How Boom tubes work?
05-22-2006, 02:03 AM
#22
The car in the GM high tech mag is mine. I just got finished running the Nevada Open Road Challenge so I am beat to **** right now and seeing as I have to be up in 3 hours to get back on the road home, I have to keep this pretty short till I get back.
Boom tubes are great on RACE CARS. Your system sounded fine until you mentioned cats. The cats will completely negate any advantages of having a boom tube. And unless this is going on a track only car, have ear plugs because they are ear shatteringly loud. When I get home in a couple days I will give you some more detail.
Boom tubes are great on RACE CARS. Your system sounded fine until you mentioned cats. The cats will completely negate any advantages of having a boom tube. And unless this is going on a track only car, have ear plugs because they are ear shatteringly loud. When I get home in a couple days I will give you some more detail.
05-22-2006, 02:22 AM
#23
What did you top out at on NORC this year?
The car I'm building is definitely a street car. If the boom tubes behind cats are just going to be fancy tips then I guess the cats are gunna have to go! How heavy are they though?
here's a pic of the last pair that I was obsessing over on ebay. The deviding runner look super thick!
The car I'm building is definitely a street car. If the boom tubes behind cats are just going to be fancy tips then I guess the cats are gunna have to go! How heavy are they though?
here's a pic of the last pair that I was obsessing over on ebay. The deviding runner look super thick!
05-23-2006, 12:38 PM
#25
TECH Senior Member
iTrader: (10)
Join Date: Mar 2003
Location: North Texas
Posts: 8,009
Likes: 0
Received 0 Likes
on
0 Posts
You DO realize that you're going to be able to be heard for about a mile with those boom tubes, right? If you just want a loud exhaust get chambered mufflers from Stainless Works and go from there. At least then you won't lose your hearing.
05-30-2006, 09:14 PM
#30
The Boom Tube will be a waste of money as stated above. You will not want to drive it more than a day. My experience with a boom tube you ask? In my senior year in auto shop at my HS I believe it was Lincoln tech brought in an old Stock Car/Similar. They started it up and revved it, the majority of the class jumped back in fear. We asked what made it so loud and the rep stated that it was a "Boom Tube". I know it was indoors but this exhaust would scare small children off sidewalk lol. Which would be cool for a day or so, but it is literally harmful to your health.
05-31-2006, 10:19 PM
#31
Teching In
Join Date: May 2006
Posts: 22
Likes: 0
Received 0 Likes
on
0 Posts
Take the advice of everyone and save the Boomtubes for race apps. Dr. Gas DOES have street applications and as mentioned, Neil and Boyd are very customer oriented.
I have a Dr GAs Xpipe and custom system on my ORR car - no cats, no mufflers. Dynoed 400/425 and the noise was actually painful at WOT on the dyno. It HURT!
This is what they looked like this spring after the 118 miles of the Big Bend race. That isn't bugs and dirt -- they are pitted from the road grind.
Here is what they sounded like at 135mph at the same race. We were blowing the horn at the girls taking the vid. They didn't hear it and you can't hear it in the video
Big Bend Pass
Andy
I have a Dr GAs Xpipe and custom system on my ORR car - no cats, no mufflers. Dynoed 400/425 and the noise was actually painful at WOT on the dyno. It HURT!
This is what they looked like this spring after the 118 miles of the Big Bend race. That isn't bugs and dirt -- they are pitted from the road grind.
Here is what they sounded like at 135mph at the same race. We were blowing the horn at the girls taking the vid. They didn't hear it and you can't hear it in the video
Big Bend Pass
Andy
06-01-2006, 04:20 PM
#33
Yes I did.
From the original post.
"Is it still as affective at the end of a full exhaust system?"
And I like to re-emphisize the "AS" effective. Because honestly I'm not even convinced that their effectiveness has been proven over an open pipe! Any one have any dyno charts/time with these things? We all know x-pipes work. And these are supposed to enhance that same balance idea. But how much? and where's the proof?
