Announcement

Collapse
No announcement yet.

Quite I-N-C-R-E-D-I-B-L-E - Stock AFM replaced without mapping.

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #46
    Some comment which i couldn't do yesterday: the A/F is quite similar to the stock AFM, the LEAN message comes up when the gas pedal is released.
    On the two and a half WOT runs the A/F goes in the 12.5 / 13.55 range from 2/3000 rpms and 7000 rpms.
    power is nothing without drift

    Comment


    • #47
      Update.

      Originally posted by france320isco View Post
      Some comment which i couldn't do yesterday: the A/F is quite similar to the stock AFM, the LEAN message comes up when the gas pedal is released.
      On the two and a half WOT runs the A/F goes in the 12.5 / 13.55 range from 2/3000 rpms and 7000 rpms.
      The 4.3V diode has been replaced with a 4.7V one.
      A 2.3KOhm resistor has been put in parallel to the Coolant Temperature Sensor to solve the cold starting issues (the car idles right, but is a little tricky to drive).
      So far, until now, the 605 MAF, the 4.7V diode and the 2.3 KOhm resistor is the cheapest way to achieve a smooth and running engine.

      I've finished some minor map modifications to attain the best A/F ratio.

      If you are interested in the transformation and getting the map for free, drop me an e-mail @ [email protected].

      This is france320isco, signing off. :blues: :blues: :blues: :blues:
      power is nothing without drift

      Comment


      • #48
        Missed all the updates until just now!
        Good stuff even if it isnt about gaining torque or power to you.

        Regarding your analogy of a 2l bottle: it is possible to get a cylinder filling of more than 100% as at higher revs you actually get into a region where the air speed is close to the speed of sound and the compressibility of air starts to play a role. pressure pulses in the intake tract are caused by the valves closing: these are reflected and travel back towards the intake trumpet. There they are reflected yet again and travel forth towards the intake valve. When they reach the intake valve just at its time of opening the cylinder filling is increased.

        This clip shows how the injected fuel actually bounces back off the valves and travels back past the injector:http://www.youtube.com/watch?v=oFm0m6sbOi8

        There's also a video that shows an S14 (or not) where you can actually see the fuel mist hovering above the trumpets clearly indicating the reflection point.
        Last edited by hardtailer; 12-23-2011, 10:40 AM.

        Comment


        • #49
          Originally posted by hardtailer View Post
          Missed all the updates until just now!
          Good stuff even if it isnt about gaining torque or power to you.

          Regarding your analogy of a 2l bottle: it is possible to get a cylinder filling of more than 100% as at higher revs you actually get into a region where the air speed is close to the speed of sound and the compressibility of air starts to play a role. pressure pulses in the intake tract are caused by the valves closing: these are reflected and travel back towards the intake trumpet. There they are reflected yet again and travel forth towards the intake valve. When they reach the intake valve just at its time of opening the cylinder filling is increased.

          This clip shows how the injected fuel actually bounces back off the valves and travels back past the injector:http://www.youtube.com/watch?v=oFm0m6sbOi8

          There's also a video that shows an S14 (or not) where you can actually see the fuel mist hovering above the trumpets clearly indicating the reflection point.
          Merry Christmas!
          I can mention the experimental formula nxL=C/8 (how to design L and C to attain the best filling at a given rpm value n) where L is the lenght of the intake path, C the cross section and n is the rpm.
          This formula means that you can't get a better filling everywhere in the rpm range which is (if you get also the correct a/f ratio) more torque by simply redesigning the L and C parameters.
          It is also true that next to the intake ports and even more in the valve region the air can get easily to the speed of sound due to the intake path restrictions (valve / valve seat), but when it happens it slows down greatly, lowering the airflow (chocked flow condition) and this is generally an unwanted.
          So, what you see in the video, is the effect of the correct L/C design to help the filling (true) at a given and only rpm range.
          With the Variable Valve Systems (VANOS, VTEC, VVT-I, VARIOCAM, etc) and the variable geometry, exists just to overcome the nxL=C/8 limitations.
          The filling ratio at 100% of load is usually 0,9 @ 4000/4500 rpms and decrease rapidly increasing rpms (while reaching the filling limit).
          @ 50% of load it is never avove 0,5 / 0,6.

          Now, maybe, in some F1 application (without turbo's or VVS systems) they can get a 100% and more (like an extremely heavy ram effect or something http://en.wikipedia.org/wiki/Ram-air_intake) @ some rpms range.

          Nice video, heavy porn sound!
          Last edited by france320isco; 12-26-2011, 04:07 AM.
          power is nothing without drift

          Comment


          • #50
            Found this:

            http://www.epi-eng.com/piston_engine...efficiency.htm

            For contemporary naturally-aspirated, two-valve-per-cylinder, pushrod-engine technology, a VE over 95% is excellent, and 100% is achievable, but quite difficult. Only the best of the best can reach 110%, and that is by means of extremely specialized development of the complex system comprised of the intake passages, combustion chambers, exhaust passages and valve system components. The practical limit for normally-aspirated engines, typically DOHC layout with four or more valves per cylinder, is about 115%, which can only be achieved under the most highly-developed conditions, with precise intake and exhaust passage tuning.


            Now, to suck air into the cylinders you must have a pressure less than the atmosferic (1 atm) in the combustion chamber. This means a pressure gradient along the intake path which values can't never get to 1 atm or the air will stop flowing from the outside environment immediately. This gradient of less of 1 atm pressure values must develop during the intake stroke to guarantee the air flowing and it is due to the piston when it moves down.
            To have 115% of air in the combustion chamber means developing a pressure greater than 1 atm when the piston is at BDC and the end of the intake stroke which means that the air continues flowing in even if the intake stroke is over and compress itself a little.
            Now this is a well known effect to improve the volumetric efficiency (ram effect) which relates to the experimental formula nxL=C/8 that i reported above.

            Another interesting link:
            http://en.wikipedia.org/wiki/Cylinder_head_porting.
            power is nothing without drift

            Comment


            • #51
              Update - Important

              Just an update about the setup and the A/F ratio when cold.

              A few months ago (sorry for the delay) i discovered that the poor driveability in cold condition was due to the filter employed, so if you ever were going to install this sensor, don't use it. Use any other open intake filter, also the stock one (with che stock airbox) is OK.

              I couldn't immagine that an air filter like that would have been so chocking for the intake!.

              The 5V diode (or greater than 5V, it's up to your knowledge about electronics ) installed in parallel to the sensor output, helps, but it is not so important: the ricochet effect of the ECU when reading the map, for the output approaching 5V, isn't so hard on a/f the ratio.

              Bye.
              Last edited by france320isco; 09-05-2012, 09:18 PM.
              power is nothing without drift

              Comment

              Working...
              X