Rc Fuel Faq
Noahb;
First the question...
"I run coolpower (total synthetic), never had a problem with any engine I have ever owned, and all have great compression. I know that castor is added insurence, not to mention rust prevention. My question is this: What is the big deal about all syn. fuel? Some people will not run this fuel cause of concer about there engines. Please shed some light on this as I have never had any problems in my engines, they are very clean inside, great compression, and run great. This includes four strokes."
Noah-
People that have a concern regarding an all synthetic fuel in most of their engines are mainly concerned with maximizing the protection available to them. I don't think that anybody will argue the point that an all synthetic fuel will run fine and protect just adequatly in a large number of engines. One of the points about castor is maximizing protection in a large number of engines and an absolute necessity in others. Castor will do a few things better than most of the synthetics used in glow fuel out there. Castor is the best rust inhibitor that we can use in a fuel and it offers a considerable protection advantage when a lean run occurs (does'nt burn up like the majority of synthetics used). Castor oil will stick around much longer when a hot condition (lean) happens because it does not flash off like most synthetics out there. This is important in the ABC type engines that need the cushion between the piston and sleeve, not to mention non ball bearing engines that rely on a film of oil to keep the crankshaft and bushing from contacting each other.One benefit to castor (even in small amounts) that many folks do not realize is the excellent protection of the large end of the connecting rod and crank pin. It's generally not as slippery as several of the synthetics but it does have a lot of "cushion".
Very few synthetic lubricants used in glow fuel today will survive a hot run where castor will. A little bit of castor (2% to 4%) in most of todays four stroke engines will not hurt them a bit, although many folks now run total synthetic in four strokes.
"Now the other issue...the reason I here for the coil in the exhuast side is to help dampen pressure pulses to the carb. Cars are driven with lots of throttle action. I don't know if this is the case or not, but it's is what I have heard."
Noah- Not being a "Car" guy, I can only look at data that I can collect and based on the experiment that I performed outlined in a post near the begining of the thread, I can say that I saw no measurable difference. Hey, if the car folks think it helps, thats great.
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Elmo Te:
"Fuelman
Thought Id ask your opinion-
I broke my tt70(heli) in on coolpower red (30%), but want to switch to green(15%) to save money/fuel. I had about a pint of red left in a bottle with some oil additive, dumped this into a 3/4 full bottle of green. Mixed up, looks like chocolate milk in color! I closed the main needle several turns but left the idle where it was. Engine starts and idles well, comes up to speed nice, but after a minute or so in hover abruptly dies. Tried lots of variations on the needle, kept happening (about 12 times). I plan to try some pure green today. Running OS8 plug. Any suggestions? Is this fuel ruined? "
OK Elmo, you have me wondering what "oil additive" you are refering to?
Mixing CP30 and CP15 would not necessarily do any harm, but if some other foreign matter that does'nt belong, well, I don't know.
As far as the needle settings, if you were running CP30 it is going to be a richer needle setting that if you were running CP15 (if tuned correctly). Now switching to 15% will be a little leaner than the CP30, but I can't believe that it would be "several turns" leaner.
My suggestion is on the conservative side: Set the engine at the factory recommended needle settings and get a fresh gallon of the fuel of your choice. It is always better to be a little richer than optimum instead of leaner. You may want to consider putting in a new glow plug too, have no idea what your "chocholate milk" did to that too.
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Thojo:
"We try to get our engines as close to 17,500 without going over to get the best performance out of the planes. During the winter months with cool dry days, this limit is easy to reach, but with the summer months with heat and humity, this limit is hard to reach.
Do you have recommendations for a "summer fuel mix" and "winter fuel mix" to maximize the potential maximum RPM's with these little engines?"
Thojo,
The performance drop you experience is because cool dry air can pack more fuel in it than hot moist air. the hot moist air has another affect- your prop is less efficient. I have no idea what fuel or nitro percentage you're running now but you may want to play around with running a little more nitro or a little less depending on what engine and fuel your running now.
As far as anything specific, I can't offer what you probably want.