RE: detecting peak engine temp
 

<hr />I forgot to add a important part...if after you killed the engine &amp; glided in the engine and the engine smelled hot or the the base of the plug has turned color...it was running hot. Sure it is nice to have all the high teck stuff...but the average flyer should know in a instant if engine has been running real hot....it will sag on RPM right away....time to shut her down. Capt,n

RE: detecting peak engine temp
 

Or back off the throttle if airborne. Reducing throttle richens the mixture if you get it to mid range rpm. That will cool the engine and provide for a power on landing.

RE: detecting peak engine temp
 

See post number 11: Try to keep the engine between 100C and 150C. Per T.O.M.

RE: detecting peak engine temp
 

I feel if you don't go much over 180C or 350F you are fine. I have had and engine with many many gallons through it that hits 350 at it's peak on every flight, granted it is only for a brief time, WOT KE spins & WOT flat spins, and has suffered no ring sticking or bearing damage yet. Plugs look good too. This is a high quality engine so your results may vary................

RE: detecting peak engine temp
 

Gotta ask Ralph, how many engines have you deliberately destroyed in heat testing or normal sport flying? You can get away with 180C a few times for extremely limited periods of time but there will be accumulative effects. May not become apparent right away but they certainly will.

Look at the side of the piston and cylinder wall. See any light brown staining on the cylinder wall or dark brown stains on the piston skirt? Typically on the exhaust port side, just ahead or right at the exhaust port relative to the piston. If you do, look to correcting ring issues for the damage has already started. The ring is no longer maintaining tension under heat and pressure loading. Heat is what did it. That brown stuff is oil plating, meaning it was breaking down from excessive heat. Then look at the top of the combustion chamber. Any carbon up there? Probably is in most engines, but if there's a section that is shiney and bright at the corner of the cylinder you just found the effects of detonation. You won't see the effects of pre-ignition unless it was started by glowing carbon on the spark plug. Then you'd see patches of carbon blown off the top of the piston. Aside from that, the effects of pre-ignition are found when rods, cranks, and rings break. Sometimes the prop bolts go first from the erratic combustion impulses. The lucky ones only have wrist pin circlips lose spring tension from the heat and depart the groove to wedge between the piston and cylinder wall.

Engines that run real hot won't have much, if any, carbon on the piston. The top of the piston will just be dark grey in color. You would not be able to "read" the plug becase the base of the plug and insulator would be close to the color of the top of the piston. You might find there is a carbon deposit on the top of the ring on the pin side a couple of thousandths thick. Doesn't take all that long to do. Not in a simple 10 or 15 minute hobby flight, but repeat that 75 or 100 times and plan on topping your engine. Treated right an engine can last 400 to 1,000 hours. Done wrong and you won't get 25 out of it.

The message is that heat can ruin an engine. Might work good today, but what you did today will have an impact tomorrow or the next day. I've deliberately burnt up a few, and seen the effects of a great many more, that were done accidentally. I try not to provide an absolute temp limit because I believe that too many people will think they can run up to that point all the time. I know this to be true because I see "professionals" do it after reading a limits sheet. They see a peak limit and think, "hey, if it can get that hot that means I can run it there all the time." People are not as perceptive and understanding of things they are told as we might hope them to be, so holding back 10C or 20C can save them some money and a broken airplane. In our hobby, there is no benefit to running as hot as you can get away with, and a lot more risk when you do. Then there's the levels of metalurgy to contend with. All engines are not made out of the same stuff and hanging out a high number that might work for one brand sure won't work with some others.

An engine can run pretty good with a stuck ring...at wide open throttle. The lower RPM bands and throttle up get pretty shakey though.

RE: detecting peak engine temp
 

No doubt heat is not good but I feel those numbers are low, six years later and temps up to 350 has not hurt one of my oldest engines.
Tell me this Pat, how come my weedie, and blower all run over 300 closer to 340 and have been doing it for 10 years without a hiccup?? My oldest blower has a zenoah 23cc or knock off in it.
Your engines are running under completely different conditions, lengths of run and at different tuning than anyone else's.

Runnig ring tension/pressure is produced by the combustion gasses getting behind the ring and expanding them out against the cylinder wall, that is what is important not resting tension. If you don't believe me read DA's comments and/or any other engine builders forums on that.

RE: detecting peak engine temp
 

Because your weedies and leaf blowers have this funny looking fan on the flywheel that is pumping a heck of a lot more air through a duct wrapped around the engine than a propeller does though even a well baffled cowl. If you can cool the exhaust port you can run hotter. A well cooled engine will have a temperature at the exhaust port the same as found at the base of the spark plug. I can assure you, there aren't many model planes flying that well baffled.

