Life would be too simple if there were single solutions

I gotta go make some more popcorn. This is good stuff.

This thread has gone a lot farther that I ever thought it could. Pe has produced some really good info on oil this time too.

Was that popcorn buttered with real butter and salted? Ummm.

What mix ratio do you use for the butter?

Run it rich, very rich. MMMMM

Sounds delicious.. but won't that create a hard sticky and restrictive buildup in the long run?

Of course. Thats why I keep telling you guys to use bacon grease at 20:1!!

But does anyone listen?!?!?! [:@] NOOOOOOOOOOOOOOOOOOOO nobody listens to Rcpilet!!! I'm right, you're all wrong. HAHA!

Tried the bacon grease. I found that unless it's maintained above 98.6 it lumps up and gets stuck in the exit pipe[X(]

Use a good quality SYNTHETIC bacon grease and it will fix that!

Mike

Just for comparison, here are the values for other oils:

Pennzoil Air Cooled:
class: API-TC
Flash Point: 104C
Viscosity@100C: 10.3
VI: 112

Redline Racing:
Class: API-TC
Flash point: 103C
viscosity@40C (can't find 100C): 76
VI: unknown

Can't find information on Belray H1R or MC1.

Pat, you don't have to retreive a manual. When I bought my Brison 3.2's from Gary, he specifically told me to run 100:1 mixed at 80:1. This part of the argument is settled.

Hey, I want some popcorn!

But:
Consider the manual was written when the Amsoil craze first hit the RC world. It was the "best thing since sliced bread" NOW--years later--there have been some tests conducted that show Amsoil mixed at those lean ratios is not as good as people first thought.

Gary is NOT an oil tester or manufacturer. He had somebody (technical writer) write the manuals for him, based on the information he provided at the time. At the time, he thought Amsoil was good stuff.

Just because a 10yr old manual was never updated -- doesn't still make it true today. Evidence from independent testing proves otherwise.

Am I the ONLY guy to have considered this?

Different topic:
How do the rings break in?

Here is my understanding. I'm sure I'll get corrected for being wrong, but here goes...............

The rings are soft when new. They wear into the shape of the cylinder over a short period of time. The chrome plating is harder than any ring. This is why you are supposed to take it easy on the motor at first. Keeping the heat loads down by not using large props and by providing good cooling (cruising around nice and easy instead of performing sustained full throttle hovers) will keep the ring soft. You want the ring to stay soft for a period of time so that it will be worn and "polished" by the chrome cylinder.

Eventually the ring will have worn down to the point where it is making full contact with 100% of the cylinder walls. All the high spots on the ring will be worn off.

Now is when you want to really start pushing it to heat up. The heating and cooling cycles will temper the ring and turn it very hard. Some people call this "work hardened" or "wear hardened" Once the ring has been work hardened, the wearing from contact with the cylinder walls will be reduced to almost zero wear. From here, it will take hundreds or thousands of hours to wear anymore off the ring.

I understand that a chrome cylinder wall is so hard, it isn't going to wear from contact with a ring. There may be little fussy spots here and there from honing that will get knocked off and smoothed from contact with the ring. But, consider that a lot of our cylinders are nakasil plated and are NEVER honed from the factory. A brand new engine will look like a mirror finish inside the cylinder. This isn't true on ALL engines, but most today.

Back in the days before I was flying gas engines, I'm sure some of them had steel cylinders that had been honed from the factory. These hone parks would have to be worn off-- along with the ridges on the ring--before the engine would come up to full power.

Flame suit on.

Of course things are not always what they seem. The flash point of oils is where the oil evaporates just enough, so a flame can be generated as a flash. It is not sustained.
Most two stroke oils that must mix with the gasoline, have been pre-mixed with lighter substances to facilitate the gas mix. This lighter pre-mix has low flash values, and it serves as fuel once it passes the carb jets.
To know what is what, you can conduct a heat test. A typical cylinder wall temperature is about 200°C That happens to be a household iron at highest temperature. I did a few tests some time ago with different oils. The good oils had no problem with 20 minutes at 200 degrees.
Elf had become tarlike thick, and castor had lost all lubrication, and had dried out.
Mobil and Putoline were spread out, but still normally thin in viscosity.
Edit.
Standard test amount was one single drop inside the small cup dremeled in the iron sole.

You may be right about the Amsoil in the manual, but you are not right about the rings.
They are not made of work hardening steel, but white cast iron. In the heydays of model engines, the cylinders were made of workhardening steel.
Because the rings, which btw are quite hard to begin with, do not alter their hardness, it is best to let the engine work as hard as you dare, but not long enough to overheat anything. Heat flow from ring to cylinder and from piston to cylinder is not all that good yet. This hard work will seat the ring in the ring lands and to the cylinder wall. At the same time, high machining spots will wear off. Due to the many heat cycles, internal stresses that were set up by several machining steps are relieved (accelerated aging). Storing your engine in the attic for ten years would serve the same purpose.

