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Josh Cyrul's Break in Method

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rccars411

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In the area of engine break-in, there are several different procedures that have been used over the years. Different manufactures, top drivers, and hobby store experts all vary in their opinion as to which is best. Over the past 10+ years of nitro racing I have found this procedure to give me good results in both areas of on-track performance as well as reliability.

Install the new engine into your chassis complete with clutch and ready to go as if you were going to race. Take a screwdriver, glow igniter, starter box, and a full bottle of fuel to a remote area where you won't annoy anyone with a running engine. Start your engine and allow it to warm up with several short ½ throttle “blips”. Once your engine has some temperature in it you can begin the break-in process. Start by opening the top end needle 1 full turn. Open the carburetor to full throttle and hold it there. Open the top end needle until the engine flames out. From here, close the top end needle ¼ turn and restart the engine again running it at full throttle. Run the engine full throttle for 3 tanks and shut the engine down.

Allow the engine to cool for 15-30 minutes. Once the engine has cooled down, run through the same process again for two additional tanks. On the third tank close the top end needle by ¼ of a turn. Instead of holding the engine at full throttle, start using the throttle by doing 2-3 second bursts of full throttle. Once you have done this for ½ of the tank close the top end needle another ¼ of a turn and continue throttling the engine. Continue closing the top end needle ¼ turn per every ½ tank of fuel. Do this until you have run a grand total of 8 tanks through your engine and then shut the engine down.

Allow the engine to cool for 15-30 minutes and then you are ready to hit the race track. Drive two tanks rich around the track slowly closing the top end needle sneaking up on that perfect mixture. At the end of the second tank your engine should be tuned to race speed. This will give you a total of 10 tanks of fuel through your engine before you really start to lean the mixture for ultimate power.

The reasoning behind this break-in procedure is that there is always a large volume of fuel flowing through the engine. Large volume of fuel means plenty of oil and lubrication for the break in process. This also helps flush out any burrs or small pieces of material that may have been left over from the manufacturing of the engine. Also, the engine has a load placed on it by trying to cycle all of the fuel through it – somewhat similar to the load that you will put on it out on the track when you try to power your car around the track. Last, the engine is broke in with rpm – if you break the engine in at idle then you will not be seating the piston, sleeve, and connecting rod at anywhere near the rpm that it will have to be ready for out on the race track.

This is the procedure that I have used with good success over the years of nitro racing. When I've hurried the break-in process I have had some engines last 30 minutes to 4 hours of racing. When I've taken my time and run through this process I've run engines as long as 16 hours of racing!! Yep, same piston and sleeve!!!! Be patient and have fun!!

Good Luck!!
Josh Cyrul
CEFX
 
How do you run the engine at WOT for 3 tanks? Wheels off the ground? I don't think I know a place that I can run WOT for a tank... With it being that rich, I'd think it's kind of hydrolocking and beating up the internals with liquid pressure. Things like the con-rod bushings and crank bearings.

I've read stuff like that for plane engines or when someone has a break-in stand. But those give you air flow.
 
Ahhh....
Running it so rich that it can't wind up. Here I was thinking you'd have this engine screaming for 3 tanks of fuel. Can't imagine that would do your conrod or crank any good.
 
I'll stick with the heat cycle. This method seems a bit off the wall to me and like was already mentioned, he's sponsored so it doesn't make a rat's bit of difference. I mean come on, he's not running the same mill for 16 hours being sponsored. Even the guys I know with partial engine deals don't run them that long.
 
Well then consider me different. I run mine until its time to rebuild it.

That guy used it on an STS, so thats gotta say something about Cyrul's break in method! STS mills take about a gallon to safely break em in.
 
olds97_lss said:
How do you run the engine at WOT for 3 tanks?

I've read stuff like that for plane engines or when someone has a break-in stand. But those give you air flow.
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I've broken in many plane engines, and that's the way it's done. WOT, but very rich, and yes, they have the added advantage of a propeller providing some major cooling.
Plane and heli engines run at an almost constant RPM, with no hard loads like car engines, so the final tuning is quite effortless with an airplane, but can be very frustrating with car engines that need to put out low end power as well as high RPM.
 
rccars411 said:
Well then consider me different. I run mine until its time to rebuild it.

