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Re: New Kohler engine coming

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  • Barry McHaine
    andy_asberry wrote: I spoke with a Kohler rep this week. There will be a 31hp Aegis engine available soon (no date). 115# dry weight including radiator. PTO
    Message 1 of 8 , Jan 31, 2005
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      andy_asberry wrote:
      I spoke with a Kohler rep this week. There will be a 31hp Aegis
      engine available soon (no date). 115# dry weight including radiator.
      PTO thrust bearing. High inertia flywheel (read HEAVY). Oil bath air
      cleaner. Belt driven radiator fan. Seems like several areas for
      possible weight reduction.

      *I'm always baffled when looking at ultralight engines, as to why
      they seem to use heavy, small diameter flywheels. Forgotten long ago
      how to do the math, but a larger but lighter flywheel could be
      fairly easily made from decent ground plate, and to save sweat a
      laser-cutting fabrication shop could profile one out with minimal
      distortion from heat. If faced with this problem on an engine with
      plenty of clearance around the flywheel, I'd machine a stack of dead
      weight away from the centre and add it in the form of a bolted or
      welded outer annular ring, cut from 1/4" plate or similar. If you
      were really smart you could shrink it on like a starter ring gear.

      Ever looked at the flywheel on a 912? No wonder the 'S' high
      compression version is so rough. We've no requirement for rapid pick
      up or changes in engine speed, quite the reverse in fact, so you'd
      expect the designer to go big, thin and light on the flywheel surely?

      Would need checking out for burst speed though, probably by checking
      out the centrifugal stresses in the material, and maybe getting a
      spare or reject one pull-tested to destruction?

      Kev A
      UK
    • JERRY
      ... Your idea moving the weight farther out and lightening the center might work to save weight. My stock Kohler flywheel is actually minimal at the center and
      Message 2 of 8 , Feb 2, 2005
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        >
        >*I'm always baffled when looking at ultralight engines, as to why
        >they seem to use heavy, small diameter flywheels. Forgotten long ago
        >how to do the math, but a larger but lighter flywheel could be
        >fairly easily made from decent ground plate, and to save sweat a
        >laser-cutting fabrication shop could profile one out with minimal
        >distortion from heat. If faced with this problem on an engine with
        >plenty of clearance around the flywheel, I'd machine a stack of dead
        >weight away from the centre and add it in the form of a bolted or
        >welded outer annular ring, cut from 1/4" plate or similar. If you
        >were really smart you could shrink it on like a starter ring gear.
        >
        >Ever looked at the flywheel on a 912? No wonder the 'S' high
        >compression version is so rough. We've no requirement for rapid pick
        >up or changes in engine speed, quite the reverse in fact, so you'd
        >expect the designer to go big, thin and light on the flywheel surely?
        >
        >Would need checking out for burst speed though, probably by checking
        >out the centrifugal stresses in the material, and maybe getting a
        >spare or reject one pull-tested to destruction?
        >
        >Kev A
        >UK
        >

        Your idea moving the weight farther out and lightening the center might
        work to save weight. My stock Kohler flywheel is actually minimal at the
        center and has a lot of weight at the outer edge.

        For direct drive I think you could get by without a flywheel at all, and
        save a bunch of weight. R.S. Hoover on the AirVW Yahoo group wrote:

        "As a point of interest, AIRCRAFT engines that attach the prop
        directly to the crankshaft do not require a flywheel. That
        requirement of the Otto engine cycle is fulfilled by the propeller,
        which thanks to its longer moment, at cruise speed will have
        several times the inertial-mass of even the heaviest flywheel."

        I think I even have somewhere the formula he provided to calculate it.

        For my 25 hp Kohler I'm thinking of getting one of the hot-rod steel
        flywheels and just use the center piece to bolt my prop hub adapter to.
        Then bolt on a minimal aluminum plate to mount the ignition magnet to so I
        can keep the stock ignition system.

        With a reduction drive you probably would need a flywheel, but I don't know
        that for sure. For engines like the Briggs and Kohler it might be better to
        run the reduction drive from the flywheel end, if there was away to mount it.

        Regards,
        Jerry Booker
      • andy_asberry
        I see a lot of drives from the flywheel end. Is there a reason for this other than changing the direction of rotation of the prop? The manufacturers designed
        Message 3 of 8 , Feb 2, 2005
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          I see a lot of drives from the flywheel end. Is there a reason for
          this other than changing the direction of rotation of the prop? The
          manufacturers designed the PTO end bearing to handle the radial loads
          of belt or chain drives. I'm not sure the flywheel end bearing is so
          designed.

