FAE, yay or nay?

[Fman]

If you've ever rode in a boat with FAE, you won't want to ride I'm one again without in my opinion.

I have no doubt its much quieter, which would be awesome, but if the wake was affected at all, deal breaker for us. I am looking to find someone with a VLX who has some substantial time with the FAE on the boat....

[Durty_Curt]

I've had the FAE on my 04 VLX since she was in the late 800s (hours) just broke 1201 hours today and still no problems. The only wake change I noticed was a little more splash going into the rooster tail. NO WAKE CHANGE.

NOTES: i've been riding this wake since the late 300s.

My has the manual wedge not power wedge.

And I'm a total btich when it comes to my wake (weight distribution, speed, etc)

I can even tell a change from having 3 riders in the boat to having 4.

[Zeke83]

I've had the FAE on my 04 VLX since she was in the late 800s (hours) just broke 1201 hours today and still no problems. The only wake change I noticed was a little more splash going into the rooster tail. NO WAKE CHANGE.

NOTES: i've been riding this wake since the late 300s.

My has the manual wedge not power wedge.

And I'm a total btich when it comes to my wake (weight distribution, speed, etc)

I can even tell a change from having 3 riders in the boat to having 4.

There you go. Almost 400 hrs and his engine hasnt blown up.

[Durty_Curt]

Hahahaha! Not yet. I also do all my own maintenance and see my drive train making it to 1500 no sweat. 2000? Meh, probably!

[Zeke83]

Im ordering mine tomorrow. Wont ship till sometime after the 19th of next month though when I can get my hands on the boat to measure, which is good. I want to do some pre FAE baseline testing and get some numbers, maybe even tap in a pressure gauge to see what my backpressure is before and after.

[racer808]

I'm confident you could get the FAE set up where there's no impact on the wake. But it might take a couple of trips to the lake to get it "just right."

What would one be tweaking if there is a wake impact? Getting the tip of the outlet further up towards the swim deck?

[shawndoggy]

What would one be tweaking if there is a wake impact? Getting the tip of the outlet further up towards the swim deck?

that's what worked in my case.

[Chia]

We suck, TMC had this discussion started 2 years ago: FAE, Yay or Nay

http://www.mastercraft.com/teamtalk/showthread.php?t=46604

[Bradley Thornton]

Just a couple observations, from a mechanics stand point. 3 psi of back pressure on a 350 is not excessive to the point that u are you going to cause engine damage, burn vales ect... effect engine performace possibly yes, burn more fuel yes, loose a couple mph on top end, probably, over time have accelerated engine wear, possible but debatable... Without getting into the theory of exhaust back pressure, less back pressure is ALLWAYS better from a power efficiency and production standpoint, but, exhaust systems cant be tuned across the board for efficient operation in all RPM and loading conditions anyway. As the pressure wave from the exhausting piston, valves open, travels down the pipe a couple things happen, one it looses velocity as it travles, cools and becomes denser, creates a vacuum behind it, and is further slowed by that vacuum becoming stronger as the valves for that piston close behind it. The subsiquent pressure pulse from the next cylinder is in effect scavenged by this vacuum as it leaves the cylinder and so on and so forth blah blah blah. There's more going on there but that's basicly it. When u say two sides firing at eachother that is actually not correct, because no one pulse is created at the same time. Yes they are crashing into eachother but never at the same point. thats neither here nor there anyway. The back pressure of the system as a whole is X, even with that ugly transition, it is engineered to operate at back pressure X to provide X amount of HP at X,XXX rpm. A tuned exhaust is optimized for the correct size of piping and manifold to create the optimum flow and scavenge effect for that engine at the targeted rpm range the engine will usually be expected to run in. Enter that really bad looking transition and yes, there will be turbulence and a disruption of flow, however, they obviously tested it and it didnt create enough back pressure that it put them into the exsessive range. Creating more back pressure also moves your power curve as I just mentioned, and does other things... And I'm getting way into the theory of exhaust back pressure... Basicly, am I concerned about an additional 1 psi of back pressure, no.

You are both right and wrong no disrespect to me you showed that you are very smart in this area but between the headers and the water the pulse makes no difference now with that said the back pressure thing it can be bad or good it all comes down to the build of the motor. Bigger isn't always better. I have seen in more than 1 ocation that a 3in exhaust made a car lose 10hp over a 2 1/2in exhaust. If anyone thinks that the FAE is restricting the flow of the exhaust as I have said before they need to take the time to take the silencer off and the will see by looking inside it that it restricts way more than the FAE ever could.

I didn't right this but I think it explains it best.

