A question about fuel and breaking in an engine.

[fohnjetzer]

I'm a new-b and I'm about to break in my engine this weekend. I just got a car that was completed and fully operational out of the box. The engine that it has is a 15CX and it has an 8.4:1 gear ratio. I was wondering the best fuel to use in the break in process and if anyone had any reccommendations as to the break-in process. I've heard about 100 ways to do it so far, but I trust the users of this site more than some yahoos on the web elsewhere. Any help would be greatly appreciated.

 

[AC48]

You should use fuel with no more than 20% nitro for break-in. If your car didn't come with instructions from the manufacturer than there are many ways to do breakin. I usually follow the instructions but if you don't have them then you can't do that. I'll leave the explaining for someone else because I'm not too good at explaining it. I hope I helped.

 

[olds97_lss]

I use the heat cycle method with all my engines. It takes a couple hours and about 10 - 12 tanks of fuel before it’s tuned for good performance. You should have a temp gun.

Some engines take a gallon before they are completely broken in and you start realizing the kind of power they produce. While others only take a quart.

First, pull out the glow plug and slowly rotate the flywheel until you know the piston is at the bottom of the stroke(This is known as BDC). Mark the flywheel with a dot of fingernail polish so you know where it's at what at BDC without having to pull out the plug.

Also, I always use 20% trinity MHP fuel in all my engines. It's been the most consistent for me.

Tank 1
You want it to run rich and with most engines the temps will range from 120-180 in the first tank. All you do is let it idle through the tank with the wheels off the ground giving the throttle an occasional blip to keep it from loading up too bad. When it runs out of fuel, position the flywheel so the piston is at BDC. Let the engine cool to ambient temps before you fire it back up.

Tank 2
You should start driving it on concrete or pavement of some sort in large figure 8's. Your not only breaking in the engine, your breaking in the driveline as well. You shouldn't get above 1/2 throttle through this tank. Start leaning the High Speed Needle about half way through the tank. You should be able to get to 160 - 180 or so by the time the tank is empty. Again, when it runs out of fuel, put the piston at BDC and let it cool to ambient temps.

Tank 3
Do the same as tank 2. Keep leaning a little bit to get the temps up. A good operating temp range for most engines is between 210 and 260. By the end of tank 3, you should be getting up to 200 or so. Again, when it runs out of fuel, put the piston at BDC and let it cool to ambient temps.

Tank 4 - 5
You should start leaning it to get the temps up above 210. If at any point in time, your temps spike up over 260, you got some issues or your being to aggressive with your leaning of the needles. Normally, as the tank empties to about ¼ tank, I refill while it’s running and keep it running. Through tanks 4 and 5, you can start opening up the throttle a little more to about ¾ for a couple seconds at a time. You still don’t want to peg the throttle. That comes later… After tank 5 empties, put the piston at BDC and let it cool to ambient temps.

Tank 6 – 9
I normally keep it running through these 3 tanks of fuel. All the while leaning a little bit every tank. Make sure your temps are within the safe range. By tank 8, you should be able to hit WOT for short 2 second bursts. After tank 9 empties, put the piston at BDC and let it cool to ambient temps.

Tanks 10 on up
Keep an eye on the temps. Nitro engines don’t like to be held wide open for extended periods of time. They are built for high RPM’s, but can’t withstand them for too long without overheating or causing some damage. Putting your piston at BDC every time you shut it down will help prolong the life of the engine. Keeping the air filter clean will also help. Keep the temps above 210 and below 270 and your engine will reward you with a long life and as much power as it will give you. Also, if your going to store the vehicle for more than a couple days, a few drops of after run oil will help keep corrosion down and again, will help extend the life of the engine.

This is how I break mine in and I get typically over 6 gallons of life out of my engines.

 

[Diver6127]

I would recomend nothing more than 20% for fuel. As for brands, I use Byron's Race 20% and have used Trinity Monster HP 20%. I would recomend both. As far as break in, I usually do what the manufacturer recomends in the manual. I came across an article on wildhobbies.com regarding break-in processes. Here it is, hope it helps ...

Nitro Motor Break-In Basics

Topic: R/C Cars
Category: Tips
ArticleID: 1054
Date: 10/13/2003 8:01:00 PM
Written By: WildHobbies

There are are more methods of breaking in a new nitro motor than there is motor manufacturers. Every nitro motor manual says something different, and every place you go, you will hear several other methods being used. Basically, no matter which method you hear described, it will break down into one of three categories:

High RPM break-in
Gradual leaning of the motor settings
Heat cycling
For each one of these, you will hear people how great it is and how much longer a motor will last using each method. I will briefly describe each one.