RE: detecting peak engine temp
 

I've read DA's stuff. They're the people that promote Amsoil and tell people to torque propellers on the 170 to a torque value that crushes the hub of a wood propeller. Even the 100 is provided an 85 inch pound prop bolt torque. You know darn well I can't tell all that I know.

At 6 years and 350 you're still just within the safe range, so you have not been running "hot".

RE: detecting peak engine temp
 

Guess I have been doing a good job on baffling and air flow:) The pistons and cylinders on my oldest are shinny like new too

RE: detecting peak engine temp
 

Not gpnna argue with ya buddy. I'll just wait until you get enough hot hours on an engine to find out for yourself.

RE: detecting peak engine temp
 

Hmmmm....I'm getting 63C and my friend is getting 65C, but with an infrared temp checker.
How far off might such an infrared temp checker be -vs- a probe style like Tower sells?

Our club has several flyers that love to tune the daylights out of their engines.
Yesterday one of them deadsticked twice, and I can just imagine the temps on his engine!
The thickest 2-cycle mix won't help THAT flyer!

RE: detecting peak engine temp
 

The readings of the I.R. type temperature guns are very inaccurate. Some of the reasons are that you have to look at exactly the same place on the engine at the same angle to have a comparison. The emissivity of different metals/paints of differing textures effect the reading also.

So using a defined temperature valve with these guns is being unrealistic.

RE: detecting peak engine temp
 

I agree with you 100% about oil in this situation. One of my vociferous antagonists where temperatures are concerned uses Pennzoil at 32-1. Good oil and lots of it. On one of his larger twins he got it so hot one piston and cylinder traded real estate. The manufacturer of one of his singles told me the cylinder and piston were pretty clean but the ring had gotton so hot it almost fell off the piston when he took the engine apart. He knows who he is;)

Oil will not save you if you run an engine too hot.

RE: detecting peak engine temp
 

Besides, the guns sees thru a cone; hence, the distance between the sensor and the surface to be measured, determines how much area the gun sees.
The computer inside just calculates an average among all the puntual temperatures in that area.
In other words, the reading includes the high temp at the plug plus the lower temp at the adjacent areas and some of the cooling fins, giving as result a lower temp than what the plug feels.

Once the piston and ring have expanded so much that there is no room between them and the cylinder wall, even the best oil is squeezed out.

Is it Castor oil used for these engines?

RE: detecting peak engine temp
 

Ah ha, we might have the answer. Since my engine only hits 350 for maybe a total of 20 seconds in very demanding maneuvers each flight and If you say 10-30 cumulative hours is the time to failure at that temp this means I have over 1000 flights before critical break down.
That's acceptable to me:) I'll plant it before that:)

RE: detecting peak engine temp
 

It is your engine. You are free to do what ever you want. No one is going to arrest you or anything if it fails

RE: detecting peak engine temp
 

Thanks for sharing your experience TOM. Piston reading is not all that common.
I told you before, my engine runs peak temperatures of 180&deg; during the gilder tow apex. Quite well baffled, but I could do with a bit more cooling air.
Just a few moments ago I pulled both jugs of my MVVS 116in order to put an extra foot gasket under the hottest cylinder. The engine has about 150 glider tows under it's belt, and has been run using quality synthetic oil1:40 from the very first start.
Piston crowns are covered in black, easily washed off in the central part. The part over the ring lands has some very thin hard carbon that will not wash off, I guess about 0.05mm thick, maybe thinner. The piston inside dome is clean. The combustion chamber is an even matt black without lighter spots. My plugs show a slightly rich condition. Judging by the pistons, I could lean out quite a bit more, but then my cylinder temps would skyrocket.
Piston sides have a burnished gleaming appearance , not a scratch on the surface. I run an air filter. Wear pattern is non-existing, though there is a rub pattern, nicely even around the pistons. Most of the original molybdenium piston coating is gone. It seems to have done it's job well during the running in..
Piston rings show brownish burnt oil on the top, not very viscous, but thicker than the oil in use. No carbon in the bottom of the ring grooves. Ring bottom surfaces have an even gleam without any cloudiness. The ring side contact surfaces show a nice even wear pattern.
This engine goes back together again, using some extra foot gaskets in order to reduce CR a few points to further smoothen out it's running. The hotter right cylinder will get 0.2mm extra. I do not need to wring out that last 0.5hp.