Rcpilet,

Thanks for finally bringing up the point about updated manuals. By the time I got my last engines from Gary Amsoil was a four letter word in his shop, but the manual never changed. I don't believe he used a tech writer, but simply sent the work to a printer for basic layout. After that it was the copy machine. Manuals change all the time as knowledge and education is gained.

OK, so this hamfisted idiot managed to strip the threads of his plug after checking it one time too often while hot! So I pulled the jug, and took a picture of the piston.
The engine has about 2-3 gallons through in short full power bursts on the test stand only. Like a digital throttle, either full, or idle. When applicable, running full bore well into the sagging region each time.
props ranging from 24x10x3 to 21x10, RPM ranging from 5200 to 8200.
Oil Putoline RS959, mixed at 3%. Plug kind of rich, from tan to darker grey. Plug mass black, but not sooty wet.

I have several ring, piston and cylinder photos, but I think that this picture tells the tale. The piston came slippery wet out of the engine. When dry, it was the smoothest ever surface to the touch I ever had the pleasure to examine. I hope the photo shows how smooo...ooth the piston was. This piston had a very thin graphite layer from day one, and after the initial rub-in, showed no further wear. Down in the machining grooves, there still is the same amount of graphit coating as there was after the first two pints of fuel. The piston crown has som black carbon, very soft. for the picture, the crown soot was washed off with gas and rubbed dry with a paper towel, of which the lint is visible on the picture.

Dare you to have the same results with a BME 115

If that BME saw synthetic oil like mine from the first power stroke, why not?
I dare you to send me the engine, so I can check it out and put it through the wringer.

My 115 pistons don't look quite that nice Pe, but I do run a 32:1 mix. Altavillan runs a leaner oil mix.

It already went through the ringer. As a matter of fact it went through the cowl, the header, the cannister etc.

Pe,

What's the possibility of getting my hands on a few containers of the oil you're using? I'm in the middle of more testing and I like very much what I see, especially with the method of running you described.

Another question concerns exhaust components. What was used and how restrictive was it? The reason I ask is I've found that exhaust restriction and back pressure has quite an impact on what happens inside the exhaust port.

Pat,

I don't know if this has been mentioned yet (I'm not wading through 7 pages just to check), but the short bursts of power method of break in is used all the time in the world of roadracing motorcycles and works well to set the rings. Many tuners will use a dyno for initial break in runs, doing something like 3 runs (all at full throttle) to 70% of redline, then 3 runs to 80% of redline, then 3 to 90% and so on. After around 8-10 hard pulls on the dyno, the engine will develop close to it's full potential with the last couple of percent coming with some track running time. Total dyno time to seat the rings is only a few minutes worth of full throttle running.

Here is a website with a lot more info on the running in process and a bunch of other 4 stroke porting stuff. It looks wacky, but the info is sound despite the presentation:

http://mototuneusa.com/thanx.htm

You want issue #9 Break In Secrets


Mark

I learned never to play truth or dare. It's either embarrassing or gets you arrested. [sm=red_smile.gif]

Off topic, but still about breaking in engines:

We run our drag motors (500 cubic inch) on the dyno after a 20 minute run to break in the cam. After the cam is broken in, strap it to the dyno and give it hell!! It's pretty cool to see how changing the spark plugs or timing will give you 50HP more. Or change the thermostat will give you 10HP more at 6800RPM, but 10HP LESS at 8500RPM. Changing the header length (shorter) usually picks up RPM to a point. There's a neat and simple way to figure out how long your headers need to be. Run a grease pencil down the header tubes. The spot where the grease stops melting is where you cut them off. The motors are built with a few thousandths extra clearance on the mains and rods. It lets in more of that 50w oil and lets them wrap up faster. A standard 500 mile break in that you'd normally do for your wifes minivan doesn't work on these engines. They run about 50 miles before we tear them down and rebuild them. [X(]

Airplanes are CHEAP compared to drag racing. The cost of a DA150 won't even buy you a good set of bare heads for a drag motor. ONE custom ground cam costs as much as a DA50. Shoot! a good set of ROD bolts cost a couple hundred bucks! And you throw them out when you rebuild the engine.

I'm learning how to balance the motors INTERNALLY. We're supposed to work on a little 289 Ford engine this weekend. Should be cool.

Did a lot of that when I was younger. Worked the 1/4 mile stuff with a AAFD for awhile with street racing the rest of the time. I don't miss the burning eyes that went with all the nitro but I sure miss the thunder. It wasn't as complicated then, nor as fast, but the exhibition tickets were a lot cheaper