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Cruise Rpm of the Generac 990 engine...?

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  • Gary Gower
    Hello Friends, Well, lots of time has passed since my last post...  I have been working as much as I can in my 3 main projects:    My retirement
    Message 1 of 21 , May 16, 2013

      Hello Friends,

      Well, lots of time has passed since my last post...  I have been working as much as I can in my 3 "main" projects:   

      My retirement paperwork (done!),  my Flying Flea cabin (done!)  and finishing the few mods to my Spoon converted Generac engine  to work well in my Flea (intake, carburetor, headers and installing the little Kubota generator, etc  including all the side work that goes with this "last minute" details)...  

      Also had some personal "time consuming" things to do that were getting in the way, like my everyday work, family (including my first granddaughter), a couple of  motorcycle trips and some bicycle tours...

      Now I  am in the process of calculate and carve the propeller....  So I will like to hear some comments/advise  from  pilots flying with this engine...  

      I will like to know the rpm's where the engine works smooth (better) in cruise, so I can estimate my first  pitch cut for the propeller,  that will be a good start... 

      I think I will need to carve two or maybe 3 props to eventually get to the best one...   A common practice here for a new airplane/engine combo, given our aerodrome altitude over sea level  (5,000 ft ASL) and outside air temperature...

      Yes, I will post some new photos as soon as possible, a few every night I think. Just got from my daughter the correct converter for my camera memory/ to my computer... Now (I think) I will be able to unload the photos to the hard drive, make a selection and upload them to the photo page...

      Thank you all very much and will keep posting...

      Gary Gower
      Flying from Chapala, Mexico
      Pouchel  "La Bamba" ladder Flea, now with a 447 for the few first flights with the cabin.
      PS:    Spoon my friend,  Thank you very very  much, one more time for the great work done to this  engine, I thought that was going the be faster to have it installed and flying.....   This is homebuilding  time... 
      "We know when we start, but will never know in advance when the project will be finished".
    • warren
      I have no idea what machine shop time costs, but maybe the easiest, and possibly therefore cheapest, would be to buy an alloy hub (or complete alloy flywheel)
      Message 2 of 21 , May 24, 2013
        I have no idea what machine shop time costs, but maybe the easiest, and possibly therefore cheapest, would be to buy an alloy hub (or complete alloy flywheel) from the folks who sell the racing parts - they obviously have the taper issue figured out. Then use that hub with your cast flywheel rim.

        Maybe the machinist can cut the center out of the cast flywheel without needing to machine a tapered arbor for it. :-)

        Just be sure the alloy web between the hub and rim is strong enough to stand the precession forces - I have no idea how to calculate that, but you don't want the two separating. I recall that the auto conversion guys had problems with that when they tried using auto trans flex plates to support the starter ring gears with less weight than the manual trans flywheels. Turns out even the relatively lightweight ring gear still caused enough stress to crack the flex plates - apparently the flex a lot when not bolted to a torque converter as they are in a standard car installation.

        Warren

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