Quieting Boats down

[Brian_Nelsen]

Terry

The hole you are talking about is just for draining the pipe basically right? This would be the one that goes rite where the stinger meets the taper on the pipe?

Thanks for the clarification.

Brian

 

[CMBrunner]

Terry

The hole you are talking about is just for draining the pipe basically right? This would be the one that goes rite where the stinger meets the taper on the pipe?

Thanks for the clarification.

Brian

That would be correct Brian.

 

[Don Ferrette]

How many drain holes do you have?

Four

Believe it or not that'll make it louder, I just put one on the bottom...

As Terry mentioned earlier anything bigger than 1/16" will add noise and 4 holes instead of one is not the way to go. Back when we ran the CMB big belly 67 pipe we found the OE stinger i.d. size to be too small. We got those pipes to really go with adding four 1/8" holes spaced 90 degrees apart right where stinger meets the pipe but it made that pipe significantly louder and this was just with a standard style stinger. Also the pipe would develop stress cracks between the holes so we started cutting off the stinger completely & welding on a new stinger with a .450 i.d. which worked quite well. The thin metal of those pipes were a pain to weld though & it got to be more trouble than it was worth. Once we found that the Macs 13cc nitro pipe with a RumRacing stinger muffler was as good or faster that was the end of running the CMB pipe. Bottom line is Terry is correct in keeping a single hole under 1/16", larger and/or multiple holes will make a pipe alot louder, especially an internal stingered pipe as the pressure in that area is much greater than a conventional stingered pipe........... :blink:

 

[Terry Keeley]

Terry

The hole you are talking about is just for draining the pipe basically right? This would be the one that goes rite where the stinger meets the taper on the pipe?

Thanks for the clarification.

Brian

Yup. Any holes near the end of the pipe to atmosphere will make it much louder though.

Saw some guys at the Nats running the "Big Belly" CMB pipe with a small after muffler but they had four holes drilled in the end of the pipe to the outside (to effectively increase the stinger size as Don mentioned above), wasn't very quiet for sure.

 

[Mark Bullard]

Mark

I do not care if you posts its not my forum I just started the topic. I really just want this thread to stay informative and not go into the issues the other thread has. Facts as to the set ups we are using are what is needed.

Your current post has some very good information in it. The nylon bolts and delrin mounts and such. This is what we all need to hear. I have nylon fasteners for my new mono's but I do not have delrin mounts. Question for you are the delrin mounts of a solid type or are they rubber mounted as well.

Now I think we need to start looking at induction noise. If your is that loud just from intake noise that is a huge issue.

Thanks

Brian

Delrin rails bolted by nylon fastners and spacers passing thru rubber grommets.

 

[lohring]

At the NAMBA Nationals quite a few of the gas boats ran inverted stingers with no other muffling. I doubt that these boats would pass the IMPBA noise rule. My dyno testing with inverted stingers vs regular stingers showed a slight power increase with some noise reduction. I think adding a small water injected can to the inverted stinger would work well toward reducing noise without reducing power. These cans are readily available from Insane and CC Racing.

Lohring Miller

 

[Terry Keeley]

At the NAMBA Nationals quite a few of the gas boats ran inverted stingers with no other muffling. I doubt that these boats would pass the IMPBA noise rule. My dyno testing with inverted stingers vs regular stingers showed a slight power increase with some noise reduction. I think adding a small water injected can to the inverted stinger would work well toward reducing noise without reducing power. These cans are readily available from Insane and CC Racing.

Lohring Miller

Wow, you mean you actually saw a power increase using an internal stinger? What motor and pipe was it on, what size stinger did you test? Please elaborate for us!!!

 

[dr gary turner]

Mark

I am not going to answer your question. This post was set up to try to discuss ideas on what can help and what cannot. Your question is better asked in the Noise and DB meter thread.

I will say that the internal stinger does not do the job in all cases. I Have two 90 nitro pipes for my rigger that will not make 92 db with an internal stinger. I have a muck pipe and a cmb pipe with internal stingers. at my site with my testing methods they run 97 for the muck and 94 for the cmb. These are just my personal results in all cases we are discussing ways to reduce the overall noise in a boat. We always tend to focus on the pipe first. I think induction noise is also important as Don has stated. There are many areas which create noise in our boats.

Thanks for your post and the information it contained

Brian Brian, I too ran 13 cc Muck pipes with internal stingers as described by Mark Bullard on my single k-90 hydro and on twin with k-90's. Both boats were over at the Nats. They measured at Huntsville and were 92db. What is interesting my 101 with a MAC 15cc with a rum runner and no cowl was legal at the Nats. Why? I think the reason is that 1] db readings were reading high at the Nats. 2] I think the Muck pipes maybe louder because their wall thickness is greater and maybe reasonnating more than a thin walled Mac pipe.

