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  1. #21
    Join Date
    Mar 2011
    Location
    Québec,Canada.
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    53

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    Quote Originally Posted by Ryan351 View Post
    Resurrecting an old thread but to Olivier 20, I'm looking to build my own as well. I have an 86 pro comp, and DAMN it is LOUD.
    My question is how did you go about forming the downpipe?

    Thanks and nice build.
    Ryan
    Hi mate ! Yeah our boats are definately really loud !! For our venturi exhaust system : we started by doing the left exhaust to the right exhaust connexion with the elbows , After that we used Hole Saw to make an exit hole in the middle of that 'L&R connexion'... For the downpipe, we took the rest of our aluminium pipe and cut one end with a Hole Saw to get a half-circle pipe end. We put that half-circle end over the exit hole on the ''L&R conexion'' and measure it down to the shaft level or propeller nuts. Then for the last part: the other end of the downpipe was machine press a bit , a cut at a 45 degree angle and weld up the downpipe to the L&R connexion with a little angle (eyes view angle that seem great for us,nothing scientific here !).

    Take a look at the pics in the 1st post while reading my explanation... I'm french and my english is not the best in the business !

    I hope i help or enlighten you a bit !!

  2. #22
    Join Date
    Mar 2013
    Posts
    12

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    Olivier Thanks for the reply!!
    I actually stumbled upon this thread via Google search hoping to find some real world noise level reduction! And from your experience I'm sold!

    Yeah makes complete sense. I was curious as to how you got the "wedge" cut on the downpipe, more for the angle, and 45° is exactly what I'm looking for.
    So from there you just kinda smashed it with a press to put the oval shape to it?
    Sounds easy enough!

    Any issues thus far with strength of the unit?
    I believe you mentioned a rooster tail at wakeboard speeds, how far does it reach out?
    My sisters waterski so 28mph is common, any issues up at that speed?


    Thanks again
    Ryan

  3. #23
    Join Date
    Mar 2011
    Location
    Québec,Canada.
    Posts
    53

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    Quote Originally Posted by Ryan351 View Post
    Olivier Thanks for the reply!!
    I actually stumbled upon this thread via Google search hoping to find some real world noise level reduction! And from your experience I'm sold!

    Yeah makes complete sense. I was curious as to how you got the "wedge" cut on the downpipe, more for the angle, and 45° is exactly what I'm looking for.
    So from there you just kinda smashed it with a press to put the oval shape to it?
    Sounds easy enough!

    Any issues thus far with strength of the unit?
    I believe you mentioned a rooster tail at wakeboard speeds, how far does it reach out?
    My sisters waterski so 28mph is common, any issues up at that speed?


    Thanks again
    Ryan
    I'm sure you will love that thing , it really reduce the sound a lot and no more exhaust smell when moving !
    -Yeah the downpipe was just pressed till the oval shape was good enough for us !! not much of R&D HaHa
    ** juste remember to but the 45° in the right direction to have the venturi effect !
    -Yet no issue at all with the strength, the only thing we ad that is not on the pics is some 3'' ID rubber hose to connect the transom pipe and the actual exhaust system. without the rubber it wasn't airthight and since it was direct metal contact it was vibrating a bit so i suggest you tu put some rubber and a good set of clamp of course !!
    -For the rooster tail , it's really not that bad. At 22-23mph (my wakeboard speed) the tail is right about the end of the swin plate and doesn't go really further. AT higher speed the tail does go further but never enough to annoy or disturb a good ride on ski or wake !

    here's a pic powder coated flat black when we paint our Sunsport last spring :

    the bolts clamps are rust i know... all the clamps parts are in stainless except the bolt ?? it's a bit stupid !

    The paint job thread if your interest :
    https://forum.supraboats.com/showthread.php?14808-86-Sunsport-NEW-PAINT-!!!
    Last edited by olivier_20; 01-14-2014 at 10:10 PM.

  4. #24
    Join Date
    May 2009
    Location
    Lafayette, IN
    Posts
    87

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    Hi, how did you know how far into the water to go? Would you suggest going any less deep? I plan on taking this project this spring. Thanks!

  5. #25
    Join Date
    Mar 2013
    Posts
    12

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    Olivier,
    Love it!! Thank you so much! I thought about adding a rubber boot there as well!

    Aaron-
    http://www.freshairexhaust.com/wp-co...nts_Needed.pdf

  6. #26
    Join Date
    Mar 2011
    Location
    Québec,Canada.
    Posts
    53

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    Quote Originally Posted by Aaron187 View Post
    Hi, how did you know how far into the water to go? Would you suggest going any less deep? I plan on taking this project this spring. Thanks!
    Hi, i really don't know how far in is the best but logically it can't go deeper than the propeller to avoid restriction...
    And if it goes to the shaft/mid-propeller level, i think the exhaust gaz & noize are expel in the propeller stream and that should help to improve the venturi effect by moving more water to it, and the stream should push all the unwanted stuff powerfully in a straight line so the rider pass over it without exhaust smell and not much sound anymore. That's what i think and experience tho !! again no R&D was made it was a one shot DIY !!

    Look at some pics on google , you'll see ...Click to see some pics
    Last edited by olivier_20; 01-15-2014 at 11:58 PM.

  7. #27
    Join Date
    Mar 2013
    Posts
    12

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    Olivier,
    Thanks a lot for the reply.
    I posted earlier but it said something about the moderator had to review it! Shoot man, 3 posts and I'm already being watched by "Big Brother"

    Anyway, that 45° is exactly what I was looking for, and I have a nice 20ton press that should do the trick nicely.
    I'm thinking I'll just get mandrel 90° from my good auto parts place, and have it all powder coated.

    Your boat looks AWESOME!

    Aaron- if you go to Fresh air exahust website the have a page that shows how to measure your boat for them to make one, so I'm betting you can derive the exact length they build to, but as Olivier said, As long as you're close, I'm betting it'll be good.

    Enjoy

  8. #28
    Join Date
    Mar 2011
    Location
    Québec,Canada.
    Posts
    53

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    it's strange i received email about new reply's on my thread but there's nothing new ??? are the messages have been bloqued ??

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