Cold-Weather Break-In or Wait?
11-05-2004, 12:36 AM
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Cold-Weather Break-In or Wait?
Hey guys, I'm planning on picking up a nitro monster truck some time around the end of this month (november). I have a choice to make with a couple options. Number one... Pick up a Revo at the end of this month and risk hurting my engine by doing a cold-weather break-in (I live in Maine and would probably break the engine in on a 35* to 40* day) Number two... Pick up a Revo at the end of this month and wait till spring rolls around to break it in (would rather not but I'll do it if would be best for the truck) Or number three... Wait it out, as there are lots of new monster trucks coming out from trinity and Duratrax and some others. In this case I would end up buying a truck when spring comes around. Any advice would be helpful. Thanks.
11-05-2004, 04:23 AM
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RE: Cold-Weather Break-In or Wait?
the trick over here in the u.k because its always cold is to get a hair dryer and heat up the heat sink and the surroning area and i should be just the same ass breking it in on a normal day
11-06-2004, 01:04 PM
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RE: Cold-Weather Break-In or Wait?
Well, breaking in in cold weather is difficult. R/c nitro engines are designed to run at anywhere from around 60 degrees outside to around 90 degrees outside, if it is really cold during break in the engine will not heat up to the proper break in temperatures because it is that cold outside, so the sleeve will be fitted perfect at, uhh, around whatever temp you broke it in at. So, this means, if you break it in without watching the temps to make sure you keep em hot enough, the sleeve will have the right tolerance for that temperature. So, then when good ol summer rolls around, when your engine heats up to its full temp, the sleeve will not fit right, it will expand more than the tolerance between the piston and sleeve during the winter. There is an article about this in depth at RCCA, you should read it.
11-06-2004, 11:00 PM
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RE: Cold-Weather Break-In or Wait?
actaully when the engine heats up the sleeve crank case and the piston expand, thats why when you change the bearings in the engine you heat the crank case up so that it will expend and the bearing will just fall out, so it wont make a big difference when you break it in in cold weather and when you run it in the summer. the piston will expend the same amount that the sleeve will, so it will always have thee same perfect fit
11-07-2004, 01:36 AM
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RE: Cold-Weather Break-In or Wait?
No, because in the winter, if you do not have the engine set to run high enough temperatures, it will not fully expand. Therefore it wears out the sleeve to where it fits right at the cooler temperature, but when summer rolls around there will be a compression loss when the engine heats up hotter than it would in the cold weather. It makes a huge difference, trust me! I have experienced it many times, some recommend having one set of piston/sleeve for "winter" driving, and another set for "summer" driving. In places that are always cold, it doesn't matter as much because the engine reaches the same temperatures, it doesn't change. But, because during the summer, the engine runs hotter than in the winter, the sleeve expands more.
11-07-2004, 04:13 PM
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RE: Cold-Weather Break-In or Wait?
i thought that u only had to break the engine in so that u get the engine piston and sleeve properly lubricated cause the metal will just expand no matter wot the temp, all metal expends when it is hot so why would piston and sleeve be any different.
02-23-2007, 07:09 PM
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RE: Cold-Weather Break-In or Wait?
Maybe i can add a little help here. I just picked upa tmaxx this past sunday. Its cold here in CT too. I broke my nitro in in about 35 degree weather and had no problem. I had no temp guage but they said in the manual that if you put a drop of water in where the glow plug is it should sizzles and bounce around for about 2-3 seconds and then evaporate. I got exactly that. They tell you to wrap the heat sink with a paper towel but i didn't see any need for that since i was getting what they said. Since break in i haev also driven the truck in 20 degree weather. O
02-24-2007, 12:56 PM
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RE: Cold-Weather Break-In or Wait?
As a mechanic on cars break in is only to season the block and parts of the engine. I would like to think that the engineers would know about expansion and contraction. the problem with breaking the engine in a cold condition without a computer to adjust the fuel and air is that you can over heat you engine very fast in the cold. cold air is dense and the engine will run lean on start up if you don't richen the fuel, after the engine warms up you can lean the fuel. The nitro engine does not have a intake manifold to warm the air or bring in exhust air so I just run my engine rich as hell untill the weather warms up. on a race car with a nos system all the the nos does is make the fuel cold and thats how you get the power, the only problem is if you run lean you melt your pistons I have see this and it's not pretty.
02-27-2007, 01:09 AM
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RE: Cold-Weather Break-In or Wait?
another point in this long dead thread - the piston and cylinder sleeve have different coefficients of thermal expansion do to thier different materials. differing rates of thermal expansion are the reason the old dial type thermometers and thermostats work. they are also the reason that with car when it overheats you see more aluminum heads crack when they are bolted to a iron block than you do aluminum head bolted to a aluminum block. the aluminum expands at a faster rate than iron when heated, and therefore is bigger, the larger head is trying to be held to a shape by the bolts through it into the iron block which is expanding at a slower speed. this causes stress and when the stress builds to a certain point something has to break, and the head will crack....
while the failure from cold weather break in is not quite like this; the only problem you would have with a cold weather break in would be getting the engine up to normal operating temps to achieve the correct fit. I use the top of a tube sock cut off and put it around my head in the winter time, if it gets too hot, i roll it up to show more cooling fins. have to have a temp gun but it works very well.
while the failure from cold weather break in is not quite like this; the only problem you would have with a cold weather break in would be getting the engine up to normal operating temps to achieve the correct fit. I use the top of a tube sock cut off and put it around my head in the winter time, if it gets too hot, i roll it up to show more cooling fins. have to have a temp gun but it works very well.
