Fresh Air Exhaust - The test results are in!

[D-GOOSE]

come on guys we are cutting hairs with some of this. Next your going to say the wax came off and created a drag.

Heck, next thing you know we will be putting the boat in a bubble and do all the tests.

I have one. Need to do the test on every motor and hull combination

[nyryan2001]

I know when I am running super heavy I can not plane if my rider is pulling on the line at all, doing inside outs or slashing, while I am trying to get up to speed…. at that point, they need to just turn their board sideways and slide until we are on plane, or get outside the wake immediately and "surf" the whitewater.

Are you already using a 2315?

[formulaben]

The OP is saying the

come on guys we are cutting hairs with some of this. Next your going to say the wax came off and created a drag.

The OP is saying the FAE slowed his boat by by some margin...all I'm saying is if he did it on a COLD day and then tested the FAE on a warm day, much of that may be down to air charge. That's all. Just trying to keep apples to apples.

[JohnnyDefacto]

Are you already using a 2315?

Yes I am, love this prop.

[TallRedRider]

The OP is saying the

The OP is saying the FAE slowed his boat by by some margin...all I'm saying is if he did it on a COLD day and then tested the FAE on a warm day, much of that may be down to air charge. That's all. Just trying to keep apples to apples.

I personally won't buy that the air temp is going to make a measureable difference. But for the record, the test without FAE was at 60 degrees and the test with it was at 75 degrees, so maybe you're onto something.

[formulaben]

I personally won't buy that the air temp is going to make a measurable difference. But for the record, the test without FAE was at 60 degrees and the test with it was at 75 degrees, so maybe you're onto something.

https://wahiduddin.net/calc/calc_hp_dp.htm

You probably don't have the dewpoint or altimeter setting (pressure altitude) numbers from the time of your test, but just plug in your altitude or use 0 for sea level and 29.92 as a baseline and see the difference between 75 and 60 degrees. A general rule of thumb is 1% per 10 degrees loss of power at the temp goes up.

[bunji169]

New one piece FAE installed on my 2013 LSV. Here's mY test before and after. Acme 2315 prop. 350ss Engine. Water pretty flat both days.

Before FAE: 4 people on board. Prob 650lbs total.

30mph no ballast 4150rpm

Top speed 37.5mph 5400rpm

Wakesurf all ballast, 2 750lb plug n play, full wedge. 10.4mph 3550rpm

After FAE installed. 3 adults on board. Prob 550lbs.

30mph no ballast 4100rpm

Top speed 37.5mph 5400rpm

Wakesurf all ballast, 2 750lb plug n play, full wedge. 10.4mph 3400rpm

Pretty much the same minus about 100lbs for an extra person. Seems like that explains why the rpm was a little lower with the FAE. No noticeable difference in performance. A little more spray at high speed, but no significant spray at surf speed. Sent from my iPhone using Tapatalk

Edited April 21, 2014 by bunji169

[TallRedRider]

ImageUploadedByTapatalk1398050838.178534.jpg New one piece FAE installed on my 2013 LSV. Here's mY test before and after. Acme 2315 prop. 350ss Engine. Water pretty flat both days. 4 people on board. Prob 650lbs total.

30mph no ballast 4150rpm

Top speed 37.5mph 5400rpm

Wakesurf all ballast, 2 750lb plug n play, full wedge. 10.4mph 3550rpm

After FAE installed. 3 adults on board. Prob 550lbs.

30mph no ballast 4100rpm

Top speed 37.5mph 5400rpm

Wakesurf all ballast, 2 750lb plug n play, full wedge. 10.4mph 3400rpm

Pretty much the same minus about 100lbs for am extra person. Seems like that explains why the rpm was a little lower with the FAE. No noticeable difference in performance. A little more spray at high speed, but no significant spray at surf speed. Sent from my iPhone using Tapatalk

Now your post is readable.

Although I am not sure that RPM's alone tell the whole story. It would certainly seem to be a good surrogate marker for power. It is also good to see some numbers put together over the entire spectrum, not just 0-22MPH like I did.

Edited April 21, 2014 by TallRedRider

[formulaben]

4 people on board. Prob 650lbs total.

30mph no ballast 4150rpm

Top speed 37.5mph 5400rpm

Wakesurf all ballast, 2 750lb plug n play, full wedge. 10.4mph 3550rpm

After FAE installed. 3 adults on board. Prob 550lbs.

30mph no ballast 4100rpm

Top speed 37.5mph 5400rpm

Wakesurf all ballast, 2 750lb plug n play, full wedge. 10.4mph 3400rpm

Anyone else find this curious?

Bunji, was the weight distribution close on both runs? Regardless of if the FAE makes more or less power, the RPM should remain the same...the fuel flow may change, but RPM should be the same for a given load/configuration, and I don't think the 100lb difference would account for 150RPMs; different deck angle maybe, but not that much weight.

