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  • #46
    ""There has to be a balanced design to enhance the maximum engine output, exhaust gas velocity, and sound. For example, imagine blowing air through a straw (comparing it to a smaller diameter pipe). This would take time to release all the air from your mouth, and you would feel pressure in your mouth while doing so. Now imagine blowing air through a paper towel roll (comparing it to a larger diameter pipe). You will relieve all your air much faster and feel little or no air pressure in your mouth because of the larger capacity of the tube. This is why it is important to get the correct size piping in order to relieve backpressure while maintaining thermal efficiency""


    do you understand that?
    1996 Silver camaro Z28. M6,<br />12 bolt, 4.11\'s, posi, Rear cover, Spec stage 2, loudmouth, more <a href=\"http://home.mainstreamtopics.com/?index=3&module=1\" target=\"_blank\">http://home.mainstreamtopics.com/?index=3&module=1</a> &lt;Mods, Pics & more <a href=\"http://home.mainstreamtopics.com/?index=3&module=2\" target=\"_blank\">http://home.mainstreamtopics.com/?index=3&module=2</a> &lt;Fbody Tech Articals

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    • #47
      Originally posted by HBHRacing:
      ""There has to be a balanced design to enhance the maximum engine output, exhaust gas velocity, and sound. For example, imagine blowing air through a straw (comparing it to a smaller diameter pipe). This would take time to release all the air from your mouth, and you would feel pressure in your mouth while doing so. Now imagine blowing air through a paper towel roll (comparing it to a larger diameter pipe). You will relieve all your air much faster and feel little or no air pressure in your mouth because of the larger capacity of the tube. This is why it is important to get the correct size piping in order to relieve backpressure while maintaining thermal efficiency""


      do you understand that?
      You're comparing human lungs with a limited capacity going thru a straw and something nearly 100 times as large. How about you do 2 straws and then double it. ****. What a crappy way to put it or relate it. I totally disagree with that comment. [img]graemlins/twak.gif[/img]
      Mustangs.. Come to the darkside...<br /><br />The dark side is the path to the shadow of greed. =D

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      • #48
        OMFG.. you will argue anything. that also came from magnaflow. you want to dissagree with one of the worlds leaders in exhaust technology? I pitty you, I really do. you seem lazy to me, instead of actualy doing your homework and understanding what would work best you just throw 3 inch exhaust at and think it's best cause you saw a 8HP gain.


        ponder this. what if you went 2.75 and only gained 4HP but gained .2 in the 1/4 over the 3 inch. would you still say the 3 inch works better?
        1996 Silver camaro Z28. M6,<br />12 bolt, 4.11\'s, posi, Rear cover, Spec stage 2, loudmouth, more <a href=\"http://home.mainstreamtopics.com/?index=3&module=1\" target=\"_blank\">http://home.mainstreamtopics.com/?index=3&module=1</a> &lt;Mods, Pics & more <a href=\"http://home.mainstreamtopics.com/?index=3&module=2\" target=\"_blank\">http://home.mainstreamtopics.com/?index=3&module=2</a> &lt;Fbody Tech Articals

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        • #49
          [img]graemlins/popcorn.gif[/img] [img]graemlins/rock.gif[/img] HBHRacing!
          Visit my Car Forum at <a href=\"Http://www.mainstreamtopics.com/forum\" target=\"_blank\">Http://www.mainstreamtopics.com/forum</a>

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          • #50
            Originally posted by HBHRacing:
            OMFG.. you will argue anything. that also came from magnaflow. you want to dissagree with one of the worlds leaders in exhaust technology? I pitty you, I really do. you seem lazy to me, instead of actualy doing your homework and understanding what would work best you just throw 3 inch exhaust at and think it's best cause you saw a 8HP gain.


            ponder this. what if you went 2.75 and only gained 4HP but gained .2 in the 1/4 over the 3 inch. would you still say the 3 inch works better?
            Ponder this, what if he didn't ask about 2 3/4 pipes?
            Mustangs.. Come to the darkside...<br /><br />The dark side is the path to the shadow of greed. =D

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            • #51
              Look HBH, we (V6 F-Body drivers) have done the 2.5" vs 3" debate OVER and OVER and OVER. EVERY time its the SAME conclusion. 3" exhaust is if you plan on/are racing it. Get 3" if you want the most gains and dont mind it being loud as hell. Get 2.5" if its a street car, you wont race it, and just want a nice little growl to your exhaust note....


