I am new to glow fuel RC flight, but I have a lot of experience with nitro RC trucks.

I was wondering, what kind of temperatures do you typically want to see out of an aircraft engine.

I have a Nextstar with an O.S. .46 FXi and it doesn't want to go over 150 F. With nitro RC cars we generally try to keep the running temps over 200F at all times to prevent excessive wear to the engine. Is this also a concern with the plane engines? If so, what are the minimum suggested temps.

I am really concerned, as this engine came with a HSN limiter on it that only allows you to adjust it so far, and according to the manual you aren't supposed to need to adjust it outside of the range the limiter restricts it to. However, I have found that even leaning it as far as the limiter would let me left the engine blubbery rich and it doesn't want to spin up smoothly. I had to remove the limiter and lean it out almost 3/4 of a turn further that the limiter was allowing just to get it running reasonably well and even then the temps would barely go over 160F. The only way I could get it up over 200 was by wrapping the head in a rag to restrict airflow.

Should I be worried about keeping the temps up or do you guys all run the airplane engines really cold?

Thanks.

Running temps are something that we really don't worry about with airplanes. Unless the engine is inside of a cowl without proper ventilation the engine will stay cool when running. Remember, you have a huge cooling fan 2 inches from the engine blowing air over it!!

Ken

Thanks for the reply. Glad it is nothing to worry about. I know with cars, running at 160 constantly will end up destroying an engine in a very short time. I'm glad to hear that RC planes aren't as sensitive to proper running temps.

after about 5-10 flights you want to get rid of the limiter its there so you don't burn your new engine up, and is set up for rich running, you will find you will need to lean out the OS 46 after about 10 flights not much,but more than the limiter will allow.
its a great motor and will be a runner for many years as long as you don't lean it out too much.

Well, I was bench running it in my backyard just trying to run it in a little, and I found that I had to remove the limiter even before ever flying it. With the limiter on, leaned as far as it would allow, the engine was blubbery rich and would stall as soon as you apply anything more than half throttle. I removed the limiter and leaned it out about 1/4 turn further than the limiter was previously allowing, and it wouldn't stall at half throttle but would sputter and never really increase in RPM's at all, so I went in another 1/4 turn leaner and it seemed nice at about 1/2 throttle but would sputter and want to die at 3/4 - full throttle, so I leaned it out another 1/4 turn and it is now running smooth at all throttle positions. If I richen it any more from where it is at, it will not run smooth throughout the throttle range.

I'm starting to wonder if my throttle limiter was installed 1 turn off from where it should have been. Does anyone know how many turns out from closed the needle on this thing should be to be in the factory start setting?

your NEXTAR should have come with a inst. manual for the OS 46fxi but for starting the recomended amount is 1 1/2 turns you should run it pretty rich for the first few flights at least 4-5, not so much that it dies when your running it but so there is oil coming out of the pipe you also should be slow and gradual when using the throttle if you jamb it open its also going to cut out on you, nice and easy untill you get to optimum tune. the 2 OS 46's II have are set around 1 1/4 to 1 1/8 turns on the needle each engine is different.
if you have run cars you know the basics of running glow powered engines, airplane engines are a little diferent but not that much,you need less nitro content and more oil usually 5-15%nitro and 18% oil in your fuel for most engines, some brands require more oil for OS engines those are the recomended #

Hey thanks for all of the info. It was the whole 4 cycle 2 cycle running thing that threw me. With cars, we never run the engines rich enough for them to only be firing every other stroke, but per the manual that is normal with the aircraft engine.

This is a just another example of why you should always read the manual twice before doing anything, even if you are an expert at running in, tuning and maintaining car engines, the airplane engines are different, so the instructions must be reviewed. Thank you. I will refer to my manual and go through the bizarre break-in it describes (bizarre to me anyway)

The Nexstar engine and the Evolution engines both come supposedly "broken in" and with limiters set to protect you from yourself. Well, the engines are NOT broken in. They MAY be pre-run slightly but still need a slight break-in period and rarely is the tuning correct. The limiters usually stop you before optimum tuning too.

If you see anybody pointing a temp gauge at a 2 stroke airplane engine---------[sm=bananahead.gif]

Car engines and plane engines are basically exactly the same, the difference is that a plane engine always has a load on it from the prop while a car engine only has a load on it while it's being driven. That's why it's so easy for us to tune a plane engine to get a rich or leaner setting instantly without having to resort to measuring head temps (which are only a guide anyway) after a quick run around. Don't worry about engine temps because so long as it's not run too lean then the temps will be what they will be and there's nothing that can, or should, be done about it.

Personally I think the limiter is a stupid idea because there's a huge difference in where the needle should be set depending on how much nitro you have in the fuel. If they said to use an 11x4 prop and 15% nitro (to pick some figures) then it might work. Otherwise it's useless.

BTW, my son went from planes to cars and he ran in his car engine starting from a 4 stroke in flat out running (he knew what sounds to listen for) then gradually leaned it out to begin building up more heat and now it howls.