RE: detecting peak engine temp
 

Some might earn a place in the presitigious........
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RE: detecting peak engine temp
 

You are correct, but there in lies the problem.............. It hasn't failed in over 6 years and once it went to 450*F. I bent over to adjust the needles and my righty tighty lefty lucy got mixed up so I kept leaning instead of richening on a 100* day. With IMAC flying it never hits 300*F even when I run it at WOT race track style flying. Extended long WOT KE spins, flat spins and flip flopping in the space of a wing span is what makes it hit 350
Baffling and more importantly extraction is what will make or break your day. Pe has some of the best articles with pictures on this.
http://www.prme.nl/forum/viewtopic.php?p=506#506

I have been running on board temp monitors for over 5 years now, I know just about where every manufacturers engines will run when tuned properly. Some are higher than others some are lower. I would never push "some" of the chinese engines to higher temps.
Again, test some of your 2 stroke yard equipment with a thermo-couple working at WOT on a hot summer day.......................


By the way, just for comparisons (I know apples/oranges again) Rotax red line on of some of there ulitralite engines is well over 400*'F

RE: detecting peak engine temp
 

The duration of exposure to high temps does indeed matter. That duration is affected by the temperature level. I didn't say at what temp took 31 hours for terminal damage to cause engine stop. One of my tests is temp versus duration to determine how long an engine can be run at a given temperature before it needs to be removed from service. The bottom temp level is 180C. It gets a lot higher, and each 10C step upwards reduces the amount of life cycle accordingly. At 210-220c your engine dies quickly, with even less permissable duration at levels above that.

Pe,

Your engine sounds pretty close to what a "normally" run engine would look like. At 180C-185C the MVVS is still a bit within bounds, as you well know. The engine has plenty of mass and well designed cooling fins that promote heat radiation quite well. The induction path also contributes to cooling capability. OTH, the engines RTK prefers do not have 1/2 the cooling capability that an MVVS 58 or 116 has, and are limited in peak thermal capability and duration because of it. Great engines with lots of power but limited in versatility. Perfect for the educated hobbyist but not ones to be used in a tow capacity.

RE: detecting peak engine temp
 

Just for comparison:

180 Celsius = 356 Fahrenheit

185 Celsius = 365 Fahrenheit

210 Celsius = 410 Fahrenheit

220 Celsius = 428 Fahrenheit

Again, is Castor oil used for these engines, in any proportion mix with two stroke oil?

RE: detecting peak engine temp
 

No, and it would be a terrible selection for a hot running air cooled gas engine. Yoy think cleaning the varnish off a glow engine is bad? It would be 50 times worse on/in an engine that runs over 100 degrees hotter.

RE: detecting peak engine temp
 

Thanks, TOM

RE: detecting peak engine temp
 

<hr />
<hr />TOM are you talking 100% castor oil mixed withthe gasfuel or what amount? There air oils on the market that conatain maybe 20 castor pecent in the oil...then mixed with fuel the actual amount of caster in fuel is not very much. Can you show us any proof of your "50 times worse" that this varnish builds up like you say? Klotz is just one oil that has a percentage of castor added. The theroy is castor holds up to extreme temps better. Thanks Capt,n

RE: detecting peak engine temp
 

More...read page 20 and 21ofthe pdf files. My cousin Wayne Koomen used Klotz oil in all his drag sleds engines he built up &amp; the race engines for like the Soo 500 mile race! <hr />http://www.thewinningedgemagazine.co...efile22808.pdf

Capt,n PS to enlarge hit +<hr /><font size="2" face="HelveticaCE"><font size="2" face="HelveticaCE"><p align="left">The show portion of the days event</p><p align="left">were highlighted by a awesome tribute to two</p><p align="left">West Michigan Sno*Jet racing legends, the</p><p align="left">late Jim Adema of Belmont, Michigan and the</p><p align="left">late Wayne Koomen of Casnovia MI. Attending</p><p align="left">the tribute were Pat (Adema) Senneker,</p><p align="left">Greg, Bruce and Cindy Koomen, Cliff Dayton,</p><p align="left">Sid McNees, Bill Reed Jr. and many others</p><p align="left">who shared with the vintage fans the stories</p><p align="left">of the good old days of snowmobile racing. A</p><p align="left">tremendous amount of memorabilia from the</p><p align="left">Koomen family was on display to a crowd that</p><p align="left">never subsided during the entire days event.</p><p align="left">Including the 3 cylinder Yamaha motor that</p><p align="left">Jim Adema competed with in the MISA summer</p><p align="left">grass drags, along with one of 3 known</p><p align="left">Phantom Jets, several hoods from Wayne</p><p align="left">Koomens days of racing with the legendary</p><p align="left">Casnovia Jets racing team from what was then</p>

known as Sno*Jet Central.</p></font></font>