RE: selecting the right tuned pipe.  
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RE: selecting the right tuned pipe. - 7/1/2007 5:36:06 PM   
SAVAGEJIM



Posts: 5170
Joined: 7/6/2005
From: behind my 'puter, USA
Status: offline 		I cracked the puzzle why sound and other pressure waves move more rapidly through less dense gasses while at temperature:

Temperature is simply kinetic energy of molecules. That means in gasses, the molecules are moving more rapidly and bounce of of each other more often (molecular collisions). Apply a pressure wave, and the already fast moving molecules begin to collide more often than thy already are. Thus, a pressure wave encountering already fast moving molecules in a gas at temperature yields a faster sound wave than it would be at standard temp (i.e. 32degrees F or 0degrees C).

I hope my explanation does not sound as confusing as it might sound.

The physics in play that helped me determine this:
Kinetic energy is mass moving at a velocity, expressed in the formula: KE=(0.5) * mass * velocity squared.
Work is force applied throughout a given distance, expressed in the formula: Work=Force * distance
Energy (Kinetic and potential) is equal to work, expressed in the formula: Work=(0.5) * mass * velocity squared (I am only intersted in kinetic energy in this case.
Pressure is force apllied to a given space of area, expressed in the formula: Pressure=Force * area
The kinematic equations for velocity and distance that we all learn in high school.

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RE: selecting the right tuned pipe. - 7/1/2007 5:42:56 PM   
ttoks



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From: leongatha,VIC, AUSTRALIA
Status: offline 		unfortunately i'm still going through high school (well in a way unfortunately, if i still have stuff to learn, i still have stuff to keep my mind busy), so i havn't learned everything yet, savage, do you think you (or me) could use this to figure out roughly how fast sound will travel in the pipe at around 350-400 degrees F (assuming that is the roughly the temp of the exhaust gases at full throttle)? at the moment this really has me stumped, 344 meters per second seems to logically fit once i'v done the calculations, more os then 438 meters per second anyway.

< Message edited by ttoks -- 7/1/2007 5:45:11 PM >

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RE: selecting the right tuned pipe. - 7/1/2007 6:51:47 PM   
savagecommander


 

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From: sterling heights, MI, USA
Status: offline 		yes but 400 deg is a big difference.

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RE: selecting the right tuned pipe. - 7/1/2007 7:10:14 PM   
Jatohulk



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Status: offline 		Holy very impress only 15 years old wow. Good job.

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RE: selecting the right tuned pipe. - 7/2/2007 1:10:22 AM   
SAVAGEJIM



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quote:

ORIGINAL: ttoks

unfortunately i'm still going through high school (well in a way unfortunately, if i still have stuff to learn, i still have stuff to keep my mind busy), so i havn't learned everything yet, savage, do you think you (or me) could use this to figure out roughly how fast sound will travel in the pipe at around 350-400 degrees F (assuming that is the roughly the temp of the exhaust gases at full throttle)? at the moment this really has me stumped, 344 meters per second seems to logically fit once i'v done the calculations, more os then 438 meters per second anyway.


I personally think we should use the temp inside the pipe as the factor for determining the speed of sound. A good way to verify this is to figure out a pipe length, its header length, and the timing profile of the engine it is designed for. If we can calculate that length and determine the time that it takes for the piston to go up from the instant the last intake ports close to the instant the exhaust port closes at the target RPM range, then calculate the speed of sound for the operating temp of the exhaust gases inside the pipe.

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RE: selecting the right tuned pipe. - 7/2/2007 1:48:30 AM   
ttoks



Posts: 3665
Joined: 3/15/2007
From: leongatha,VIC, AUSTRALIA
Status: offline 		yes yes i see what your saying, although i don't think i'll be taking the RB to pieces unless i have a reason to, however i do have the old stuffed TRX 3.3, i'll see if i can get my hands on a vernia caliper, a don't think i'll be able to use a micrometer for this.

but then a vernia is only accurate to .002 of a mm (.001 of an inch) and i'm sure that is enough to cause a change in the timing profile of an engine, so i don't know.

< Message edited by ttoks -- 7/2/2007 1:50:04 AM >

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RE: selecting the right tuned pipe. - 7/2/2007 4:29:11 AM   
The Real Dogman



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From: Tucson, AZ, USA
Status: offline 		UM ttoks Check it out!! .001" X 25.4 = .0254mm
Imperial X Constant Conversion = Metric

BAD INFO!! TSK! TSK! At least your tolerance numbers are on!!

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RE: selecting the right tuned pipe. - 7/2/2007 4:57:14 AM   
ttoks



Posts: 3665
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From: leongatha,VIC, AUSTRALIA
Status: offline 		ah i'm sorry, i left a 0 on that, congratulations on discovering a typo.

and a Vernia is accurate to .002 of a millimeter, work it out if you wish, but i will be using metric, so it is of no use to me.