Some have suggested that the inclusion of cats, completely negates any effects of scavenging that the boom tubes may contribute. I don't think I buy it. Cats don't completely negate the effects of a good header...
And on another line of logic:
Cats simply add a little more backpressure.
If you want to look at that effect relative to what an exhaust valve "sees" when it opens up, so does driving down a mountain and lowering your elevation!
And AndyJ, thanx for the video, that thing is so freaking loud that you can't tell the difference in volume between when the thing was 40 ft. away and 1/4 mile away! Damn!!!
I know the paine of open exhausts VERY well, I used to work with unmuffled 2-stroke expansion chambers. Let's just say that it's not something that I'm looking to revisit with my sometimes street car.
Thanx for all the input guys, keep it coming.
From the original post.
"Is it still as affective at the end of a full exhaust system?"
And I like to re-emphisize the "AS" effective. Because honestly I'm not even convinced that their effectiveness has been proven over an open pipe! Any one have any dyno charts/time with these things? We all know x-pipes work. And these are supposed to enhance that same balance idea. But how much? and where's the proof?
Some have suggested that the inclusion of cats, completely negates any effects of scavenging that the boom tubes may contribute. I don't think I buy it. Cats don't completely negate the effects of a good header...
And on another line of logic:
Cats simply add a little more backpressure.
If you want to look at that effect relative to what an exhaust valve "sees" when it opens up, so does driving down a mountain and lowering your elevation!
And AndyJ, thanx for the video, that thing is so freaking loud that you can't tell the difference in volume between when the thing was 40 ft. away and 1/4 mile away! Damn!!!
I know the paine of open exhausts VERY well, I used to work with unmuffled 2-stroke expansion chambers. Let's just say that it's not something that I'm looking to revisit with my sometimes street car.
Thanx for all the input guys, keep it coming.
06-02-2006, 02:29 AM
#34
Teching In
Join Date: May 2006
Posts: 22
Likes: 0
Received 0 Likes
on
0 Posts
Call the guys at Dr. Gas and pick their brains. They are very involved with the performance aspect and up on the latest stuff. Though it isn't publicized they provide all the exhaust system for the IROC series cars as well.
06-02-2006, 07:14 AM
#35
I already tried that...
over a month ago:
Dr. Gas has their own forum, that they obviously don't take very seriously.
here is the address:
http://exhaustforums.com/
you can find the post below by going to forums, then modifications:
If you don't want to read it the short version is I posted the same questions that I posted here and 3 weeks later they told me of two products that they sell. I already know what products they sell! Not very helpful.
SicBastard
Posted: Fri May 05, 2006 10:21 am Post subject: Boom Tube Tech
New User
Joined: 05 May 2006
Posts: 3
I am building a corvette LS1 powered nissan with all the usual bolt-ons, a 4.08 rear, and a healthy cam around 230. My original intention was:
1.75" primary HEADERS w/ 3" collectors
->
X-pipe
->
dual 3" Catalytic converters
->
dual 3" perforated core, glass pack, RV mufflers (as long as possible, hoping to fit dual 31"x7"). [Small 3" resonator mufflers B4 or after?]
->
Dual Side exit Pipes (Boom Tubes?)
I read in GM Hitech that a boom tube creates venturis that induce a scavenging effect. I tried to find out more specific technical information on this by searching the web, but was unsuccessful.
Do the tubes have to be cut on a slant to achieve this?
Is it still as affective at the end of a full exhaust system?
Does the length of the boom tubes matter?
Do they increase or decrease sound at all?
Is their performance affected by their location relative to the back wheel or the vertical plane of the side of the carl?
Are two boom tubes on opposite sides of the car as affective as a single larger one on one side?
