Dr. Blockhed

HelloAll,

I'm new to nitro RC and my wife recently got me an ofna ultra lx1. I've broken in it in the past week and have run about 3 -5 tanks after that. I broke it in in colder weather (about 30-40 degrees) and have tuned it in the same weather. My lhs said this is fine and these engines like the cold, I also read that running it in weather that is too cold could ruin the sleeve and piston and they may have to be replaced when it warms up out due to metal expansion.

Any thoughts would be much appreciated.

Thanks

tommygun32

Hi and welcome to RCU and the addiction Allenmr.

I would say two things mate. In those kind of temps (around zero f or so), I'd try and heat the engine up with a strong hair dryer or heat gun prior to starting it. Then as soon as your engine stops, make sure you position the piston at BDC of stroke (bottom dead center). That way your sleeve can cool down to it's original position without being impeeded by the piston itself. Also, you'll want to use a very hot glow plug.

(I'm wondering what happens to fuel at those kind of temps or the oil viscosity in the shocks and diffs??)

Good luck and enjoy.

Fuel Crazy

My Feedback: (1)

i run all the time when its in the 30's and 40's here... my engines do not like hot plugs though. Just remember when its cold out, the air is denser..so you need to tune a little richer.

I run cold plugs in my engines in the winter here... they dont like hot plugs, and only mediums they seem to like are O'donnell.

tommygun32

True that...need to know what engine and fuel you're running please....[&:]

378

My Feedback: (4)

Ok, first of all, these engines do NOT like cold weather very much. They're air cooled, so in cold air, they tend to not get hot enough. They rely on a pinch, literally squeezing the piston, to get compression. Get them too cold and they will sieze. If you start them while they're at room temp, and if you can get the temps up above 200 degrees or so, then yes, they'll run just fine. They'll make more power, too, seeing as you'll be able to burn more fuel per cycle.

Mine never have a problem with this, as the shell insulates them well enough to heat up and I store/prep indoors during the winter, but if yours won't, you may have to wrap a few fins on the head. I suggest cutting a sock, since aluminum foil can cause radio interference. Always leave a few exposed, and check your temps so you don't overheat it.

As for starting, here's how I do it:

While inside the house, I:

Pre-run radio check
add fuel
Check glow ignitor
prime engine
another pre-run radio check

Then I go outside and:

Start engine
Mount body
Drive

When it's time to shut down for the day, I:

Bring the car to me
Pinch the line
The exact moment the engine stops running, I pick the car up and place it on a table indoors. I then go back outside and bring the rest of my gear in
Shut down radio gear, fold antennas, park the car on a paper towel, and done.


Doing this ensures the engine is still at room temp when I try to fire it off, and I don't have to fiddle around with finding BDC when I shut down for the day, though I usually do anyways.

As for what plug to run, etc etc, I run the same plug year round. The engine, if it's being allowed/forced to warm up to full temp, isn't going to care what the outside air temp is. The conditions inside the engine will be the same when it's running in January as they are in July. My engine, by the way, absolutely loves OS #8s. Makes sense, it's an OS engine. It came with an A3, oddly enough...worked for breakin but I threw an 8 in shortly thereafter. The engine before it also loved OS 8's. The fuel I use varies, but it's always a brand name 20%N 18%O blend. Right now, Blue Thunder, but sometimes I'll run Odonnel or Byron's. To accommodate the denser air, I usually go an eigth or a quarter turn on the HSN, usually right around October or so since I run year-round, and that keeps things running well. I don't have to touch the LSN or idle screw most of the time, the HSN adjustment is more than sufficient for my engine.

These engines do not like to start when they're given a chance to cool off. If you store them in a garage or something where they can get cold, bring 'em inside for a while to warm up. The servos don't like it any more than the engine. Ideally you'll store it inside as well, I park mine on some paper towels to catch the oil drips.

Dr. Blockhed

Thanks for all the replies guys!

