Loading ...
Sorry, an error occurred while loading the content.

Re: [Small4-strokeEngines] Kohler V-twin or 2A042

Expand Messages
  • Norman Heistand
    The 2 cylinder 4 stroke engines are often used without a redrive. It is a tradeoff of weight, complexity, and thrust. For example, a 1/2VW engine driect drive
    Message 1 of 6 , Mar 1, 2013
    • 0 Attachment
      The 2 cylinder 4 stroke engines are often used without a redrive. It is a tradeoff of weight, complexity, and thrust. For example, a 1/2VW engine driect drive with 37hp does a good job on a draggy ultralight like the Weedhopper. The 1/2VW weighs about 80-85 lbs. A Rotax 277 with a redrive also does a good job with a little less weight.

      With the 2A042 you have 690cc and no real possibility of increasing the displacement. So the best you can do is put on a better carb, raise the compression, etc. A used snowmobile engine with a belt redrive will likely give more power than the Rotax 277. For example a Rotax 377 or Kawasaki 340 will give about 35 hp and more thrust than the 1/2VW. If you really want a 4-stroke, I would recommend the Kohler CH740 which starts out at 27 hp but can easily have the power increased by putting on a Weber type 2 barrel progressive carb. I have my Kohler V-Twin down to 64 lbs (estimated) by replacing the flywheel with a hub, bolting on a front drive adapter shaft, and putting my DC CDI ignition on the power shaft side with a small battery pack. I have compression release valves in the heads so the engine is easy to start by hand propping. All the other extras, original ignition, alternator, blower, shrouding, flywheel, and starter are removed. I believe this will be as light as the Rotax 277 setup and almost as much thrust.

      If you could get the 2A042 down to 64 lbs, and if you could get 32 hp or more from it, the thrust with direct drive might approach the Kohler. However, you are stuck with 690cc versus 740cc and latest technology versus older tech. If you can rig the cog belt redrive and get the weight down to 80-85 lbs you might match the Rotax 277 for thrust, this would do a good job.

      So there you have my recommendation. If you have not yet seen it, take a look at my engine running. Also consider the fact that I have a 35 hp Rotax 377 with belt redrive ready to ship with everything except the propeller for $995 + shipping. And I have a Kohler V-Twin conversion plans CD for $8.99 free shipping. And I would build you a hand prop 64 lbs Kohler all new for $2300.

      http://youtu.be/1IRo6jU8zQE

      Norm Heistand  my .02

      On Thu, Feb 28, 2013 at 2:05 PM, bill_ladd@... <bill.ladd@...> wrote:
       

      Starting an ultralight project and want some feedback on which of these two engines to try - modern industrial V-twin or the 2a042. My preliminary calcs are showing I can get away with just under 100lbs for the powerplant.

      My design is draggy - I'll need a redrive.

      I'm planning on spending a good bit of time with engine development to find optimal thrust. I'm designing a polychain (cogged belt) redrive setup so I can hand prop, that way I can ditch the starter. Perhaps do away with charging entirely and run off a lightweight battery?

      Y'all help me spitball this thing. Real world weights, hand propping experience, magneto/charging/ignition ideas, etc..

      Thanks much!!


    • George Bearden
      Thanks for the great post Norman. ... ... more from it, A thing I notice and wonder about, Your Kohler starts out at 27 hp... but that is at 3600 rpm,
      Message 2 of 6 , Mar 1, 2013
      • 0 Attachment

        Thanks for the great post Norman .

         

        > I would recommend the Kohler CH740 which starts out at 27 hp

        <snip>

        > If you could get the 2A042 down to 64 lbs, and if you could get 32 hp or more from it,

         

        A thing I notice and wonder about, Your Kohler starts out at 27 hp... but that is at 3600 rpm, isn't it? What hp do you get at direct drive rpm after your mods?  Also when we compare to the 2A042 we must consider the hp achieved at the rpm we run the engine, not the peak hp available.