 

[lohring]

I was testing a new pipe design on a Zenoah. I made it with a 5 inch long screw on stinger that could be screwed in with the long end out or in. I could also change the diameter. The stinger tests were not the main part of the program, so I only had a few runs to compare. It looked like a 2 to 5% increase in power, but our dyno has that much run to run scatter. Averaging several runs is the only way to separate tests that are that close. By the way, the pipe added 1/2 hp, about 20%, to the particular engine I was testing. A later series of timing changes dropped the difference between my pipe and an M&D pipe to very little except at the low end. It just shows that the complete package is what counts.

Lohring Miller

 

[Terry Keeley]

It's interesting that someone has confirmed with dyno testing what I have seen on the water, there's no power loss running an internal stinger, thanks!

 

[Brian_Nelsen]

Mark

I am not going to answer your question. This post was set up to try to discuss ideas on what can help and what cannot. Your question is better asked in the Noise and DB meter thread.

I will say that the internal stinger does not do the job in all cases. I Have two 90 nitro pipes for my rigger that will not make 92 db with an internal stinger. I have a muck pipe and a cmb pipe with internal stingers. at my site with my testing methods they run 97 for the muck and 94 for the cmb. These are just my personal results in all cases we are discussing ways to reduce the overall noise in a boat. We always tend to focus on the pipe first. I think induction noise is also important as Don has stated. There are many areas which create noise in our boats.

Thanks for your post and the information it contained

Brian Brian, I too ran 13 cc Muck pipes with internal stingers as described by Mark Bullard on my single k-90 hydro and on twin with k-90's. Both boats were over at the Nats. They measured at Huntsville and were 92db. What is interesting my 101 with a MAC 15cc with a rum runner and no cowl was legal at the Nats. Why? I think the reason is that 1] db readings were reading high at the Nats. 2] I think the Muck pipes maybe louder because their wall thickness is greater and maybe reasonnating more than a thin walled Mac pipe.

Doc

I have to agree with you the Muck pipes are much thicker than almost all of the pipes from other manufacturers, I am not sure but I think the material runs a little harder than others as well. I should see if I have any testing equipment at the shop that would show that.

I really like my Muck pipes, thats why I added a can muffler to one to try on my 90 rigger. Went to the pond today to test but the weeds have taken over the course. Guess that will have to wait till after the next race when they clean out the weeds.

Brian

 

[Chris Wood]

Well here is what i found from testing today..

we tried 5 pips..

a cmb 67/80 pipe stock

a cmb 67/80 with a seducer boats muffler

a cmb 67/80 cmb pipe with a ( ERNIE LEFLURE MUFFLER )

a mac's 13cc nitro pipe with a ( ERNIE LEFLURE MUFFLER )

first off i would like to say these were tested on two boats 67 and 80 crapshooters..

ALL THE PIPES ARE OVER 94 DB. EVEN THE PIPS THAT ERNIE'S MUFFLER'S WAS ON.. THIS IS THE EXACT SAME MUFFLER COMBO THAT ERNIE RAN AT THE NATS..............

The highest reading was 96db with a stock cmb pipe. quiets was 94 db between ernie's and seducers mufflers..

as far as performance the stock pipe ran 84mph

all others was 79mph..

I tried 10 different props to make them run better.... this was between both boats... 79mph is all they had..

not enough to be competitive in my book..

so, that is where i stand for testing as far as what we have. the only other thing to try is a internal stinger like what terry keeley runs..

then i am OUT OF OPTIONS..

don f. how did the pipe's you were suppose to test work?

chris

 

[Terry Keeley]

Hey Chris:

Excellent data! We need more of this!!!

What motor were you running, the 67 or 80 (Green Head CMB's I assume)?

The stock pipe only came in at 96? Did you open up the stinger on it? That's odd, I swore Randall told me he had me at 105+ with a P67 and the CMB pipe. Maybe it was right at the shore line.

I'm not going any slower with the internal stinger.

 

[Chris Wood]

Hey terry,

ya both were green head 67 and 80 motors.. i can't keep the rs 80 sleeves from breaking otherwise i would have tried it out.

the pipe that ran 84 was a stock cmb pipe

if i get a chance to try the internal stinger i will let you know, oh, as for the induction noise, this was also done with 2 different size carb's. one was a .500 bore and one was a .550 bore carb..

2 weeks prior we tested a stock bore cmb carb and a os 9b carb with the same noise.. so anyone that says that the unduction noise is a part of it is nuts... i tested it i saw it.. end of story..

any more testing i will let you guys know

chris

 

[Terry Keeley]

I was wondering if you opened the stinger on the CMB Big Belly pipe 'cause it's small to begin with. It's a little tricky but I managed to stretch mine to 0.460" or so and used a 1/2" tube with 0.035" wall, think stock they're around 0.400".

