I'll be using an OS .61FX in my plane, and was wondering which type of fule to use, and what percentage of nitro.

Thanks

Not sure what brabds are common in the USA but any 10% nitro will be fine. I run all my 2 and 4 strokes on XP 10%, no problem.

Any 10% or 15% nitro fuel will be fine. I will suggest using a castor oil/synthetic oil blend since castor oil is still the best protection against a lean run.

Our club uses 12.5 % nitro, 18 % synthetic and 2 % castor. I use the same formula for all my engines, which are mostly O.S. The brand name we use is S&W, which is produced nearby in PA. We pay $ 10.50/gal and pick it up.

DaveB

Morgan Fuels Omega 15% has worked for me for 10+ years.

if ur running a engine in uu need 2 use 5% ore 10% (recomend 5%) the lower percent fuel the oiler the fuel is so if u use 5% formila irvine fuel you engine will have a longer life i got a plane 4 christmas and i have just run a gallon of fuel through my engine 5% and 2 be on the safe side and make my engine last longer i am running a second gallon through it wot is 5% and so far its never cut out and its still got 100% compretion and its well oiled should last me a long time..... touch wood....hope this helps.. email me and tell me how u get on....

Thanks for all the responses. Is there a clear advantage between, say, 5%, 10%, and 15%? I'll be using the engine for casual use (I'm not racing or anything).

thanks

15% will be the fastest fuel 2 use 10% 2nd fastest last is the 5% but good 4 running in......................

J421,
For your casual flying 5%, 10%, or 15% should be fine. What you should use is pretty much a personal preference (unless you live at a high altitude, then you need a higher percentage to stay even). The higher your percentage of nitro the more power you are going to have. The down side is more power equals more heat. But with anything below 15% you will be just fine. Experiment around with the different fuels and see which one you prefer to fly with. Try to find some people at your flying field and explain to them what you are doing. See if you can get a tank of fuel from them to see the differences. This might be a way to avoid having to buy a full gallon of fuel just to try it out.

Hope this helps.

i a have a .46. I use Cool Power 15%, andi ts just great.

Just a heads up, overseas posters will suggest using low nitro or even no nitro, which is fine. This is mainly due to nitormethane being very expensive in many overseas locations. However, in the states, nitro is comparably quite cheap, and there are advantages to using nitro.

Like in the previous posts, more nito generally = more power. Lots of factors in play here as to how much more power you will actually see, if any, but ~1% for every 1% of nitro is generally close. Keep in mind that power when measuerd as prop RPM is a powered, not linear funtion. If you bump nitro by 10%, your power may bump by 10%, but RPM will NOT. For example, if your engine runs 10K RPM, a 10% boost in power will only increase prop RPM by about 200 RPM. Based on that, I suspect that small nitro changes don't effect engine wear much.

Something else to keep in mind is that nitro does more than produce more top end power. It also can play a large part in idle reliability and transition. Higher nitro generally make for a more reliable idle and better transition.

Another tidbit, often in cool weather, higher nitro can be the diff between a stubborn engine and one that runs properly.

But keep in mind that there are limits. Engines are designed for specific fuels. Some engines can tollerate a wide range of nitro, but most will have a small range where they run best. For most sport type engines found in the US, this is 5%-15% nitro.

Lastly, if you change nitro %, recheck your needles. Nitro burns at a 3:1 air/fuel mix. Methanol burns much leaner at 6:1 air/fuel mix. When nitro goes up (and the alcohol portion of the fuel is reduced), you will need to richen mixture. (another side effect here is you get less runtime with high nitor becasue of the required richer needle settings.) Of course Vica versa for reducing nitro, i.e., you will need to lean mixture.