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View Full Version : 07 X2 Stainless Exhaust tip Problem


Waterski-Marcoisland
12-01-2006, 07:48 PM
Has anyone had their baffles come out on their stainless exhaust tips? The other day I thought that my engine threw a bearing. (50hrs) It was making a weird knocking sound that came and went. I dropped off the boat at the dealer and they went through the boat and found that the port baffle was rattling really bad and making the knocking sound. Nonetheless; they removed the baffle completely because there is no way to weld it back in place. My question : Is anybody runnig their 07 MC without the baffels in the tips? And will this cause a problem with my engine and how load is it? Keep me posted... I will attach a pic with the baffles in place.

erkoehler
12-01-2006, 08:01 PM
Why is your 07 in the marketplace? Are you selling already?

Waterski-Marcoisland
12-01-2006, 08:06 PM
Yes it is for sale.

H20skeefreek
12-01-2006, 11:59 PM
What's the thing in the middle? Why are you selling so soon?

Waterski-Marcoisland
12-02-2006, 12:02 AM
to get a black one

milkmania
12-02-2006, 01:15 AM
Has anyone had their baffles come out on their stainless exhaust tips? The other day I thought that my engine threw a bearing. (50hrs) It was making a weird knocking sound that came and went. I dropped off the boat at the dealer and they went through the boat and found that the port baffle was rattling really bad and making the knocking sound. Nonetheless; they removed the baffle completely because there is no way to weld it back in place. My question : Is anybody runnig their 07 MC without the baffels in the tips? And will this cause a problem with my engine and how load is it? Keep me posted... I will attach a pic with the baffles in place.

I'd be sure and get documentation that is is upon their recommendation to run this thing without the baffle!

Chief
12-02-2006, 01:29 AM
Has anyone had their baffles come out on their stainless exhaust tips? The other day I thought that my engine threw a bearing. (50hrs) It was making a weird knocking sound that came and went. I dropped off the boat at the dealer and they went through the boat and found that the port baffle was rattling really bad and making the knocking sound. Nonetheless; they removed the baffle completely because there is no way to weld it back in place. My question : Is anybody runnig their 07 MC without the baffels in the tips? And will this cause a problem with my engine and how load is it? Keep me posted... I will attach a pic with the baffles in place.

As with most motors that you run WFO all the time then straight pipe is okay, but for what we usually use our boats for, pulling wakeboard or skiing then some back pressure is good for torque and efficency.

H20skeefreek
12-02-2006, 09:25 AM
Oops, double post.

H20skeefreek
12-02-2006, 09:25 AM
to get a black one
And what is that rectangle thing in the middle of the picture?

rick s.
12-02-2006, 12:20 PM
that thing in the middle is a sacrificial anode to protect the metals in the boat from electrolysis. These are needed on boats used in saltwater to prevent the shafts, thruhulls, props, rudders, other stuff from being eaten away. It gets eaten away first to protect the good stuff.

essentially a very slight electrical current is generated by the metals being in the water, and some materials are more affected than others. The electricity flow is into the water, and the electrons have to come from somewhere. In this case the anode is grounded to the rudder and shaft, so the anode corrodes instead of the props, shaft, rudder, stainess steel exhaust tips, etc.

H20skeefreek
12-02-2006, 03:31 PM
ok, just didn't recognize it, seems like a strange place to put it. Normally on a boat like that, it'd be on the prop shaft. I know how they work, just couldn't tell what it was.

sully
12-02-2006, 04:08 PM
The baffles are installed to protect your engine from taking in water thru your exhast when you slow down coming off plane or from a wave when just sitting. I would replace the exhaust tips with new baffles.

Chief
12-02-2006, 04:52 PM
Shouldn't that be taken care under the warranty?

Waterski-Marcoisland
12-03-2006, 12:09 AM
they are replacing em

Waterski-Marcoisland
12-03-2006, 12:10 AM
I went out on the water today with the one baffle missing. It sounded like a race boat taking off. Funny......