              You're arguing with people who've been doing this for YEARS.
              Mustangs.. Come to the darkside...<br /><br />The dark side is the path to the shadow of greed. =D

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              • #52
                When I had a 3" exhaust on the V6 bird I had, it didn't hurt my 1/4 times at all. But, I also upgraded to a 3" exhaust because I started spraying it also. ;)
                <b>99 Camaro Z28 A4</b><br />R.I.P. 00 Firebird 3.8<br />14.89 @ 90, 2.03 60\'

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                • #53
                  but if you have been doing it wrong for years does that make it right?

                  you are a master at avoiding my questions. I say AGAIN..


                  what if you went 2.75 and only gained 4HP but gained .2 in the 1/4 over the 3 inch. would you still say the 3 inch works better????


                  come on that is a simple simple question. you can not fualt that logic. you are stuborn and it is draging EVERYONE else down the same path that you take.


                  with your next post ANSWER that quetion or be labled as someone how would rather avoid that admit.


                  now. I have been talking to a friend of mine that is without a doubt the smarted person that I talk to on a regular basis. He is the one that I learned most of the theory from. he has great examples inclusing the straw example that you again AVOIDED.

                  this is what he says for an example.

                  As for the 8 HP increase with the 3" exhaust,
                  that has probably happened way up around 5000 RPM.

                  What that guy doesn't realize is peak power is
                  not as important as AVERAGE Horsepower.

                  Big F'n deal if you gained 8 horsepower at 5000 RPM. He probably dropped a bunch of torque and
                  Horsepower from 2000-5000 RPM.

                  Compare the before and after curves

                  Before (stock exhaust system):

                  175 HP @ 2000 RPM
                  180 HP @ 2500 RPM
                  185 HP @ 3000 RPM
                  190 HP @ 3500 RPM
                  195 HP @ 4000 RPM
                  200 HP @ 4500 RPM
                  205 HP @ 5000 RPM
                  207 HP @ 5500 RPM

                  After (large exhaust pipe):

                  145 HP @ 2000 RPM
                  150 HP @ 2500 RPM
                  155 HP @ 3000 RPM
                  160 HP @ 3500 RPM
                  165 HP @ 4000 RPM
                  190 HP @ 4500 RPM
                  200 HP @ 5000 RPM
                  215 HP @ 5500 RPM

                  Check out where the power sits in both charts.

                  Where does this guy happen to spend most of his
                  time shifting?

                  What sort of transmission ratios is he using?

                  He would have to have a transmission and final
                  ratio setup that kept the motor between 4500-5500
                  at all times to take advantage of that small 8 HP
                  increase.

                  In the above examples, if he dropped below 4500 on
                  any shift he will run slower than the stock setup.

                  This is why horsepower peak means absolutely nothing.

                  It's all about the most average power over a band
                  of RPM. Normally, most transmissions are geared
                  to use at least a 2000 RPM window.


                  now. if you can actualy understand all this. and really honestly think about it logicly and NOT avoid the points then maybe we will have someone.


                  My msg to everyone other then KBeezy is this:

                  Don't listen to someone esle. Don't even listen to me. Look at the facts and deside for your self. Just because he refuses to use logic and basic education doesn't mean that everyone has to. yes, you can make 3 inch work, but the point is that it might not work well or you have to do other things in other areas to make it work.

                  Be your own person and make your own choices. Don't just follow him because he labled me a V8 guy who knows nothing about the V6's even tho it's the same theory that aplys.

                  Thank you for your time everyone.
                  1996 Silver camaro Z28. M6,<br />12 bolt, 4.11\'s, posi, Rear cover, Spec stage 2, loudmouth, more <a href=\"http://home.mainstreamtopics.com/?index=3&module=1\" target=\"_blank\">http://home.mainstreamtopics.com/?index=3&module=1</a> &lt;Mods, Pics & more <a href=\"http://home.mainstreamtopics.com/?index=3&module=2\" target=\"_blank\">http://home.mainstreamtopics.com/?index=3&module=2</a> &lt;Fbody Tech Articals

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                  • #54
                    Originally posted by HBHRacing:

                    Compare the before and after curves

                    Before (stock exhaust system):

                    175 HP @ 2000 RPM
                    180 HP @ 2500 RPM
                    185 HP @ 3000 RPM
                    190 HP @ 3500 RPM
                    195 HP @ 4000 RPM
                    200 HP @ 4500 RPM
                    205 HP @ 5000 RPM
                    207 HP @ 5500 RPM

                    After (large exhaust pipe):

                    145 HP @ 2000 RPM
                    150 HP @ 2500 RPM
                    155 HP @ 3000 RPM
                    160 HP @ 3500 RPM
                    165 HP @ 4000 RPM
                    190 HP @ 4500 RPM
                    200 HP @ 5000 RPM
                    215 HP @ 5500 RPM

                    Check out where the power sits in both charts.

