Checklst

+2 Tune for reliably on the ground and break-in in the air.

captinjohn

+3 Tune for reliably on the ground and break-in in the air.

kmeyers

+4 But, tune for reliablity on the ground while in the air plane or a test stand engineered for the requirements of the engine and break-in in the air.

There is more than one good reason to break-in an engine in the air.

One of the best and most powerful reasons is safety!

When DL came out with their 50cc years ago a flyer was badly injured by running the engine on a solid bench held in a heavy ridged vise. The engine broke away from the vise.

Most companies today because of this type of incident recommend mounting on the air plane for break-in.

So the simplest and safest recommendation is to mount in a plane and break-in the air.

At our field we also recommend easy flying and big loops. Loops especially because of there power requirements (power on 4 or 5 seconds followed by idle for 4 or 5 seconds with speed and air flow).

dirtybird

My Feedback: (5)

I have just one question before I leave this thread. If the manufacturer recommends breakin on the ground, why would you buy his product if he is so incompetent that he does not know the best way to operate his product?

Lifer

My Feedback: (1)

Truckracers' comments are spot-on. The only engines I routinely break-in on the ground were ABC racing engines. Those I would run at peak for 3 minutes then allow for a complete cool down. Thermal cycling. Ringed engines just need running time. Plus, they run cooler in the air because of airflow and the fact that the prop unloads in the air, but not on the ground.

willig10

On all my gasoline engines, I tune for reliable transition from idle to full throttle. Then might put a couple of 30 seconds or so of heat cycles on the engine. Take her out to the field and break her in, in the air. Now what I do in the air is takeoff at close to 100% then once the plane has turned downwind at altitude, throttle back to a low setting say around 15 to 20% throttle and just fly around and enjoy the flight. Get the plane trimmed etc and perform some mild aerobatics with throttle manipulation. Tune as needed for atmospheric conditions i.e. I can't stand to hear an engine 4 cycling/dieseling while in flight. Make sure the engine does not sag while flying downwind after takeoff. If it does you might want to check airflow on the engine, and exhaust hole in the cowling. Also ensure the Tyson tubing for your overflow does not contact the muffler. If it does it will melt closed. Kill your engine and implode the fuel tank.

I hope this helps some. Good luck


Glenn

Granpooba

My Feedback: (5)

Dittto !

BobH

My Feedback: (2)

Typically you won't "dead stick" while breaking your engine in on the ground... just a consideration.
A reliable engine is the best engine

Truckracer

My Feedback: (19)

I reviewed the pile of engine manuals I have in my files and none specifically said to break in the engine on the ground or in the air. They mentioned things like engine mounting, cooling, oil, safety factors, etc. and some said the engine would probably take "X" amount of gallons before it was fully broken in. Overall they pretty much left it up to the owner to pick the break in location and method. I have seen manuals that recommended long ground break-in periods but wondered where would one do this without driving everybody in the area completely crazy with the noise. Where would one find a clean enough area to assure the engine was breathing decent air and how would the user assure the engine is receiving proper cooling without some kind of ductwork. And how would a person do this all safely.

I pretty much subscribe to the theory that once I pay my money, the engine is mine and I'll break it in as I please. I believe that most companies understand the nature of modelers and their surroundings and are OK with the engine being run in as the owner sees fit as long as proper operating conditions are met and the owner doesn't abuse the engine. Lets face facts, 99% of us are going to do as we please regardless of recommendations anyway! Thankfully, we don't have any break in police ..... yet!

av8tor1977

My Feedback: (6)

Well, just one last comment from me too, about manufacturers recommendations. An example. DA obviously makes very good engines. Not so long ago, their advice was to break in on Lawn Boy, and then switch to AMSOIL. How many engine guys do you know that agree with that? Not even DA anymore.....

Breaking in while flying is great for the engine. If the cooling system is set up right, this allows for the best cooling, and also alternately loads and unloads, heats and cools the engine, and it is pretty much universally accepted that these are the things that contribute to a good break in and resultant ring seal.

AV8TOR

Truckracer

My Feedback: (19)

I firmly believe the various companies are constantly learning from their customers and especially from viewing the engines returned for service. Fuels, oils and engine performance requirements are constantly changing. A company may recommend something in good faith one day only to change that recommendation later on when they learn the first suggestion was not so great.

As users, we have to realize that for the most part, our engines and many other hobby related products come from relatively small companies. These are companies that don't have unlimited engineering, testing and research facilities that an aerospace company might have. These are companies that are growing and evolving constantly to meet their customers needs while trying their best to remain profitable in a very competitive environment. As such I believe a fair amount of the R&D that goes into these engines is done in the field by end users ..... and yes this includes break in recommendations.

speedracerntrixie

My Feedback: (29)

A couple years ago I drove through a large puddle of water in my SUV. I found out the hard way that water inside an engine will not compress. Even worse is that the one cylinder that water hits first will lock up while the rest of the motor keeps moving. I'm sure you can imagine the end result. So to shorten the story some it took a while for the insurance co to approve a new engine rather then a used engine with the same or less mileage. The the wait for one to actually get built. Then the couple of days for it to be bench run before installation in my awaiting SUV.


True story except for one small part, anyone want to take a guess at what was false?

Lifer

My Feedback: (1)

The insurance company was reasonable?

speedracerntrixie

My Feedback: (29)

actually they were great. My rep was calling me every couple of days to check in. Their policy was to locate a used engine with the same or fewer miles. Problem was my SUV is a 2002 year model but at the time only had 72,000 miles on it. They couldn't locate an engine with less milage. After looking for 2 weeks she pushed to have a new crate motor approved. Once approved the dealer then sent out a national ping to see if any GM dealers had an engine. No dice, I had to wait until Detroit had enough orders for a 6L Vortech engine before they would ramp up production. That took 3 months. In the meantime I had to argue with the dealership to maintain my battery and a tire had a slow leak and they didn't want to roll a tank out and top off the tire weekly. Nor would they install new tires because " there is no way to get the car to the tire shop ". In the end Flo paid $12,800 for my new engine and install, it took 4 months, the dealership were complete DB's and the SUV that had a full tank of gas when it went in was bone dry when I picked it up. The insurance agent did a follow up call after the fact and I told her about the gas. She called the dealer and his response was " gas isn't my problem ". She called me back and apologized for the issue. 4 days later I got a Shell 50.00 gift card with a note from agent saying " sorry it doent cover the full tank but it's the best my boss would approve ". Capitol Chevrolet lost any business I would have given them in the future, Progressive has a customer for life. Sorry to go off topic here but IMO customer service is something we should all reward or punish accordingly.


back on topic, for 15+ years of competitively flying IMAC, all engines are broken in while being flown and tuned according to what is seen and heard in the air. I can only assume that some engine manufacturers know their brand are going to be used by gasser newbies. By suggesting they be bench run could help the newbie get aquainted with the engine and thus reduce an irate guy calling up wanting his airplane replaced because the engine quite without warning. That and they sell more parts that get heat damaged.

willig10

Great story speedster.

Glenn

willig10

Speed racer. Hate spell check

Glenn

acerc

I don't think either method, air or ground, makes any difference on the engine. If I have a scale build that I don't want the break-in crud on, I do it on the ground. If the airframe does not matter, such as an ARF, then in the air. And in all my years I have not noticed a difference in the engine.