RE: JC 60cc Engine
from cactus aviation website:
When 3W started engine production of the 3W120B2 (old style technology in 1985), a casting of an existing chainsaw cylinder was used. 3W modified this cylinder with 2 additional transfer ports milled into the cylinder. Timing had been changed as well. Both steps were taken to increase power and torque. Then 3W received their own customer number on this cylinder design.
3W was never satisfied with this design. They have always been looking for more torque and power while still running in lower RPM bands. Hence, in the last few years they came up with a lower RPM, higher torque cylinder design. This new design used the 2 large transfer ports, adding 2 small transfer ports and a 30 degree angled exhaust port. This would give the new style engines (including the 3W150iB2) a faster saturation (filling) of the crankcase. Approximately 30% more than the older style 120 ccm cylinders. And with the 30-degree angled ports, give much faster release of exhaust gases. All 3W Engines develop their optimum power/torque curve between 5500 RPM and 6100 RPM. Anything above this is really giving you not much more than prop noise.
All our engines now use the Nikasil liquid plasma coating, which incidentally is done by the same company that coats the cylinders for BMW Motorcycle cylinders. 3W has minimum play between cylinder and Piston; 0.015mm = theoretical lifetime – 2000 hrs. before TBO. You may want to compare these numbers to other engine manufacturers to get an idea of what their criteria are. There are no engines in the U.S., to my knowledge, that can make this claim. Also all cylinders are classified which are a solid engineering practice and a base for a long lifetime. The reason for this cylinder classification is to keep a very close cylinder/piston tolerance. This is why, if you notice, all 3W cylinders are stamped on the top "A" or "B" to designate classification. Again, to my knowledge, no other gas engine in the US can claim this. All gas model engines in the US have open tolerances. The 3W crankshafts are forged instead of turned making for a much stronger unit. The metallurgy process is superior. 3W crankshafts are 2mm thicker than any other that have been checked. Crankcases have structural webbing for strength. The longevity of the 3W engines far exceeds the compromise made for a few extra-added ounces in some 3W engines.
The new ignition system 3W developed creates a 30% more powerful spark than its predecessor. Spark gap can be increased to .020 thousands for a softer and cleaner burning process. Giving a much better midrange burn. We have also experienced some widespread ignition cap problems. This problem is mostly directly related to the higher voltage the ignition is developing. Also some customers are running very high cylinder head temps due to inefficient cooling. 3W has corrected this problem by the time this information goes on this website. Again, not every customer is experiencing this problem. In addition, 3W has its new modified carburetors on the big block engines (120,140,150). This includes the Front Intake and Rear Intake engines. This is giving the engines virtually a 0 to 100% linear throttle response, thus making the midrange transition a problem of the past. Quique Somenzini flew this carb as a prototype at the 1999 T.O.C. with pleasing results!
All this gives the new 3W150iB2 a maximum power output of 17 – 18 H.P. Static thrust 84 lbs. To 97 lbs., depending on propeller size.
In closing, 3W and Cactus Aviation are working together to bring you, the customer, nothing short of the very best in "Two Stroke Technology".