RANIERY

My Feedback: (3)

HELLO, I HAVE NEW NELSONS (Q-40 AND Q-500), SO BEFORE I DO THE BRAKE IN I WAS WONDERING HOW DO YOU GUYS DO IT (RPM, PROPS, ETC).
THANKS FOR THE HELP

oddy

A friend of mine which frequently have the best engines show me the next:

1.- To a 8.8x8.75 prop cut aprox 1 to 1.5 inch each side and balance it
2.- Run 1 tank with this prop and the engine will give you aprox 22,000 RPM´s without needing to close much the needle
3.- After that put on a regular 8.8x8.75 prop and fly it at 18,200 RPM´s for 5 to 8 flights.

Hope this helps.

splatt

22,000 RPM's on a gray prop may not be the right thing to do. I'm not the biggest expert, but isn't there formula for figuring out how many R's a prop can turn safely ?

Wood or a black prop may be a better choise

DHG

My Feedback: (7)

Go 'til it blows up, then back off 100 rpm.

Seriously, the gray APC 8.8 x 8.75 can probably stand 22,000, but why risk it? Use the black APC 7.4 x 8.0. Trim the ends if necessary, but it should run close to 22K even at the stock length.

And ALWAYS wear safety goggles. Not only for the prop, but for a battery clip or neck strap that might fall into it, or if the engine vibrates loose and starts chewing up the test bench ... whatever.

Once Burned Twice Shy

Ed Smith

So far the Break-In advice has not been all that good. If this process is not done properly the engine can be ruined as a racing engine before it ever gets into an airplane.

So let us start at the very beginning. Before you do anything to the engines, I mean anything, do not even crank them over cold, Take the engines apart and thoroughly clean them out. There are aluminum chips inside them. Lubricate before re-assembly. I use Transmission fluid.

Just lately the shimming set up of these engines has been a bit of a hit and miss affair. When I used to get my engines direct from the factory they were set up as follows.

428 deck height (D.H.):- 0.190", head clearance 0.013". For break in set the D.H. to 0.195", keep the clrnc as specified.

422 deck height :- 0.193", clrnc. 0.016. For break n set the DH to 0.198" maintain the 0.016" clrnc.

Cut one of the APC 7.4 x 8.0 carbon props down to 7.0 dia and balance. A balanced prop should stop anywhere on the balancer, not always horizontal.

You will need a very firm, steady test stand with a fuel tank mounted to it. Get some powermaster 15% fuel as this is the fuel usually used at contests. You will also need a tachometer and a blow torch.

When you have done all this come back to this thread and we will go to the next step.

Ed S

daven

My Feedback: (1)

Wow, Ed and I are on the same page for a change.

Nearly Identical to what I do.

Good write up.

Curious what your next steps are.

Ed Smith

Probably, Dave, because there is only one way to properly break in a Nelson engine.

Ed S

daven

My Feedback: (1)

Well, I'm not so sure about that statement, but lets not take steps backward quite yet

I know some people use specially blended fuels for their brake in, including Mr. Shadel.

Anyone got any favorite recipes?

garys

I know the fuel Shadel and many others use typically has 20% oil, with half of that being castor. I usually just use Powermaster 15% heli fuel with castor/synth blend, as it has more oil than the airplane fuel, with extra castor. I actually use it for whatever little practice I get as well, just to have the extra oil. I know some people claim to think it's best to run the fuel you race, but frankly, all fuels do change slightly batch to batch, so it's impossible to always be running the "same exact" fuel, it's just a fact of production. I'd rather always know I should have a little extra oil.

I don't preheat my engines like Ed, and he's one of the few that I know that actually do it. I kind of figure if the best in the world don't (including the manufacturers who test run the engines before sending them out), it's probably not worth the risk of over heating the case. Remember that when the engine is running, the front and left sides of the cylinder (viewed from behind) are running cooler than the rear and exhaust side (from the cool raw fuel coming in and prop blast). Also, the sleeve itself his much hotter than the outside case when it's running. If you heat it with a torch, the case will be much hotter than the cylinder.

I think in order to get the sleeve/piston temp up anywhere near enough to where it should be, you'll overheat the case and possibly cause it to warp. If the case is warped, you'll never have a good engine.

When I get a new engine from Shadel, I don't bother to take the engine apart to clean it, measure it or anything (remember he typically test runs them to make sure they're up to par). I try to put a handful of runs on it on the bench with a light prop (turning about 22k for Q500 and 27k for Q40), and then I use a light flying prop (either lighter pitch for Q500 or a APC carbon prop (V1 or V3) cut to about 7-7.125" in diameter for Q40) for a handful of flights. For flying, I make the sure the needle is always on the rich side (but not blubbering rich). I typically run about half a dozen flights with a light flying prop, slightly leaning it out each flight, but still rich. After this, I go to my regular flying prop, again rich. It'll probably be another half dozen or so flights before I set the needle to a regular racing setting.

