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Jesus_Freak
03-27-2011, 05:32 PM
Some of you may have seen the work OJ and I did with prop design here (http://www.mastercraft.com/teamtalk/showthread.php?t=35593). Larry at FAE (http://www.freshairexhaust.com/) has sought similar work on his exhaust system design. See some pictures below. I found that his design, in terms of fluid mechanics, fairs well. I cannot speak on anything related to emissions reduction and/or sound. This is more of an FYI FWIW and not an endorsement. I stand to gain nothing if you purchase an FAE system. :)

vision
03-27-2011, 08:02 PM
Thanks JF. As an owner of a FAE, it is good to see that the fluid mechanics are not greatly altered. I certainly can not tell that the FEA is present except for a larger rooster tail and the fact that it is so much more peaceful riding behind the boat and talking while in the boat.

gotta_ski
03-28-2011, 05:50 AM
Cool pics. What do they mean? I've been looking into getting a FAE but have wanted to know more. (I know, I know, everyone that has them loves them. I should just stop worrying and buy it already.) Can you provide some info on what we are seeing in these pics?

CantRepeat
03-28-2011, 08:18 AM
I saw video on the FAE system. It showed there was no change in CO at the surfer's position on the wake. However, it did lower CO levels at the transom and to a lesser degree in the boat while at surf speeds.

Jesus_Freak
03-28-2011, 08:19 AM
Thanks JF. As an owner of a FAE, it is good to see that the fluid mechanics are not greatly altered. I certainly can not tell that the FEA is present except for a larger rooster tail and the fact that it is so much more peaceful riding behind the boat and talking while in the boat.

Let me clarify that the gas and liquid flow in the exhaust, along with the water under the hull passing around the submerged exhaust tip, are most certainly altered. I concluded from the study, however, that the design is, for the most part, as good as it gets. In other words, only if manufacturing costs (and FAE's budget) were unlimited, could it be improved. I have gotten to know Larry during this endeavor, and he is being detailed and diligent in his design processes to the extent his budget allows.

Jesus_Freak
03-28-2011, 08:20 AM
I saw video on the FAE system. It showed there was no change in CO at the surfer's position on the wake. However, it did lower CO levels at the transom and to a lesser degree in the boat while at surf speeds.

I did not study emissions at all.

Jesus_Freak
03-28-2011, 08:24 AM
Cool pics. What do they mean? I've been looking into getting a FAE but have wanted to know more. (I know, I know, everyone that has them loves them. I should just stop worrying and buy it already.) Can you provide some info on what we are seeing in these pics?

The short version (longer version via PM) is that I looked at exhaust flow inside the unit along with water flow around the submerged tip. The submerged tip creates additional hull drag, but this added drag creates a suction on the exhaust gases to help mitigate the additional back pressure caused by FAE. It does not completely compensate for it, but it helps it. Please see also Post # 5 above.

Edit: I used an OJ prop in the analysis.

CantRepeat
03-28-2011, 08:28 AM
The short version (longer version via PM) is that I looked at exhaust flow inside the unit along with water flow around the submerged tip. The submerged tip creates additional hull drag, but this added drag creates a suction on the exhaust gases to help mitigate the additional back pressure caused by FAE. It does not completely compensate for it, but it helps it. Please see also Post # 5 above.

At what speed does the suction reach it's peak? How adverse is the back pressure at say 11 mph?

Jesus_Freak
03-28-2011, 08:34 AM
At what speed does the suction reach it's peak? How adverse is the back pressure at say 11 mph?

Excellent questions. I will have to let Larry share specific data/results.

prostar205
04-05-2011, 12:15 PM
I have a FAE installed on my X-30 with the L-18 engine. While the FAE website promotes only a 2-3 mph reduction of top speed, I found I lost 10-11 mph at top speed with the FAE installed. What's more, I had a really hard time getting the boat out of the hole when loaded with water (2,000 lbs evenly distributed) for wakeboarding with the FAE installed. I have come to surmize that the L-18 engine needs to breathe a lot more than a small block engine and the FAE is not allowing that to happen. Any thoughts???

Holman J.B.F
04-05-2011, 02:10 PM
I have a FAE installed on my X-30 with the L-18 engine. While the FAE website promotes only a 2-3 mph reduction of top speed, I found I lost 10-11 mph at top speed with the FAE installed. What's more, I had a really hard time getting the boat out of the hole when loaded with water (2,000 lbs evenly distributed) for wakeboarding with the FAE installed. I have come to surmize that the L-18 engine needs to breathe a lot more than a small block engine and the FAE is not allowing that to happen. Any thoughts???

same problem here,LY6...although it is not an original fae,..i made one out of epoxy.
I cut the pipe a few inches,but never installed it back.

prostar205
04-05-2011, 02:13 PM
I will be running the boat without the FAE as soon as it stops raining in Seattle to get an accurate comparison of perfomance with and without the FAE. I really love the FAE for the reduced noise (especially with a big block engine) and the reduced CO2 while surfing. I'm hoping to re-install it down the road.

WAProstar
04-06-2011, 01:03 AM
as soon as it stops raining in Seattle

I hear 'ya. Last year we went out in April, but this April so far hasn't showed any signs of getting nice. How long until July? :mad:

H20skeefreek
04-06-2011, 08:57 AM
JF, did you study this on a slalom boat or a wakeboard boat or in a lab setting? Just curious as to the effect on wake at 15 and 22 off on an old "junky" slalom tug at 32/34mph.