Thank you all for any input, and any recommendations/advice on the rest of my proposed system are sought and welcome
Back to top
SicBastard
Posted: Mon May 15, 2006 9:29 am Post subject:
New User
Joined: 05 May 2006
Posts: 3
Oh and the real question:
What kind of HP gain on a 400 whp LS1 with full exhaust would be expected over just a round pipe tipe?
Back to top
Funbus
Posted: Sun May 21, 2006 1:41 pm Post subject:
Administrator
Joined: 14 Jul 2005
Posts: 15
You are really building a 'Sic' car!
Basically the naca ducts that are built into every boom tube we make achieve balance by allowing exhaust the flow evenly through-out the casing. Duel 3" may be a tad large( even for you're mighty ls1) and we can keep it streetable with these......
http://www.drgas.com/store/product.p...2&cat=2&page=1
or these where the muffler is built right in!
http://www.drgas.com/store/product.p...4&cat=2&page=1
Back to top
SicBastard
Posted: Wed May 24, 2006 9:46 am Post subject:
New User
Joined: 05 May 2006
Posts: 3
Thanks for the reply Funbus! I've seen the products, but I'm trying to make an informed decision. Any help with the tech q's?
I've got a pretty serious thread going on over at LS1tech.com, and Dr. Gas is given all the props for building the lightest, best sounding system.
How does "balance" at the END of a pipe help flow? By spreading it out over a wider area Like a horn would? Wouldn't that create a high pressure zone just before the exit? What am I missing?
over a month ago:
Dr. Gas has their own forum, that they obviously don't take very seriously.
here is the address:
http://exhaustforums.com/
you can find the post below by going to forums, then modifications:
If you don't want to read it the short version is I posted the same questions that I posted here and 3 weeks later they told me of two products that they sell. I already know what products they sell! Not very helpful.
SicBastard
Posted: Fri May 05, 2006 10:21 am Post subject: Boom Tube Tech
New User
Joined: 05 May 2006
Posts: 3
I am building a corvette LS1 powered nissan with all the usual bolt-ons, a 4.08 rear, and a healthy cam around 230. My original intention was:
1.75" primary HEADERS w/ 3" collectors
->
X-pipe
->
dual 3" Catalytic converters
->
dual 3" perforated core, glass pack, RV mufflers (as long as possible, hoping to fit dual 31"x7"). [Small 3" resonator mufflers B4 or after?]
->
Dual Side exit Pipes (Boom Tubes?)
I read in GM Hitech that a boom tube creates venturis that induce a scavenging effect. I tried to find out more specific technical information on this by searching the web, but was unsuccessful.
Do the tubes have to be cut on a slant to achieve this?
Is it still as affective at the end of a full exhaust system?
Does the length of the boom tubes matter?
Do they increase or decrease sound at all?
Is their performance affected by their location relative to the back wheel or the vertical plane of the side of the carl?
Are two boom tubes on opposite sides of the car as affective as a single larger one on one side?
Thank you all for any input, and any recommendations/advice on the rest of my proposed system are sought and welcome
Back to top
SicBastard
Posted: Mon May 15, 2006 9:29 am Post subject:
New User
Joined: 05 May 2006
Posts: 3
Oh and the real question:
What kind of HP gain on a 400 whp LS1 with full exhaust would be expected over just a round pipe tipe?
Back to top
Funbus
Posted: Sun May 21, 2006 1:41 pm Post subject:
Administrator
Joined: 14 Jul 2005
Posts: 15
You are really building a 'Sic' car!
Basically the naca ducts that are built into every boom tube we make achieve balance by allowing exhaust the flow evenly through-out the casing. Duel 3" may be a tad large( even for you're mighty ls1) and we can keep it streetable with these......
http://www.drgas.com/store/product.p...2&cat=2&page=1
or these where the muffler is built right in!
http://www.drgas.com/store/product.p...4&cat=2&page=1
Back to top
SicBastard
Posted: Wed May 24, 2006 9:46 am Post subject:
New User
Joined: 05 May 2006
Posts: 3
Thanks for the reply Funbus! I've seen the products, but I'm trying to make an informed decision. Any help with the tech q's?
