DIY Fresh Air Exhaust system - 1987 TS6M

[rludtke]

Hi Folks,

As much as I like the sound of the PCM through the open exhaust of my Comp, I wanted to nock down the noise and the carbon monoxide. After talking about it for several seasons, I finally got around to making my variation of "Fresh Air Exhaust" for my 1987 TS6M today. This exhaust system connects to the transom, and directs the exhaust under the water.

It's built of 4" ABS plastic pipe and fittings, and secured to the transom using the same threaded fastners that secures the Super Trapps. The threaded fastener is lenghtened about 9 1/2" to reach through a the pipe and hole drilled on a 90 degree elbow (one on each side). I used the rubber from 1/2" livewell plugs below the securing nuts to absorb the curvature of the pipe.

These elbows are connected with pipe to each other, which Tee into the tailpipes. It isn't finished, I will have to follow up with another post showing the finished tail pipes, and the strut I intend add to brace the pipe assembly from water loads. Hopefully next weekend I'll get her out on the water, and can let you all know how the system performs.

Check out the pictures...

Cheers,

[wake beater]

definatly will keep my eye on this thread,as i was thinking of ordering a fae...hope everything works..

[87SunSportMikeyD]

Looks great. You may want to give it vertical support to the swim platform like FAE does.

[wotan2525]

Love the idea... What is between the ABS and the supertrapp mounts? It's got to have more than just that skinny bolt holding it on, right?

[tg0824SSVGG]

Nice.

If it was "ME" ... I would tie a rope around that bad-boy, as it's not going to float
if all goes bad and it falls off ... at least you could get it back - until you know if
this is going ot work or not.

I love your thinking here!

[Kip]

Looks good. I can't wait to hear how it performs.

[rludtke]

At the moment, it is only supported by the supertrapp through-bolts, but I do plan to design and fab support struts that will connect the pipe assembly to the swim step braces (like the FAE system). This will probably use large 4-1/2" P clamps (if I can find them), and some aluminum angle. I may have to fab my own clamps.

It is very stout and stable now, but I expect the water loads will apply aft and upward loads to the outlet pipes. The struts will brace for these loads, and help maintain security to the boat.

I plan to install the outlet pipes with bolts inctead of glue, so that they can be removed if dinged, and that will allow me to play with adjusting the lenght.

I probably won't get back to it untill the weekend, I will post more photos of these details when it is finished.

[mapleleaf]

Really looks great, My only concern would be the temp at which the ABS starts to off gas at. Power vent PVC might be better over the long term....Canadian Building codes are requiring all new heating and cooling systems to use PVC now instead of ABS, because it would crack and fail over time...
Just my 0.02, I could be wrong, otherwise that system looks amazing, I would totally do one on my boat........

[rludtke]

Well, due to forces beyond my control, I didn't get as much done on the boat as I wanted, and wasn't able to put the boat in the water to test the new exhaust system. But I did complete the Fresh Air System installation. New pictures and a Bill of Materials is attached.

The support strut didn't become quite as elegant as I originally envivisoned, but it may actually be a better installation in the end. I was limited by the materials I could find locally, and the only large clamp I could procure was a 5" exhaust clamp from NAPA auto parts. I shimmed the clamp to fit around the 4 1/2" OD pipe with a pieces of ABS trimmed from a spare 4" coupler. I also had to do some digging at the salvage yard, as Ace hardware stopped carrying aluminum angle. I live on an island in the Puget Sound, which can make some things harder to aquire.

My original plan was to fab two brace struts that would capture the centerline swim step brace, and support the pipes near the outbd elbows. My thinking was that this would offer lateral rigidity as well as vertical rigidity. Limitations on the size and amount of angle availible, and the number and style of clamps I could find forced a redesign to a simpler installation using one strut, and one clamp.

You can see in the pictures how I picked up the exhaust clamp u-bolt with the angle, which in turn attaches to the swimstep brace with one new bolt hole.

The installation is very rigid, both vertically, and laterally. I pushed and pulled on the exhaust tips enough to move the boat around on the trailer, and experienced little relative movement.

I'm curious: How far below the hull does the real FAE system extend? My outlets are currenlty trimmed to ~ 8" below the hull. It would be nice to make them shorter, but I think the exhaust pressure could blow the water away from the pipe at higher power settings.

I'll update this thread with system performance as soon as I am able. I am hoping to get the boat wet next weekend.

Cheers,

[warek1814]

Those are some BIG pipes coming down. It looks like they will disturb the wake due to the size. I think a single down pipe in the middle would have been better. Get some wake pics next time out and post them up.