CantRepeat
04-06-2011, 10:24 AM
I will be running the boat without the FAE as soon as it stops raining in Seattle to get an accurate comparison of perfomance with and without the FAE. I really love the FAE for the reduced noise (especially with a big block engine) and the reduced CO2 while surfing. I'm hoping to re-install it down the road.

The guys at wake9 did a CO test and found the FAE didn't change the levels of CO at the riders location. In fact they also found that there was no unsafe levels anywhere in the boat or at the riders distance to begin with. What the FAE did was reduce the CO at the transom, swim deck area. There was a small reduction in the CO in the seating area but like I said it wasn't unsafe at surf speeds to begin with.

H20skeefreek
04-06-2011, 11:33 AM
I'm pretty sure that it CO that they are concerned about, not co2

CantRepeat
04-06-2011, 11:34 AM
I'm pretty sure that it CO that they are concerned about, not co2

You are correct it's CO not CO2.

Here is the test video.

http://wake9.com/wakesurfing-boating-carbon-monoxide-safety-information/

Jesus_Freak
04-08-2011, 06:53 AM
I have a FAE installed on my X-30 with the L-18 engine. While the FAE website promotes only a 2-3 mph reduction of top speed, I found I lost 10-11 mph at top speed with the FAE installed. What's more, I had a really hard time getting the boat out of the hole when loaded with water (2,000 lbs evenly distributed) for wakeboarding with the FAE installed. I have come to surmize that the L-18 engine needs to breathe a lot more than a small block engine and the FAE is not allowing that to happen. Any thoughts???

Thanks for posting this here instead of your original PM to me. I wanted to get this information out in the open. It is excellent that you brought this up. I only studied a 350 CID engine. Also, I did note in my OP that there is indeed a measurable effect of the FAE on back pressure. This is true for the 350, so imagine it is even more so for the larger engines (back pressure rises with increasing engine displacement to about the second power). The point with my conclusions, however, is that the FAE design is currently reasonable given limiting financial resources. There are improved designs Larry is considering which will reduce the back pressure, but these cost cash. Larry will have to comment on his corporate strategy.

The only obvious improvement that I (and probably many of you) can think of is to move to a dual pipe approach. However, I have not taken the time/energy to think through the overall effects this has on the design/installation package.

JF, did you study this on a slalom boat or a wakeboard boat or in a lab setting? Just curious as to the effect on wake at 15 and 22 off on an old "junky" slalom tug at 32/34mph.

I did nothing regarding the wake effects. That represents an entirely different family of studies and computational methods.

swatguy
04-08-2011, 10:36 AM
The guys at wake9 did a CO test and found the FAE didn't change the levels of CO at the riders location. In fact they also found that there was no unsafe levels anywhere in the boat or at the riders distance to begin with. What the FAE did was reduce the CO at the transom, swim deck area. There was a small reduction in the CO in the seating area but like I said it wasn't unsafe at surf speeds to begin with.

I would argue this statement. Sure the levels at the surf position stayed around the same however there was a change at the cabin/sundeck/ballast seating position while surfing eliminating the station wagon effect. The amounts on the sundeck/ballast position were originally measured at 100-150ppm on average and were able to spike to 300ppm. These numbers are definitely enough to make you ill after an hour or so of sitting up there. With the FAE exhaust installed that number went to 0 from the 100-300ppm in the sundeck/cabin seating, thus eliminating the station wagon effect in that seated position where 99.9% of people sit when someone surfs. That info was right around the 5:20 mark.

Also the amount of noise reduction from the FAE is 10fold. The only thing I noticed was that wake9's FAE seems to have a huge angle on it. Even with his wakeplate there was still plenty of room to put that more perpendicular as the angle has to be near max recommended for the FAE.

get_sum
04-10-2011, 05:10 PM
Nice! Finite Element Analysis? If so, what program? I dabbled a bit in that this year while designing my senior design project... a concrete canoe.

CantRepeat
04-10-2011, 09:16 PM
I would argue this statement. Sure the levels at the surf position stayed around the same however there was a change at the cabin/sundeck/ballast seating position while surfing eliminating the station wagon effect. The amounts on the sundeck/ballast position were originally measured at 100-150ppm on average and were able to spike to 300ppm. These numbers are definitely enough to make you ill after an hour or so of sitting up there. With the FAE exhaust installed that number went to 0 from the 100-300ppm in the sundeck/cabin seating, thus eliminating the station wagon effect in that seated position where 99.9% of people sit when someone surfs. That info was right around the 5:20 mark.

Also the amount of noise reduction from the FAE is 10fold. The only thing I noticed was that wake9's FAE seems to have a huge angle on it. Even with his wakeplate there was still plenty of room to put that more perpendicular as the angle has to be near max recommended for the FAE.

I said there was reduced cabin levels.

But, they said that it was around 100 ppm and would spike to 300. How long did the spike last? There is a big difference between 100 and 300. I think the big issue is how long you are stopped at idle. But, even then the exhaust still comes straight up. I just can't see where moving at 10 to 12 miles an hour would allow a constant 300 ppm in the cabin area. Sure sitting on the back of the boat might be bad, but why would you let people ride there in the first place.

Jesus_Freak
04-16-2011, 07:43 AM
Nice! Finite Element Analysis? If so, what program? I dabbled a bit in that this year while designing my senior design project... a concrete canoe.

Thanks, but this is 3-D computational fluid dynamics. It is similar to FEA in that there are partial differential equations being solved, but more coupled non-linear systems of equations are involved. In addition, the results, unlike FEA, are extremely sensitive to various inputs, subroutines, and numerical stencils.