MYMC
12-04-2006, 10:38 AM
Just to clear things up (and this comes up ALOT) no amount of back pressure in an exhaust system is "good". It doesn't add anything...well, other than to add to overall pumping losses of the engine. If an engine runs better with back pressure it is because the ancillary systems have been tuned to take into account the exhaust system that is adding the back pressure. If you remove the back pressure (i.e. the exhaust system) and then re-tune the engine for the free flowing exhaust it will make more power than it did with the restrictive exhaust.

This is exhaust theory in its most simplistic form...I'm not referring to 12" long zoomie pipes but full length exhaust systems. Backpressure doesn’t add torque or low end...no matter what you've been told over the years by shade tree mechanics. Your boat is no exception to this rule.

Chief
12-04-2006, 11:58 AM
Just to clear things up (and this comes up ALOT) no amount of back pressure in an exhaust system is "good". It doesn't add anything...well, other than to add to overall pumping losses of the engine. If an engine runs better with back pressure it is because the ancillary systems have been tuned to take into account the exhaust system that is adding the back pressure. If you remove the back pressure (i.e. the exhaust system) and then re-tune the engine for the free flowing exhaust it will make more power than it did with the restrictive exhaust.

This is exhaust theory in its most simplistic form...I'm not referring to 12" long zoomie pipes but full length exhaust systems. Backpressure doesn’t add torque or low end...no matter what you've been told over the years by shade tree mechanics. Your boat is no exception to this rule.

Learning something new everyday, I guess it goes to apply when you upgrade the exhaust you need to upgrade air intake.

MYMC
12-04-2006, 12:19 PM
Learning something new everyday, I guess it goes to apply when you upgrade the exhaust you need to upgrade air intake.
Won't hurt...tough in a boat but well worth the expense...come summer time. (hint check out Rewind 2007 for a little of what I'm talkin about)

bigmac
12-04-2006, 12:29 PM
Just to clear things up (and this comes up ALOT) no amount of back pressure in an exhaust system is "good". It doesn't add anything...well, other than to add to overall pumping losses of the engine. If an engine runs better with back pressure it is because the ancillary systems have been tuned to take into account the exhaust system that is adding the back pressure. If you remove the back pressure (i.e. the exhaust system) and then re-tune the engine for the free flowing exhaust it will make more power than it did with the restrictive exhaust.

This is exhaust theory in its most simplistic form...I'm not referring to 12" long zoomie pipes but full length exhaust systems. Backpressure doesn’t add torque or low end...no matter what you've been told over the years by shade tree mechanics. Your boat is no exception to this rule.

No, back pressure doesn't ADD anything, but in some exhaust systems on some engines,the LACK of appropriate back pressure can HURT performance because of exhaust reversion. Anti-reversion cones, which are nothing more than cone-shaped baffles, are common in small airplane engines as well as motorcycle systems. I just had experience with that two days ago on a missionary flight in Haiti where the pilot blew out that cone on takeoff and it partially jammed in the pipe. We landed and removed the loose cone. It was loud, and performance suffered, but it was safe enough to get out of the bush (like we had a choice). Those cones are there in part for noise, but also because some backpressure is needed.

A properly designed exhaust system won't have that reversion problem - addressing reversion can be done by changning a variety of aspects of the exhaust system (tuning), but depending on diameters, lengths, engine type etc, baffles may be part of that design to prevent standing waves close to the exhaust port(s). I have no idea how or if this applies to boats with V8 engines and water-filled manifolds, I'm just sayin'....

MYMC
12-04-2006, 02:02 PM
No, back pressure doesn't ADD anything, but in some exhaust systems on some engines,the LACK of appropriate back pressure can HURT performance because of exhaust reversion. Anti-reversion cones, which are nothing more than cone-shaped baffles, are common in small airplane engines as well as motorcycle systems. I just had experience with that two days ago on a missionary flight in Haiti where the pilot blew out that cone on takeoff and it partially jammed in the pipe. We landed and removed the loose cone. It was loud, and performance suffered, but it was safe enough to get out of the bush (like we had a choice). Those cones are there in part for noise, but also because some backpressure is needed.