I have a Q500 engine that I got from Shadel in January, before the Winterfest race. I didn't have a chance to bench run it, so I just started with a light flying prop and broke it in in the air as described above. It now has roughly 40 flights on it, with four fast times, three wins, and a second, in five races. I can't imagine it would be much better if I changed anything on it. It still hasn't had the head off of it, although I probably should take the head off and wipe the carbon off of it and the top of the piston. By the way, I never use any kind of abrasive polish (Mother's ect) on heads, or anywhere inside an engine. I don't believe it will come out, and will work itself through the piston and sleeve over time. Ask Mike DelPonte about his experience with this. Also, it puts a radius on the edges of the "double bubble" in the head, which you do not want.

Many people mess with stuff from the beginning, often when they really don't know what they are doing. If they don't know what they are doing, it's more likely they are going to mess it up.

GS

RANIERY

My Feedback: (3)

ok' i got the prop allready cut down to 7" (q-40 prop), that will turn 22000 easy on the q-500. now what kind of prop i need to run the q-40 @ 27000 rpm.


now, when i put shimms under de deck waht i'm doing? gettin more rpms or what. will spins higher pitchs props or what?


sorry but i like to know what i'm doing so i have an idea. i can use the clearances that you recommended but i like to know the why?

i'm knew to nelson and i have a few and don't wan't to do anything wrong.
thanks

splatt

I believe your saving the "pinch" of the ABC sleeve for later use, not being so hard on the conrod and such. Right folks?

I'd break in the Q500 motor and cut your prop down further for the Q40

daven

My Feedback: (1)

Thats exactly right Jesse. If you start with the sleeve raised .003-.005" of an inch your not putting as much stress on the internals during the break in phase. As things start to break in, you can lower the sleeve, which will give you a new squish band and a tighter fit because of the taper in the sleeve.

To get the Q40 engine just slightly over 26k (thats about where I break them in), Just take a Q40 prop and cut down the tips evenly and run on a already broken down engine to check the approximate Rpm. A broken tipped black CF or wood both would work fine, just make sure its balanced.

HighPlains

My Feedback: (1)

I'm going to agree with Gary (sorry Gary, where did you go wrong?).

Raising the sleeve 0.003 to 0.005 is a waste of time. The sleeve doesn't have much more taper than that over the entrie length of the sleeve, so the change in pinch is minor or slightly less.

It is far better to do like Gary and just run it without taking it apart. That is where it is broke in, so your best piston/sleeve seal will be in the inital position as received. You can never reassemble the engine and restore the sleeve to the exact same position.

garys

Bob,
I'm not sure how to take the fact that we agree?

I used to always run my engines with the sleeves up higher and ran slightly lighter props than most (sleeve always high, not just for break-in). I liked the higher RPM setups with the props at the time, and always thought as it wore, I could lower the sleeve and get some performance back. I never noticed this to be actual work in real life.

Then I figured this out. The engines only have a few thousanths of an inch of taper in the sleeve, which is in roughly the top .250" of it. most of the taper isn't even reached by the piston because the piston doesn't go all the way to the top of the sleeve. Moving the sleeve even .005" will only gain you about 2% of the total taper back. So if there was .005" of total taper (I don't remember how much there actually is, it's been a long time since I've measured it), you're only gaining .0001" of "pinch". Do you really think it's going to gain anything?

I try to not ever take a top end out of an engine that's running well. You're right about a piston/sleeve being broke-in in a certain position, and it's pretty much impossible to get it back to the same place once it's been moved at all. Yeah, 99.99% of the time you won't see a difference, why take the chance? If you see me with a sleeve outside the engine, I'm in trouble, because it means that either the engines giving me issues, or it's been in the dirt.

I did used to do the initial runs with the head slightly higher, but have since stopped even doing that.

GS

Ed Smith

Well, the experts have spoken. There is no need to describe my pathetic attempts at engine break in. I trust Raniery, that you now have all the information you need.

Ed S

garys

Ed,
I was just saying what I do and my reasons for it. Didn't mean to offend you. You should show your way as well. People all do things differently. Best to pick for themselves what they like from what they see.
GS

HighPlains

My Feedback: (1)

Come on Ed, where's the love?

Give it up, or we will go back to talking about bogus boogie boards!!!!!!

daven

My Feedback: (1)

I am no expert Ed. Would love to here your procedure, everyone seems to have their own black arts and we only learn by sharing what we know.

