Originally Posted by
2W0EPI
This is an excellent thread because an internet search of a os 46axii and a Force 46 shows little information about these two engines, however the F46 goes for around £85 whilst the OS 46 AXII costs about £130~£140 depending where you buy it from. Both engines produce about 1.6hp@16000rpm so engine life is going to be about same. I just want to point out that engine manufactures can easily kick out more power at higher rev band but this will unduly result in shorter engine life so keep the rpm specs as low as possible.The OS 46 AXII offer a 2 year warranty on this engine which gives some indication of how long the OS engine will last.
I do not have any experiences with the OS 46AXII engine but I do have a F46 and I found it to run okay, in particular when buying new check all the nuts and bolts are tight and I have found that the optimum operating conditions of the needle valve is 1/4 open, whilst initial starting requires the needle to be a full 2 turns out(rich). Once the engine has started decrease the needle valve towards 1/4 open at the same time reduce the servo throttle to bring the engine down to about 3000~4000 rpm idle then remove the glow starter from the glow plug. During break in I have used both a hot and cold plugs and have yet to see any difference between the two.I did notice that the hot plug glows a lot brighter than the cold plug.
Also, I notice the fuel lasts a lot longer when the engine is running 1/4 open(lean) and there is a lot less castor oil spraying out of the exhaust.
My knowledge of Force 46 is pretty limited however I have been using the OS46AX & 46AX ii for many years. They run extremely well once broken-in and when set up correctly.
In fact I hardly ever touch the High Speed fuel needle (maybe two or three clicks at most if I change the fuel %) and I never touch the idle screw (LS) setting at all once tuned. Bearing in mind the F46 and OS46 are from the 'same page' I would have thought the settings are VERY similar. My needle valve is set to 1 3/4 turns which is a bit rich but still very snappy from idle to max throttle (I run them hard depending on the aircraft I'm flying). No spurting or coughing at all.
It burns pretty clean on Optifuel 12% Nitro. I also use 5% but with little or no gain in fuel consumption however, it does gives a slightly better idle on 12% using an OS Hot or Medium Plug (I also use Redline or Fox plugs depending what's in my field box on the day).
When you say you didn't see any difference with the plugs during break-in (hot or cold), I don't think you would.
Most people use an old plug to break-in and until the engine is fully set up correctly, only then can you make a comparison IMO.
Having said all of that, I'm sure the F46 is a good engine for the price but until I try one for myself - only then can I compare BUT for now I'll stick with my OS46 & Irvine 46.