Subthread 32:1 vs 50:1 (heat data)

[brncreeper]

Engine Temps

Too many variables such as ethanol content (preferably less that 10 percent), possible methanol (God forbid), octane rating, type of oil, ratio of gas to oil, relative humidity, outside air temperature, dirty air filter, ignition timing, spark plug heat range, and carb settings.

Wouldn’t it be nice to have an EGT (Exhaust Gas Temperature) readout on the saw and knobs on the mixture screws to correctly set the EGT for the optimal temp as the saw is being used?

Hmmm, I have a type “J” sensor rated from 32-1500 degrees F and a digital readout…

 

[Lakeside53]

]Wouldn’t it be nice to have an EGT (Exhaust Gas Temperature) readout on the saw and knobs on the mixture screws to correctly set the EGT for the optimal temp as the saw is being used?

heck, if we had a EGT with readout, just close the loop have it adjust the mixture.

On the other hand, just stay a bit rich and to hell with the emissions.

 

[brncreeper]

heck, if we had a EGT with readout, just close the loop have it adjust the mixture.

On the other hand, just stay a bit rich and to hell with the emissions.

No room for servos and a controller but food for thought for a dyno. We got by with that crap in aviation anyway.
I'd love to build a hydraulic dyno for small engines.

 

[brncreeper]

On the other hand, just stay a bit rich and to hell with the emissions.

You don't perfom as well, but yep...can't go wrong running rich.

 

[yungman]

Hey, lets stay with what we can do best with the assumption that people don't know how to do close loop and get the most out of the equipment as is. This is safely the assumption of what the people going to use it at. Thats is the reason I did not even talk about changing the air fuel to richen the mixture or anything. Something that is benefit the ordinary people.

 

[Fish]

This is a good one too....

 

[Fish]

bump

 

[GASoline71]

What'er ya doin'?

Gary

 

[teatersroad]

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[splitpost]

Bump,good read

 

[Fish]

Yes, it is a good read, with data from someone that knows his bizness.

That is the sad thing about these forums.. Someone can post an accurate picture, but the rest will not see/believe it, because they have already set up other members as the authority-sources, and they are real reluctant to change their first "snapshot"......

I always read all of it, and like to see who actually knows what they are talking about, and those that just regurgitate some big words....

 

[edisto]

I always read all of it, and like to see who actually knows what they are talking about, and those that just regurgitate some big words....

I wish I'd read all of it, so I would have noticed the date on the OP! I read the first post, and started messing with a spreadsheet.

I "tested" an idea, that 2 of the posters that discussed: heat transfer. The key is that the exhaust temperature varied little, while the head temperature increased the most. This is what you would expect to see if more heat were being transferred from the piston to the cylinder, without a large change in combustion.

The lines below are based on least-squares linear regression (a "trend line") of the data TW supplied. Temperatures are expressed as the proportion of the maximum temp for a given location on a given saw.

I have read a number of cases where an increase in power was found by adding more oil to the mix. In terms of heat transfer, less heat in the piston means less heating of the mix in the crankcase, which increases charge density. A better delivery ratio means more power...just how much is the question. TW noticed little, if any gain.

 

[weimedog]

I would be interested in the case and bearing temps and other areas where lubricity is an issue....I suspect there is less latent heat potential in a charge of 32:1 vs 50:1 the cylinder "head" temp difference has to come from other issues. Is it possible more oil allows the rings to seal better? Does the additional oil effectively lean the mixture enough to show a slight temp change ? Wonder what would happen if the measuring was done on a long sustained cut under load. More heat in the the head might point to a more efficient combustion generating more energy therefore heat. Also some two stroke oils burn more completely than others...interesting stuff. I certainly wouldn't draw too many conclusions..certainly not going to change how I do business with my two strokes as so many other data points over the years in my life, just as tangible; point to the benefits of more oil than less.

 

[tree monkey]

i rember this thread, don't rember if i posted or not.

russ lemke tested oil ratio with a rotex on a dyno. started at 50/1 and ended at 6/1.
he hit peak hp around 20/1 and didn't loose hp until around 8/1
don't know if he tested heat at the time

 

[husq2100]

i rember this thread, don't rember if i posted or not.

russ lemke tested oil ratio with a rotex on a dyno. started at 50/1 and ended at 6/1.
he hit peak hp around 20/1 and didn't loose hp until around 8/1
don't know if he tested heat at the time

as has others in controlled inviroments with the similar results 16-1 was peak hp

 

[husq2100]

Yes, it is a good read, with data from someone that knows his bizness.

That is the sad thing about these forums.. Someone can post an accurate picture, but the rest will not see/believe it, because they have already set up other members as the authority-sources, and they are real reluctant to change their first "snapshot"......

I always read all of it, and like to see who actually knows what they are talking about, and those that just regurgitate some big words....

where we reading the same thread??? TW asked some questions with an open mind (and some interlect/knowledge) BWalker added and others jumped in to discuss....seems like your view may be a bit skewd

 

[weimedog]

i rember this thread, don't rember if i posted or not.

russ lemke tested oil ratio with a rotex on a dyno. started at 50/1 and ended at 6/1.
he hit peak hp around 20/1 and didn't loose hp until around 8/1
don't know if he tested heat at the time

I have seen similar data over and over again in the motorcycle world, good to hear that others in this paradigm have seen similar things. The kicker for me wasn't even the power differences, it was piston/cylinder life over a race season when I was a much younger person thrashing two stroke motorcycles on the scrambles & motocross tracks during the 1970's and 1980's and again in the late 1990's before going four stroke (dumb move BTW)

One thing still nags at me though, and that is with the really over square design's saw motors have vs. the rest of the two stroke world, it would seem to me things related to rings and sealing & therefore working compression would have a greater effect than in other more "square" designs.

 

[Fish]

Dagger posted to a few similar threads on the topic, I am always "skewd"..

Do a search of his posts, some good reading.

 

[edisto]

I would be interested in the case and bearing temps and other areas where lubricity is an issue....I suspect there is less latent heat potential in a charge of 32:1 vs 50:1 the cylinder "head" temp difference has to come from other issues.

It isn't about absorbing heat, it is about transferring heat to the cylinder.

Is it possible more oil allows the rings to seal better? Does the additional oil effectively lean the mixture enough to show a slight temp change ? Wonder what would happen if the measuring was done on a long sustained cut under load. More heat in the the head might point to a more efficient combustion generating more energy therefore heat.

I would expect that difference to also show up in the exhaust temperature. That isn't what was seen.

Also some two stroke oils burn more completely than others...interesting stuff. I certainly wouldn't draw too many conclusions..certainly not going to change how I do business with my two strokes as so many other data points over the years in my life, just as tangible; point to the benefits of more oil than less.

I think this also shows the benefits of more oil...

 

[c5rulz]

I will qualify this post with, "I am not a chainsaw mechanic", but do know a little about physics and scientific method.

So:


A. Ounce for ounce, gasoline does not have the heat content of 2 cycle oil. i.e. less BTUS. Much like diesel fuel having more energy than a gasoline. So it stands to reason that the temps would be less elevated.

B. Granted the temps have elevated slightly with the additional lubricating oil. However, how significant is this rise relative to the temp that would cause excessive wear on the motor. Just because the temps have elevated that does not mean that is a bad thing. An example of this is the global warming debate. In order for warming to be a bad thing, that would mean that temps on earth are at the perfect tempature right now. In fact warmer temps might be better.

My 2 cents.