Originally Posted by
doxilia
We should be able to improve performance yet by tuning the exhaust for smaller props. If you plan to turn an 11x7, 11x8, more RPM should be available. With the larger "long stroke" props (12x8, 12x9), the exhaust is actually a little restrictive and a longer pipe may be needed.
I'm reading that Wildcat Premium has 16% oil with a 20/80 castor/synthetic mix. That's pretty low castor content for the beast. No doubt it will perform well but it might be somewhat life limiting in the long run. It's likely a good thing that you added the 3 oz of castor. 5 oz might be even better.
Personally I'd really like to source 50/50 20% oil fuel (e.g., Sig Champion or Morgan 4-stroke) and dilute it with methanol. Find out where the sweet spot is ;-)
David
Guys.....If you are thinking of adding more oil....don't add castor.....add synth.
Modern engines really do not need castor for good running.
A VECO/K&B 61....yes....22% straight castor, 15% nitro and they run great......with a lot of slobber.
Go to a motorcycle shop and get a quart of KLOTZ KL-200 all synth and bring the total oil to 19>20%
I wouldn't go any higher than 20% oil.....don't need it anyway.
In any event...I think all the engine mfgrs like to spec castor oil because ot corrosion considerations....and they spec excessive oil content as well....they are doing a CYA manouver.
Straight synth of any mfgr is well known to promote rust and corrosion if left sitting....that is why the mfgrs spec some castor.
I have been using Castrol 0-20W synth motor oil available at Wal-Mart as an after run/storage oil.
After every flying session I run out the fuel, then remove the plug, open the carb and shoot a bunch of it down the intake with the shaft hole open....about an ounce.
I put this oil in a plastic ketchup bottle I stole out of a skid-row ptomaine tavern.
Then I put a rag over the head and spin the prop with the electric starter.
Put the plug back in and it's ready for the next time.
This oil does not affect the starting next time out....does not gum up etc.
I have a YS 140 Sport pickled up with this stuff now for 4 years and a OS 91 4 stroke for 3 years at least and they are in perfect condition.....I check them about once every 6 months.
Works great!
Dave