          I wonder if Mr. Hoover would agree also that a flywheel is not needed
          on a PSRU since the prop inertia/mass is several times a flywheel. It
          seems to me we only need to equal the flywheel effect to have a
          smooth engine.

          --- In Small4-strokeEngines@yahoogroups.com, JERRY <jerbook@m...>
          wrote:
          >
          > Your idea moving the weight farther out and lightening the center
          might
          > work to save weight. My stock Kohler flywheel is actually minimal
          at the
          > center and has a lot of weight at the outer edge.
          >
          > For direct drive I think you could get by without a flywheel at
          all, and
          > save a bunch of weight. R.S. Hoover on the AirVW Yahoo group wrote:
          >
          > "As a point of interest, AIRCRAFT engines that attach the prop
          > directly to the crankshaft do not require a flywheel. That
          > requirement of the Otto engine cycle is fulfilled by the propeller,
          > which thanks to its longer moment, at cruise speed will have
          > several times the inertial-mass of even the heaviest flywheel."
          >
          > I think I even have somewhere the formula he provided to calculate
          it.
          >
          > For my 25 hp Kohler I'm thinking of getting one of the hot-rod steel
          > flywheels and just use the center piece to bolt my prop hub adapter
          to.
          > Then bolt on a minimal aluminum plate to mount the ignition magnet
          to so I
          > can keep the stock ignition system.
          >
          > With a reduction drive you probably would need a flywheel, but I
          don't know
          > that for sure. For engines like the Briggs and Kohler it might be
          better to
          > run the reduction drive from the flywheel end, if there was away to
          mount it.
          >
          > Regards,
          > Jerry Booker
        • clairco2000
          On the subject of flywheels and their environment; There is a few good reasons to retain the stock heavy cast iron anvil that sits on the front of the engine.
          Message 4 of 8 , Feb 2, 2005
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            On the subject of flywheels and their environment;
            There is a few good reasons to retain the stock heavy cast iron
            anvil that sits on the front of the engine. First is the handy
            tapered shaft up there is not subjected to the mayhem possible when a
            prop on the other end is constantly banging against a flat pin. Of
            course there are fixes for that but why not just use the flywheel to
            mount the prop and be done with it. The heavy center will easily
            mount a modest flange.
            Second is the problem of the moment of vibration that occurs when
            the prop is on the opposite end of the crank. A prop is not a
            flywheel. Props do interesting things out on the end of a shaft. An
            industrial engine is almost never exposed to this regime and may rebel
            after so many crank flexes and free itself. With a prop next to the
            flywheel and a single crankpin vee twin the compound vibration is
            minimal.
            Third is the fact that ignition and alternator on most of the
            twins are right there on the flywheel and a work around to change that
            is expensive and time consuming. Just live with the extra weight and
            suffer the smooth running, easy starting stock engine.
            Fourth is not to worry about the thrust bearing. I have not yet
            detected a a thousandth of difference in end play after ten hours of
            full throttle testing but I will keep at it. But for the fearful an
            accessory bearing can be mounted on the free end of the crank and made
            to bear on the casting there.
            Finally a downside. On a tractor setup your front end will be
            blunt if your flange is reasonable ( 2 in. or less ) on a pusher the
            airflow is not stock and problems might result from blowing hot pipes
            back into the cooling fins.
            To see my crude testing setup look to photo files named "test"
          • captain_jims
            One reason I enjoy these forums is that you can always learn something new. Now we have the moment of vibration . Here I have been stuck in the world of
            Message 5 of 8 , Feb 3, 2005
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              One reason I enjoy these forums is that you can always learn
              something new. Now we have the "moment of vibration".

              Here I have been stuck in the world of "moment of inertia" and "mode
              of vibration" but those terms are getting old. Can't wait to hear
              the definition for "moment of vibration".

              ps. Google did not provide a definition.