That guy used it on an STS, so thats gotta say something about Cyrul's break in method! STS mills take about a gallon to safely break em in.
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Most mills take about a gallon to get good and broken in.
 
I'm glad people on this forum understand! Other forums are nothing but OS fan boys and think they only need half a quart to a quart before its finally race ready.
 
Rolex said:
I've broken in many plane engines, and that's the way it's done. WOT, but very rich, and yes, they have the added advantage of a propeller providing some major cooling.
Plane and heli engines run at an almost constant RPM, with no hard loads like car engines, so the final tuning is quite effortless with an airplane, but can be very frustrating with car engines that need to put out low end power as well as high RPM.
Click to expand...

Yeah, I understand the plane engines on a stand and how that can be done. I was just trying to imagine how you could do it with an on-road/off-road engine in a vehicle. Find a huge parking lot I guess.
 
You know what, its a losing battle at this forum. You are criticized for digging up a dead topic... but when you recreate it, you are criticized for doing so.

And one can easily argue the flaws with the heat cycle method that is stickied here on the forums. Most big blocks take a good gallon before they are correctly broken in. Many done under the heat cycle method (20-25 mins of runtime then head to the track) end up in failure. See what I posted about it for more details. This is something EVERYONE should read.
 
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rccars411 said:
You know what, its a losing battle at this forum. You are criticized for digging up a dead topic... but when you recreate it, you are criticized for doing so.

And one can easily argue the flaws with the heat cycle method that is stickied here on the forums. Most big blocks take a good gallon before they are correctly broken in. Many done under the heat cycle method (20-25 mins of runtime then head to the track) end up in failure. See what I posted about it for more details. This is something EVERYONE should read.
Click to expand...
It's great to see your a know it all, thanks for your contribution.
 
All engines are different. I'm running a STS.21 that was a complete dog until I had put 4litres through it.

On the other hand my LRP spec3 only needed a quart through it before it was fully broken.

The STS now has almost 7 litres through it and it's still not completely broken in. I am expecting this mill to last me a long time. It was heat cycled, only instead of 25min it was 4 litres. :cool:
 
rccars411 said:
Many done under the heat cycle method (20-25 mins of runtime then head to the track) end up in failure. See what I posted about it for more details. This is something EVERYONE should read.
Click to expand...

Can you provide the source of the data that led to this conclusion? Also the heat cycle method is not just 20-25 minutes of runtime and then hit the track. If done correctly it will take longer to break in an engine due to all the time spent waiting for the engine to cool down between cycles. Maybe you are confusing the heat cycle method with something else?
 
neobart, your "LRP" only needed that much fuel because its an SH engine. If you can find a bad SH engine, it'd surprise me. SH used to have a few bad mills over a decade ago, but they have really stepped up and delivered what peeps want.

Oh and diesel, the idea of the heat cycle method is the 20-25 minutes of engine RUN TIME ;). Gotta love how they say its track ready right after those 20-25 minutes. I learned the hard way that your engine isn't track ready until you pull the plug and check for how tight it is (the pinch). And now that I sell engines, I inform anyone. I'm not arguing, I'm stating what is in print in USA RC magazines and online.

After cycling the engine in this manner for about 20-25 total minutes, it'll be ready for the track and race tuning.
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Says that in the stickied thread.
 
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you're right on the money with SH mills. They don't need that much breakin. And I really like the Spec3. It the best engine I've had in my LST2 yet. I even have a .21 spec2 in my Muggy. Also a nice engine.

But as far as .21's go, out of the LRP and the STS, the STS takes the win. This thing revs to the moon and never seems to stop. I currently have it in my 8ight-B and like how it runs.
 
It's the .21T I have in the buggy. Do you now what the have changed for the .21T rev.2?
 

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