I've got a pretty serious thread going on over at LS1tech.com, and Dr. Gas is given all the props for building the lightest, best sounding system.
How does "balance" at the END of a pipe help flow? By spreading it out over a wider area Like a horn would? Wouldn't that create a high pressure zone just before the exit? What am I missing?
06-02-2006, 10:58 AM
#36
Teching In
Join Date: May 2006
Posts: 22
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by GIGAPUNK
I already tried that...
over a month ago:
Dr. Gas has their own forum, that they obviously don't take very seriously.
here is the address:
over a month ago:
Dr. Gas has their own forum, that they obviously don't take very seriously.
here is the address:
Andy
06-03-2006, 08:56 PM
#38
Teching In
Join Date: Jan 2006
Location: ShenZhen, China
Posts: 18
Likes: 0
Received 0 Likes
on
0 Posts
My experience with using boom tubes on the street was noisy at best.
Here is a link to a page with some vids on it- the car has a moderate old school SBC. Dynatech headers into oval pipes, oval crossover and Flowmaster muffler, then into a set of custom built boom tubes. Ear buster- way too loud for the street unless you like talking to the police a lot.
Please bear in mind that the videos were taken on fun runs- the car was not really even finished and we were carefully testing it out a little at a time. Playing around, not a lot of traction and trying not to crash a 4 year project car on day one….
http://www.rscamaro.com/downloads/
Later changes to the exhaust system revealed that the boom tubes did not really change the overall SPL at a particular RPM / engine load, but they do change the pitch and sound a bit. With the right muffler, they are fine for the street, but with the wrong muffler… There are some significant changes to this car in the early stages of development now (LSX + turbos etc…) and we will end up going back to something similar to the original system, but better built and using quieter mufflers.
A not so hot pic of the exhaust system in the car - http://www.rscamaro.com/project/driv...EXHAUST_IN.jpg
And a pic of the system out of the car, but of course, missing the boom tubes which this thread is all about… http://www.rscamaro.com/project/drivetrain/EXHAUST.jpg
And another pic from under the car also missing the ends of the system- http://www.rscamaro.com/project/body/UNDER.jpg
I would also like to share a comment about building them or buying a set- Make sure that you either do a very good job with your weld up or buy a set of very high quality boom tubes. The pressure makes the walls of the tube want to flex a lot- on my car you can actually hear some rattling of the tubes and that was just on initial shakedown runs where we were just playing around. The tubes were very “young” at the time, perhaps less than one hour on them. They looked strong, but use in the real world indicated otherwise. If I had it to do over again, I would add more dividers and make sure that we are really penetrating into the divider with the TIG operation. They are done similar to the Dr. Gas tubes; stich welded along the dividers which works, but some of the welds may fail and let the things rattle or buzz quite a bit. Also, it could be possible to have some rattling between the welds. Not saying that the Dr. Gas product is poorly built; not at all; in fact I think they are great for a race car and they definitely know their business quite well. I have not used their street version boom tube or even seen one, so they may have taken care of this issue before going to production. Heck, maybe the ratting was something that only I have experienced?
The set of tubes in the post above look heavy, but I bet they were built by someone that knows what they are doing and has perhaps had a similar experience as me. While we all want parts to be light weight, if you have to have a heavy part, where better to have it than low and towards the rear of the car.
Just my $.02… Hope it is a useful contribution to this thread.
Here is a link to a page with some vids on it- the car has a moderate old school SBC. Dynatech headers into oval pipes, oval crossover and Flowmaster muffler, then into a set of custom built boom tubes. Ear buster- way too loud for the street unless you like talking to the police a lot.