A properly designed exhaust system won't have that reversion problem - addressing reversion can be done by changning a variety of aspects of the exhaust system (tuning), but depending on diameters, lengths, engine type etc, baffles may be part of that design to prevent standing waves close to the exhaust port(s). I have no idea how or if this applies to boats with V8 engines and water-filled manifolds, I'm just sayin'....
Airplanes go to my line about full length exhaust systems (not alot of room & issue of weight)... but as a matter of fact there are now companies building full length tuned exhasut systems for airplanes to take advantage of the power hidden in exhaust systems. Has nothing to do with number of cylinders or anything else really...it comes down to pupming losses.

Lastly, I may be wrong but it was my understanding that the cone was used as a reflector of the wave and had nothing to do with backpressure.

TX.X-30 fan
12-04-2006, 02:35 PM
Just to clear things up (and this comes up ALOT) no amount of back pressure in an exhaust system is "good". It doesn't add anything...well, other than to add to overall pumping losses of the engine. If an engine runs better with back pressure it is because the ancillary systems have been tuned to take into account the exhaust system that is adding the back pressure. If you remove the back pressure (i.e. the exhaust system) and then re-tune the engine for the free flowing exhaust it will make more power than it did with the restrictive exhaust.

This is exhaust theory in its most simplistic form...I'm not referring to 12" long zoomie pipes but full length exhaust systems. Backpressure doesn’t add torque or low end...no matter what you've been told over the years by shade tree mechanics. Your boat is no exception to this rule.


Based on that then why did the thunder header on my Harley make significantly more horse power in the lower rpm range that those nasty straight pipes. i guess then my pipes were actually flowing more air than those so called straight pipes even though they were all curved from the opposite side to achieve equal length.

MYMC
12-04-2006, 03:36 PM
Based on that then why did the thunder header on my Harley make significantly more horse power in the lower rpm range that those nasty straight pipes. i guess then my pipes were actually flowing more air than those so called straight pipes even though they were all curved from the opposite side to achieve equal length.
Key word..."equal length" as in equal length headers (were they stepped as well?)...then I'll assume someone jetted the bike? So now you have a total package...tuned exhaust scavenging a richer intake to make more power. Ahhh, the world in balance. As in balance pipe but that would be another story...

TX.X-30 fan
12-04-2006, 04:01 PM
Yes they were 2/into1 then a progressive cone. (stepped that is). thanks for the reply. I remember no one wanted to ride behind me for any length of time.

MYMC
12-04-2006, 04:30 PM
Yes they were 2/into1 then a progressive cone. (stepped that is). thanks for the reply. I remember no one wanted to ride behind me for any length of time.
Anytime...after almost 10years in a dyno cell I better remember something cause I sure can't hear much!

ski36short
12-04-2006, 09:40 PM
Back to a basic question - is this baffled exhaust in question similar to a SuperTrapp muffler where baffles can be added or removed?

bigmac
12-05-2006, 01:09 AM
Based on that then why did the thunder header on my Harley make significantly more horse power in the lower rpm range that those nasty straight pipes. i guess then my pipes were actually flowing more air than those so called straight pipes even though they were all curved from the opposite side to achieve equal length.An engine is just an air pump, and the more it breathes, the more power it makes (up to a point, obviously). Today's cars and motorcycles (maybe boats too? - I don't know) have rigorous EPA standards they have to meet and one cheap way they do that is by de-tuning the engine - run it as lean as possible. Conversely, you buy a new motorcycle and one of the easiest ways to improve performance is to make it "breathe" more by increasing air/fuel inflow (rejetting+high flow air cleaner) and increasing air outflow (low restriction exhaust). You car too - a K&N filter system combined with a low restriction exhaust will generally increase power. It makes no sense to do one without the other though. Even closed-loop EFI's would probably benefit from re-mapping, although, they do have more latitude than open-loop systems. There is a point on motorcycle exhaust where the flow can be increased too much and you get reversion, which robs performance- The solution is to "tune" the pipe - essentially getting maximum air flow without getting standing waves. This balance is achieved by a combination of pipe diameter, configuration, length, and the use of baffles or anti-reversion cones, but any performance gain will only be realized if the carb is rejetted or EFI remapped too.

