JoeMaxx

Yup many engines will never make it thru a full breakin process without replacing the Glow Plug. Heat cycling is just a term they use for short breakin process. You did good to keep it around the 190 heat range which means you ran rich. Heat Cycling calls for higher temps over a shorter period of time. Up and Down thanUp and Down with shorter runtimes.

A longer breakin procress will never hurt the engine shorter ones do. Some engine manufactures ask you to run rich for 8 tanks of fuel. I am a 5 or 6 tank guy then never really tune for performance until my 6th or 7th tank.

1QwkSport2.5r

The only engines I've ever had a glow plug fail from break-in is the first ringed engine I ran, and even being fouled, the engine still ran well. These ABC engines really shouldn't foul a plug unless the fuel you use sucks chode. I've broke in lapped iron/steel engines on new plugs and after a 1.5 gallon break-in they still fire the engine fine. In fact, I have a little .30 iron/steel engine that has 4 gallons on the very first plug the engine ever saw. I think it comes down to the quality of the plug you're using. Some plugs are of lesser quality (crappy wire alloy) and don't hold up well.

I'm a big fan of lots of oil for break-in... Usually the first gallon is high oil - 14-16% usually although I have used 18-20% oil which didnt affect anything. Sometimes it takes that long for the engine to loosen up enough to really wind up and the extra oil really helps the hydrodynamic oil film stay thick and keep that piston from rubbing metal to metal with the liner.

The plug pictured above is probably a swing and a miss in the QC department.. I've had engines come with bad plugs in the past, but its been a very long time. The last half dozen engines I bought didnt come with plugs from the factory which is fine since I rarely use the OEM glow plug anyway... Those go into my 'break-in' box if they actually work.

If ya'll want some good educational reading about glow plugs, check this thread: http://www.rcuniverse.com/forum/m_10626380/tm.htm

This thread is in the Aircraft forum but there is a lot of discussion about heat ranges, the wire alloys, and how the plated finish of the plug affects the heat range among a host of other things.

supertib

Race tuning is definitely very challenging and requires a very high level of skill to be successful at...... I think every nitro enthusiast owes it to themselves to check out a 1/8th track/race......... I believe its one of those things that you have to see for yourself to fully understand and appreciate......Many people get into and out of the hobby without ever seeing or hearing a full out competition nitro in action, which is IMO a shame....as there is a very large gap between a typical RTR nitro bought at the LHS as compared to some of the higher end modified rigs we see at the tracks.... I think many nitro hobbyists likely have no idea the level of performance these engines are actually capable of.....

JohnP2

I agree with this 100%. I have plenty of RTR engines and know them inside and out. I've found they are either tuned or not. The "terminal tune" for each one is veryeasy to find.

Once you get into racing engines, however....it's a different game altogether! At my track I see and hear these things where I step back and say, "Yeah....that's what I want!". You are correct about level of skill to properly tune these as there are aslew of variables involved. I am an apt pupil and getting there slowly but surely with lots of practice. I have two very good stock engines (O.S. 25xz and Werks B6) and once I cut my teeth on these for the next 6-12 months, I'll know exactly what to expect when ready to upgrade to a modded engine.

rccheech

When Im.done with my engines on the stand, they are pretty close to a race tune. The last run on the stand is to check the performance of the engine and its ready for the car, a few tweaks of the needles and its about all set.

When you do enough of them, you can feel when they are broken in, some take longer than others.

JohnP2

I'm definitely intrigued with that break-in method.

rccheech

When I have a good video cam handy, Im going to do that full video with details.

eemilioc

Hi Guys
Due to the country where I live, the shipping of a break-in stand is really expensive. So I am trying to make one and everything seems easy from what I see in the pictures the only thing is the prop (talking about the Hudy break in bench). Does anyone have an idea of what airplane props can be used (I fly airplanes and have a wide variety of props that I could try) or any other Ideas or just the whole idea is too crazy.
I would appreciate any info

1QwkSport2.5r

The rpm that car engines turn will almost exclusively require carbon fibre props. To get up to those kinds of rpm, you'd probably be looking for a 6x3 or 5x4 or something. My little junk yard FP .10 turns over 18k on a 6x3, so I would think a decently powerful .18-.28 should get close to the rpm needed. I suggest contacting Hudy to find out what prop they use. It's going to be small, that's for sure.

eemilioc

Thanks 1QwkSport2.5r , do you think Hudy would be open to give that info?

1QwkSport2.5r

I don't know. It doesn't hurt to try. If they don't tell you, there are a few guys here on the forum that have one of those break-in stands that might be able to tell you. I know APC props have a rotational limit of 190,000/prop dia. so a small APC might work. A 5" prop has a limit of 38,000 which is right in the wheel house of a typical car engines top rpm.

nitroexpress

$40.00 and you're good to go.

http://www.nitrorcx.com/mad-cp0047.h...FWdo7AodDQ0AGQ

Or you can buy the prop.

http://www.rdlogics.com/search.asp?k...tand&search=GO

llkoolskillet

Those blades are to short, you need a 10x7 the longer the blade and more pitch the more drag put on the motor.

http://www.savage-central.com/module...er=asc&start=0

1QwkSport2.5r

You do realize that an ABC engine needs to turn at its peak/intended rpm to break in properly, right? A 10x7 prop will load a car engine way too much. It wouldn't turn more than 10,000rpm on that prop if even that. A .46 has a hard time turning faster than 13k on a 10x7. Not to mention you'd need to up the oil content of your fuel to run a prop that big.

Car engines don't spend much time at 40k, that's why they don't incinerate themselves on that break-in stand. They're only at WOT for a second at a time.