Please bear in mind that the videos were taken on fun runs- the car was not really even finished and we were carefully testing it out a little at a time. Playing around, not a lot of traction and trying not to crash a 4 year project car on day one…. http://www.rscamaro.com/downloads/
Later changes to the exhaust system revealed that the boom tubes did not really change the overall SPL at a particular RPM / engine load, but they do change the pitch and sound a bit. With the right muffler, they are fine for the street, but with the wrong muffler… There are some significant changes to this car in the early stages of development now (LSX + turbos etc…) and we will end up going back to something similar to the original system, but better built and using quieter mufflers.
A not so hot pic of the exhaust system in the car - http://www.rscamaro.com/project/driv...EXHAUST_IN.jpg
And a pic of the system out of the car, but of course, missing the boom tubes which this thread is all about… http://www.rscamaro.com/project/drivetrain/EXHAUST.jpg
And another pic from under the car also missing the ends of the system- http://www.rscamaro.com/project/body/UNDER.jpg
I would also like to share a comment about building them or buying a set- Make sure that you either do a very good job with your weld up or buy a set of very high quality boom tubes. The pressure makes the walls of the tube want to flex a lot- on my car you can actually hear some rattling of the tubes and that was just on initial shakedown runs where we were just playing around. The tubes were very “young” at the time, perhaps less than one hour on them. They looked strong, but use in the real world indicated otherwise. If I had it to do over again, I would add more dividers and make sure that we are really penetrating into the divider with the TIG operation. They are done similar to the Dr. Gas tubes; stich welded along the dividers which works, but some of the welds may fail and let the things rattle or buzz quite a bit. Also, it could be possible to have some rattling between the welds. Not saying that the Dr. Gas product is poorly built; not at all; in fact I think they are great for a race car and they definitely know their business quite well. I have not used their street version boom tube or even seen one, so they may have taken care of this issue before going to production. Heck, maybe the ratting was something that only I have experienced?
The set of tubes in the post above look heavy, but I bet they were built by someone that knows what they are doing and has perhaps had a similar experience as me. While we all want parts to be light weight, if you have to have a heavy part, where better to have it than low and towards the rear of the car.
Just my $.02… Hope it is a useful contribution to this thread.
06-03-2006, 10:11 PM
#39
All I can say is WOW & Oh, so that is how you're supposed to build a car!
Your web site is something else too!
I love how the camera man can't keep the camera steady, and you can hear the wheels break loose every time the power comes into the powerband.
That little flowmaster didn't sound like it was doin a whole lot! As an aside: Do you buy into the theory that a flow master can emulate an open header collector? Beautiful work with the oval stuff too. Did using the thick flanges help to maintain the shape?
How did the boom tubes change the sound? Higher/Lower pitch, more or less even, or smaller cam sounding?
Your web site is something else too!
I love how the camera man can't keep the camera steady, and you can hear the wheels break loose every time the power comes into the powerband.
That little flowmaster didn't sound like it was doin a whole lot! As an aside: Do you buy into the theory that a flow master can emulate an open header collector? Beautiful work with the oval stuff too. Did using the thick flanges help to maintain the shape?
How did the boom tubes change the sound? Higher/Lower pitch, more or less even, or smaller cam sounding?
06-03-2006, 11:31 PM
#40
Teching In
Join Date: Jan 2006
Location: ShenZhen, China
Posts: 18
Likes: 0
Received 0 Likes
on
0 Posts
Thanks for the compliments on the car.
I have zero website development skill, but I am lucky enough to have a friend that does.... He is the administrator of the following site - http://www.lateral-g.net/forums/ Cool and casual forum
The flanges- Used mild steel and wire cut them to be a tad bigger than the actual tubing. Where there is a joint, one flange is slipped down about 3/8" past the end of the tube then welded. The opposing tube is slipped about 1/8" into it's flange. This way when you bolt them together, the flanges are guides to make the tubes come up end to end, very flush. The way it works allows for some very smooth junctions and as they heat up, the tubes snug up and seal quite well. They are easy to do on a wire cut or typical CNC. If you CNC mill them, you may need to make the thinner areas of the flange a little thicker or make a nice perimeter clamp jig to help them hold shape. Wire cut is the way to go on this IMO.