                    Where does this guy happen to spend most of his
                    time shifting?

                    What sort of transmission ratios is he using?

                    He would have to have a transmission and final
                    ratio setup that kept the motor between 4500-5500
                    at all times to take advantage of that small 8 HP
                    increase.

                    In the above examples, if he dropped below 4500 on
                    any shift he will run slower than the stock setup.

                    This is why horsepower peak means absolutely nothing.

                    It's all about the most average power over a band
                    of RPM. Normally, most transmissions are geared
                    to use at least a 2000 RPM window.


                    I'm catching the tail part of this..

                    The above numbers you posted:
                    I assume they were on the same car?
                    Were they on the same dynojet/mustang?
                    same temp and humidity on the testing days?
                    With or without (after market) headers?
                    Please define "Large exhaust pipe" new cat? Hiflow cat? 3".. 4"? what muffler? ect....?

                    ECT.....

                    The only reason why I am even posing these questions is because those numbers look funny to me (I am no expert just trying to understand that's all)....

                    Exactly 5 HP for every 500 RPM's? Did you round your numbers?

                    I'm not trying to be a jerk just trying to understand where and how you got your numbers?


                    My car is not stock (you can see in my sig) but I am going to run her on a dyno this weekend. I'll post my results (I have a 3" exhaust).

                    [ October 01, 2004, 01:18 PM: Message edited by: Linxs ]
                    Patrick<br />Sick Sixx Member<br /><b>97 Mystic Teal Camaro</b><br />425RWHP @14PSI<br />Old setup:<br />330RWHP @7PSI 13.9 @ 106.6 <a href=\"http://www.fullthrottlev6.com/forums/vbgarage.php?do=view&id=4\" target=\"_blank\">Mods</a>

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                    • #55
                      the numbers are just to be used as an exmple to try and elaborate on exactly what I am trying to say. Sometimes actualy showing some exampled works a lot better then talking till your blue in the face.

                      The dyno I am sure WILL show you that you gained HP, but the question is where did you gain it and where did you lose it. If you could dyno with the stock diamiter and then the 3 inch and place it side by side it would look a lot like the numbers above. It shows you what RPM's your motor needs to be running to actualy make power.

                      I thik that Kbeezy is just stuck on the idea of "it showed more HP so it must me faster" which I hope that I have shown everyone is not always the case at all.
                      1996 Silver camaro Z28. M6,<br />12 bolt, 4.11\'s, posi, Rear cover, Spec stage 2, loudmouth, more <a href=\"http://home.mainstreamtopics.com/?index=3&module=1\" target=\"_blank\">http://home.mainstreamtopics.com/?index=3&module=1</a> &lt;Mods, Pics & more <a href=\"http://home.mainstreamtopics.com/?index=3&module=2\" target=\"_blank\">http://home.mainstreamtopics.com/?index=3&module=2</a> &lt;Fbody Tech Articals

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                      • #56
                        Originally posted by shortdog273:
                        When I had a 3" exhaust on the V6 bird I had, it didn't hurt my 1/4 times at all. But, I also upgraded to a 3" exhaust because I started spraying it also. ;)
                        This statement here should have put an end to all the bickering and help him make a decision as well. It all depends on how far he's gonna go with his mods. If one day he plans on spray, an engine buildup, turbo, etc. he should go with 3". If all he's gonna do is intake, exhaust, and a couple of other bolt-ons then stick with the 2.5". 'Nuff said....

                        Personally, I love my 3" setup. I just switched to a Hooker muffler with dual/dual tips, and the look and sound of it is pure sweetness.
                        2000 3.8L Firebird, Silver Metallic<br /><br />\"Yes, London. You know, fish, chips, cup o\' tea, bad food, worse weather, Mary f***in\' Poppins, London!!\"

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                        • #57
                          The only end to this depate is what someone mentioned earlyier, and i don't have the money to do it. Go out and buy something like a dyno max exhaust system that comes with 2.5 or 2.75 or 3 inch pipes, and one by one dyno them and stock. This way you are using the same companys muffler every time and the same type of bends and piping, and then there will be evidence to show who is right.
                          2002 M5 camaro- VTR CAI, custom cat-back exhaust, battery compacitor, pullie, lowering springs, 32mm sway bar, cross-drilled slotted rotars. 1-10\" L7 in cubby.

