Tired Old Man

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You're welcome.

It's not often anymore than I get into a mood to type that much. At least on this forum...

RTK

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This is one point I disagree with TOM, and we have had much discussion over it Every 2 cycles lawn implement (chainsaws, weedies, etc) I own runs over 300*'s F (150C) on a bi-weekly basis for over 10 years without fail or degradation. Some saws much longer, and more frequently. Pistons skirts, cylinders, and bearing all are perfect without a stuck ring or hick-up in all those years, but 20 years ago we never ever thought about running over 32 to 1. A lot had to do with the quality of oils though, but I still choose oils close to that ratio even today.

captinjohn

I got to agree with what RTK says
Every 2 cycles lawn implement (chainsaws, weedies, etc) I own runs over 300*'s F (150C) on a bi-weekly basis for over 10 years without fail or degradation. Some saws much longer, and more frequently. Pistons skirts, cylinders, and bearing all are perfect without a stuck ring or hick-up in all those years, but 20 years ago we never ever thought about running over 32 to 1. A lot had to do with the quality of oils though, but I still choose oils close to that ratio even today.
THAT IS IT FOLKS....RUN GOOD OIL AT ABOUT 32-1....WORKS GREAT .... Capt,n

Tired Old Man

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I'm not going to argue the point. Run yours as hot as you feel acceptable. Mine will last longer and remain stronger.

It gets even more involved than that. As the engines run hotter there is an effect on the ignition timing. The hotter the engine the more retarded the timing has to be for the engine to run correctly. The timing being to advanced for the temperatures assist the initiation of detonation. It's a viscious circle. We almost have to have two different ignition systems for our engines. One for cold to "normal" running temps, and another for when it gets hot.

RTK

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Not discounting your readings Pat, but Stihl and Echo wouldn't make their engines run at those temps for no good reason. The new ecological one I just bought even runs hotter, had to remove the eco-caps to richen it up a bit more than allowed by big brother to cool her down a tad.

captinjohn

Another interesting fact is some stock flywheel mags on leafblowers ect, have a advance curve built in. I placed a timimg lite (good old Sears) on even a low priced engine & found this out. I went to the website for that brand of ignition and read more.....kinda neat. I took a photo with timing lite on and you can read the size of prop, with engine running! Capt,n

Tired Old Man

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I do the same with ignitions, but you have to modify the shielding to do so. Not something you want to do with the ignition you plan of flying over the weekend.

Ralph,

Our little airplane engines are not the same as those found in leaf blowers and such. Those ALWAYS have more case mass, and typically more cylinder fin area than model engines. Our model engines generally do not have a finned flywheel hanging on the front that is ducting air to the cylinder. Take a couple apart and see for yourself. Our engines typically have the smalles, thinnest case they can get away with. Many have reduced fin area. You favorite, BME, and DA are examples of this. DA does the better job of cooling though. Combine all the above and you have an engine that cannot sustain the same amount of heat, or for the length of time, that the yard equipment engines can.

Now for the temperature performance losses and ring issues, you guys are going to have to invest in some equipment a little (a whole lot) better than a simple Venom temp monitor and do some extended engine runs at various temps and rpm levels. "My weedeater still runs fine after reaching high temps" just doesn't cut it where accuracy in data collection comes into play. Might want to invest in an exhaust gas monitor in order to view the change in the combustion process while you're at it. After that you'll need to pull those engines apart and perform some accurate measurements and use a magnifying glass to look at the rings, and ring grooves. Then get into the shielded bearings in the bottom end to inspect the condition of the end seals. There hasn't been an engine I've tested yet that did not indicate an rpm loss when they exceeded 148c. Those that experienced a permanent performance loss busted 160c. At 180c it takes about 7 seconds for the creation of carbon deposits on top of and behind the rings to initiate, later becoming the cause of a stuck ring. At 200c the bearing seals degrade, at times to the point they depart the bearing and stick (lock up) the end of the crank. If they manage to remain in place they start leaking grease. Our little engine bearings don't like to be swimming in an oil bath. They skid and flat spot the balls and rollers when they do.

Sorry, but you guys are taking a knife to a gunfight when it comes to your engine monitoring and inspection processes. You don't have the tools.