In the past, I had always left a good running engine alone, but recently started messing around with them after every race. Not sure if its helping yet or not, we will see.

splatt

The magic of the racing... the allure... the passion... the BS.

Darn guys, loosen up and relax folks.

I must admit that it seems once an engine is broken in you would not wish to change it, but hey it's my toy to break so ***.

I'd like to hear all ideas too. I'm curious, why make all those shims then, to confuse the timid?

I just want to try things, be safe, learn from others and have fun and enjoy my hobby.

So Ed, keep it coming, in pefect english of course

diggs_74

I too am relatively new to this Nelson thing and have learned a great deal already, correct or not... I don't think anyone would post something that they themselves hadn't practiced... That's how this racing thing is, one big happy, sharing family

Please don't take this the wrong way Ed, but the blow torch thing sounds a little crude... If I was going to preheat the engine before it's initial run I would prefer to heat in an oven. Slowly increasing the heat over time to ensure all parts are at the same temp.. I would think that if you just heated the outside of the engine there would be hot spots next to cold spots and so on.. Maybe I'm missing the purpose but I don't know for sure because you haven't finished your procedure... I have all the things you listed right out in the garage.. Please, go on.

Ed Smith

Aw shucks, if you all insist!!

As for the Bogus Boogie Boards, I figure about now I would be recovering from the gigantic hangover from drinking all the Rum I would have surely won in the "Great Boogie Board/Pylon racer shootout"

Diggs, do not put your engine in the oven. When it is running the bottom is never as hot as the top is it? If the bottom of the case is as hot as the head you have major problems. There is nothing crude about the use of a blow torch. Have you ever seen a plumber wipe a lead joint?

A little background here. Our engines are produced on high speed machinery. These machines remove metal at a furious rate. The finished parts are under some stress. Die cast parts (Crankcase) are stressed when they come out of the dies. The only parts that have this stress relieved are the crankshaft and the Gudgeon pin (Perfect English). These are hardened and tempered steel and then ground to size. Look upon the break in process as gently relieving these stresses by heating and allowing the various metals to assume their final shape. We are talking about very small amounts of movement. If this is done as an assembly while running they will all go in the same direction and fit as they are designed to. The running fits of the engine are designed to be correct at operating temperature not when it is cold. The combustion chamber volume is very small. As a percentage a .005" shim under the head will change that volume considerably. The reason for lifting the sleeve has been described and disputed in a previous post. I will not enlarge on that.


My break in process is to start the engine, needle it up to operating rpm and temperature, let it run for a while then kill it. Let it cool completely and repeat the process five times.

In detail, we know the operating rpm of 428 engines, 19k+ and 422 engines 23k+.

The very worst thing we can do to an ABC type engine is to start it cold. Jamming the piston into the liner and then ripping it out again does nasty things to the internals. So, using the crude blow torch I gently warm the head of the engine from the top, not down the sides. I get it warm enough so the engine will turn over by hand with hardly any grab. Immediately start the engine and needle it to above it's operating rpm. For 428, 21k, 422, 25k. This is the reason for the small prop. the engine can be needled up to the desired range but still with a fairly rich needle setting. there should be lots of smoke and fuel coming out of the exhaust. I monitor the rpm throughout the run and adjust accordingly. It is quite surprising how much the rpm changes. I do not let the tank ( 6 oz.) run dry, I choke off the engine to stop it. Let the engine cool completely. I do this five times. My engines are then ready for use. After this all of my engines have plenty of "Pinch". If you look at the piston you should see an evenly polished band all round the piston about 1/8" down from the top. There should not be any scoring or bruise marks on the piston sides. Gary probably gets these as he does not wash out the aluminum chips. A comment on operating temperature. There is little point in breaking an engine in at 150deg (As dictated by the slobbering rich brigade) and then using it at 350deg. I use the same principle for all of my engines, ABC or ringed and four strokes. My oldest Nelson is now ten years old and all original. Sure it is past its prime and rattles a bit but it still runs good.

After the break in comes the black art of shim changing. I return mine to the original setting. Shims may have to be changed depending on the propeller being used. Then of course there is always the expert of the day.

Ed S

garys

Ed,

I understand your logic in your procedures, whether I agree or not. I think you misunderstood part of what I said. I don't believe in absolutely never changing head clearances, etc. What I do believe in, is breaking in the engine with the sleeve set at the height you really intend to run it at all along, rather than raising it for the break in period, and then bringing it down. I didn't say I never adjust any shims, I just said I try not to change the sleeve shims or remove the piston/sleeve unless it's needed. Yes, .005 is a big difference if you're talking combustion chamber volume (changing compression). It is not a big difference if you're talking about changing the piston/sleeve fit. I was describing the fit, not the compression. I do periodically adjust head clearances depending on conditions and props, although I've found that I do it considerably less that I used to.

