[NSRCA-discussion] Prop for 1.40 DZ??

[george w. kennie]

My buddy brought his YS-140 sport by the house yesterday for a break in session. He had a standard wide blade APC 16X10 prop on it and I was shocked that this prop was so undersized for the output that this engine was delivering. I tried to run a full tank through it running rich (tons of smoke and lotsa oil residue), but when we got to the second tank and I went to WOT I could hear that it was way over-rev ving. Cut it back immediately and ran and got my tach and checked it and it was turning 96. Needless to say, we only took it there for a few seconds and I advised him to go to at least a 17X10 to get the revs down to the 85-86 level. This prop was also extremely loud at these rpms.I'm wondering if he might need to go to even slightly more load, especially with 30%, which is what we were using.
What a Monster !!!!!!!!!!!
G.  



  ----- Original Message ----- 
  From: Troy A. Newman 
  To: NSRCA Mailing List 
  Sent: Monday, March 12, 2007 12:40 PM
  Subject: Re: [NSRCA-discussion] Prop for 1.40 DZ??


  Matt,

  the 17-12W is way too much prop for a 140DZ

  Run the engine between 8200-8500 and you will get the best performance from it. On the 140DZ's Insane power is 16-12. The 16.5-12W is also good if you are getting a little too loud. The 17-10 standard might be good, but a bit loud. I would look at the 16inch props.  The 17-12's will pull the RPMS down too low and below 8000rpm. this loads the engine too much its designed to run at higher rpm over 8000...you want to be over 8200 for sure.

  I know guys run the bigger props and don't have trouble but usually they complain it doesn't have the power they want. Then they stick a  good prop on it and it goes like stink. 

  Depending on the fuel you have chosen to run the  prop will vary. If you are running 30% Heli then you might get away with a 17-12 regular. the 17-12W is a bit more load and I only have used this on the 160dz. If you are trying to run some 20% nitro you need to really back off on the prop. Follow the rule of RPM above and keep the engine happy in the 8200-8600 range and it will not only run better with more performance but it will live longer too.

  The 18-10s are the same way. These are a bit too much load on the 140DZ to get the good power. The engine is setup to run at a certain RPM. If you run it there it will be equal power to the 2 stroke 140's and in most cases more. If you try to load it down to 7700 like guys do to the 2 strokes you will not keep up. As far as power pulling the model in the air the DZ will have more if you run it at the right RPM. 4 stoke vs 2 stroke is a different gear in the car. Run the engine at the right RPM and it will make more than you need even for a heavier model.

  troy Newman
    ----- Original Message ----- 
    From: Matthew Frederick 
    To: nsrca-discussion at lists.nsrca.org 
    Sent: Monday, March 12, 2007 7:49 AM
    Subject: [NSRCA-discussion] Prop for 1.40 DZ??


    I'm currently running a 17x12W on my 1.40DZ but I'm not getting the vertical performance I would like. I was wondering what prop size I should try? I've considered an 18x10. Any thoughts?


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