< Message edited by ttoks -- 7/2/2007 4:58:15 AM >

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RE: selecting the right tuned pipe. - 7/2/2007 5:08:30 AM   
downunder



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From: Adelaide, AUSTRALIA
Status: online 		Just for interest's sake, if you go to http://www.clstunt.com/PipChart.htm you'll see a chart for actual full length pipes used on CL stunt engines which obviously turn much lower revs but the idea is the same. Of interest is the difference in length for the same rev but different exhaust timings.

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RE: selecting the right tuned pipe. - 7/2/2007 5:29:10 AM   
The Real Dogman



Posts: 1957
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From: Tucson, AZ, USA
Status: offline 		No ttoks its not!! Vernier Calipers are graduated in .001" which translates to .0245mm Read the specs of vernier Calipers.Even digital calipers are graduated to the same tolerences Read these specs on These digital CalipersTypo's in math are very bad, you should know that, as smart as you are!!

This is very interesting thread. When you fellas Figure out a simpler means for everyone in the hobby to figure what pipe would best compliment the engine they choose and rpm range they wish operate in, please post the formula. We all would be very interested in your findings

Good work so far


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RE: selecting the right tuned pipe. - 7/2/2007 5:31:10 AM   
ttoks



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From: leongatha,VIC, AUSTRALIA
Status: offline 		oh yes my mistake, .02 of a millimeter.

now unless you have something to add to the topic of the thread i am going to report you to the forum moderators for drifting off topic and have your posts here deleted, i suggest you leave now.

< Message edited by ttoks -- 7/2/2007 5:33:20 AM >

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RE: selecting the right tuned pipe. - 7/2/2007 5:37:08 AM   
The Real Dogman



Posts: 1957
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From: Tucson, AZ, USA
Status: offline 		uh oh,, (see the dog running away and his tail bouncing) Yeah right!! I will when ready I have right to read this kiddo, and I find it interesting. Geeze... who does this guy think he is?? Sorry you made a minor mistake, didn't mean to get you in a lather just figured since you are into math so much you might need that critical bit of info corrected... Soorrryyeee.. lol


< Message edited by The Real Dogman -- 7/2/2007 5:38:13 AM >

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RE: selecting the right tuned pipe. - 7/2/2007 5:51:36 AM   
SAVAGEJIM



Posts: 5170
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Status: offline 		Its not that you pointed out an error, it was the way you did it. Anyone would have felt that it was being rubbed in. I'm not saying you were trying to rub it in, it just came out that way.

You are right, when off by a power of magnitude, even by 1 magnitude power, that erroe is off by 10 or a tenth, which could be significant, especially when calculating speeds of sound in terms of cm/sec.

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RE: selecting the right tuned pipe. - 7/2/2007 5:58:24 AM   
ttoks



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From: leongatha,VIC, AUSTRALIA
Status: offline 		me and dogman have been having a little dicusstion about the power output of the CEN .46 engine in comparison the the nova 528 over the past few days, if i linked you to the thread, the name calling alone (he actually told me to grow up when i asked him to delete all of the insults he had thrown about) i think would be enough for a term of moderated status, but thats a besides the point, and is a completely different thread.

dogman i have sent you a pm



< Message edited by ttoks -- 7/2/2007 6:03:24 AM >

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RE: selecting the right tuned pipe. - 7/2/2007 5:58:47 AM   
The Real Dogman



Posts: 1957
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From: Tucson, AZ, USA
Status: offline 		Thank you exactly my point... And I appologize if it seemed as tho I was rubbing it in. Some people can be a bit stubborn. In this case, it is extremely important to get the numbers correct.. So... him reciting an inaccuracy again after correction, spells stubborness.

EDIT ADDED: Check your facts... the discussion was about the accuracy of info...ttok please be accurate!!! and you wonder why I reacted as I did Here is the link!! Check the facts for yourself... it started out as supposed dyno results I did not agree with....And Yes the CEN engine was the catalyst, but went on from there.. Abit too far in my opinion!!! My appologies to the original author!!!

< Message edited by The Real Dogman -- 7/2/2007 6:04:19 AM >

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RE: selecting the right tuned pipe. - 7/2/2007 2:26:51 PM   
Krixxer


 

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From: , ON, CANADA
Status: offline 		This weekend I had a chance to play with my RB C5 with 063 adjustable pipe.

Initially I had it set to 25 cm and proceeded to make .5cm adjustments (now in my case the header protrudes into the exhaust)

By the time I had the pipe out to 27cm the buggy lost all it's balls so I started to shorten it again which made me think how we are taking the measurements of the entire system .

At first I would remove the exhaust and with a piece or wire would measure its centerline, I subsequently started adding the length from the exhaust port to the header itself. This small adjustment made a substantial difference in the calculation.


As for pipe construction, I think we will be quite disappointed if we are looking for any fancy engineering. From the ones I have they are all but empty cylinders.

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