Mandrel Bent Exhaust and Muffler Bypass

Very Nice!
I did exactly the same thing, stainless mandrel bends are cheap. 
yours is much more complicated than mine because of the wedge but same concept. Looks great!
 

Awesome!  Nice work @Catman   Totally agree on mandrels --- I bought premade when I did mine as well!  Larry at FAE will do them custom, but his challenges are relying on customers for perfect measurements and requires some pretty tight turns, etc.  And I think it's easier for him not to deal with it.

Man those blended welds and polish turned out great.  You'll be glad you took the time... looks amazing.

Now I have to pull mine back off to polish it lol

great work!  did you make that hydraulic press shaper to narrow the down tube just for this project?  if they're easy enough to reproduce just the narrowed downpipe i would gladly pay you for it.  i'm converting my centurion sideswipe exhaust to a single rear outlet (4" downtubes to 3.5" exit) and am not looking forward to having to shop around to my local exhaust shops to have that downpipe done.

Fellow Wakegarage guys,  I appreciate the positive comments.

jtryon,  Yes, I did make them for this project only. My buddy and I actually made 2 sets of wood dies, one set for the 3” oval tube I did not use, and another for the 3 1/2” oval tube I did use. A set consists of: one round and one v-shaped oval (last photo above). I threw both 3” oval dies away already. I gave the 3 1/2” v-shaped oval die to a friend, because he was going to possibly do a similar down pipe for a Moomba. Do you just need the dies? Or a formed down pipe?

The 3.5” formed down pipe would be awesome because I’m sure it will be hard to get an exhaust or fab shop around here to make that exact piece.

2 hours ago, jtryon said:

The 3.5” formed down pipe would be awesome because I’m sure it will be hard to get an exhaust or fab shop around here to make that exact piece.

What length would you need? I started with a 12” long piece of 3 1/2” oval tube. Would you want the the weld-on end to be 3  1/2” round? And the outlet end the same shape as mine? Can you make the cuts shown in the photo?

yes a 3.5" round weld-on end is perfect, because i'll be welding a single 3.5" tube to it rather than duals like you did.  12" long is great and I can trim from the top if needed, and the outlet end the same shape as yours as well, or if it's easier to do a straight angled cut on the outlet that's perfectly fine as well.

I need to order the pipe, so it may take 2 weeks before you get it. I will order it today.

thanks!

Amazing. Curious why you went to the trouble of the muffler delete. Why not just attach your dual custom exhaust tubing? Is it to get more space in the engine compartment or mufflers no longer needed for noise reduction? Curious if your boat got quieter after the install as FAE describes on their site.

Sorry, I have been out all summer enjoying my homemade surf tabs and exhaust system.
Yes, the extra room is great, especially when changing the impeller on the raw water pump. I put 85 hours on it this summer and it is definitely quieter than before these modifications. I debated a lot on wether to put those flappers in my exhaust vs. keep the muffler. I did not want any chance for water to push into the engine.  I finally decided to install them, thus I deleted the muffler. I’m very happy with the noise reduction inside the boat and while surfing. My only downfall of this modification was that I lost 1-2mph on the top end. This is a result of the drag of the exhaust down pipe producing drag, it’s not a back pressure problem. I have modified the down pipe from my first design to reduce the drag.

Hey it looks really great! just wanted to ask you some questions. why didn’t you go up and down through the center of the wedge? I’ve been looking at doing it, and i’m wondering if there was a reason you didn’t?

I did think about doing it that way, but decided not to because of the swim deck clearance. I did not want to raise my swim deck. It just looked like it would be extremely tight. You would also have to use really tight radius on the tubing. I’m sure someone could make it work.

Thanks man, I’m going to proceed to give it a try!

"My muffler connections are 3 1/2”, so all I’d did here was purchase (2) 45 degree 3 1/2 mandrel bent SS tubes and cut one end off to make it fit.  I just had to rotate my SS exhaust outs on the manifolds a little and then rotated my rubber transom connect hoses a little also."

@CatmanI didn't realize the connections coming off the manifolds are able to rotate. Do you know what the CLR is of the 45degree elbows you used for the muffler delete? 

This is great as I want to do a muffler delete for my FAE project as well and this makes it a whole lot easier! Great info and great project. Very well done!

The CLR for those 45 degree tubes is 5.5”. I bought them from Summit.

Thank you

What changes did you make to the shape of your down pipe?

I pinched the leading edge of the pipe down from approx a 1” diameter to less than 1/2”. It lessened the water spray out the back. Might of helped top speed also.