JLTD
JL, actually that's the volume here it is:



The volume of a cylinder equals the (area of the base)*height = r2h


http://www.aaamath.com/geo79-volume-cylinder.html

Simple mistake, I make them all the time.



Tamago First off Tamago means egg in Japanese. FWI So that means: I’m not only a science wiz, I can weld, make exhaust systems teach graduate level science course and um know Japanses too. Can’t write but hey.

Now to you:

http://www.aaamath.com/B/geo79x10.htm

Here The surface area of the side is the circumference times the height or 2 PI r h

two PI radius Height = PI diameter height = PI diameter length if the cylinder is laying flat which it is.

As I already calculated. QED

Oh and what does Pascal's law have to do with simple area calcs? NOTHING . Obviously I’ve have correctly applied ye old Pasal’s law to the internal surface and just as Mr Pascal stated the pressure is EVEN within the muffler – some minor pressure differential due to restriction and flow propagation heat rejection via the muffler body. Pascal’s law applied correctly to the area of the cylinder not the volume as the previous poster INCORECTY tried to do by squaring the radii.

I WOULD SAY YOU JUST GOT OWNED!!!

Here’s Pascal’s law: http://www.britannica.com/ebi/article?tocId=9312902 and I should note it deals with working media: ONLY in a sealed container, not moving hot air with an entry and exit, and is NOT entirely true.

 

this is sooooo flawed..

8TONS OF PRESSURE??

how does 18PSI EVER CREATE 8TONS OF PRESSURE? 18PSI is 18PSI.

there is 18PSI pushing on each and every surface of the supposed muffler, not 8tons.

using your theory, if i blew into a balloon til i reached 3PSI, that the air would somehow intensify to TONS OF PRESSURE, the balloon would explode and kill me..

FORCE = PRESSURE X AREA, not PRESSURE X VOLUME

i think you just OWNED YOURSELF

 

As much as I hate to get into all of this:

He did not say TONS of PSI, he said tons of pressure. There is a difference depending on what you are relating the pressure to. And yes, Force = Pressure X Area... that would be SURFACE area inside of a volume.

But, as many who have actually built and tested motors know, backpressure does make a difference, so calculating all the results is redundant, and of course Magnaflow is going to give you answers that support their products. Common sense. Now stop bashing each other over something so completely ignorant!!!

 

As much as I hate to get into all of this:

He did not say TONS of PSI, he said tons of pressure. There is a difference depending on what you are relating the pressure to. And yes, Force = Pressure X Area... that would be SURFACE area inside of a volume.

But, as many who have actually built and tested motors know, backpressure does make a difference, so calculating all the results is redundant, and of course Magnaflow is going to give you answers that support their products. Common sense. Now stop bashing each other over something so completely ignorant!!!

 

there's STILL NOT TONS OF PRESSURE..

how else is pressure measured?

 

Oldman, engifneer, and niguels seem to get the big picture here. If you want a race car, build a race car! If your starting point is an Xb you're ____ing in the wind. Disapointment will be your fate. All these HP figures measured at the brochure are not worth the ink it took to print them. Try all these great ideas and report your findings back to us all so we can benifit from your ignorance. If you truly understand physics and internal-combustion engine dynamics you will understand, If your knowlege consists of a stack of brochures you read and reapeat at will, I would suggest some proper education. Just a thought.

 

Thanks for the clarity. I should add I’m not bashing anybody, I politely corrected somebody who incorrectly thought I made an error. My calculations were as usual precisely correct. I should point out that Tamago started with the name calling and I for one don’t like to be called a “moron”, especially by somebody who obviously has a tenuous grasp of physics and the application there of. I was more the proper with my reply and will continue to do so. IMO you go around calling your peers “morons” you better have your act together.

We all agree that backpressure effects engine performance, a dynomax superturbo can flow 410 CFM of air at .5 PSI of backpressure, be quite as stock, cost $50.00 and cost to install including a crush bent 2.5 inch pipe and a neat slash tip is sub $100.00. Power gain over stock OEM non-TRD um safe to say less then 5 WHP, IMO maybe ½ that, and only in the upper RPM ranges. System would flow enough for even mild turbo applications I ran one on my T04e Integra GS-R, stock quite, brutal HP even capped, 350 WHP capped up plain fuel, 400 WHP+ uncapped at the down pipe 3” with race gas. Big gains in response uncapped but loud too (even with the turbo).