02-27-2007, 12:21 PM
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RE: Cold-Weather Break-In or Wait?
heads don't crack from over heating they warp, but you will most likely just blow the gasket because the head bolts on most cars are torque to yeild bolts and they stretch. If a head cracks from over heating it would be due to poor casting. My point is the only danger to the engine is runnig to hot, as the piston and other parts expand they were out the cylinder and if still going will seize. when you try to start up the engine after it cools you have no compresion. Are little nitro engines spin a lot of RPMs, at that speed heat build up is way fast, the engine gets it's lubrication from the fuel. a very hot engine will evaporate some of the fuel before it gets to the head and you have less lubrication. cars engines do have a problem with not getting to operating temp, thats condinsation build up and can't burn off the water that forms in the engine contaminating the oil and producing sluge.
02-27-2007, 12:41 PM
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RE: Cold-Weather Break-In or Wait?
ORIGINAL: basic
another point in this long dead thread - the piston and cylinder sleeve have different coefficients of thermal expansion do to thier different materials. differing rates of thermal expansion are the reason the old dial type thermometers and thermostats work. they are also the reason that with car when it overheats you see more aluminum heads crack when they are bolted to a iron block than you do aluminum head bolted to a aluminum block. the aluminum expands at a faster rate than iron when heated, and therefore is bigger, the larger head is trying to be held to a shape by the bolts through it into the iron block which is expanding at a slower speed. this causes stress and when the stress builds to a certain point something has to break, and the head will crack....
while the failure from cold weather break in is not quite like this; the only problem you would have with a cold weather break in would be getting the engine up to normal operating temps to achieve the correct fit. I use the top of a tube sock cut off and put it around my head in the winter time, if it gets too hot, i roll it up to show more cooling fins. have to have a temp gun but it works very well.
another point in this long dead thread - the piston and cylinder sleeve have different coefficients of thermal expansion do to thier different materials. differing rates of thermal expansion are the reason the old dial type thermometers and thermostats work. they are also the reason that with car when it overheats you see more aluminum heads crack when they are bolted to a iron block than you do aluminum head bolted to a aluminum block. the aluminum expands at a faster rate than iron when heated, and therefore is bigger, the larger head is trying to be held to a shape by the bolts through it into the iron block which is expanding at a slower speed. this causes stress and when the stress builds to a certain point something has to break, and the head will crack....
while the failure from cold weather break in is not quite like this; the only problem you would have with a cold weather break in would be getting the engine up to normal operating temps to achieve the correct fit. I use the top of a tube sock cut off and put it around my head in the winter time, if it gets too hot, i roll it up to show more cooling fins. have to have a temp gun but it works very well.
you are right about the thermal expansion rate of metals, but aluminum cools much faster then steel. try to cut aluminum with a torch it's very hard because as soon as you hit the air to blow off the molten aluminum it cools that fast. old cars might have cracked heads but they are cast heads that have very thin cooling jackets. Metals today are superior to that of thirty years ago. now we run are egines hotter for emissions to get a better more complete burn. all egines have a point of overheating and thats when the cooling fans come on, but unless you live were oil will freeze cold is not a problem. In canada they have block heaters on gas engines[X(].
02-27-2007, 12:50 PM
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RE: Cold-Weather Break-In or Wait?
ORIGINAL: [email protected]
you are right about the thermal expansion rate of metals, but aluminum cools much faster then steel. try to cut aluminum with a torch it's very hard because as soon as you hit the air to blow off the molten aluminum it cools that fast. old cars might have cracked heads but they are cast heads that have very thin cooling jackets. Metals today are superior to that of thirty years ago. now we run are egines hotter for emissions to get a better more complete burn. all egines have a point of overheating and thats when the cooling fans come on, but unless you live were oil will freeze cold is not a problem. In canada they have block heaters on gas engines[X(].
you are right about the thermal expansion rate of metals, but aluminum cools much faster then steel. try to cut aluminum with a torch it's very hard because as soon as you hit the air to blow off the molten aluminum it cools that fast. old cars might have cracked heads but they are cast heads that have very thin cooling jackets. Metals today are superior to that of thirty years ago. now we run are egines hotter for emissions to get a better more complete burn. all egines have a point of overheating and thats when the cooling fans come on, but unless you live were oil will freeze cold is not a problem. In canada they have block heaters on gas engines[X(].
In Wisconsin we have block heaters on a lot of our cars.
I've done break-in on 3 different engines when the temps were between 30F and 40F. None of them had problems when summer came around, just a little tweaking of the needles and it was ready to go. I had an OS .15 CV that lasted 3 gallons and I sold the vehicle while it was still running well. The guy ran another 1/2 gallon through it before he decided he wanted a little more and dropped a .18 engine in there. Just a couple of weekends ago, I did break-in on my MGT w/4.6. I anticipate that one will last me a good long time as well.