              Jim

              --- In Small4-strokeEngines@yahoogroups.com, "clairco2000"
              <clairco@r...> wrote:
              >
              > On the subject of flywheels and their environment;
              > There is a few good reasons to retain the stock heavy cast iron
              > anvil that sits on the front of the engine. First is the handy
              > tapered shaft up there is not subjected to the mayhem possible
              when a
              > prop on the other end is constantly banging against a flat pin. Of
              > course there are fixes for that but why not just use the flywheel
              to
              > mount the prop and be done with it. The heavy center will easily
              > mount a modest flange.
              > Second is the problem of the moment of vibration that occurs
              when
              > the prop is on the opposite end of the crank. A prop is not a
              > flywheel. Props do interesting things out on the end of a shaft.
              An
              > industrial engine is almost never exposed to this regime and may
              rebel
              > after so many crank flexes and free itself. With a prop next to
              the
              > flywheel and a single crankpin vee twin the compound vibration is
              > minimal.
              > Third is the fact that ignition and alternator on most of the
              > twins are right there on the flywheel and a work around to change
              that
              > is expensive and time consuming. Just live with the extra weight
              and
              > suffer the smooth running, easy starting stock engine.
              > Fourth is not to worry about the thrust bearing. I have not
              yet
              > detected a a thousandth of difference in end play after ten hours
              of
              > full throttle testing but I will keep at it. But for the fearful
              an
              > accessory bearing can be mounted on the free end of the crank and
              made
              > to bear on the casting there.
              > Finally a downside. On a tractor setup your front end will be
              > blunt if your flange is reasonable ( 2 in. or less ) on a pusher
              the
              > airflow is not stock and problems might result from blowing hot
              pipes
              > back into the cooling fins.
              > To see my crude testing setup look to photo files named "test"
            • nutnbolt2002
              Can anyone tell me the taper that the briggs has on some of there engines? PTO end, is it 10-1? Thanks Ted Anyone --- In
              Message 6 of 8 , Feb 5, 2005
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                Can anyone tell me the taper that the briggs has on some of there
                engines? PTO end, is it 10-1? Thanks Ted




                Anyone --- In Small4-strokeEngines@yahoogroups.com, "captain_jims"
                <captain_jims@y...> wrote:
                >
                > One reason I enjoy these forums is that you can always learn
                > something new. Now we have the "moment of vibration".
                >
                > Here I have been stuck in the world of "moment of inertia" and "mode
                > of vibration" but those terms are getting old. Can't wait to hear
                > the definition for "moment of vibration".
                >
                > ps. Google did not provide a definition.
                >
                > Jim
                >
                > --- In Small4-strokeEngines@yahoogroups.com, "clairco2000"
                > <clairco@r...> wrote:
                > >
                > > On the subject of flywheels and their environment;
                > > There is a few good reasons to retain the stock heavy cast iron
                > > anvil that sits on the front of the engine. First is the handy
                > > tapered shaft up there is not subjected to the mayhem possible
                > when a
                > > prop on the other end is constantly banging against a flat pin. Of
                > > course there are fixes for that but why not just use the flywheel
                > to
                > > mount the prop and be done with it. The heavy center will easily
                > > mount a modest flange.
                > > Second is the problem of the moment of vibration that occurs
                > when
                > > the prop is on the opposite end of the crank. A prop is not a
                > > flywheel. Props do interesting things out on the end of a shaft.
                > An
                > > industrial engine is almost never exposed to this regime and may
                > rebel
                > > after so many crank flexes and free itself. With a prop next to
                > the
                > > flywheel and a single crankpin vee twin the compound vibration is
                > > minimal.
                > > Third is the fact that ignition and alternator on most of the
                > > twins are right there on the flywheel and a work around to change
                > that
                > > is expensive and time consuming. Just live with the extra weight
                > and
                > > suffer the smooth running, easy starting stock engine.
                > > Fourth is not to worry about the thrust bearing. I have not
                > yet
                > > detected a a thousandth of difference in end play after ten hours
                > of
                > > full throttle testing but I will keep at it. But for the fearful
                > an
                > > accessory bearing can be mounted on the free end of the crank and
                > made
                > > to bear on the casting there.
                > > Finally a downside. On a tractor setup your front end will be
                > > blunt if your flange is reasonable ( 2 in. or less ) on a pusher
                > the
                > > airflow is not stock and problems might result from blowing hot
                > pipes
                > > back into the cooling fins.
                > > To see my crude testing setup look to photo files named "test"
              • jeremy_harris_uk
                ... listed as 2.25 taper per foot , which seems a bit of an odd size to me. Jeremy
                Message 7 of 8 , Feb 5, 2005
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                  --- In Small4-strokeEngines@yahoogroups.com, "nutnbolt2002"
                  <nutnbolt2002@y...> wrote:
                  >
                  > Can anyone tell me the taper that the briggs has on some of there
                  > engines? PTO end, is it 10-1? Thanks Ted
                  >
                  >According to the AutoCad drawing I have for the Vanguard it's
                  listed as "2.25 taper per foot", which seems a bit of an odd size to
                  me.

                  Jeremy
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