Hello,
I still have old Jett60 that was run on Windy's pipe in my first plane (Intrepid XL) named Great White.
This engine is a hybrid of old and new parts, with the liner and piston being almost new (1.5 years old) and the rest being old (17 years).
I have tried to run this engine in the pipe mode and partially succeeded: on Oct.31,2016 on 12.25x3.75 APC prop. and using 12.5% Nitro Omega with splash of SIG castor, the ground RPM were 11,400 max. and 11,100 just below 2 cycle. The pipe was set at 18 and 1/8" distance from the baffle to the glow plug for 11,400 RPM., after trying 17.5, 17.75 and 18" that delivered lower RPM values.
There was an audible increase in RPM for 18 and 1/8" v/s the other distances but I did not measure the RPM for 17.5, 17.75 and 18".
When the 18 and 1/8" distance was set, I have tried also 3 blade cut Bolly (11 and 7/8" dia. and 4 or 4.25" pitch). Unfortunately the owner of this prop. who kindly lent it to me for the ground tests, did not know its pitch.
Previously, I run this prop. without pipe and got 10,100 RPM max. The pipe "added" 1,000 RPM to the engine that buzzed at 11,100 RPM. in the 2 cycle mode.
Considering the above and the fact that I "cooked" my Evo60NX in RToucan to death running it in full 2 cycle, very lean, mode with 10,400 launch RPM on 13x4 MAS prop: can I use Windy's pipe as muffler and try to run Jett60 on 13x5 prop. in rich, wet 2-4-2 mode at, say, 8,200 RPM.?
I am assuming such wet 2-4-2 mode will help the engine not to overheat that killed my EVO60NX.
How much SIG castor will be needed for my usual fuel ( Omega 5 or 10% nitro ) to carry the heat away and, at the same time, do not leave too much carbon residue on piston?
Thanks,
M