It seems that if someone were to ask ten different RC enthusiasts how to break in a Nitro RC engine, they will get ten different answers. There are old school methods, and new methods – all of which argue on what will allow the engine to live the longest.
Below are some expert tips that actually mix the best advice from each expert, allowing for a reliable-running engine that will last a long time.
The most commonly suggested method of breaking in a Nitro RC engine is the heat cycle method. That means the engine must reach an operational temperature of 190 degrees, but it must do so properly.
#1 – Start the engine!
Allow the engine to idle for a moment for warming up. Do not rev the engine as it will wear out the pistons and sleeves faster (think: expensive to replace). After about three minutes, place the car on level ground, and run it in figure eights around the area. Use low throttle and do not go over 1/4 throttle to avoid stress on the rod and crank pin. Never blip the throttle on a new engine – it must be broken in, first.
#2 – Cool down time
Once the engine temp has gotten to operational level, stop the car and let the engine cool completely. Ensure the piston is at bottom dead center (BDC) while it cools to avoid trouble later on. This complete cycle should take about 15 minutes – three minutes for initial warm-up, then play time, then cool down.
#3 – Interval training
After the complete cool down of the engine, run it again for five minutes, allowing up to half-throttle on the figure eights, but no more than half-throttle. Then, let the engine cool down completely again, with the piston at BDC. Do another five minute interval after that, with no more than half-throttle and two bursts of full throttle. Let the engine cool down again as before. Then, run it at least one to three more times in five minute intervals. Some experts suggest only three minute intervals, but check the engine temp frequently – whichever time frame it takes to get the engine to operational temperature will be the correct time frame. This will have given the engine a minimum of thirty minutes break-in time, with minimal effort on the part of the controller (and much more fun than just idling the engine). That's all there is to it.
There are many ways to break in an engine – heat cycling is probably one of the most tried-and-true methods of getting the new Nitro engine to last. A word of advice to newcomers: avoid running the engine lean to raise the temperature – this will cause damage in the future. Let the engine run rich with plenty of lubricant, and the life of the engine will last a lot longer (much better for the budget in the long run, too).