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Re: Vanguard 23 Hp power @ 4000rpm

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  • Kev A
    The stock engine can be revved to 4,200 in the Briggs & Stratton Handbook, this is their limit when used on welding generators, check out the official
    Message 1 of 6 , Jun 2, 2013
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      The stock engine can be revved to 4,200 in the Briggs & Stratton Handbook, this is their limit when used on welding generators, check out the official handbook.

      Mudbuddy limit theirs to 5,200 using an electronic governor but I'd assume they fit a rev kit, which is valve spring packers, an advance stepped key and stronger billet spring caps.

      Fixed ignition on the Briggs is aimed at being able to pull start a 630cc engine, which in a motorcycle would be impossible; however the retard and low compression used to make this possible, damps the performance-hence the pretty cheap upgrades for more power.

      Good power can be had just by bumping compression to 9.5-10:1; you don't do this by skimming the heads, but by swapping the pistons for shallow dish or flat tops, Al Hodge sells them. I cautiously used shallow dished and stock head gaskets, but saw it perk up more with thin head gaskets added later. If building a second engine would use flat tops and stock gaskets.

      More top end comes from either stepped flywheel key, which is all too easy to get wrong way round and retard the ignition, or using 2mm alloy plates to move the coils 8° round advanced. stock is 21°.

      I like Al's roller-tipped alloy rockers to reduce side load on the valves instead of the cheap stamped stock rockers, these give an easy increase in valve lift by being 1.5 ratio instead of 1.1

      Best of all just bolt the carb on off the 61" engine, but open out the inlet elbow to clear the butterflies.

      No overheating, at all, runs too cool in fact, at around 320F on hottest cylinder with the later big fan.

      Cheers

      Kev

      PS if you change the cam like I did add in a heavy duty John Deere starter, stock one won't spin it without the stock cam's decompressor rig.

      PPS don't know what prop pitch is, adjusted it for 4,600rpm static, at 4,800 static got 100kilos/220 pounds thrust but it was too fine once in the air.

      --- In Small4-strokeEngines@yahoogroups.com, "wannibi" <wannibi@...> wrote:
      >
      > Can anyone help with the predicted performance increase/decrease revving the stock vanguard 23 Hp engine to 4000 rpm instead of 3600 rpm. According to the power curves the maximum power is generated at 3600 dropping to a predicted 20 Hp at 4000 rpm extrapolating the power curve.
      >
    • Rick Martin
      Which Briggs engine are we talking about here? ... From: Kev A To: Small4-strokeEngines@yahoogroups.com Sent: Monday, June 03, 2013 01:16 Subject:
      Message 2 of 6 , Jun 3, 2013
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        Which Briggs engine are we talking about here?
         
         
         
         
        ----- Original Message -----
        From: Kev A
        Sent: Monday, June 03, 2013 01:16
        Subject: [Small4-strokeEngines] Re: Vanguard 23 Hp power @ 4000rpm

         

        The stock engine can be revved to 4,200 in the Briggs & Stratton Handbook, this is their limit when used on welding generators, check out the official handbook.

        Mudbuddy limit theirs to 5,200 using an electronic governor but I'd assume they fit a rev kit, which is valve spring packers, an advance stepped key and stronger billet spring caps.

        Fixed ignition on the Briggs is aimed at being able to pull start a 630cc engine, which in a motorcycle would be impossible; however the retard and low compression used to make this possible, damps the performance-hence the pretty cheap upgrades for more power.

        Good power can be had just by bumping compression to 9.5-10:1; you don't do this by skimming the heads, but by swapping the pistons for shallow dish or flat tops, Al Hodge sells them. I cautiously used shallow dished and stock head gaskets, but saw it perk up more with thin head gaskets added later. If building a second engine would use flat tops and stock gaskets.

        More top end comes from either stepped flywheel key, which is all too easy to get wrong way round and retard the ignition, or using 2mm alloy plates to move the coils 8° round advanced. stock is 21°.