 

sighhhh...... 10PSI applied to a 10 Sq Inch surface = 100 lbs of force.... It is not measured differently, and I am not trying to validate or invalidate the calculations. What I am saying is that 18PSI does not mean that the system has 18lbs of force on it. It is 18lbs per every sq inch of surface area.

 

exactly. i agree. there are 18PSI pushing on each and every surface of the canister..

now factor in atmospheric pressure

 

Ok, you are making no logical sense at this point, so I will let you guys argue it amongst yourselves now. Have fun.

 

Call me crazy but I think I'll trust the opinions of the 2 engineers (engifineer, oldman). :D

 

i'm an industrial hydraulic engineer, and believe me, what we're talking about is VERY relavent in industrial hydraulics

 

can someone please expain the 8TON THEORY to me first?

then we'll talk about atmospheric pressure.

 

Dude, pounds or 2,000 pounds = 1 ton have been used in traditional lingo aka common everyday plain simple easy to understand English to be a unit of mass and a unit of force. So pounds or tons of pressure x area does indeed = force which can be measured in POUNDS or TONS since it would still retain this unit of measure and also retain the units of time squared.

Look at my exact words: 16290 lbs of pressure pushing out of the case

Obviously this is FORCE I have even included the vector of said force being the summation of the normal angle out of the case. QED

YOU HAVE BEEN OWNED ONCE AGAIN


Right from a definition page on Physics:

The “8 ton theory” is that if there really were 18 PSI of pressure, which is above atmospheric just for Tamago’s FYI, in the exhaust system as backpressure. Then the force on large exhaust system components would be so incredible that it would blow them up, (being made out of cheap tin gauge steel and all). Since you don’t see mufflers, CATs, composite exhaust gaskets and the like just flying apart all over the road. You can rest assured there is NOT 18 PSI in the exhaust system.

I have blown up many mufflers with my 440 Mopar. But ahem that is another story.

Tamago

 

The 18psi thoery makes sense if there were no outlet to the muffler but since there is, there's no way that much pressure could build up in the exhaust. I'd imagine no exhaust could be so restrictive to allow that kind of pressure build-up. So if you plugged your muffler to allow such a build-up of pressure, something would blow.

Like with an air compressor, it builds pressure because the air has no place to go. But if you open the release valve, the pressure would drastically drop and never build. 18psi in a tire is capable of holding up a 2ton automobile (yes I know the avg 30psi). So Tamago, since you work with hydraulics, what would the dimensions of a hydraulic cyclinder be to lift 8tons with 18psi?

Now I'm no engineer nor am I a physics major, this is just what I'm gathering from this conversation.

 

18PSI is 18 PSI.. there is 18 pounds of pressure per square inch of surface area in the muffler. this number is not additive. you cannot multiply 18PSI (which is POUNDS PER SQUARE INCH) BY THE VOLUME OF THE CYLINDER MUFFLER AND GET ANY USEABLE NUMBER.

i will give you an example of your theory being incorrect..

ready?

ok.. water hose.. 1/2" ID
water pressure. 40PSI
water hose length: 50 ft

according to your theory, there would be .. let's see.. .5X.5X.7854 (the easy way to find area) X (50 X12) 117.81 LBS OF FORCE pushing out on the interior of the hose.

now.. what if the hose is 2,000 feet long?

your number is now 4,712.4 POUNDS OF FORCE pushing out on the interior of the hose.

so.. my garden hose is now 3FT in diameter to withstand the 2.3 TONS of force being exerted against it?



i bow to your superior brain power

 

Force = Pressure X area

so.. we know force and pressure

16,000 / 18 = 888.89 SQUARE INCHES.

(SQRT of (888.89 /.7852) = 33.64
with 18 PSI and no fudge factor for friction, a 33.64" diameter cylinder with 18PSI would lift 8tons.

 

Thanks for answering, so based on circumstance you're both technically right. oldman's is right but his calculation is based on a closed cylinder. So based on your answer if you had a hydraulic cyclinder roughly the size of the muffler in his calculation then technically it's feasible to exert 8tons of force. So in this case oldman is stating that it's impossible to build 18psi in an exhaust which is also technically right. Since the exhaust is open, the pressure cannot build that high, so therefore 18psi of backpressure is not happening.

 

-THE DON

 

no. you cannot exert 8 tons of force with a muffler. there is not 8 tons of force pushing out on a mufller wall.. there would be 18PSI

now, to totally throw this ENTIRE ARGUMENT OUT, there wouldn't be 18psi AT THE MUFFLER ever anyway.

the only place that would feel the 18PSI woudl be at the exhaust manifold...