[oldjeep]

Anyone else find this curious?

Bunji, was the weight distribution close on both runs? Regardless of if the FAE makes more or less power, the RPM should remain the same...the fuel flow may change, but RPM should be the same for a given load/configuration, and I don't think the 100lb difference would account for 150RPMs; different deck angle maybe, but not that much weight.

Yes, made me wonder if one run was up river and the other was down river. Regardless of the FAE or weight you shouldn't have prop slip once you reach a static speed.

[cowwboy]

I like the Y design much better over the rubber joints and a 90 downward turn outlet.

[85 Barefoot]

Anyone else find this curious?

Bunji, was the weight distribution close on both runs? Regardless of if the FAE makes more or less power, the RPM should remain the same...the fuel flow may change, but RPM should be the same for a given load/configuration, and I don't think the 100lb difference would account for 150RPMs; different deck angle maybe, but not that much weight.

Except that the FAE could have an effect on the

Yes, made me wonder if one run was up river and the other was down river. Regardless of the FAE or weight you shouldn't have prop slip once you reach a static speed.

Mathematically, props do slip, even at speed. Take for example a response with a 13x12. Assuming its turning 3000 rpm that "should" be going 3000 feet per minute which "should" be 34 mph meaning a boat on plane is slipping 13% (as most DD owners "hope" for 1:1). Compared to a boat at a 30 degree angle with thousands of pounds of ballast, you'll get even more slip. However, I would have expected that the drag with FAE would have required more RPM. My guess is the higher hydrodymanic pressure caused between the exhaust and the prop is having the effect of more "grip".

[formulaben]

The drag from the FAE pipe notwithstanding, the only effect should be a different throttle position/fuel flow, not a different prop RPM...but this assumes same payloading and accurate accounting of the speed.

[shawndoggy]

considering tracking fins and shaft/strut/prop/rudder (which are all in front of and lower in the water than the fae) can the FAE really be introducing that much drag?

[oldjeep]

considering tracking fins and shaft/strut/prop/rudder (which are all in front of and lower in the water than the fae) can the FAE really be introducing that much drag?

Hard to believe that dragging a 3" pipe through the water would make much difference in drag on a 3500lb + boat. It would be interesting to know how much pressure is actually on that pipe - given the way it is attached it doesn't seem like there could be much or the thing would be rotating in the hose clamps/rubber boots

[formulaben]

No, it shouldn't, IMHO...but in the post I highlighted it says the RPMs went down. Something is up...

[shawndoggy]

less weight in the boat on the fae test, right?

[formulaben]

Yeah, but 150RPMs worth?

[bunji169]

I tried to pick a few simple before and after tests that I could easily re-create in similar conditions. The only difference was the extra person missing afte the FAE was installed. Other than that, all factors were the same. I plan on going out again this week. I will do the same tests again for confirmation. I did take pics of my Maliview during each test before and after FAE installation for reference....

Any other suggestions on things to test, I'm all ears. Of course, FAE is now installed, and I don't think I want to remove it, so any tests now would only be with the FAE..

The look is much cleaner from rear. The sides however, still have the rubber hoses connected with hose clamps. But I do like the way Larry re-designed the 1-piece rear section into a V-Shape...

[cowwboy]

Depending on what equipment you have acces to. If you tapped into the exhaust outlets and put a calibrated pressure gauge to the taps. You coukd say without a doubt if it added any backpressure. Also if you could set up a spring (fish scale) so it can tell how much drag is being applied to the pipe. The drag portion is harder to quantify.

Sent from my SCH-I535 using Tapatalk

[D-GOOSE]

If you are looking for the FAE discount PM me.

[racer808]

I can't exactly confirm since conditions sucked last weekend & I will try again this weekend. But it really seems like out of the hole the boat feels like it has drag & takes longer to plane. BUT, it was really windy & choppy so not the best to compare things. Night & day difference with how quiet it is though.

[wakedncsu]

Just got mine installed. It feels the same to me. The only difference is getting used to not hearing the exhaust. It feels like there is a delay now because I hit the throttle and then the boat goes. Before, as you increased throttle you heard the motor coming to life. Now there is just this "whooshing" sound and then the boat goes. I think it is a perception thing and not that the boat has really lost power. The thing we all queue on has been taken away.

[formulaben]

Just got mine installed. It feels the same to me. The only difference is getting used to not hearing the exhaust. It feels like there is a delay now because I hit the throttle and then the boat goes. Before, as you increased throttle you heard the motor coming to life. Now there is just this "whooshing" sound and then the boat goes. I think it is a perception thing and not that the boat has really lost power. The thing we all queue on has been taken away.

Kind of like the car/motorcycle with a LOUD exhaust and they seem to be going faster than they really are...

[wakedncsu]

Kind of like the car/motorcycle with a LOUD exhaust and they seem to be going faster than they really are...

Yeah.