Fresh Air Exhaust

[Razorskier1]

Installed this today on my 2015 Prostar. Amazing! From behind the boat is silent. It is also much quieter inside. Really cool. Will report back on ski performance once I get a chance to ski it.

 

 

[Fine409]

Interested to hear how the boat skis with it!

 

 

[colo_skier]

I installed one on my 2007 lxi. The Hole shot was significantly reduced. That may have been due to the altitude here though. The wake was not effected as far as I could tell. Great for all around noise reduction and fume reduction when surfing though.

[Razorskier1]

My ProStar has a 6.2L so power won't be an issue. It didn't look like the wake was impacted. The noise reduction both inside and outside the boat was remarkable. I will feel less bad about my early morning ski sets knowing I'm not making quite so much noise.

[Than_Bogan]

If we want our sport to survive on public lakes, noise reduction is huge!

 

I look forward to more reports.

[jackski]

All the little tiny old fishing boat motors going out at 5:30 and 6:00 in the morning are louder that our boats. Had one this morning at 5:45am the guys were screaming to talk to each other. That said the new motors are quiet.

[RazorRoss3]

When I was standing on the dock and he went out if the hole I could hear the water breaking off the bow louder than the exhaust. I could t believe it.

[6balls]

You should send a note of excitement out to your lake association about this cool new product you bought to reduce the impact of your boat on others. Then they know the guy who runs the buoys all the time is making an effort and will probably take notice.

[xrated]

I love the sound of any boat motor on the lake while laying in bed...except jet skis.

 

That looks good Razor.

[oldjeep]

The gearhead in me hates that they fire opposing banks straight into each other at the T junction.

[Wish]

@oldjeep isnt your description that of every SN going waaay back?

[Bulldog]

@Razorskier1 any chance of a quick phone vid of the sound?? would love to hear / see that.

[oldjeep]

@wish I'd have to find a picture, but I suspect that nautiques 2-1 exhaust is a y pipe.

[Wayne]

@oldjeep is it an issue when there is negative pressure at the outlet? There is video of the FAE pipe run vertical and open to atmosphere and the water passing the opening "sucks" air out of the pipe. Granted when the boat is taking off from a stand still this effect will not be in play. I don't see it really effective performance above some critical speed where the water flow generates enough negative pressure to overcome the "poor routing".

[LeonL]

Nauriques 2-1 exhaust is within the muffler. Two in, one out.

[colo_skier]

I have a hammerhead in the boat and there was certainly less hole shot. Not an issue just an observation. Short end set up was just a little later to settle.

[6balls]

That 6.2 Prostar RIPs out of the hole so it may make her a little more friendly.

[Andre]

Is the hole shot less powerful because of the excess drag or restriction of the exaust and the engine having trouble breathing?

[ozski]

I saw something fitted to a Nautique in Europe back in the 90's which was just rubber pipe fitted to the tail pipe, it redirected the sound down rather than out the back. From memory it worked really well.

[Texas6]

Restriction on exhaust flow

[PBD]

Any thoughts on back pressure issues?

[Wish]

cost?

installation..easy, hard?

Have a Bu on my lake that could really use one.

[Razorskier1]

I will ski and drive it tomorrow and let you know. Cost around $500. Install easy.

[Horton]

I heard a story many many years ago of a boat where the exhaust hose was extended another 5 feet behind the boat. Not sure this makes sense but the story was that it was crazy quite.

[ozski]

I've heard the argument the the submarine exhaust protects the wake surfers from ingesting too many fumes, probably a valid point. Fumes would probably stay under water for about 10.75m or so....

[Razorskier1]

Raining this morning. No test yet.

[Razorskier1]

Tested! Skied after the rain when the water got calm. Report. On the noise level, a neighbor told me that there was no sound behind the boat. As a skier behind the boat, I can confirm that about the only sound you heard sounded like an electric motor running. Pretty sure I was hearing the tranny or prop. REALLY QUIET!

 

My driver said there was no noticeable difference in boat performance out of the hole or accelerating.

 

As a skier you notice that the boat throws a small rooster tail about 12-15 feet behind the platform. Normally with an inboard I see a rooster, but it is only maybe 5 feet long. So you definitely see that.

 

However, I skied 28 through 35 and noticed no difference in wakes and didn't get any spray on me from the rooster. Would have shortened to 38 but the knot was stuck and my wife couldn't get it open and we were pressed for time.

 

All in a very positive report in terms of achieving my objectives of noise reduction and no noticeable change in either boat or skiing performance.

[Lars]

@Razorskier1 Well great, now how am I supposed to hear when you guys are done at the course?? ;)

 

Seriously though, Monday morning we were waiting to go until we finally just went down to the dock and saw you had quietly come back already.

 

[Razorskier1]

@Lars. Is this Dave or Joe? It is my effort to keep peace and keep my course permit!

[colo_skier]

The noise reduction is fantastic. People say my boat is louder coming towards them than going away when I have the Fresh Air attached.

[Lars]

@Razorskier1 this is joe. Hoping to get dave in the course at some point!

[Razorskier1]

I drove it last night for my son at 36mph. I would say that getting to 36mph is slightly slower with the FAE than without. That is probably where the backpressure starts to come in. Also did a top speed test. Again, somewhat slower to top speed, and dropped about 3mph to about 43.5mph. These are all tolerable differences, but it does make me wonder about the T-Junction as mentioned by @oldjeep. Seems like you could design a similar system with either two separate exhausts conjoined by a solid connector, or something with more of a Y-shape.

