Another chainsaw dyno...

[Walter Glover]

Mounted and cal check with 6 pounds at 24” after torque arm and cal rod balanced out.

 

[Walter Glover]

Getting 1.5hp for Husky 51
3.2hp for the 372xp FT
5.33hp for the ms660 FT
Need more sturdy brake for the 660

 

[Red97]

Getting 1.5hp for Husky 51
3.2hp for the 372xp FT
5.33hp for the ms660 FT
Need more sturdy brake for the 660View attachment 290397

Figure out a way to calibrate 2hp more into your calculations. Then those numbers would be pretty close to stock.

As long as you do a before/after with the same settings the dyno should show a change. Not really a matter of what the numbers are.

 

[Nutball]

How would he dyno a 2511t? It would have to do 2hp just to read 0hp. Any weaker and the saw would be measuring the dyno's power.

 

[markds2]

Hope this is OK posting this Joe

 

[Red97]

How would he dyno a 2511t? It would have to do 2hp just to read 0hp. Any weaker and the saw would be measuring the dyno's power.

That will be difficult.

 

[Walter Glover]

Figure out a way to calibrate 2hp more into your calculations. Then those numbers would be pretty close to stock.

As long as you do a before/after with the same settings the dyno should show a change. Not really a matter of what the numbers are.

Thinking of connecting an electric motor to measure drag in amps increase and see where that gets me

 

[Walter Glover]

Hooked up a motor and with the amp draw and voltage with assumed 80%EFF at a 0.8PF my dyno has 0.25hp losses at 860rpm. As I understand it inertia increases by velocity squared. 3x velocity = 9x hp loss. Therefore 0.75hp lost in spinning the drivetrain on my dyno. That helps the numbers some

 

[Sawrain]

Hooked up a motor and with the amp draw and voltage with assumed 80%EFF at a 0.8PF my dyno has 0.25hp losses at 860rpm. As I understand it inertia increases by velocity squared. 3x velocity = 9x hp loss. Therefore 0.75hp lost in spinning the drivetrain on my dyno. That helps the numbers someView attachment 290829

Hard to say what output power is that precisely, PF (power factor) varies greatly with load, and is most likely less than 0.8 if you are not near full load on the electric motor, could be 0.5 or less, what is the motors full load output rating?

0.75hp seems like a lot, for comparison picture what a 0.75hp rated bench grinder can achieve, I would not have thought the parasitic loss would be equal to that, it could be, I’m just thinking out loud.

You could just try to replicate Red97s results, find your correction factor by dividing your dyno HP reading by Reds dyno reading with a few different unmodified saws that have figures available in the dyno thread.

It’s not really a calibration I know, but why not simply match the current aftermarket Dyno benchmark set by Red?

 

[Red97]

Pair of ported 390's nice gain over the muffler mod only baseline.

 

[Duane(Pa)]

Any guess what took the duce into the next digit hp wise? (and torque too I guess)

 

[Red97]

Any guess what took the duce into the next digit hp wise? (and torque too I guess)

Broke in vs brand new. That works out to 4% ish. Not as drastic as it looks.

 

[jacob j.]

Broke in vs brand new. That works out to 4% ish. Not as drastic as it looks.

That's what my last old lady told me...

 

[MustangMike]

Very impressive, not just the increased Hp obtained, but the breadth of the increased power.

I'll bet those saws will be real nice to work with.

 

[Red97]

Nice gains from the 4910.

 

[CJ Brown]

Nice gains from the 4910.

View attachment 291233
View attachment 291234

That's quite a transformation for a small saw to gain 60% horsepower! From a dud to a stud!

 

[huskihl]

Nice gains from the 4910.

View attachment 291233
View attachment 291234

What’s it weigh? Is that the light one you mentioned?

 

[Red97]

That's quite a transformation for a small saw to gain 60% horsepower! From a dud to a stud!

Thank you. It should be a runner for sure.

What’s it weigh? Is that the light one you mentioned?

10.4 pho

Don't have that other one yet. But I plan on getting one as soon as I can...

 

[Nutball]

Any internal changes compared to the 490? Do you go for lots of compression on them? I think they do great with just a BGD and good porting.

 

[Red97]

Any internal changes compared to the 490? Do you go for lots of compression on them? I think they do great with just a BGD and good porting.

Basically a 501 with a plastic handle and clutch cover