HP/Bar Length Ratio

[R Mac]

Is there a general guide to power output (HP/kW/Ps) relating to the maximum bar length a saw can handle assuming similarly sized chains?

 

What HP would you expect to need to pull a 3/8 .058 regular (not Skip) semi chisel at e.g. 24", 28", 36" max in each case?

 

Also why are Husqvarna the only manufacturer to list max Torque arguably a better indicator of cutting performance than max power?

[Joe Newton]

General rule of thumb for max bare length on a pro saw is displacement (cc) divided by 3. 60cc is 20" bar etc. I prefer smaller bars in general for faster cutting, less fatigue and engine wear.

[R Mac]

Cheers Joe, got to say I'm surprised that displacement is used a a guide as there's a fair difference in power output between saws of similar engine capacity. Surely power/bar length while not perfect, is a better indicator than capacity?

 

Seems there's a trend though for large capacity (and heavy) saws with short bars for faster cutting, personally I prefer a smaller lighter saw with a longer bar, that's why I'd prefer to see manufacturers list max torque and at what rpm.

 

I don't mind a slower cut if it's consistent under load, max power at max revs is fine but with most 2 stroke engines the power drops significantly if the revs drop.

 

Interestingly back in the day a 5hp saw was delivering max at about 6000rpm and was expected to handle up to a 36" bar, a lot of seriously large trees were felled using saws like that so there's no question that they were effective.

[Joe Newton]

Cheers Joe, got to say I'm surprised that displacement is used a a guide as there's a fair difference in power output between saws of similar engine capacity. Surely power/bar length while not perfect, is a better indicator than capacity?

 

 

 

Seems there's a trend though for large capacity (and heavy) saws with short bars for faster cutting, personally I prefer a smaller lighter saw with a longer bar, that's why I'd prefer to see manufacturers list max torque and at what rpm.

 

 

 

I don't mind a slower cut if it's consistent under load, max power at max revs is fine but with most 2 stroke engines the power drops significantly if the revs drop.

 

 

 

Interestingly back in the day a 5hp saw was delivering max at about 6000rpm and was expected to handle up to a 36" bar, a lot of seriously large trees were felled using saws like that so there's no question that they were effective.

 

 

Well it seems you know your saws well enough to figure out what bar you want to run

 

I mainly climb, so I prefer a fast saw as opposed to a long bar. Nothing worse than having a max bar length saw constantly bogging down when your on spikes on a big stem.

[R Mac]

Well it seems you know your saws well enough to figure out what bar you want to run

 

I mainly climb, so I prefer a fast saw as opposed to a long bar. Nothing worse than having a max bar length saw constantly bogging down when your on spikes on a big stem.

 

Bogging down is soul destroying anywhere, I don't know saws really, just wondered why the max recommended bar size seems quite low now compared to years ago even though the power is the same or more, the only thing I can come up with is that they used to rev lower and probably had more torque.

 

I guess in the end it's a case of trying the bar you want on the saw you have and seeing if you can live with it.