Exhaust flow is fairly irrelevant in the sense that stock manifolds, shorties and long tubes will all flow plenty of exhaust through them. They are by no means a restriction. But with exhaust you are not trying to “flow” exhaust. There is no exhaust flow in the literal sense. There are exhaust pulses (which are little columns of “flow” if you want to get technical) which if timed correctly can be used to increase momentum (scavenging) of the exhaust gases. A simple way of thinking about it is if an exhaust pulse from one tube reaches the collector right as another tubes exhaust valve opens it will create a kind of vacuum in the collector which will help the just created exhaust pulse move faster. Consequently if the timing of the pulse is off a reverse pressure wave can be created that will bounce back against an exhaust pulse and therefore slow down the exhaust gases.

Log style manifolds (stock) have no “timing” in them and they are effectively very short tubes dumping into a big plenum. And they don’t even have a “collector” to speak of. Stock manifolds, if they create any sort of scavenging effect is purely by accident. Stock manifolds are so simple that they can only be defined by their “flow”. It’s a good thing they have an abundance of it. The stock exhaust manifolds have proven to be a very small restriction to supercharged motors which don’t rely on scavenging like a naturally aspirated motor does. You can make a lot of power with a supercharged motor while still retaining the stock manifolds.

Unequal length shorty headers probably don’t have a flow advantage over a log style stock manifold and if they do have some scavenging effect it is by accident again and minimal. What they do have is a collector. I could go on forever about collector design and why some designs work with some combos better than others but the basics are that a collector should help the individual tubes to merge the gases together in an orderly, smooth and in some cases timed fashion to increase exhaust velocity. The collector is about the only measurable advantage that an unequal length header will have over a stock manifold. I have yet to see concrete dyno results that show unequal length shorty headers offer an hp advantage over the stock manifolds. I have seen a few dyno tests but the testing procedures were sloppy at best and the gains claimed within the standard un-repeatability of chassis dyno’s. Any result from a chassis dyno under 15hp can be easily attributed to inconsistent testing conditions. Simply getting the differential and transmission fluids up to temperature will show as much as a 5hp gain. And that is only one example of many possible variables. The lack of articles about shorty headers and their “gains” is also a big clue that they don’t offer much of a gain if any. If there was a set of shorty headers out there that made even as little as 10hp and 10tq the manufacturer would most certainly be going WAY out of their way to organize a test for one of the magazines to report on. A PROVEN 10hp gain from a set of shorty headers would assure that manufacturer a truckload of sales. And to add insult to injury shorty headers are only about 1.5lb lighter than the OEM manifolds so there isn’t a big weight savings either. In my opinion unequal length shorty headers are a complete waste of money unless you think the money spent is worth how much better they look than the OEM manifolds. I want to want some. They are relatively inexpensive, easy to put on, and may sound a bit better. But the lack of PROVEN hp gains makes them a dumb buy.

An equal length shorty again will “flow” the same amount of exhaust gas as an unequal length shorty and not much more than a stock manifold but by equalizing the tubing lengths there may be a slight advantage in scavenging effect because of exhaust pulse timing. But the primary tubes are way too short to be able to take advantage of exhaust pulse timing. F1 Motors use very short headers, but not as short as a set of “shorty” headers and the F1 motors rev to 18,000+rpm’s! They of course also have a collector which will help a little with exhaust gas velocity. The collector design has everything to do with how well that works though and the only nice equal length shorty with a good collector design I have seen are the JBA ones. Just like the unequal length shorty headers the equal length ones have not been proven to make power over the stock manifolds and for all the same reasons. Technically the equal length shorty header should out perform the unequal length shorty headers but if the unequal length headers are only worth 2hp, which is entirely probable, the equal length ones could be 50% better, which would be a lot and still only be worth 3hp. The equal length shorty headers are a colossal waste of money just like the unequal length ones are. There are literally hundreds of ways to spend your money smarter.

Now long tube equal length “tuned” headers are the cats a$$. Now the primary tubes are long enough to start timing exhaust pulses correctly (or most efficiently) and since they are so long the collector design can be very good because a long smooth merging collector is the most efficient. I’m pretty sure the optimum length for a long tube header on a 4.6L is 32” or there a bouts, that’s what I mean by tuned length. The length dictates the timing of the exhaust pulses and when they get to the collector. If everything is perfect every exhaust pulse helps the one behind it and it will actually start to “suck” the following exhaust pulse (scavenging) behind it. Tuned length and the timing of the exhaust pulses is the key to making a header work. There is a lot of Voodoo in the design of a great header. Take a look at some NASCAR headers sometime, they are incredible.

Other factors in exhaust performance are the heat inside the tubing. The hotter the gases inside the tube the faster they will flow. That’s why ceramic headers or heat wrapped headers are an advantage, they keep the heat in. On some motors, and I don’t know if the 4.6L is included will see a massive exhaust gas pulse timing advantage by taking one primary from each side of the motor and running them over to the other sides collector. This is a product of the firing order of the motor. Windsormotors are like this. This style of header is a “180 Degree” header. You don’t see them much outside of pure race cars because obviously packaging is a nightmare. Strangely enough the X-pipe design came from someone (Dr. Gas) who was trying to mimic the 180 deg style of header. X-pipes help with exhaust timing and balance. It can almost be looked at as a third collector. H-pipes help with balance only.

