cummins 4BT exhaust elbow silly price

[Todd Pearce]

I am surprised by the cost of this part, ( part no 3897800) exhaust elbow,$2700 usd,,,,,, it seems so excessive for what it is, is there an alternative supplier, a better than factory part? it seems like these fail a lot, any and all thoughts welcome

[Carl]

I agree, very expensive for what they are.

It's a flange to mount onto turbo, than a tube within a tube going to a showerhead.

I made a pair as I didn't like the stock elbows for my boat. I wanted to increase distance from waterline to turbo outlet, wanted the upside of the riser dry so if and when the wet side started to leak it would not go back into the motor. I also wanted motor to breathe more so increased the diameters of everything. Cost was less then 1/2 a stock riser for both.

I made my own stuff, buying tube n elbows from industrial suppliers. SB Marine also sells most of the items to build on there site...turbo flange, showerhead and tubing. Not cheap, but a one stop shop allowing you to customize as wanted with some cutting and welding.
https://www.sbmar.com


If I had to buy something made, I'd use these guys. They do great work with most of the patterns on the shelf. Not always cheaper, but easier breathing and longer lasting has been the norm from people I have sent their way.
http://www.marinemanifoldcorp.com

[S Ritzert]

I did the same, I built my own mixer, and dry exhaust.

[Carl]

Yup, that looks familiar, nice job!

On your showerhead it looks like you did a flared end to introduce the raw water. I was thinking of going that route, but wasn't sure about the flow pattern, creating hot spots etc. The hole, sizes and quantity of holes is in the Cummins book, so I played it safe.

I liked the openness without the crossover on the Port side so made riser fit in same space as the stock elbow. Starboard riser is same as everyone's...aside from keeping exhaust in stock ally way. Relocating exhaust outboard had advantages, but that opened the scope of the project further and it was time to be done.

[S Ritzert]

like wise! fine job to you too!

Athens calls it a spray ring, I made it so the water enters the wet portion from the side, and hopefully causes a swirl effect if you will, and the spray ring should scatter the water in an outwardly fashion (if that makes sense). I was going to garden hose test it the same way you did.

I just purchased my second turbo, and business is starting to slow down here. In the next month or so before my winterization season hit, I will finish this install

[Carl]

Swirl effect...LOL, yes that is why my raw water inlet is high and off to the side. The hope is to have water going around the shower head to cool and disperse water evenly across the holes.
I read about the Spray Ring/Flare to disperse outwards, I also watched a u-tube video of showerhead spray ring working, very impressive to say the least.
In the end I went old school as I wasn't sure my smaller 1-1/4" 210 Cummins pump produced enough volume to properly spray out of the larger than stock riser at low speeds.

[Todd Pearce]

Thanks to everyone for the input and great photos, we have decided to follow suit and make our own, , to buy the part here in NZ the first quote was 9k, its ridiculous and whats insulting is the part is only 4 years old and its failed, youd think Cummins would recognize they have made a shit part and improve it or at the very least make the part available at a reasonable price , very poor form on there part i think

[Carl]

Its so expensive as 1 or 2 elbows cannot be replicated "exactly" for less.

Those elbows are mandrel bent with rolled ridges to secure hose. Flanges are miserable to machine in SS, shower head transition is fun, lots of welding and fitting unless jigs n fixtures are made.

If willing and able to think outside the box with some access to a means to fabricate, its mind time, labor and material.

[scenarioL113]

This is a great thread! Always good for others to understand the basic concept of designing a marine exhaust system that (as Tony A would say) not doomed to fail!

[Carl]

Frank-

One day these dry exhaust risers systems will fail. The big difference is that when they do fail, the water will not leak back into the motor. That is the up side...the down side is having extremely hot pipes in the engine compartment.

Yes the dry section does get wrapped and/or blanketed...but it is an area with potential to fail.

Hot oil or diesel spray in contact with hot piping vs stock elbow leaking back or elbow not high enough and being forced back to motor. Two big issues...me I fell on the side of the fence that feels safer monitoring the external condition of the heat wrap/place hands on and around when running to verify condition. I took that over not knowing how far the corrosion process is on the insides. Even if elbows are removed its a tough call. My old stock elbows look OK and do not leak....yet.