Saws . torq versus rpm

[sand sock]

When your looking at saws to purchase. How do you say this is a torq saw and this is a rpm saw. When you havent run it. Ive had a 250,251,029,034,361 and some echo . the 361 and 250 were the only ones. I would say were great saws. Good rpm and torq. What is it that balances it out? Piston width or piston stroke or is it something else.

Somebody was saying everyone is moving to rpm saws . 13 pound heads and 60cc is what fits.me pretty good making firewood efficient

 

[huskihl]

Generally speaking, todays saws turn more rpm than saws did 35 and more years ago. They’re all more about speed and less about torque.
Typically, open port motors found more on homeowner saws turn fewer rpm and don’t make as much horsepower. But even in the pro saws, some have completely different attitudes, like the ms462 and 500i. For the most part, you’d have to run them directly compared to the other to be able to know the difference

 

[NSEric]

There's different saws for different cutting needs.
Locally big trees are few and far between so smaller saws with high rpm are prefered as they are lighter and cut up smallish trees quickly. If you have to cut up 2 foot trees all the time you want a big torquey saw. IMO if you need a long bar you need low rpm torque, if you can get by with a 16-18 inch bar you want rpm.
I know very little about stihl's but a 362 should work pretty good for fire wood, the other stihl in the 60cc range is the farm/ranch 391, it has less rpm and weighs more.

 

[StihlSolo]

Getting back to the original question, an undersquare engine will produce more torque at a given RPM. Undersquare is when the stroke length is greater than the bore diameter. Also called a long-stroke engine.

Undersquare engines do not rev as high as oversquare “rpm” engines with bore diameters greater than stroke lengths. Stroke lengths directly affect piston acceleration-deceleration. Piston acceleration-deceleration is what eventually limits engine RPM’s, shorter strokes allow higher RPM's.

Modern chainsaws have oversquare “rpm” engines, period. But the closer you can get with having an engine with stroke length nearer to bore diameter, that engine would be a bit more “torque-y”. The older 61cc claimed-4.3hp Stihl 041 was “torque-y” because its 44mm bore and 40mm stroke were close. The 61cc claimed-4.5hp Stihl 036 produced about the same power at higher rpms, with an undersquare 48mm bore and 32mm stroke.

And then there is the old adage about “nothing like displacement” to produce power. If you want more power go for a 48mm x 32mm MS360 versus a 42mm x 32mm MS250. I have an older 036, it works well.

 

[davidwyby]

If you want 60cc torque, get a Dolmar 6100