It's well-known on open-loop EFI Harleys that the best performing pipes are the 2-into-1 's and the worst are straight ("drag") pipes.

edwinfuqua
12-05-2006, 02:48 AM
An engine is just an air pump, and the more it breathes, the more power it makes (up to a point, obviously). Today's cars and motorcycles (maybe boats too? - I don't know) have rigorous EPA standards they have to meet and one cheap way they do that is by de-tuning the engine - run it as lean as possible. Conversely, you buy a new motorcycle and one of the easiest ways to improve performance is to make it "breathe" more by increasing air/fuel inflow (rejetting+high flow air cleaner) and increasing air outflow (low restriction exhaust). You car too - a K&N filter system combined with a low restriction exhaust will generally increase power. It makes no sense to do one without the other though. Even closed-loop EFI's would probably benefit from re-mapping, although, they do have more latitude than open-loop systems. There is a point on motorcycle exhaust where the flow can be increased too much and you get reversion, which robs performance- The solution is to "tune" the pipe - essentially getting maximum air flow without getting standing waves. This balance is achieved by a combination of pipe diameter, configuration, length, and the use of baffles or anti-reversion cones, but any performance gain will only be realized if the carb is rejetted or EFI remapped too.

It's well-known on open-loop EFI Harleys that the best performing pipes are the 2-into-1 's and the worst are straight ("drag") pipes.
Here is a good place to start if you are wondering what is 'anti-reversion'. http://www3.bc.sympatico.ca/Volvo_Books/maint4.html

Jesus_Freak
12-05-2006, 11:35 AM
Just to clear things up (and this comes up ALOT) no amount of back pressure in an exhaust system is "good". It doesn't add anything...well, other than to add to overall pumping losses of the engine. If an engine runs better with back pressure it is because the ancillary systems have been tuned to take into account the exhaust system that is adding the back pressure. If you remove the back pressure (i.e. the exhaust system) and then re-tune the engine for the free flowing exhaust it will make more power than it did with the restrictive exhaust.

This is exhaust theory in its most simplistic form...I'm not referring to 12" long zoomie pipes but full length exhaust systems. Backpressure doesn’t add torque or low end...no matter what you've been told over the years by shade tree mechanics. Your boat is no exception to this rule.

Excellent point about the need to separate various effects in complex systems before jumping to conclusions.

I only wanted to comment on the back pressure issue. A restrictive exhaust port (reduced diameter) will, of course, speed up the exiting gases. Although this adds "pumping losses" (in this case a rise in static pressure only; total pressure is mostly conserved), an increased scavenge will result. The increased scavenge is possibly not worth the cost in a 4-cycle engine, in which there is much time between port openings and the cylinder is fairly isolated between cycles. In a 2-cycle however, this effect is much more pronounced and can be important. I figure this is review; just thought I would throw it out.

Hollywood
12-05-2006, 12:09 PM
edwin, thanks for the article. I've gone through several exhaust systems on my camaro and now understand why they perform differently.

MYMC
12-05-2006, 12:47 PM
Two basic phenomenon are at work in the exhaust system: gas particle movement and pressure wave activity. The absolute pressure differential between the cylinder and the atmosphere determines gas particle speed. As the gases travel down the pipe and expand, the speed decreases. The pressure waves, on the other hand, base their speed on the speed of sound. While the wave speed also decreases as they travel down the pipe due to gas cooling, the speed will increase again as the wave is reflected back up the pipe towards the cylinder. At all times, the speed of the wave action is much greater than the speed of the gas particles. Waves behave much differently than gas particles when a junction is encountered in the pipe. When two or more pipes come together, as in a collector for example, the waves travel into all of the available pipes - backwards as well as forwards. Waves are also reflected back up the original pipe, but with a negative pressure. The strength of the wave reflection is based on the area change compared to the area of the originating pipe. This reflecting, negative pulse energy is the basis of wave action tuning. The basic idea is to time the negative wave pulse reflection to coincide with the period of overlap - this low pressure helps to pull in a fresh intake charge as the intake valve is opening and helps to remove the residual exhaust gases before the exhaust valve closes.

Gas speed is a double edged sword, too much gas speed indicates that that the system may be too restrictive hurting top end power, while too little gas speed tends to make the power curve excessively 'peaky' hurting low end torque. Larger diameter tubes allow the gases to expand; this cools the gases, slowing down both the gases and the waves. Exhaust system design is a balancing act between all of these complex events and their timing. Even with the best compromise of exhaust pipe diameter and length, the collector outlet sizing can make or break the best design. The bottom line on any exhaust system design is to create the best, most useful power curve. All theory aside, the final judgement is how the engine likes the exhaust tuning on the dyno and on the track.

