ProComp/Speedmaster aluminum heads

Mopar Racers Forum

  1. Cuda416

    Cuda416 Well-Known Member

    Messages:
    577
    Likes Received:
    242
    Joined:
    Jun 12, 2014
    Location:
    South, TX
    Local Time:
    8:32 AM
    Temperature doesn't affect pressure, it affects density. Cool are is more dense than warm air.

    The analogy of tires and balloons is flawed because the amount of air in the space hasn't changed, only the density. Now, with the reduced density, there is less volume, and less volume in a given space equals less pressure against the inside of the container it's in. This is why newer cars have nitrogen in the tires, it's less affected by temp changes and so the density isn't as affected and tires maintain a more equal pressure with changes in weather.

    With engines, if it's normally aspirated, we tend to do things to try and keep the air cool to get a more dense intake charge. Hood scoops, cold air boxes, air gap intakes etc.

    The other ways to increase the "density" is to use mechanical means, blowers, turbos, or chemical means, nitrous oxide etc.

    The "cooling" of the heads is not going to matter since you're not "cooling" a flame. The burn is the burn and whatever made it into the chamber, is there to stay, until the valves open and let it out.


    Science.... :)
     
    • Agree Agree x 2
    • Like Like x 1
    • Thanks! Thanks! x 1
    • Mopar Sam

      Mopar Sam Well Fed Member

      Messages:
      714
      Likes Received:
      896
      Joined:
      Jul 18, 2008
      Location:
      Indiana
      Local Time:
      10:32 AM
      Cuda416, Good post.
       
      • Agree Agree x 2
      • Thanks! Thanks! x 1
      • 318willrun

        318willrun Roadkill '80 D150

        Messages:
        12,822
        Likes Received:
        12808
        Joined:
        Sep 13, 2013
        Location:
        I'm here
        Local Time:
        9:32 AM
        Agree with Sam, good post. I had considered fresh/cool air and hood scoops, etc. My way of thinking is once the valve is closed, the air in the cylinder, if ran cooler at that point (valve closed) would be less pressure. In other words, as the piston approaches the compression stroke, the cooler head would reduce density (like the tire) vs a hotter iron head. Certainly some flaw to the thought, but maybe a little truth to it as well....
         
        Last edited: Nov 8, 2019
      • Phreakish

        Phreakish Well-Known Member

        Messages:
        575
        Likes Received:
        212
        Joined:
        May 28, 2015
        Location:
        N. Idaho
        Local Time:
        7:32 AM
        Except that if it's cooler in the chamber, it was cooler before the chamber - which would mean more dense, which means more air/fuel in the chamber, which means more power.

        I get what you were trying to say/ask, but it just doesn't/can't happen that way because the incoming air is almost always cooler than the engine induction components themselves, and so the charge mixture can only increase in temperature once it's through the manifold...

        The physics of combustion mean that nearly all heat transfer is from the burning gasses themselves, because until the mixture ignites there's not enough convection for the incoming mixture to have any effect on the engine components, or for the engine components to have an effect on the mixture.
         
        • Like Like x 2
        • Agree Agree x 1
        • 318willrun

          318willrun Roadkill '80 D150

          Messages:
          12,822
          Likes Received:
          12808
          Joined:
          Sep 13, 2013
          Location:
          I'm here
          Local Time:
          9:32 AM
          I guess this is the deepest I've ever thought into the theory as I've always ran iron heads on my old rides. I'm glad this conversation has happened, because I see my thoughts with aluminum heads had holes in it. :D Do not mistake this as I opposed aluminum heads, because I do not and may run some soon in my own future.

          thanks to all that took the time to work through this conversation :)
           
          • Like Like x 1
          • Phreakish

            Phreakish Well-Known Member

            Messages:
            575
            Likes Received:
            212
            Joined:
            May 28, 2015
            Location:
            N. Idaho
            Local Time:
            7:32 AM
            I'm no expert at all, and will also run alum heads in the future, but the whole iron/alum myths have always bugged me because so many things get repeated without backup info.

            Combustion is complicated, and alum vs iron definitely has an impact but it seems to be in different ways than 'common sense' would seem to suggest. I'm still digging through the occasional engineering or research paper where I can - always fascinating stuff to find.
             
            • Agree Agree x 2
            • 318willrun

              318willrun Roadkill '80 D150

              Messages:
              12,822
              Likes Received:
              12808
              Joined:
              Sep 13, 2013
              Location:
              I'm here
              Local Time:
              9:32 AM
              100% agree.
               
            • Phreakish

              Phreakish Well-Known Member

              Messages:
              575
              Likes Received:
              212
              Joined:
              May 28, 2015
              Location:
              N. Idaho
              Local Time:
              7:32 AM
              http://web.mit.edu/2.61/www/Lecture notes/Lec. 18 Heat transf.pdf

              Here's at least one of the items I found which I've found interesting. Note that the aluminum head ran cooler, but that both materials remain below ignition temperature. That the spark plug tip and the exhaust valve are the hottest items in the chamber and so likely the greatest contributors to pre-ignition.