         

      • Norman Heistand
        My engine is perfectly capable of turning more than 3600rpm. When I attach the prop I will be getting near 3600rpm simply because I will select a prop that
        Message 3 of 6 , Mar 1, 2013
        • 0 Attachment
          My engine is perfectly capable of turning more than 3600rpm. When I attach the prop I will be getting near 3600rpm simply because I will select a prop that lets the engine make that rpm and that is the factory recommended maximum rpm. The engine can produce more power at a higher rpm and others have done that, however I am simply being a bit conservative trading off reliability and service life against max power output. The easy and best way for me to measure the power is with a static thrust test using a selected propeller.

          The 2A042 is designed to run a generator and it also is designed for recommended maximum power at 3600rpm using a governor. We remove the governor, but for full power climbing with an ultralight aircraft, I like to target the max power at the 3600rpm. Just like the 1/2VW designs do.

          Norm Heistand  my .02

          On Fri, Mar 1, 2013 at 3:06 PM, George Bearden <gab16@...> wrote:
           

          Thanks for the great post Norman.

           

          > I would recommend the Kohler CH740 which starts out at 27 hp

          <snip>

          > If you could get the 2A042 down to 64 lbs, and if you could get 32 hp or more from it,

           

          A thing I notice and wonder about, Your Kohler starts out at 27 hp... but that is at 3600 rpm, isn't it? What hp do you get at direct drive rpm after your mods?  Also when we compare to the 2A042 we must consider the hp achieved at the rpm we run the engine, not the peak hp available.

           


        • George Bearden
          Oh, I see! So many people run direct drive at or near 3000 rpm I just supposed...
          Message 4 of 6 , Mar 1, 2013
          • 0 Attachment

            Oh, I see! So many people run direct drive at or near 3000 rpm I just supposed...

            >My engine is perfectly capable of turning more than 3600rpm.

          • dagwodzz@bellsouth.net
            Norm, the 3600 RPM is not the redline. The motor peaks out at 3600 to coincide with a generators elec cycles. ... From: Norman Heistand Date: 3/1/2013 3:25:07
            Message 5 of 6 , Mar 1, 2013
            • 0 Attachment
              Norm, the 3600 RPM is not the redline. The motor peaks out at 3600 to coincide with a generators elec cycles.     
               
               
               
               
              -------Original Message-------
               
              Date: 3/1/2013 3:25:07 PM
              Subject: Re: [Small4-strokeEngines] Kohler V-twin or 2A042
               
               

              My engine is perfectly capable of turning more than 3600rpm. When I attach the prop I will be getting near 3600rpm simply because I will select a prop that lets the engine make that rpm and that is the factory recommended maximum rpm. The engine can produce more power at a higher rpm and others have done that, however I am simply being a bit conservative trading off reliability and service life against max power output. The easy and best way for me to measure the power is with a static thrust test using a selected propeller.

              The 2A042 is designed to run a generator and it also is designed for recommended maximum power at 3600rpm using a governor. We remove the governor, but for full power climbing with an ultralight aircraft, I like to target the max power at the 3600rpm. Just like the 1/2VW designs do.

              Norm Heistand  my .02

              On Fri, Mar 1, 2013 at 3:06 PM, George Bearden <gab16@...> wrote:
               

              Thanks for the great post Norman.

               

              > I would recommend the Kohler CH740 which starts out at 27 hp

              <snip>

              > If you could get the 2A042 down to 64 lbs, and if you could get 32 hp or more from it,

               

              A thing I notice and wonder about, Your Kohler starts out at 27 hp... but that is at 3600 rpm, isn't it? What hp do you get at direct drive rpm after your mods?  Also when we compare to the 2A042 we must consider the hp achieved at the rpm we run the engine, not the peak hp available.

               


               
            Your message has been successfully submitted and would be delivered to recipients shortly.