[Skoot1123]

@Razorskier1 - or you could make the diameter bigger of the outlet pipe to reduce backpressure. I don't see any reason why you couldn't have dual pipes (of course I don't know what kind of validation/testing was done to come up with the current design).

[DW]

The T intersection is certainly a main contributor to performance loss, I assume by not seeing any weld marks on the top of the tube there is no diverter directing the water/exhaust mixture downward. That probably increases backpressure substantially with exhaust mixture aimed directly at each other assuming no diverter, the other contributor is volume reduction and 2 bends for the exhaust to negotiate.

 

@Razorskier1: you might want to do a simple exit area v. original exit area comparison to see how much that has been restricted. The FAE outlet will have some suction on it based on the angle cut and design.

[Lieutenant Dan]

From the FAE website...."Boat engine manufacturers specify that the exhaust back pressure not exceed 2 psi as higher levels may impair engine performance. On typical boats FAE does not increase exhaust back pressure above 2 psi except at engine speeds above 3500 rpm. With FAE installed, the typical boat loses 1-1/2 to 2 mph of top end speed."

[EFW]

Patent infringement? Gotta keep them Packards quiet. No sense telling Yamamoto were at the front door.

[MISkier]

@Razorskier1, can you post some video with clear sound of the boat accelerating from stop and also passing by. For the "fly-by" portion, it would be great if the camera were in another boat away from shore and have the FAE boat blast by at about 34.2 mph within a few feet or so.

 

We are looking for new ski sites for one of the club's to which I belong. I'd like to have this option in my back pocket if any discussions about noise occur.

[Razorskier1]

This is from Larry Mann at FAE. He asked that I post it along with a couple of pictures. He is a great guy and was very helpful in getting my system order right and, via his cell phone on a SUNDAY, with the installation. Excellent customer service!

 

Thank you for your interest and thoughts about FAE. We now have over 2300 FAE installed. We have a very liberal return policy and yet our returns are less than 2%. We had one guy return his FAE because it was “too quiet”. The louder your boat to start with the greater noise reduction you will experience. We had another return from a slalom skier whose lake was in the Rocky Mountains at about 7000’ elevation. FAE slowed his boat down to where he could not come to speed before entering the course; though at lower elevations it performed fine. We have lots of customers in the Denver area (5200’ elevation) with no reported problems.

 

The reduction in performance is due primarily to the drag caused by the downpipe in the water. If a customer is experiencing spray, handling or speed issues we work with them on fine-tuning their installation to minimize the issue.

 

The attached image “FAE Internal Flow Analysis” shows that the T junction does not cause much back-pressure. We’ve experimented with internal flow diverters and found no improvement in performance. The image “FAE Flow Analysis Outlet” shows the area of reduced pressure at the opening of the FAE that “sucks” the exhaust out of the system.

 

We just completed another round of computational flow analysis where we experimented with different shapes of the downpipe. Essentially the shape we’ve been using on the 3” diameter FAE has been excellent from the beginning. We have though recently modified the shape on the 3-1/2”and 4” diameter FAE downpipes. One customer that was having spray issues with his 4” diameter FAE reported a 90% reduction in spray with these changes. Yes, we could increase the diameter of the FAE to improve flow but the trade-off will be increased drag (no free lunch). We typically size FAE to the smallest diameter of the exhaust system inside the boat.

 

I trust this answers all the questions posted but will be pleased to respond to any more.

 

Larry Mann

Fresh Air Exhaust

 

[Razorskier1]

The top image is the internal, the bottom image at the outlet.

[DW]

@Razorskier1: Thanks for posting the info and the CFD pressure diagrams. Not sure I totally agree with his analysis based on the internal pressure diagram shown but it is nice to see they did some CFD and analyzed the results and verified results with some testing. I would be curious to know what code was used since water/air mixed analysis is pretty damn difficult.

[Skoot1123]

The geek side of me loves this. Not often do I see some analyses results outside of work. Generally this is considered proprietary stuff - obviously he is interested in what we (Ballers) have to say/think. Great Stuff Larry!

[Razorskier1]

My neighbor shot this video from behind the boat from his boat. This was out of the hole to 36mph.

 

[Andre]

No sound on the video for me... :(

[oldjeep]

@Andre - its just that good ;) I get sound - mostly just wind noise though

[Razorskier1]

It is really quiet

[Jordan]

Hmmm......okay, that's really impressive.

 

It's primarily quieter because the exhaust goes down into the water....so it seems that we should have the exhaust go down through the hull and make little Eric Lee bubbles! @eleeski

 

 

[ToddL]

@Jordon, ah, yes. However, the exact exit location and path of those hull exhaust bubbles will be the next big wake tuning project for manufacturers... LOL.

[Lars]

@Andre I took the vid, It was a windy day, but on takeoff you'd almost hear the spray/water noise more than the exhaust note.

 

[Andre]

Sorry guys!

Had really no sound at all on my Commodore 64...

Just watched it on my phone,quite impressive!

Noise reduction is great and i hope your neighbors appreciate the effort you made to quiet things down.

 

[MISkier]

Amazing.