One last factor to consider in exhaust performance is if you have FI. The scavenging effect or the desire for it isn’t nearly as critical as a NA motor. Why you ask? Because the exhaust pulses are being pushed out with a lot more force because the next piston that is getting its intake charge is being force fed which actually turns the intake stroke into a sort of mini power stroke in the sense it is helping move gases somewhere else in the motor. Now with a FI car the percentage of actual true exhaust flow goes up in comparison to exhaust pulse timing quite a bit because the size of the tubing can now become a restriction and since the exhaust pulses have something behind them pushing scavenging is not nearly as important. A good example of this is that a 325rwhp-ish NA car can pick up 20-25rwhp with some long tube headers and a solid tune. That is a 7-8%hp increase and it will be all the way across the rev range. Putting the same set of headers on a 450rwhp FI car will pick up about 15-18rwhp. That’s only a 2% hp increase. Clearly FI motors are not nearly as dependant on exhaust gas pulse timing, or scavenging as NA motors are. I imagine that if you sat down to design a FI specific full length header you would find that the tubing size, primary tube length and the collector design would need to be a lot different than the NA long tubes to be 100% efficient.

Edited April 23, 2014 by Bradley Thornton

[Bradley Thornton]

Look I'm not saying that the FAE is right for everyone. Just that some of the theories are way off. In all the people that have talked bad about it. I think only 2 have had it. Now as in anything. If a 1000 like something you will still have 2 that don't. I'm also with a few others on that. When properly set up I think them 2 would have liked it. As Forrest Gump would say and thats all I have to say about that. LOL

[Fman]

I just got some feedback from Bunji, he said he can't really notice much of a sound reduction from the STE's to the FAE. He just installed it on his LSV. Maybe those turn down tips really do reduce noise substantially.

[Bawshogg]

I have the turn downs and can attest that my 247 is much quiter than my VTX was. The VTX just had the slash cut stainless tips. I think it was actually louder than my XTI before that just had the plastic flappers.

[Zeke83]

Yes Bradley, all things I hit on in greater detail. You said it lost 10 hp, when actually if it were dyno'ed you would "see" that 10 hp moved up as far as the rpm it would be applied to. it moves your power curb upward in most automotive applications if you increase exhaust diameter without increasing engine performance as well. With these boats, they run a pretty small rpm range being direct drive with a 1:1 trans ratio. If I was really worried about the extra back pressure, I could run the #'s for this engine with efi and probably would find that increasing my exhaust size right after the manifolds .25" to the transom would probably even my backpressure back out to factory specs and "re-tune" my exhaust by adding flow minus the new restriction.

[D-GOOSE]

For those looking at buying the FAE system make sure to place your order today and receive the CREW discount.

[racer808]

First good ride day with the FAE. No power loss but it seems it runs higher RPM's, I used to be about 30mph at 3,000rpm now its like 3,800rpm. Pulling a boarder at 23mph it is 2800 to 2900 rpm? Manifolds seem to be hotter as well? Not sure if that is in my head but I don't remember them being so hot last year. Tons of spray! Seems to be affecting the surf wake, no idea what to do about that. With the FAE I hear all sorts of noises now that I don't remember so I found myself poking around all day to make sure everything is okay, ran fine otherwise. I also no closer to riding ropeless, I really wish I could figure this out already.

Oh, my new 1,100 pound bag doesn't stop draining itself out the drain hole? I am not running a vent line on it but was just comes out all day long? Can't see how I could make an antisiphon loop with how the drain pump & line are?

Edited May 3, 2014 by racer808

[formulaben]

First good ride day with the FAE. No power loss but it seems it runs higher RPM's, I used to be about 30mph at 3,000rpm now its like 3,800rpm.

You sure about that? That's a HUGE swing. Did you happen to change the prop too? My basic prop pitch calculator shows you would need an 18" pitch prop with 15% slippage to achieve 30MPH @ 3000RPM...with a 14 or 15" pitch it does not compute.

[racer808]

You sure about that? That's a HUGE swing. Did you happen to change the prop too? My basic prop pitch calculator shows you would need an 18" pitch prop with 15% slippage to achieve 30MPH @ 3000RPM...with a 14 or 15" pitch it does not compute.

Nope, still running the acme 1235. About 27mph I am still at 3400-3500 rpm. What should it be with your calculator?

