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TORQUE!

Robin Wood

Robin Wood

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Oh I learned that plenty well in my early 20's.
Sounds like you have alot things, what do you think of my hypothesis about heavier crank with more stroke of same class cc saw against its competitors. Has more torque?

Cs1200/1201 definitely feels like it has some acceleration lag compared to 070, 084/088 has to be the fastest accelerating among them. If my calculations are right torque output by cs1201/1200 should be close to 090, the boys at masterminds gtg few years back did a race 090 vs cs1201 and the cut times were almost the same. Maybe if they go with 72" bar 090 will pull ahead? It surprising for a saw that has about 20cc less can hang with 090

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sawfun

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Sounds like you have alot things, what do you think of my hypothesis about heavier crank with more stroke of same class cc saw against its competitors. Has more torque?

Cs1200/1201 definitely feels like it has some acceleration lag compared to 070, 084/088 has to be the fastest accelerating among them. If my calculations are right torque output by cs1201/1200 should be close to 090, the boys at masterminds gtg few years back did a race 090 vs cs1201 and the cut times were almost the same. Maybe if they go with 72" bar 090 will pull ahead? It surprising for a saw that has about 20cc less can hang with 090

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I'm thinking a heavier crank throw of lesser stoke is smoother if balanced correctly. What I don't know is if energy applied to a heavier throw produces a different torque characteristic. 72" and longer are best handled by a geardrive, that said an 090 or 797 are two direct drive that CAN handle a 72" bar. The 1201 likely can as well. A strong clutch is pretty essential to this. These lower rpm high torque saws would work even better if 1/2 chisel was available. Anyone with enough 60" + bar experience likely knows the advantages of slow torque over the safety disadvantages of high rpm chain speed. If I were still cutting large wood, I would get the big Echo without a doubt. My Echo 1001 would probably pull and oil a 60" bar just fine, so a 1201 would be even more of a good thing
 
Robin Wood

Robin Wood

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I'm thinking a heavier crank throw of lesser stoke is smoother if balanced correctly. What I don't know is if energy applied to a heavier throw produces a different torque characteristic. 72" and longer are best handled by a geardrive, that said an 090 or 797 are two direct drive that CAN handle a 72" bar. The 1201 likely can as well. A strong clutch is pretty essential to this. These lower rpm high torque saws would work even better if 1/2 chisel was available. Anyone with enough 60" + bar experience likely knows the advantages of slow torque over the safety disadvantages of high rpm chain speed. If I were still cutting large wood, I would get the big Echo without a doubt. My Echo 1001 would probably pull and oil a 60" bar just fine, so a 1201 would be even more of a good thing
I agree, the closer crank end and pins are the smoother it should be?

I think heavier bobweight will give a broader range of power with acceleration and can handle more load with ability to hold rev more under load. The big echo can be loaded up good and it will still spin the chain, it will sound like a tractor when dogged in hard.

I think 090, 797, 166, 1201 are all in league on their own. 1200 has similar clutch to 166, 1201 has similar clutch with 070.

Im a high torque low rpm on big saw guy myself, hate tensioning chain and pulling out with this new high rev low torque machines.

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sawfun

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I must agree, 090 gains some torque from that big 6 piece clutch. If you can put that big clutch in cs1201 you'll have something

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The old 900 series Homelites like the 990g had such clutches as well. Those machines sure weren't built for firewood cuttin.
 
Huskybill

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Robin is correct about crank weight, especially the bobweight of the rod journal vs its distance from the crank centerline. More rotating mass will prefer to stay in motion, though, all things being equal, be slower to accelerate, the trade off. I remember doing a tow up a hill experiment with a couple of similarly geared Chevys. One had a big block 400 (402), the other a small block 400. The big block out towed the small block by a good margin. Then I pulled a plug wire off #5 cylinder on both. The small block shook and really struggled, the big block with its heavier rotating mass had little trouble. With #5 & #7 wires off the small block barely ran, the big block shook a little but pulled the load, though not well. Both vehicles had the same size torque convertor and turbo 400. My 500 caddy engine can easily idle down to 450 rpm in gear and is hard to kill with its giant crank. While heavier cranks do give the flywheel effect, there seems to be more going on than just that.
Food for thought,

My one ton 4x4 had a 400th auto tranny. When the tranny went I put in a granny four speed. The 400th auto tranny pulled harder. The torque converter multiplies the torque. Back in the 50’s dodge had a auto tranny with a clutch and torque converter, fluid drive it was called.

My race car went from a 350 hp Sb to a 400hp bigblock. Your right about mass being bigger crank wise. The bb pulled way harder than the Sb.
 
sawfun

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But the stihl 1124 models have smaller clutch than 070 ?

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I never measured the size, but I believe the three shoes had less contact area. They are definitely of much lighter construction. I would guess the springs on an 070 have less tension. I ran one of my 070's with a 60" bar in 60" Doug Fir and it started to smoke the clutch, that kinda surprised me. I bet with a 090 clutch it would have cut fine as the power was there. Admittedly I did not look at the clutch much to see its condition but it started out cutting fine until the bar was in the wood over 3 feet.
 
