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Old 25 August 2010, 08:55   #1
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exhaust relief?

Does anyone know anything about drilling the exhaust somewhere in the mid section of the leg so it is releived there rather than exiting through the prop hub?
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Old 25 August 2010, 11:31   #2
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What for?
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Old 25 August 2010, 16:11   #3
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once had to drill one out on a 1960s J.A.P. SEABEE,as the owner wanted to use it on a shortshaft transom boat and the engine was a long shaft shaft and it would not start owing to to much exhaust back pressure, but that was a one off ,
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Old 25 August 2010, 16:23   #4
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Does anyone know anything about drilling the exhaust somewhere in the mid section of the leg so it is releived there rather than exiting through the prop hub?
It was an 80's raceboat mod. The idea was to let the exhaust gases escape via a short-cut giving less resistance. The noise was incredible.

'SeaBee', that's a blast from the past. A pal had one when we were kids, we ran it on an old ex-RN sailing dinghy.
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Old 26 August 2010, 04:02   #5
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Purely interested for the increase in noise. The ones i've heard, they basically sound like when your motor is out of the water and your flushing it, only with the whole leg in the water!
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Old 26 August 2010, 07:20   #6
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Exhaust is usually a tube inside the leg, so unless you can fabricate a duct to the outside, there's going to be exhaust pressure getting to places it shouldn't.

Sounds like a fast road to a dose of Tinitus to me!
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Old 26 August 2010, 08:44   #7
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The OCR racers drill the Yamaha 130's out as they are far too quiet for a race boat as standard, I would never drill out a leisure engine as it will knock quite a bit of value of it and unless you do it right it will reduce the back pressure and reduce the power!
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When a boat looks that good who needs tubes!!!
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Old 26 August 2010, 10:47   #8
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The OCR racers drill the Yamaha 130's out as they are far too quiet for a race boat as standard,
is this something learned off the Saxo chavs?


Noise = Power
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Old 27 August 2010, 04:36   #9
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And you forgot Power is also directly proportional to the diameter of your tailpipe!
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Old 29 August 2010, 15:49   #10
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And you forgot Power is also directly proportional to the diameter of your tailpipe!
And inversly proportional to the number of active brain cells
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