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                          • #58
                            remember when the rumbler just came out and they dynoed with a cutout and with it, and the rumbler showed a gain in horses over the cutout
                            ever wonder why?
                            97 polo metallic green v6<br /><a href=\"http://www.cardomain.com/id/tdaddyz\" target=\"_blank\">My Car</a>

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                            • #59
                              The main thing that I wanted everyone to learn here is that conventional thinking is not always 100% correct. It's unfortunete that along the way i met with such resistence and from that 1 high resistence many people followed. I hope that some of you, even one of you looks through this post and desides to challenge tradition a little bit. Maybe then some of you can actualy use your own minds to make your choices and plans for exhaust and can fell really good about it when your done knowing that it was all about you. [img]smile.gif[/img]
                              1996 Silver camaro Z28. M6,<br />12 bolt, 4.11\'s, posi, Rear cover, Spec stage 2, loudmouth, more <a href=\"http://home.mainstreamtopics.com/?index=3&module=1\" target=\"_blank\">http://home.mainstreamtopics.com/?index=3&module=1</a> &lt;Mods, Pics & more <a href=\"http://home.mainstreamtopics.com/?index=3&module=2\" target=\"_blank\">http://home.mainstreamtopics.com/?index=3&module=2</a> &lt;Fbody Tech Articals

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                              • #60
                                Hello All,

                                Harlan asked me to view this post and share my
                                thoughts.

                                Initially I was given bits and pieces of this
                                thread via e-mail, but now reading the entire
                                story I'm able to give better judgement on the
                                topic.

                                First off, this thread is so far gone, it's probably
                                not my place to interfere and there are so many
                                opinions over fact, I'm not so sure I want to
                                get too deep into this.

                                For what it's worth, everyone has a valid point
                                to a certain extent.

                                One thing everyone fails to realize is the 3"
                                pipe IS too big for the 3.8L displacement.

                                What is happening is, the frontal surface area of
                                the catalytic converter creates a backpressure
                                (resistance of flow) which causes a reduction
                                in power.

                                This is due to a high pressure value residing in
                                the exhaust system.

                                By increasing the surface area of the catalytic
                                internals, the exhaust gas has more area to flow
                                through which allows the pressure in the exhaust
                                system to drop.

                                This is why you are seeing a modest increase in
                                horsepower.

                                If the pressure in the exhaust is lower than the
                                pressure in the manifold and cylinder, the air and
                                fuel charge will move downstream at higher velocities
                                according to the pressure differential.

                                If you were to install a tuned performance exhaust
                                system which consisted of a high flow catalytic
                                (let's say 800 CFM) with a 2 inch diameter pipe,
                                the pressure before and after the catalytic would
                                be less because the smaller diameter pipe will
                                increase the gas flow velocity.

                                With a catback system that is properly sized and
                                tuned, you would allow the power band to stay
                                relatively stable while augmenting the power across
                                the entire range.

                                In addition, you'd see more than 8 HP with tuning.

                                If you don't understand pressure differential with
                                fluid/gas in a pipe, have a read on Bernoulli's Principle.

                                http://www.mste.uiuc.edu/davea/aviat...Principle.html

                                You would find without a doubt that installing
                                a higher flow catalytic (800 CFM+), or removing it totally
                                while installing the correct length and diameter
                                intermediate pipes will see a gain over a 3" inch
                                pipe and 3" cat.

                                This all has to do with, pipe volume (velocity)
                                resonance and pulse tuning using valve timing.

                                EDIT: The muffler flow also has the very same impact
                                on the exhaust system internal pressure.

                                More flow = more power.

                                Short pipe, large diameter = top end resonance, High RPM
                                Long pipe, small diameter = low end resonance, Low RPM

                                [ October 02, 2004, 05:34 PM: Message edited by: Adrenaline_Z ]
                                Welcome to the Internet where everyone\'s a mechanic and has a 10 second car.<br /> <a href=\"http://www.gmthunder.com\" target=\"_blank\">http://www.gmthunder.com</a> <br /> <a href=\"http://www.rudyhelds.com/Customer_Rides/80_Camaro_Z28.htm\" target=\"_blank\">http://www.rudyhelds.com/Customer_Rides/80_Camaro_Z28.htm</a> <br />When the green flag drops, all the bull**** stops.

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