The flowmaster not doing much- maybe changes the sound a bit, but I am not so sure about any significant reduction in amplitude.
The way that the boom tubes changed the sound- The car sounds like a late model oval track car with the original setup on it. Higher pitched, not the deep mellow sound that you get out of a typical old school V8.
Using the modified setup where we had the tubes, but quieter mufflers- The tubes definitely change the pitch of the exhaust a bit, but not as significantly as the muffler. Hard to describe.
Flomaster increasing the flow over open exhaust. Yes, I think it can. Boom tubes helping power output or flow? Yes. But I feel that the gains are most prominent in steady state and in high flow / high power situations. Circle track race cars, particularly superspeedway situations where the motor is running in a pretty narrow RPM band. Other situations? Sure, and likely some are significant, but perhaps more difficult to identify the real source or cause for the gains without a lot of careful experimentation.
I used the tubes and oval stuff for ground clearance and as a coolness feature. Would I do it again? Yes, but with better preparation and execution. I may fab up a new set of tubes to go on the system. This thread has sort of rekindled my interest in the subject.
I still have the original setup for that Camaro and it would be neat to put the car on a chassis dyno and look at the output comparing a few different setups. The power will be low compared to a lot of the guys on this board; but it would be a neat look into what changes or doesn't change. I would also like to use a good quality SPL meter and get a RTA or spectrum analysis capture of the system at different RPM; that would somewhat paint a picture of the acoustic situation which I am sure is the biggest difference on this particular car.
I have zero website development skill, but I am lucky enough to have a friend that does.... He is the administrator of the following site - http://www.lateral-g.net/forums/ Cool and casual forum
The flanges- Used mild steel and wire cut them to be a tad bigger than the actual tubing. Where there is a joint, one flange is slipped down about 3/8" past the end of the tube then welded. The opposing tube is slipped about 1/8" into it's flange. This way when you bolt them together, the flanges are guides to make the tubes come up end to end, very flush. The way it works allows for some very smooth junctions and as they heat up, the tubes snug up and seal quite well. They are easy to do on a wire cut or typical CNC. If you CNC mill them, you may need to make the thinner areas of the flange a little thicker or make a nice perimeter clamp jig to help them hold shape. Wire cut is the way to go on this IMO.
The flowmaster not doing much- maybe changes the sound a bit, but I am not so sure about any significant reduction in amplitude.
The way that the boom tubes changed the sound- The car sounds like a late model oval track car with the original setup on it. Higher pitched, not the deep mellow sound that you get out of a typical old school V8.
Using the modified setup where we had the tubes, but quieter mufflers- The tubes definitely change the pitch of the exhaust a bit, but not as significantly as the muffler. Hard to describe.
Flomaster increasing the flow over open exhaust. Yes, I think it can. Boom tubes helping power output or flow? Yes. But I feel that the gains are most prominent in steady state and in high flow / high power situations. Circle track race cars, particularly superspeedway situations where the motor is running in a pretty narrow RPM band. Other situations? Sure, and likely some are significant, but perhaps more difficult to identify the real source or cause for the gains without a lot of careful experimentation.
I used the tubes and oval stuff for ground clearance and as a coolness feature. Would I do it again? Yes, but with better preparation and execution. I may fab up a new set of tubes to go on the system. This thread has sort of rekindled my interest in the subject.
I still have the original setup for that Camaro and it would be neat to put the car on a chassis dyno and look at the output comparing a few different setups. The power will be low compared to a lot of the guys on this board; but it would be a neat look into what changes or doesn't change. I would also like to use a good quality SPL meter and get a RTA or spectrum analysis capture of the system at different RPM; that would somewhat paint a picture of the acoustic situation which I am sure is the biggest difference on this particular car.