But hey, I'm an idiot.

llkoolskillet

What is the intended practical rpm for a .28 then?

What size prop would you use then to mimic the drag the vehicle would put on the motor during break in?

1QwkSport2.5r

The practical rpm of an engine depends on its port timing and port area. I'd hazard a guess at 28,000-41,000rpm depending on the engine. I'm sure Neal's modifieds are turning 40k+rpm.

The prop itself puts drag on the engine, the drag is merely there to prevent the engine from shaft running. The whole idea of breaking in the engine is to get the piston to find its perfect fit to the liner and for the conrod bushings to seat to the wristpin and crankpin. The only way this will happen is if its running at the proper rpm. Too low of a rpm and you're basically wasting power. Once the engine gets its "seat" at a lower rpm, it likely wont ever run at its full potential. I would prop the engine so it will turn at its intended rpm. For a racing engine, say a .21 buggy or truggy engine, I'd run it at at least 38,000rpm. For a RTR basher monster truck engine, I'd expect it to peak around 26,000-28,000rpm. As to actual prop size, I dont know. I am guessing a 5x3 or 6x3 would be a good start. A tachometer is necessary in this situation.

I broke-in my first airplane .46 engine on a 10x6 as was suggested by other members and now 4-5 gallons in, it is easily down 1000rpm from where it should be with the pipe thats on it. I should have run a 9x6 on it to get it in its powerband. A new piston and liner will fix it.

llkoolskillet

The seat/ fit whatever you speak of is the pinch area, notice in this pic of my ERCM Picco that chrome looking ring. When its a complete ring with no gaps, that's a perfect seal. This picture was taken at the one gallon mark of break in. I don't shut my motors off, I run as much fuel as possible thru them before I do shut down. It's not about getting the motor up to proper running rpm, it's about getting up to temp and keeping it there. That's how the seal is formed. If I was to break in my motor pushing it to 30k rpm on the bench the motor would be stupid lean cause the pinch is so tight.

purenitro33

That bench was designed to be gear drive so you could reduce the speed of the propeller while still achieving full rpm capabilities quite easily. It also has the clutch engagement so when your at idle the blade comes to a stop, it's also set up so all your adjustments are done behind the blade for safety. By changing the spur and clutch bell along with all the options of props available you can custom set the gearing and prop pitch to load the engine to whatever you like, from .12's to .36's.

As for heat cycling, I think it's a marketing ploy from the manufacturer so they can sell a whole lot of extra pull starters, one way bearings etc. It's as simple as when you are breaking in an engine, if you took it apart mid run and looked at the piston it would have a coating of oil on it. So if the piston isn't getting hot enough to cook/burn the oil, how is it anywhere near the temperature required to change the molecular structure of the aluminum? it simply can't and doesn't, so "imo" it is a waste of time. Start it and feed it fuel for as long as you can for the break-in and save all the wear and tear on the starting components. Also (and I can't stress this enough) use a HOT plug during break-in, the engine will start and idle so much better compared to the cold plugs that often come in the rtr engines.

1QwkSport2.5r

I didn't say an engine won't break in at a lower rpm. It will just not perform as well as its capable of.

I have an AAC Jett engine for airplanes that (is of better quality than even your picco) the manufacturer says the main reason for doing a break-in run is to seat the rod ends. He doesn't mention piston fit to the liner though the crown of the piston does squish a little and makes a sort of raised edge to the piston. Dub Jett specifically states to run the engine at the target rpm as this is where the engine is going to spend its life running. Why would a guy selling $340-$600 engines CNC'd from aluminum barstock say to run the engines hard and fast to break then in? I know you car guys like beating me up about my aircraft engine references, but the fact is they operate and run in the same way. They would run 40k just like a car engine if you wanted it to. That is if they have the timing for it anyway.

I looked closer at the prop on the stand; it could be a 9" prop cut down to a 4-5" diameter. With that much of the blade surface cut off, I doubt the pitch will have much of an effect on engine load. It will provide more cooling than load.

Purenitro33 - how come the prop is bolted directly to the engine in the pictures in the links provided above? Doesn't look like a gear drive to me. The prop nut especially made for a short car engine crank...

But I'm no engineer, or chemist, or any other sort of smart guy. I just call it as I see it.

1QwkSport2.5r

I do agree "heat cycling" is kinda pointless. Heat cycling is basically annealing and in order to anneal aluminum, brass, or steel, the temperature would need to be well over 600 degrees farenheit.

eemilioc

Hi Guys
I now have a really good idea of the basics and its inevitable to try different props while measuring rpms and temperature. I broke in a picco 28 and a jammin 28 after I had to repair them totally and their final performance was much better than what I felt the first time I broke them in (new motors) with the manufacturer´s specs. They even idle much better and their transition curve is much smoother.
Thanks again and I will post maybe in one week my work bench for breaking in motors.
Thanks again for all your ideas.

supertib

You cannot breakin a offroad engine at operating RPM's, you will tear up the piston and do substantial damage.......I breakin at 14-16 000 RPM

the prop on a breakin bench may look small, but it provides more load then you will get wth the engine on the ground in the RC car.......... A strong 28 engine will only spin the Hudy prop to 25 000 RPM under max power and tune........It does a hell of alot more then just pass air over the engine....

1QwkSport2.5r

Interesting... This inspires me to get the Hudy prop and try it for myself. Only to satisfy my own curiosity.

eemilioc

I have been trying to find the Hudy prop and cant, do you know where they sell it. It has me thinking how does this prop accepts any size engine, the design must be the key for it.

eemilioc

Thanks supertib for the info on the rpms, that is a good reference for me to start.