              Also, the lower running temp of the alum cylinder head suggests that the reduced thermal resistance doesn't result in more heat extracted but instead in a lower surface temperature of the combustion chamber. At least that's my take-away..
               
              • Thanks! Thanks! x 2
              • yellow rose

                yellow rose Doctor of Thinkology.

                Messages:
                19,973
                Likes Received:
                16080
                Joined:
                Jun 19, 2015
                Location:
                Living on the razors edge
                Local Time:
                7:32 AM
                And let's remember that an IC engine, in its best form is about 28-30% efficient. You can get a couple of points better but its costly.

                The biggest loss of heat (power) is the exhaust. I remember my first data logger. I forget the brand but I had EGT's and all the rest. At that time...the sampling rate was 5 times a second!!! 5 times a second. At the time that was pretty good. A few short years later a sampling rate of 100 times a second was easy.

                I mention this because it's relevant. This is because if you think about it, if you divide a second into five segments, and then understand that once you sample the data there is a huge gap in time until the next sample. Let me see if I can show this in text.

                Let's make a dot the sample point and a dash the time in between the sample points. Sooooo...

                .----.----.----.----.

                That is five samples per second. What do you see??? Huge gaps between samples. That is all time the computer isn't getting information.

                Now think about sampling 100 times a second and how much less time you have between samples. I'm looking at a data logger that can sample two hundred times a second.

                My car at that time was a 9.80ish car. At 5 samples a second you only get 50 samples per run! That ain't much. If it was sampling 100 times per second, you'd get 1000 data points per run.

                I said all that to say this:

                The rate of change of almost any function you can measure happens so quick that transient response time is critical. IOW's things happen so fast that one system can't overcome another. As in, the rate of temperature change happens so quickly that even the head can't reject the heat fast enough to affect detonation resistance. I hope that makes sense.

                Another thing I learned when I started data logging was even with relatively quick sampling rates, some other limits were expose. Such as transient response time of the EGT probes. Those damn things respond so slow it's almost useless to use them for anything other that cylinder to cylinder balance, and that can take you right down a rabbit hole all by itself. You make changes based on those slow buggers and you'll be sorry.

                I also learned that when running alcohol (it happens on gasoline too but you have to be real rich to see it) if you get too far to the rich side the exhaust gas temp will go through the roof. I think the highest EGT's I'd seen on my junk was like 1660 or so. The headers should have melted off the car, the plug should have been missing it's ground wire and much more.

                What happens when you get too rich the fuel doesn't get burned before the exhaust valve opens and that combustion continues into the exhaust pipe. It makes you think you are lean but you are pig rich and adding fuel makes it worse. That's just one more way a measuring tool can screw you if you aren't thinking about the entire process.

                Slow ignition timing does the same thing.

                Funny story. A customer had a friend who was running an ex Pro Stock Truck in Comp Eliminator. He called me from the pits and said my buddy has EGT's that are going through the roof and he's deathly afraid to lean it out as he can't afford to kill his engine.

                I forget what engine it was but it was a Dodge. Anyway, I said what does he have for timing and jets? The timing was 24 degrees total and I forget the jets, but they were way too big. I said tell him to drop 4 jet sizes and put the total timing to 30 degrees. Make a pass and check the EGT's.

                He was scared but he did it. Temps started dropping like a rock. He eventually got to 32 total and ended up dropping 8 jet sizes.

                You can get real crossed up in a New York second of you ain't careful.
                 
                Last edited: Nov 8, 2019
                • Like Like x 1
                • Thanks! Thanks! x 1
                • j par

                  j par Well-hung Member

                  Messages:
                  20,049
                  Likes Received:
                  9853
                  Joined:
                  Jul 2, 2014
                  Location:
                  Portland Oregon
                  Local Time:
                  7:32 AM
                  Holy AJ..!!...
                   
                  • Agree Agree x 1
                  • j par

                    j par Well-hung Member

                    Messages:
                    20,049
                    Likes Received:
                    9853
                    Joined:
                    Jul 2, 2014
                    Location:
                    Portland Oregon
                    Local Time:
                    7:32 AM
                    I had a question about quench...
                     
