Conference vmszoo::rc

    An ABC engine is supposed to give more power. I think it is only
    marginal. Here (Netherlands) ABC are priced the same as ringed.
    Ringed are cheaper if certain repairs are needed. But if you 
    donot severely mistreat the engine that's no problem. By mistreating 
    I mean run it with a large prop, lean, to little oil, then an ABC
    is (theoretically) easier to damage the piston/cylinder. 
    
    I run a .46 SF ringed and I am very pleased with the performance. for
    the level of funflying that I do I have an engine that give a lot of
    power, is very quiet, and easy to start.
    If I could get a good SF engine cheap I'd go for it.
    
    I am running it in my first low wing trainer. This is a PUMA designed
    with a semi-symetrical wingprofile for .40 engines. The .46 does a good
    job of pulling it out of the high grass we have here. And being able to
    go up vertical very high is impressive. 
    
    Cheers Johan Eikelboom 
    
    P.S. Low and fast is also impressive 8-()
    

    Johan,
        Thanks for the reply. My first choice is the OS 46 SF, but this
    deal on the OS 40 SF RC is very, very tempting. I would think that
    there is a big difference is performance between the two. Specs call
    for the OS 40 to be 1.22 horse power and the OS 46 to be 1.43 horse
    power. Another question does it require longer breakin for a ringed
    engine?
    
    Dennis
    

What is the number to call???   Any ad to reference?

                       <<< Note 1556.0 by SALEM::DEAN >>>
                               -< OS RINGED ENG >-

    
    There is no add. This a special deal the local hobby store has with OS.
    If you want info on the store let me know.
    
    Dennis
    

    OS did a similar sale last fall.  I got my OS61 Hanno through Ray's at
    a price a bunch less than Tower's.  For sport flying, a ringed engine
    is just as good as ABC.  A good ABC engine will turn out more power,
    but if you damage your piston or sleeve, you need to replace both as a
    matched set.  I've gone through several pistons on a ringed engine and
    was able to reuse the ring and sleeve.  ABC engines are sensitive to
    running temperature due to the close fit of the piston/sleeve.  You do
    not want to run them very rich on breakin and you don't want to change
    the nitro content of the fuel after breakin because both affect the
    running temperature.  
    
    Charlie
    

    Ringed engines always take longer to break in!  The more the engine is
    run, the better the rings/cyl seal, giving better compression.  A
    ringed engine should run through several tanks of fuel with a rich
    setting before they can be leaned out for maximum performance.  This
    takes some time however, especially when you consider most ABC engines
    break-in after about one tank of fuel.  
    
    
    Keep em' flyin'
    
    Carl

    I've run ABC engines that take many tanks of fuel to break in.  The
    latest example for me is my new OS25FP.  It has about six tanks run
    through it and it is still too tight to pull a streamer on a Combat
    Gremlin.  It's true that some ringed engines take more breakin but it's
    not a general rule.  
    
    Charlie
    

    I ran one tank with a very rich mixture. (My wife was very gratefull
    having the lawn full of grease) Then I ran 2 tanks gadually leaner.
    
    Then I went flying. On reflection .... I must admit that I crashed that
    plane to toothpicks on of the first flights. I was simply not ready at
    that time to handle that amount of power, coming from an antique OS 30
    RC with .30 hp.
    
    I learned a bit more on powermanagement with my Freedom 20 and OS 25
    FP, and then went back to the .46 SF.
    
    Since I build it on the PUMA it has been running smooth. I have
    now changed the prop from 11x6 to 11x7. It doesn't rev-up that much if
    you go vertical (down).
    
    So it probably depends on what stage you are in. In primary trainer
    phase the FP's are probably a better choice. in the hotdogging phase
    the SF ringed are good. If you move to serious competition flying you
    want the ABC, and hope you are not outperformed by someone with a
    ringed version. As flying skills make more difference then ring or ABC.
    
    For myself I have decided to invest in fuel-consumption rather then
    gear for the time being.
    
    Cheers Johan