Edited May 4, 2014 by racer808

[formulaben]

It says it's impossible (even with zero slip) for a 14.5" pitch to turn 3000RPM and go 30MPH...

http://www.csgnetwork.com/marinepropcalc.html

Anyway, the point is that no matter what effect the FAE has on the motor, a given RPM of the prop should reproduce the same basic speed for a given configuration. The change would be fuel flow; the RPM/SPEED relationship really won't change except for the small amount of drag the FAE introduces.

[racer808]

It says it's impossible (even with zero slip) for a 14.5" pitch to turn 3000RPM and go 30MPH...

http://www.csgnetwork.com/marinepropcalc.html

Anyway, the point is that no matter what effect the FAE has on the motor, a given RPM of the prop should reproduce the same basic speed for a given configuration. The change would be fuel flow; the RPM/SPEED relationship really won't change except for the small amount of drag the FAE introduces.

How do you figure slip & gear ratio? I am not sure what you are saying, is there a solution to this, what should the RPM to speed be? The RPM's show the same on the gauge & the perfect pass so I would assume that is accurate. I doubled checked the speedometer with my GPS & that was right on. Should I take video?

EDIT: It seems possible based on this thread

http://www.themalibucrew.com/forums/index.php?/topic/48456-acme-2315-prop-rpms-at-30-mph/

Edited May 4, 2014 by racer808

[formulaben]

How do you figure slip & gear ratio? I am not sure what you are saying, is there a solution to this, what should the RPM to speed be? The RPM's show the same on the gauge & the perfect pass so I would assume that is accurate. I doubled checked the speedometer with my GPS & that was right on. Should I take video?

EDIT: It seems possible based on this thread

http://www.themalibucrew.com/forums/index.php?/topic/48456-acme-2315-prop-rpms-at-30-mph/

I want to be clear here, you said that before the FAE it "used to be about 30mph at 3,000rpm now its like 3,800rpm." This is the part I'm discussing.

In the calculator, you'll probably have a 1.47 (aka 1.5) v-drive reduction ratio. Even with a 0% slip, it's cannot compute with even a 15" pitch prop, so your recollection of 3000RPM@30MPH before the FAE must be off...

As I mentioned previously, the RPM/SPEED relationship for a given configuration won't change except for the small amount of drag the FAE plumbing introduces.

[racer808]

I want to be clear here, you said that before the FAE it "used to be about 30mph at 3,000rpm now its like 3,800rpm." This is the part I'm discussing.

In the calculator, you'll probably have a 1.47 (aka 1.5) v-drive reduction ratio. Even with a 0% slip, it's cannot compute with even a 15" pitch prop, so your recollection of 3000RPM@30MPH before the FAE must be off...

As I mentioned previously, the RPM/SPEED relationship for a given configuration won't change except for the small amount of drag the FAE plumbing introduces.

So instead of helping by pointing out what it should be you just want to keep telling me I'm wrong, you're right. Thanks for the help

[formulaben]

Sorry if it came across that way...I gave you the v-drive reduction ratio as requested so you could put it into the calculator. And I'm agreeing with you that the "after" numbers are good, not disputing that at all.

[Nordicron]

Not sure it helps in the calc war going on now but I have a FAE on a 08 San 210 with a 1235 prop. Run about 2500lbs total ballast and at 22.7mph gps was turning over 3400rpms with a 343 PCM.

And I love having FAE, so quite and no obnoxious smell. And I rarely ever surf!

Sent from my iPhone using Tapatalk

[racer808]

Sorry if it came across that way...I gave you the v-drive reduction ratio as requested so you could put it into the calculator. And I'm agreeing with you that the "after" numbers are good, not disputing that at all.

Okay, so sounds normal. Can you help me understand this WOT deal. Indmar says load the boat down, wot open should be 4800 rpm. Doesn't give a relation to speed though. Am I supposed to just peg the throttle all the way down & see what it does? I was probably wrong about last years operating & meant 3500 rpms at 30mph, but I wasn't paying as close attention as I am now being first ride out, making sure everything is ready to roll for the summer.

Edited May 5, 2014 by racer808

[formulaben]

Okay, so sounds normal. Can you help me understand this WOT deal. Indmar says load the boat down, wot open should be 4800 rpm. Doesn't give a relation to speed though. Am I supposed to just peg the throttle all the way down & see what it does? I was probably wrong about last years operating & meant 3500 rpms at 30mph, but I wasn't paying as close attention as I am now being first ride out, making sure everything is ready to roll for the summer.

They probably don't give a speed because even with same weights, different loading fore and aft will change the speed. Indmar just wants the prop to naturally limit the RPM; the old ideal was you wanted WOT to match your RPM limit, but with everyone surfing that rule goes out the window, you now have props that would easily exceed the RPM limit (unballasted) at WOT if not for an electronic rev limiter. So to answer your question, yes just go full throttle and see where the RPMs stabilize...