Saw Chain Surface Speed

[tommyhnavix]

This is interesting math. Engine RPM rules in similar horsepower saws
Figuring surface speed in feet per minute.

www.sawmillchainsaws.com/sawfacts.htm

Chain pitch x 2 3/8=.750 .404=.808 Take this x teeth on drive sprocket. Then that number x engine RPM. Take that number divided by 12 for surface feet per minute.

Chain Speed ______SFPM @ _______RPM
Drive
Teeth _________11,500 RPM , _____8000 RPM , _____6000 RPM

7 tooth STD ____3/8 ____5031sfpm, ____ 3500sfpm, ____2625sfpm

.404 ____ 5424sfpm, _____3773sfpm, _____2830sfpm

8 th ____3/8 ______5750sfpm, ____ 4000sfpm, _____ 3000sfpm

.404 _______ 6191sfpm, ____ 4307sfpm, _____ 3230sfpm

9 th ___3/8 _____6469sfpm, _____4500sfpm, _____3375sfpm

.404 _______ 6967sfpm, ______4847sfpm, _____3635sfpm


10 th ___3/8 _______ 7188sfpm, _____ 5000sfpm, _____3750sfpm

.404 _________ 7743sfpm, ______5387sfpm, ______4040sfpm


11 th ____3/8 ________7906fspm, _______5500sfpm, ______4125sfpm

.404____________ 8520sfpm, _______ 5927sfpm, _______ 4445sfpm


12 th___ 3/8 ______ 8625sfpm, ________ 6000sfpm, ________ 4500sfpm

.404____________ 9296sfpm, _________ 6467sfpm, _________ 4850sfpm


13 th___ 3/8 ________ 9344sfpm, _________ 6500sfpm, _________ 4875sfpm

.404 _________10,063sfpm, _________ 7000sfpm, _________ 5250sfpm


14 th___ 3/8 __________10,063sfpm, __________ 7000sfpm _________ 5250sfpm

.404 __________10,839sfpm, __________ 7540sfpm, __________ 5655sfpm

WOW!!! Just a few more drive teeth really jumps the speed!!

I have a saw I put an 8 tooth sprocket on with shorter bar and had trouble with the sprocket on the end of the bar smoking in heavy cutting. Started putting a little synthetic oil in the bar oil and it works fine now and cuts like wildfire.
More teeth eats up horsepower in a hurry!!
Shortening the bar length helps up to a point. I checked my engine RPM in a cut with a 24 inch bar on and jumped 1 tooth from a 7 to an 8 and lost RPM. Put an 18 in bar on and engine RPM the came back in the cut but could see much faster cutting. Tried a 9 tooth and saw RPM was very low and power was poor. WOW!! Amazing how much difference 1 tooth can make!!

This guy has many different size available.
www.ebay.com/itm/Chain-Saw-Racing....Y-/360398399396

[sweepleader]

Now that my XL-500 is running, I am curious about the 8 tooth sprocket issue. I have noticed a large difference in performance between the 500 and a SXL that I have. Both have 16 inch roller nose bars. What saw did you refer to in the above post? Is it stock or hopped up? Anything else you could offer? My 500 is stock.