Robin Wood

Robin Wood

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I never measured the size, but I believe the three shoes had less contact area. They are definitely of much lighter construction. I would guess the springs on an 070 have less tension. I ran one of my 070's with a 60" bar in 60" Doug Fir and it started to smoke the clutch, that kinda surprised me. I bet with a 090 clutch it would have cut fine as the power was there. Admittedly I did not look at the clutch much to see its condition but it started out cutting fine until the bar was in the wood over 3 feet.
I've experienced the same, I've smoked 2 070 3 piece clutches. Then i did 090 upgrade on that saw and it had so much torque the chain was getting beat up

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sawfun

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I never measured the size, but I believe the three shoes had less contact area. They are definitely of much lighter construction. I would guess the springs on an 070 have less tension. I ran one of my 070's with a 60" bar in 60" Doug Fir and it started to smoke the clutch, that kinda surprised me. I bet with a 090 clutch it would have cut fine as the power was there. Admittedly I did not look at the clutch much to see its condition but it started out cutting fine until the bar was in the wood over 3 feet.
I have a new sealed pac of three 070 shoes and it is feather light if that means anything. 090 shoes, even individually ain't exactly what I'd call light.
 
holeycow

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I don't believe that reciprocating weight increases torque as much as it increases resistance to stalling (could be seen as torque, I guess), as in what was done on many old farm machines with heavy flywheels (square balers, for example). The rotating mass smooths out the power and allows the machine to easily accommodate variable resistance and shock loads.

it's just an accepted method of "increasing torque". Haha.

plastic chainsaw flywheels reduce overall weight and produce a faster-revving motor with less torque, all other things being equal.

same goes with anything...
 
Ted Jenkins

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Wow this thread has gone some place, but where?? Torque has nothing to do with crank, crank size, stroke vs. short stroke, displacement, rpm or most things mentioned so far. When I built drag racing engines or road racing engines they produced very little torque as compared to the amount of HP they produced. Top range of RPM for some motors were between 20,000 and 25,000 RPM. Some of those motors had much heavier cranks than others why. A crankshaft has to have some weight to create some inertia or after delivering its power to the end of crank it will stop. A heavier crank will have more inertia thus allowing engine to have a little more stored energy to keep it going between shifts as an example. Some engines that were used for road racing had to have fairly heavy cranks so as not to deliver HP too fast thus breaking traction at high speeds. A heavy crank will deliver power more gentle than a light crank. A engine that has much more torque has the ability accelerate from a certain RPM to the next 1000 RPM. My diesel engine in my skid steer loader can not rev past 28 or 2900 RPM with out breaking some thing. At 2,500 RPM it produces about 85 HP while my race tuned snow mobile motor produces about four times that with much less displacement. On chain saws in general factories tune porting crank mass ignition timing muffler volume to create a usable combination of torque verses HP to make a smooth cutting experience for use for operator. Any OP can take a chain saw advance timing and lower port timing to increase torque, but sacrificing HP in the process. Or the OP can decrease timing advance porting to increase HP. Many chainsaw mods aim to increase a more robust power stroke by opening porting up slightly with out increasing RPM dramatically. Thanks
 
sawfun

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Wow this thread has gone some place, but where?? Torque has nothing to do with crank, crank size, stroke vs. short stroke, displacement, rpm or most things mentioned so far. When I built drag racing engines or road racing engines they produced very little torque as compared to the amount of HP they produced. Top range of RPM for some motors were between 20,000 and 25,000 RPM. Some of those motors had much heavier cranks than others why. A crankshaft has to have some weight to create some inertia or after delivering its power to the end of crank it will stop. A heavier crank will have more inertia thus allowing engine to have a little more stored energy to keep it going between shifts as an example. Some engines that were used for road racing had to have fairly heavy cranks so as not to deliver HP too fast thus breaking traction at high speeds. A heavy crank will deliver power more gentle than a light crank. A engine that has much more torque has the ability accelerate from a certain RPM to the next 1000 RPM. My diesel engine in my skid steer loader can not rev past 28 or 2900 RPM with out breaking some thing. At 2,500 RPM it produces about 85 HP while my race tuned snow mobile motor produces about four times that with much less displacement. On chain saws in general factories tune porting crank mass ignition timing muffler volume to create a usable combination of torque verses HP to make a smooth cutting experience for use for operator. Any OP can take a chain saw advance timing and lower port timing to increase torque, but sacrificing HP in the process. Or the OP can decrease timing advance porting to increase HP. Many chainsaw mods aim to increase a more robust power stroke by opening porting up slightly with out increasing RPM dramatically. Thanks
You certainly did not build any drag race engine I could think of, to be run at 20k to 25k rpm. I believe, even 180 degree crank V8's, like Indy cars, don't get that high. Inertia is one thing, exactly how that inertia is/was created is another. Try running a clutch made for top fuel in an alcohol engine and you will quickly find that plain inertia alone does not explain all that takes place. The same piece of metal at the same rpm can behave much differently depending on the source impacting it. Source + inertia = power output? Different sources were what was being discussed.
 
Ketchup

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I think it’s important to compare power band location in the saws mentioned and examine the timing and design of each cylinder.

What changes crank and flywheel weight have on the pulling power of the saw would be best observed if one model could be modified to fit them all but that’s an insane amount of work or impossible.

I’d love to see all the cylinders side by side and a good spreadsheet of port numbers. (With compression specs).

At least hang the same bar on all of them and make some cuts. Sounds like a good GTG.
 
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