        I like Al's roller-tipped alloy rockers to reduce side load on the valves instead of the cheap stamped stock rockers, these give an easy increase in valve lift by being 1.5 ratio instead of 1.1

        Best of all just bolt the carb on off the 61" engine, but open out the inlet elbow to clear the butterflies.

        No overheating, at all, runs too cool in fact, at around 320F on hottest cylinder with the later big fan.

        Cheers

        Kev

        PS if you change the cam like I did add in a heavy duty John Deere starter, stock one won't spin it without the stock cam's decompressor rig.

        PPS don't know what prop pitch is, adjusted it for 4,600rpm static, at 4,800 static got 100kilos/220 pounds thrust but it was too fine once in the air.

        --- In Small4-strokeEngines@yahoogroups.com, "wannibi" <wannibi@...> wrote:
        >
        > Can anyone help with the predicted performance increase/decrease revving the stock vanguard 23 Hp engine to 4000 rpm instead of 3600 rpm. According to the power curves the maximum power is generated at 3600 dropping to a predicted 20 Hp at 4000 rpm extrapolating the power curve.
        >

      • David Downey
        Hi Kevin, what is your airspeed at what engine rpm, close to seal level? I assume this is with the 1.8:1 stock ratio Ace unit? What is the prop diameter?
        Message 3 of 6 , Jun 3, 2013
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          Hi Kevin,
          what is your airspeed at what engine rpm, close to seal level? I assume this is with the 1.8:1 stock ratio Ace unit? What is the prop diameter?
          Thanks!
          Deividi (Downey) 215-527-5899
          Quando a saudade nao cabe no peito transborda nos olhos! Oi Brasil!


          From: Kev A <kevin@...>
          To: Small4-strokeEngines@yahoogroups.com
          Sent: Monday, June 3, 2013 2:16 AM
          Subject: [Small4-strokeEngines] Re: Vanguard 23 Hp power @ 4000rpm

           
          The stock engine can be revved to 4,200 in the Briggs & Stratton Handbook, this is their limit when used on welding generators, check out the official handbook.

          Mudbuddy limit theirs to 5,200 using an electronic governor but I'd assume they fit a rev kit, which is valve spring packers, an advance stepped key and stronger billet spring caps.

          Fixed ignition on the Briggs is aimed at being able to pull start a 630cc engine, which in a motorcycle would be impossible; however the retard and low compression used to make this possible, damps the performance-hence the pretty cheap upgrades for more power.

          Good power can be had just by bumping compression to 9.5-10:1; you don't do this by skimming the heads, but by swapping the pistons for shallow dish or flat tops, Al Hodge sells them. I cautiously used shallow dished and stock head gaskets, but saw it perk up more with thin head gaskets added later. If building a second engine would use flat tops and stock gaskets.

          More top end comes from either stepped flywheel key, which is all too easy to get wrong way round and retard the ignition, or using 2mm alloy plates to move the coils 8° round advanced. stock is 21°.

          I like Al's roller-tipped alloy rockers to reduce side load on the valves instead of the cheap stamped stock rockers, these give an easy increase in valve lift by being 1.5 ratio instead of 1.1

          Best of all just bolt the carb on off the 61" engine, but open out the inlet elbow to clear the butterflies.

          No overheating, at all, runs too cool in fact, at around 320F on hottest cylinder with the later big fan.

          Cheers

          Kev

          PS if you change the cam like I did add in a heavy duty John Deere starter, stock one won't spin it without the stock cam's decompressor rig.

          PPS don't know what prop pitch is, adjusted it for 4,600rpm static, at 4,800 static got 100kilos/220 pounds thrust but it was too fine once in the air.

          --- In Small4-strokeEngines@yahoogroups.com, "wannibi" <wannibi@...> wrote:
          >
          > Can anyone help with the predicted performance increase/decrease revving the stock vanguard 23 Hp engine to 4000 rpm instead of 3600 rpm. According to the power curves the maximum power is generated at 3600 dropping to a predicted 20 Hp at 4000 rpm extrapolating the power curve.
          >



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