Preparing your Nitro RC Engine only takes a few hours, but the benefits are worth the investment in time. In a nut shell RC 2-stroke engine use a tapered sleeve to create compression, while most full scale cars use piston rings. The process of breaking the engine in is to make sure that the piston and the sleeve have the best fit possible. Like all things RC it just depends on who you ask about breaking-in an engine.
From experience I can tell you that all the methods work well, when in doubt refer to the manual, they will have break-in procedures specific to your engine. the only important thing to remember is not to be too harsh on the engine, break it in slowly taking your time. Remember your not racing yet…
The 7 Step Break in Procedure
While most people recommend running about 5 tanks of fuel through the engine I generally like to run 7, I just like to make sure that I get the engine broken-in correctly. If you look at the oil that comes out the exhaust you’ll see that by the 5th or sixth run the tiny bits of metal will be gone from the flow, initially you can see the engine breaking-in from the oil and unburnt fuel.
Refer to your manual for the specific settings for your engine. The problem is that because each RC Nitro Engine is different you can’t just copy your buddies settings, you have to work these out. Break in settings must be as rich as possible, this keep the engine cool and the excess fuel and oil will help flush out the tiny metal bits that come off during the break-in.
Fuel Tank #1
I’ll idle the engine for the entire tank, you often need to keep the throttle open about 10% during the first few minutes, at least while the engine warms up. Keep the revs as low as possible, but don’t change the mixture needle settings just yet. Once the tank is complete let the engine cool down for about 5 – 15 minutes. Be sure to leave the piston at dead bottom center while it cools, or else the shrinking sleeve could cause a problem if the piston is also there.
Fuel Tank #2
After the initial idle stage I’ll run the car with as little throttle as possible, but keep the car moving, I make sure when I accelerate (not more than 25%) I’ll do it smoothly and consistently. It’s important to start putting some load on the engine, because when you race your RC Car there will be load on the engine. Try to match your break in conditions to your expected running conditions as closely as possible. The idea is to slowly build up the revs of your engine until your able to hit max speed by the end of the 7 th tank. Run your car in a figure-8, as turning makes the engine work slightly harder. After the 2nd Tank you can start to lean your motor out a little.
Fuel Tank #3 -#5
Now we’re ready to start getting some speed out of your RC Nitro Car. What I do is start to run the car up and down a long straight, with figure-8 patterns at a low idle between them. I will run at max 25% throttle for about a minute, then rev the RC car flat out for at most 2 seconds. then return to a the standard max 25% throttle. Make sure you get your car to rev right through it’s range, but don’t keep it at full throttle for too long.
Fuel Tank #5 – #7
I continue as above, but shortening the periods between the bursts of full throttle. I also start to work out the tune of my car, I only change the air / fuel mixture before the 5th tank if I’m struggling to keep the engine running. After the 5th tank I start to lean the mixture by 1/8th turn. I still like to run it until there are no small metal bits in the exhaust discharge.
Once your done with the above break-in procedure I would still run my RC Car gently for the first couple of times on the track, this will ensure that you get the most life our of your brand new RC Nitro Engine.