I also think oftentimes people adjust themselves out of contention at contests by looking for that 500 RPM that they were down on the morning test flight compared to the day before, the week before, or whenever. Usually it's back by the first round. Case in point. At the recent race in Medford, Oregon, on Saturday morning, my Q40 was only turning my normal APC prop at 23k (I say normal because I tend to run the same exact APC prop until it's worn or otherwise damaged, rather than randomly grab any one of several that are in my box). I decided not to mess with it yet, and see what it did in the first round, as it would be considerably warmer in the day. The first round it was back up to 24.4k, within a hundred of the highest I've ever seen. I very easily could have adjusted it in the morning and possibly got it up to 23.5k, and would have been happy. It then could have been at 23.9 come the first round. Yes, I know, it also could have been 24.6k, but it's never been over 24.5 on the ground in the best conditions. I'm not going to worry about being 100 down.

You may be surprised to find that I'm not the only person that doesn't start out with a brand new engine by taking it apart. I know for a fact that Travis Flynn, Randy Bridge, Fred Burgdorf, Jim Allen, , and Richard Verano don't disassemble their new engines prior to running them. I really don't think that's bad company to be in.

I challenge you to take a look at my pistons the next time we see each other and find the scoring and bruise marks you claim my engines should have. Simply put, there's nothing but the nice, thin, polished area where it's sealing. Also, don't try to say my engines don't last as long because of wear from chips and stuff inside from the beginning. My two current Q500 engines have about 40 and 80 runs, respectively, and both can turn the 8.75x9.5NN prop over 20k. I set the Q500 and Q40 national records in 1999 with engines that had well over 100 runs on them.

I'm not the one that came up with any of my ways of doing things. I learned it from well known engine guys like Dave Shadel. Rob Metkmeyer recommends a similar procedure with his F3D engines. When it comes to engines, not bad company. When people get new engines, it wouldn't hurt to ask the manufacturers what they recommend. Believe it or not, they'd be happy to tell you their procedures, as well as if they agree or not with somebody Else's that may be different.

I will give you this. If we were talking about a normal sport engine like a Thundertiger or OS, I absolutely would take it apart to clean it out.

I also have a question for you regarding pre-heating your engine prior to break-in. If you're heating it up to get the parts up to operating temp before turning it over, when the parts come back down to air temp after running, wouldn't a lot of the tight cold fit of the piston and sleeve come back? After all, isn't the reason for heating it in the first place is to get the sleeve to swell up to closer to what it is while running? You did say there is plenty of "pinch" after break-in. Isn't this pinch from the same thing you're trying to avoid by pre-heating? Wouldn't it still do damage to the engine if you turned it over without pre-heating it? How do you get around this at a contest?

GS
I'm not an "RCPRO", but I did stay at a Holiday Inn Express last night.

Ed Smith

In the last sentence of my post I stated that I returned evrything to spec. afer break-in.


Noble company indeed. However aluminum chips are aluminum chips. I have never yet taken ANY engine apart and NOT found chips inside. Why take a chance. One of those chips in between the piston and sleeve or in a bearing..............


Now who is offended?


One would hope that at a contest the engine is broken in. Everything is set. The preheat is at the break-in only. The "Pinch" of a new engine is far more vicious than when it is broken in, help it out a bit for the first few runs.


For some reason I do not understand, engine break-in seems to be an emotional subject. It is a simple mechanical procedure. Out of all the people that contributed to this thread I am the only one that took the time to answer Ranierys question with a detailed procedure and the reasons for it. Of course I then expected to be jumped on. There are probably many ways to achieve the same end. I am always willing to learn. If there are better methods then please somebody enlighten us all with details and the reasons for doing them. If my procedure is followed closely the engine will NOT be damaged, it will be broken in and ready for use.

I will gladly try and answer any questions.


Ed S

P.S. all of the information I gave was free. You get what you pay for!

diggs_74

Thanks Ed, it was very interesting... I see what you are doing with the torch.. I was a bit confused about what you were going to do with it.. Thanks for taking the time to share it...

garys

Ed,

I'm not offended. If I was I guess I could've taken my ball and gone home because somebody had another way of doing something I'm simply telling you that you are free to check for scores or bruises on my engines. Maybe Henry Nelson and Dave Shadel leave shavings in the engines that are shipped to Canada to avoid some extra international cleaning duty or something?

GS