                  • 318willrun

                    318willrun Roadkill '80 D150

                    Messages:
                    12,822
                    Likes Received:
                    12808
                    Joined:
                    Sep 13, 2013
                    Location:
                    I'm here
                    Local Time:
                    9:32 AM
                    LOL... sorry, I had to borrow your thread for 3 pages. It was healthy for my brain. Here, I'll return it now... :)
                     
                  • fishmens67

                    fishmens67 Well-Known Member

                    Messages:
                    6,828
                    Likes Received:
                    3948
                    Joined:
                    Nov 10, 2012
                    Location:
                    idaho
                    Local Time:
                    9:32 AM
                    and
                     
                    • Thanks! Thanks! x 1
                    • oldkimmer

                      oldkimmer FABO Gold Member FABO Gold Member

                      Messages:
                      13,626
                      Likes Received:
                      3201
                      Joined:
                      Nov 11, 2006
                      Location:
                      Kindersley, Saskatchewan,
                      Local Time:
                      9:32 AM
                      Dam, it almost looks like I should be giving my cheap CNC flimsy Procomp heads away b4 they destroy my short block. They will be flopping around like a chicken with its head cut off. Kim
                       
                      • Like Like x 2
                      • Agree Agree x 1
                      • Disagree Disagree x 1
                      • 318willrun

                        318willrun Roadkill '80 D150

                        Messages:
                        12,822
                        Likes Received:
                        12808
                        Joined:
                        Sep 13, 2013
                        Location:
                        I'm here
                        Local Time:
                        9:32 AM
                        drop one on the floor and it will hit ya in the nogg'n on the rebound! :eek:
                         
                      • j par

                        j par Well-hung Member

                        Messages:
                        20,049
                        Likes Received:
                        9853
                        Joined:
                        Jul 2, 2014
                        Location:
                        Portland Oregon
                        Local Time:
                        7:32 AM
                        Well I remember what it was about when I asked it this morning but 318 has valves that will fly took the discussion off into his own world and now everybody is left wondering what this thread was all about...
                         
                      • 318willrun

                        318willrun Roadkill '80 D150

                        Messages:
                        12,822
                        Likes Received:
                        12808
                        Joined:
                        Sep 13, 2013
                        Location:
                        I'm here
                        Local Time:
                        9:32 AM
                        :eek::eek: I was right on Que !~~ Aluminum heads!!!!
                         
                        • Disagree Disagree x 1
                        • j par

                          j par Well-hung Member

                          Messages:
                          20,049
                          Likes Received:
                          9853
                          Joined:
                          Jul 2, 2014
                          Location:
                          Portland Oregon
                          Local Time:
                          7:32 AM
                          Then you can believe the hype like 318 has valves that will fly and think Promax is going to be better quality...
                          he's had laboratory core test done for evidence..
                           
                        • 318willrun

                          318willrun Roadkill '80 D150

                          Messages:
                          12,822
                          Likes Received:
                          12808
                          Joined:
                          Sep 13, 2013
                          Location:
                          I'm here
                          Local Time:
                          9:32 AM
                          BWAHAHAHAA Jpeghasrubberheads!!!!!!! :D :D
                           
                          • Disagree Disagree x 1
                          • j par

                            j par Well-hung Member

                            Messages:
                            20,049
                            Likes Received:
                            9853
                            Joined:
                            Jul 2, 2014
                            Location:
                            Portland Oregon
                            Local Time:
                            7:32 AM
                            It's just spaghetti now forget it....
                            We'll figure things out on my own I usually do...
                             
                            • Like Like x 1
                            • 318willrun

                              318willrun Roadkill '80 D150

                              Messages:
                              12,822
                              Likes Received:
                              12808
                              Joined:
                              Sep 13, 2013
                              Location:
                              I'm here
                              Local Time:
                              9:32 AM
                              why does every thread turn to spaghetti... :(
                               
                            • yellow rose

                              yellow rose Doctor of Thinkology.

                              Messages:
                              19,973
                              Likes Received:
                              16080
                              Joined:
                              Jun 19, 2015
                              Location:
                              Living on the razors edge
                              Local Time:
                              7:32 AM
                              I know it. It's hard to be succinct and still give enough detail to make it cohesive and understandable.
                               
                              • Agree Agree x 1
                              • yellow rose

                                yellow rose Doctor of Thinkology.

                                Messages:
                                19,973
                                Likes Received:
                                16080
                                Joined:
                                Jun 19, 2015
                                Location:
                                Living on the razors edge
                                Local Time:
                                7:32 AM

                                Did you actually ask the question yet? I may have missed that post.
                                 
                                • Like Like x 1
                                • j par

                                  j par Well-hung Member

                                  Messages:
                                  20,049
                                  Likes Received:
                                  9853
                                  Joined:
                                  Jul 2, 2014
                                  Location:
                                  Portland Oregon
                                  Local Time:
                                  7:32 AM
                                  give me a second I'll look back a few pages here it should be the first post or two today since a week ago...
                                  it seems like I can't say anything anymore without 318 turning everything into a fiasco or basically spaghetti...(with ketchup)...
                                   
                                • j par

                                  j par Well-hung Member

                                  Messages:
                                  20,049
                                  Likes Received:
                                  9853
                                  Joined:
                                  Jul 2, 2014
                                  Location:
                                  Portland Oregon
                                  Local Time:
                                  7:32 AM
                                  Here it is again from 6:33am....
                                   
                                1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
                                  By continuing to use this site, you are consenting to our use of cookies.