I'm running a .28 force (came w/ the car) and 20% nitro. I've been preheating the engine w/ a heat gun every time Irun it and it starts w/in the first 2 pulls every time. Ihave been pretty much following what you have recommended, doing all m setting up inside then firing it up and putting the body on and running it. I'm using the glow plug it came w/ also. I have not positioned the piston BDC, I'm not sure how to do that. Ihope I didn't mess the engine up.

It has been running real good as far as I can tell (being new to the hobby) I tuned it a little today and it only seemed to need one turn to lean it out. It has been running rich as it has been at the factory settings for break in. It hasn't stalled once (after my first run) and seems to run strong. I am having some problems w/ the servo but from what I'm reading the stock servo is crap.

rc awesome

Its ok to break in a nitro in the winter but if I was you i would have waited until spring or a warm day. Breaking in a nitro in the winter will shorten it's liefspan by several gallons, which is actually a lot. You will need to run rich in winter because the engine needs the extra luberication.

378

My Feedback: (4)

You shouldn't need to pre-heat it, but that won't hurt it either. As for finding BDC, you can use the pull starter. Simply gently tug it over. When you feel it go over compression, give the starter another half-inch of pull and you're close enough to BDC. The goal is to get the piston out of the pinch zone.



Actually, breaking one in in the cold is just fine as long as the engine warms fully. As long as the engine gets hot enough it doesn't matter how cold the outside air is.


Also, it doesn't 'need more lubrication' because it's cold. You have to richen the mixture slightly because cold air is dense air. You're simply matching the fuel mixture to the amount of oxygen going into the engine. You would have to do this to your car, too, if it had a carb on it.

Dr. Blockhed

Thanks guys, so do you think I shortened the life span of the engine? Or just have to change the piston and sleeve sooner, or it just fine?

I've heard both things I'm just looking to get the most out of my car w/o having to upgrade and/or repair. My lhs had originally said the cold weather is fine and didn't mention anything about BDC (which I followed your advice and I think I got it). To get BDCI pulled the pull start heard it click and/or compress once, then pulled alittle more and it felt "looser", is that near BDC?

Thanks again

378

My Feedback: (4)

You haven't shortened your engine's life any. Don't sweat it. These little engines are tougher than people credit them for. And yeah, you're close enough to BDC.

rc awesome

Maybe slightly, (gallon at the most) but you will be fine. Take care of your motor and don't overheat it or fun it crazy hard and it will last you a really long time. 378, I was watching a mobile 1 commerical lol. Don't really know what i was talking about

dustin7837

My Feedback: (1)

30 F is not cold. Nitros CAN be run in much colder ambient than that. But like others have said, it is critical that the engine does get up to it's specified operating temperature. In the ballpark of 210* depending on the engine.

If you are heating it up with a heat gun and making sure it gets up to running temps, you will not do any damage to the engine. Having a temperature gun is important. It doesn't need to be an expensive one, a $10 unit from your LHS will be just fine.

moe7404

i broke in a traxxas 3.3 in the cold. i did all wrong according to the experts. i put it on the street truck tail gate. started it and let it idle, after 8 tanks it was broke in. allso i have an idea, just an idea no proof. on traxxas 3.3 the con breaks cause the rpm was held at top rpm to long, i think top rpm should not be held for more than 3-4 seconds. i formed this idea after splitting 3 con rods

The_Shark

ive heard by many the 3.3s are too weak to handle abuse.

welcome to the hobby, OFNA is a great brand, and the force .28 are known work horses. if you cant get the motor very hot to the touch, put some aluminium foil on the head.

i ran a couple days ago at -3F and did just fine

stock servos are terrible, you can replace them at hobbypartz, i just got a coreless, digital, metal one and its just stupid fast for $15. i would suggest running high torque as both servos, for well known brand stuff, hitecs are great all around, speed is decent, smoothness is buttery, and they are bullet proof.