High RPM Break-In
This is one that has been heard more and more lately. The simple concept is that you run the motor at as high of an RPM as possible and burn through a full gallon of fuel. During the process you keep an eye on the temperature and try to maintain between 190-200 degrees. If you are tempted to try this, be forewarned, this should ONLY be attempted by very advanced users. It is very easy to not pay attention and have the motor cook itself before you ever get a chance to run it. this particular method has been recommended to me by several pro drivers. My concern is that those same pro drivers get their motors for free or deeply discounted so while you may get the performance out of the motor, lifetime is potentially decreased.

Gradual Leaning of Motor Settings
This is the process recommended in virtually all manufacturer manuals. The basic concept is that you start with settings that are as rich as the motor will fire up and run on. Let the motor idle through two tanks of fuel keeping an eye on the temperature to make sure it isn't getting too warm. After the initial two tanks, stop the motor and make sure the piston is at the bottom of the stroke and let it cool off.

Next, top off the tank and adjust the high speed needle 1/8 of a turn clockwise (leaner) and after every tank or so, lean out the needle another 1/8 of a turn. Most manufacturers will recommend letting the motor cool down between tanks. After 3 - 6 tanks (depending on which manual you read) you continue to lean the settings 1/8 of a turn at a time while also allowing the motor to run at slightly higher RPMs with each tank.
This method is recommended by motor manufacturers because it will get you started and running in a relatively safe zone. The more stretched out you make this process, the better your results.


Heat Cycling
Heat Cycling is the most time consuming break-in process but what is sacrifices in time, it makes up for in performance and lifetime. Heat Cycling is the preferred method of break-in used by many of the top motor builders. The point of heat cycling is to warm up the motor, let it cool down, and repeat. The exact procedure as recommended by Nitro Dan of Affordable Nitro Tech Racing is as follows:
Start the engine and let it idle, after 1-2 minutes feel the cylinder head, you want it to be hot enough so you can't grab on to it for more than 10 seconds at the base of the head. Stop the engine, make sure the piston is at the bottom of the stroke, let it completely cool down, back to stone cold.

Repeat this process at least 10 times! I usually dedicate the first tank of fuel to this process. It's going to take some time to do this so be patient. Now you can take it out and run it. Open the main needle one full turn. The next 4 tanks, run at no more than 1/2 throttle and vary the speed up and down. Let it completely cool down between runs and always make sure the piston is at the bottom of the stroke while it is cooling. Try to run the engine in the 200 degree range during this period.

Now 4 more tanks running up to 3/4 throttle, run it in the same manner as before.

Now you can go wide open, make sure to run it on the rich side for another 6 tanks. It should still be running somewhat rich at this point.

Now you can let it rip. These engines run best at temps 220 to 240 degrees. There should always be a VISIBLE line of smoke coming from the exhaust stinger


Click here for article

 

[ToRqUe]

I just let it ideal for 3 or 4 tanks, then start driven it on the 5th tank at no more than 1/2 open throttle. Then by the 6 or 7 tank i start 2 leanning it out.

 

[fohnjetzer]

Thanks for the help. I really appreciate it!

 

[Rochellcommaj]

Ok guys, I'm gonna chime in and ask another question.....

I understand the heat-cycle concept, but have to know something? In the manual to my car, it says letting it idle too long will heat up the clutch bell and possibly ruin it.
Now, How long is too long? When I broke it in, I was paranoid as hell about letting it sit too long while running it and not having it moving. I did baby it around about 10 mph and then would turn it off and heat cycle it... start over... It's a long process and when I leaned it gradually it got stronger and stronger... now that I'm on my third quart of fuel, Its starting to run like a scalded dog. Maybe everything is settling in quite nicely. Anyway, I just wanted to know how long was too long and is there a reason a manufacturer puts this in the manual, or are they affraid that maybe the person will have the idle high enough that the clutch shoes are dragging?

 

[olds97_lss]

I guess it depends on the car. But that's why I said keep the wheels off the ground for the first tank. That way, if the clutch is dragging, the drivetrain will spin with it.

In most cases, you can set the idle low enough so the clutch isn't engaged at all. Niether my savage or maxx drag at an idle.

Although, I was helping someone awhile back, they were having issues with an Associated RC 10 GT with the clutch dragging. After looking at the parts explosion and the parts list, there wasn't a spring on the clutch. It's like it was designed to constantly drag.

If your in the same boat as that, then definitly keep the tires off the ground or don't let it idle to long keeping it stationary.

 

[Skandranon]

I just let it ideal for 3 or 4 tanks, then start driven it on the 5th tank at no more than 1/2 open throttle. Then by the 6 or 7 tank i start 2 leanning it out.

Was just wondering how many galleons of fuel you are able to run though a engine?

 

[ToRqUe]

The first engine i ever had lastted 7-n-1/2 gallons but i never raced it, i just drove it in my front yard on the street.I just recentally took apart the old engine, boy did it look bad.