Originally Posted by rcdude236
Every 2-3 minutes, shut the engine down & let it cool completely with the piston at BDC, and then fire it back up; continue this cycle until you've run 15 min or so, and then bump up to 3-4 minute intervals. Vary the RPM and don't be afraid to get the temps in the 200's. What you want is heat cycling of the components without the incredible stress that comes with breaking an engine in when it's overly rich & cold. After cycling the engine in this mannerfor about 20-25 total minutes,
So when it says 25 total minutes does that mean only do 10 minutes of driving on 3-4 minutes or does it mean do 25 miuntes on 3-4 intervals? Thanks
25min @ 3-4min runs with varied throttle.
Here's what I do and am doing currently...
Heatgun on the engine to 180F-200F each time I start it up during break in.
15min run it 3min at a time 1/4 throttle or so down straight. turn around come back 1/4 throttle. Stop and BDC the piston and let it sit 10min.
Next I do 4 min at a time doing 1/2 throttle going away from me, ease off and turn it around and bring it back toward me at 1/4 throttle. Repeat for 25min or so. BDC the piston and let it sit 10min.
Then I do another 15 min at 1/2 and 3/4 the same way I mentioned above.
Let it sit 10min after this, again piston at BDC.
Then I do 1 tank (whatever minute mark it ends up being doesn't matter) where I ease the throttle in and pull it back to 100% and count to 3 while I do it. So when you start pulling count 1 and by 3 you should be at WOT. Then back it off, bring it around and repeat. Again, when you start pressing the throttle count 1 and at 3 you're WOT and you back off. I leave it sit here for 10min again at BDC.
Then I do 100% throttle just like above, but I let it run a second so I start at 1 and hit the throttle, when I get to a 3 count I'm at WOT...then at 4 I ease off and bring it around for another pass. Then I leave it cool again at BDC.
After that I run it carefully around, not leaning it out very far unless it needs it to keep running properly. I play around with it somewhere and am very cautious of my throttle control. I don't like to slam the trigger back to 100% like you're trying to run a drag race, I ease into it. Driving normally, only doing enough to get you through. No wild man stuff here.
When it's broken in, which depends on the engine in question, you just know it. It will start having more power but the engine will show signs of being overly rich. At this time you may lean it out slightly and run it some more watching temps if you have a temp gun of some kind. I don't really worry about an engine running hot if there's plenty of smoke, some engines run great at 260F and some run great at 220F. There's no best temp to my knowledge. I test the temp to make sure it isn't too cold when I run it. Remember you are looking for heat to get things worked in, cold temps in the engine make the engine run slower but also take longer to fully break in. I am not aware of an engine failing flat out from being too cold, but it seems that Nitro engines open up better (that is achieve optimum power) more quickly and reliably with a bit more temp.
I'm still learning a lot of the technical aspects of Nitro engines etc, but I've done this break in method on numerous engines in various vehicles with good results.