MYMC
12-05-2006, 12:50 PM
Back to a basic question - is this baffled exhaust in question similar to a SuperTrapp muffler where baffles can be added or removed?
No, they are not made to be removable (shame).

bigmac
12-05-2006, 01:14 PM
Two basic phenomenon are at work in the exhaust system: gas particle movement and pressure wave activity. The absolute pressure differential between the cylinder and the atmosphere determines gas particle speed. As the gases travel down the pipe and expand, the speed decreases. The pressure waves, on the other hand, base their speed on the speed of sound. While the wave speed also decreases as they travel down the pipe due to gas cooling, the speed will increase again as the wave is reflected back up the pipe towards the cylinder. At all times, the speed of the wave action is much greater than the speed of the gas particles. Waves behave much differently than gas particles when a junction is encountered in the pipe. When two or more pipes come together, as in a collector for example, the waves travel into all of the available pipes - backwards as well as forwards. Waves are also reflected back up the original pipe, but with a negative pressure. The strength of the wave reflection is based on the area change compared to the area of the originating pipe. This reflecting, negative pulse energy is the basis of wave action tuning. The basic idea is to time the negative wave pulse reflection to coincide with the period of overlap - this low pressure helps to pull in a fresh intake charge as the intake valve is opening and helps to remove the residual exhaust gases before the exhaust valve closes.

Gas speed is a double edged sword, too much gas speed indicates that that the system may be too restrictive hurting top end power, while too little gas speed tends to make the power curve excessively 'peaky' hurting low end torque. Larger diameter tubes allow the gases to expand; this cools the gases, slowing down both the gases and the waves. Exhaust system design is a balancing act between all of these complex events and their timing. Even with the best compromise of exhaust pipe diameter and length, the collector outlet sizing can make or break the best design. The bottom line on any exhaust system design is to create the best, most useful power curve. All theory aside, the final judgement is how the engine likes the exhaust tuning on the dyno and on the track.Yeah. That's what I said...;)

Workin' 4 Toys
12-05-2006, 01:29 PM
Back to a basic question - is this baffled exhaust in question similar to a SuperTrapp muffler where baffles can be added or removed?
I had a boat with those......It sounded awesome (I thought) A little loud for conversations sitting in the back of the boat, I guess I never saw the problem since I never sat there.
I have no idea if my reversion:rolleyes: changed when the discs were removed for cleaning out the sand, but it sure sounded alot better when they were clean...And I liked the option to TUNE the reversion even though previous to this conversation I had no idea what it meant...:D

Jesus_Freak
12-05-2006, 02:24 PM
Two basic phenomenon......tuning on the dyno and on the track.

Excellent, inclusive explanation based on experience and principles of compressible flow theory. Thanks. I would only interchange the word "particle" with the word "pocket." Gases only behave as particles at temperatures much higher and/or pressures much lower (high Knudsen number) than experienced in the typical exhaust system transient. ;)

TMCNo1
12-05-2006, 02:33 PM
typical exhaust system transient. ;)


Stupid question, but are you refering to a street person, who rides around hanging on the back of a school bus while standing on the exhaust pipe getting his feet warm?:confused: :rolleyes: :D
Sorry, when I saw that I just had to ask it!

Jesus_Freak
12-05-2006, 02:36 PM
Stupid question, but are you refering to a street person, who rides around hanging on the back of a school bus while standing on the exhaust pipe getting his feet warm?:confused: :rolleyes: :D

Absolutely! Or, it could be a city bus...not necessarily a school bus.

MYMC
12-05-2006, 03:02 PM
Excellent, inclusive explanation based on experience and principles of compressible flow theory. Thanks. I would only interchange the word "particle" with the word "pocket." Gases only behave as particles at temperatures much higher and/or pressures much lower (high Knudsen number) than experienced in the typical exhaust system transient. ;)
I stand corrected;)

TX.X-30 fan
12-05-2006, 03:37 PM
:confused: This whole thread is making me feel like TMC'S avatar:confused: