet. The tip would have a welded transom mounting flange drilled for fastening the flange to transom. However, how would you get the tip through the transom with a standard jumper pipe welded in place ? Perhaps a recessed bung could fitted in the tip to provide for a screw in sweep elbow after the tip was installed (5 " OD ) The double wall tip would assure minimum exhaust heat at the transom and the collar would provide some protection for transom flex and motor mount shift. However, the tail pipe over hung load will increase as the collar may flex. Therefore, perhaps the tail pipes could be connected together with a strap. A strap should also reduce loading on the header and header bolts. Perhaps the strap would be located 6 to 8 " from the header. |
Originally Posted by CcanDo
(Post 2090547)
Brad, I plan on using a variation of your design and would like to have your input and opinion.
I would prefer to have the tip double wall ( two pipes )through the transom. The tail pipe would connect to the tip with a rubber collar and double clamps on each end of the collar. A typical dry tail pipe jumper would connect the tail pipe to the tip. The tip would be turned down and wet. The tip would have a welded transom mounting flange drilled for fastening the flange to transom. [Why go to all the trouble if you are going to be wet exhaust any way? There are a lot of boats with through transom exhaust that never get to hot at the transom tip as it is wet at that point. However, how would you get the tip through the transom with a standard jumper pipe welded in place ? Perhaps a recessed bung could fitted in the tip to provide for a screw in sweep elbow after the tip was installed (5 " OD ) Have CMI weld a screw in bung that will only be 1/2" or so and you could cut out a notch in the transom hole and seal it as you slip the tip through. The tip flange will cover that anyway on the outside. The double wall tip would assure minimum exhaust heat at the transom and the collar would provide some protection for transom flex and motor mount shift. However, the tail pipe over hung load will increase as the collar may flex. Therefore, perhaps the tail pipes could be connected together with a strap. A strap should also reduce loading on the header and header bolts. Perhaps the strap would be located 6 to 8 " from the header. |
Wow... That sure looks different. I cant wait to see how it runs.
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---what about piercing a hole in the tip instead of welding on a fitting that needs an over size transom hole....Then piercing a like size hole in the rubber collar....Then cap the collar hole with a split SS pipe that has the jumper pipe welded to the split SS pipe....The SS pipe would be fitted with two angles for bolting together causing a tight clamp at that end of the collar. The other end of the collar would get double clamps.
Water would flow through the jumper pipe, through the collar hole, through the pierced hole in the tip and out the wet tip. Therefore the transom hole can be glassed in with a smooth surface We have re-thought connecting the two tail pipes together. Instead of the SS strap ---maybe two ball ends screwed into a necked adjuster tube. The ball end method would provide finite adjutment that the strap would not. |
Turns out CMI does not make a internal flap for the turndown tips. Installed them anyway. It works great. The 525 engines are very quiet at idle with the exhaust under water. Once on plane we were making some noise but less than normal as the exhaust is directed down near the drives. Zero reversion!
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Thanks for your report !
Did water spit forward over the transom ? In reverse ? Sure would like to see some pictures. |
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Here are photos of the boat completed. Tails are in, the new hatches are painted (by me), and the old exhaust holes are now flap/vents with hinges. The Harlequin paint changes color from every slight angle green to purple. The material to paint the hatches and vents covers cost me about $1000.
Boat runs great. Even in hard reverse no reversion or scooping with tips underwater. Even when I was testing without the hatches and the vent covers no water came in the bilge. The engines have a nice deep rumble at idle with the exhaust fully underwater. No way the noise police will bother me. |
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paint
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Thanks Brad, The total package looks better than I thought it would and I expected it to be very sanitary. Of course, I knew something was going on to drive the market over 13,000 !!!!
Has Leon tried to buy it back ? If not, wait untill he sees the pictures ! We will be talking with ATECO in the next few days. |
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