I turned the O/D of the tube to 0.460" to fit the pipe, leaving the stinger with an 0.015 wall. I/D is 0.430". I know the "Old man" can handle it! :lol:

 

[Mike G]

Try one of these http://cooperpipes.com/myPictures/100_0409_edited.JPG inexpensive and very effective!

 

[dr gary turner]

Mark

I am not going to answer your question. This post was set up to try to discuss ideas on what can help and what cannot. Your question is better asked in the Noise and DB meter thread.

I will say that the internal stinger does not do the job in all cases. I Have two 90 nitro pipes for my rigger that will not make 92 db with an internal stinger. I have a muck pipe and a cmb pipe with internal stingers. at my site with my testing methods they run 97 for the muck and 94 for the cmb. These are just my personal results in all cases we are discussing ways to reduce the overall noise in a boat. We always tend to focus on the pipe first. I think induction noise is also important as Don has stated. There are many areas which create noise in our boats.

Thanks for your post and the information it contained

Brian Brian, I too ran 13 cc Muck pipes with internal stingers as described by Mark Bullard on my single k-90 hydro and on twin with k-90's. Both boats were over at the Nats. They measured at Huntsville and were 92db. What is interesting my 101 with a MAC 15cc with a rum runner and no cowl was legal at the Nats. Why? I think the reason is that 1] db readings were reading high at the Nats. 2] I think the Muck pipes maybe louder because their wall thickness is greater and maybe reasonnating more than a thin walled Mac pipe.

Doc

I have to agree with you the Muck pipes are much thicker than almost all of the pipes from other manufacturers, I am not sure but I think the material runs a little harder than others as well. I should see if I have any testing equipment at the shop that would show that.

I really like my Muck pipes, thats why I added a can muffler to one to try on my 90 rigger. Went to the pond today to test but the weeds have taken over the course. Guess that will have to wait till after the next race when they clean out the weeds.

Brian

Brian, As mentioned I had internal stingers on the Muck 13 cc and then added rum runners in addition and my twin was still over at the Nats. Then ussing rubber pieces that tuned the exhaust away from the meter I was legal, but by then it would not run well if at all. Doc

 

[Don Ferrette]

.... so anyone that says that the unduction noise is a part of it is nuts... i tested it i saw it.. end of story.

So you are the final know all word on induction noise? Wrong answer. Induction noise becomes a bigger part of the equation when you start getting noise levels down under 90, you ain't even close.

Also, you base all you testing on trying to make a pipe that has a nickname of "Boom pipe" quiet? These bandaid approaches to try to squeeze the noise out of something never designed to be quiet in the first place is a waste of time. The CMB big belly pipe is one of the loudest pipes out there as I have at one time recorded well over 100dB on one of them unmuffled as Terry did.

I finally got to get a couple runs in with the new prototype pipes & I'm pleased with the results. I need more time on the water to find the optimum settings but the power seems to be there. Somewhat different pipes to drive, VERY broad & deceptively smooth torque curve, went from a slow cruise right on up into top end power without the typical "hit" most pipes have. I will by getting together with a couple people for a hard core test session next weekend but for the record, and with plenty of witnesses, 82dB on the twin today with the meter 25 feet from the bank but about 10 feet off the water due to elevated bank at the club site. The meter was also hand held & not on a tripod since that is starting to sound like an issue. People were totally amazed that a twin could run that quiet.

And BTW- when my pit guy was carrying the boat to launch it when I hit the trigger a couple times you could distinctly hear the carbs pulling harder, you know that thing called induction noise..........

 

[Roxyflash]

Seems like a lot of wasted time to go slow.I think opening the stingers on the big belly pipes makes them loader also.Its real easy to expand them i use a long tapered punch thats clamped in the vise just spray some wd 40 on the punch and work the pipe over it.I had a CMD quiet pipe for the 67 and it worked ok till it got over 85 degrees out it trapped so much heat then i drilled it out was better but never did have any luck with it.Put the cmb big belly pipe on it runs great again.Be nice to find a pipe that will work on a rigger without having to be 2 foot long.I have a macs 13 cc pipe i think i might try Terrys trick on it.I know Steve and Chris are on a mission to find out what works they have tried lots of other pipes with not much luck for speed.There quiet but wont win races LOL.

 

[Chris Wood]

So you are the final know all word on induction noise? Wrong answer. Induction noise becomes a bigger part of the equation when you start getting noise levels down under 90, you ain't even close.

No don you get the final word.. I am tired of trying to explain my side.. you win.. when you figure it out let me know..

If you think that i am not trying other options you are nuts.. Like i said you win. no more on this topic.. every time I try to put something you have a reply that i am wrong so i am wrong.. you figure it out.

chris