RTK

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But they keep on running, and that is the most important fact. We never run our plane engines as you do, constant hours on end at high throttle setting. Our engines see on and off throttle and rarely stay WOT for more than a brief period of time. You know how fast an engine will cool once you back off the throttle. I have a particular engine that hit a CHT of close to 500*F, although for a brief moment, it has not lost any power, the rings show no sign of sticking, bearing not leaking and tight, rpms are the same as before that brief hot run 15 gallons later. Maybe I was just lucky

captinjohn

No fancy test..real life! look at the pile of wood that was cut with my old chainsaw I sold to my son-in-law. That saw is going on 20 years old and I always flooded the engine out at end of day. I held it full RPM and threw the choke on. Now the additives in the wet cyl can soften up the carbon. I did the same with a snowmobile. On restart you could see the crap fly onto the snow on startup the next day. Sometimes never needed to be choked in winter. Capt,n Take that $$ for fancy test stuff & by airplanes. Capt,n Note...the engine must have had special non-skid bearings HA!

captinjohn

RTK is right. We are not running our airplanes wide open like in a pylon race! Capt,n now back to work[:-]

RTK

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Looks like you have your work "cut" out for you capt'n

Oh, buy the way. Here in california we had a big storm with winds and 3 inches of rain in one day. Yesterday I broke out the chainsaw and cut up all the downed limbs, today I pulled out the trusty old blower and ran it for over 30 minutes at WOT. When I temp'd it, it was at 366*F as always. The needles are set by leaning the high until it breaks from 4 cycle to 2 cycles, every once in a great while you can hear a blep of 4 stroking.
The must use different technology and or metallurgy because it has never stuck a ring or scored a cylinder in all these years.

pe reivers

Ralph, There is truth in your statements, and I believe T.O.M. as well.
There is no way of knowing your leaf blower has lost some power. Would you be flying the device, small differences would show up. As it is now, it blows leafs away and that is what it is designed to do.
360F is still ways short of 420F, when damage realy sets in. Don't be mistaken about that. The damage can take many shapes, and sneak up on you, so you loose your reference frame. If it runs like last time it's OK isn't it?

As for end of day killing the engine with choke, that is a well known trick that works well.
It thins the oil inside the hot engine, so capillary action can take the oil to all pars that need. it. The fuel evaporates, and the oil is left behind to lubricate and protect next time you start up.

Tired Old Man

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I just finished running an engine for varous time periods from 180 to 194c. You guys can do that all you want. I have an engine to rebuild....

pe reivers

Suits you right!
You know that an engine needs to cool down in between?

RTK

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TOM,,-Time to change your brand of engine or put the sensor under the plug or around the cylinder, not on the fin where I have seen others do. You could be off my many degrees.

captinjohn

HERE IS THE STATEMENT: There is no way of knowing your leaf blower has lost some power. Would you be flying the device, small differences would show up. As it is now, it blows leafs away and that is what it is designed to do.
NOW HERE IS MY REPLY I have a lot of leaves to remove at my other place in the woods. Now I sure can tell if the blower is loosing power. The wet leaves will not move unless you got full power. There is a lot of time on this leaf blower too. I use it sometimes to blow snow of the car, truck, and side walk. It has been gaining a little more rpm right along..it even blows the dirt and stones...this thing screems. I guess I need to take a short video...then you will know what high reves it gets!!! Capt,n

Tired Old Man

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+/- 10c. Don't forget that the "front" is the "back" for some people. You're quite welcome to come on up and let everyone know how they are doing it wrong

I can plainly see there's some mighty well documented scientific data collections being done by a few in this thread.

RTK

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Just keeping you on your toes Pat, you know I was going to minor in engineering, but had to choose one or the other. Gotta visit you at work one of these days.

Tired Old Man

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It would be enlightening for sure.

Just for funnies: Never tell an engineer he's wrong. They'll do everything they can to tell you how that's not possible.

Example: Was about a year ago I told some engineers that the engine/exhaust was fine but the prop was terribly loud. Not for the usual reasons though. They proceeded to inform me in many ways how misinformed I was. Matter of fact, I was shunned by the engineering group for about 4 months over the prop noise comment. Much later there was a big test using various engines and props, up to and including a rather large electric version of the platform to compare relative noise levels between all of them. Got down to the electric version where there was no exhaust noise and you could hear that prop for 1/2 mile or better. Same prop I had been referring to in my original declaration.

So as far as the engineers were concerned, the layman was initially wrong, the engineers were right, as always. Ultimately, many thousands of dollars were expended for those same engineers to determine the engine/exhaust was fine, but they had a propeller problem. For all intents and purposes the claims of the layman never happened.

tkg

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T.O.M. you ain't been loaning out them engineers to other companies have you???? I ran across one else where recently.

Tired Old Man

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They all studied the same books.... It's an arrogance that goes far beyond the defination.

Jezmo

Got one on my wife's side of the family. Makes for real interesting holidays. My side are all cops so that's pretty interesting in the holiday season as well. I think I'll drag brother-in-law into a two stoke oil debate this Christmas, should be quite interesting.