So are you measuring PSI and volume?
I call B.S. on Stihl. My dyno doesn't lie. MS 461 is king over MS 660
- Thread starter chadihman
- Start date
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chadihman
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Neither
Brush Ape
The Port Authority
Thank you for your service to our community.
Infrared. (lol)
I guess I'm not understanding then.
real world performance is what counts .. there's NO way a 461 is out performing 660 .. provided both saws have similar hours and prepped the same
chadihman
Addicted to ArboristSite
Sorry I was eating dinner with my Kiddo's.
The pump is just a brake to put a load on the saw. The output side of the pump has a needle valve inline. I can adjust the needle valve closed or open to vary the pressure between the pump and the needle valve. The load on the saw is increased as the needle valve is tightened. Now here's how I get my #'s. The pump is bolted inside a square piece of tubing and a shaft is welded onto the tubing. The shaft and tube were machined to keep the shaft and pump input shaft perfectly in line. I mounted bearings to hold the pump. The driven shaft from the saw has a love joy coupler that mates a Lovejoy on the pump. The pump rotates. A torque arm is attached to the rotating pump housing. I put a digital scale on the end of the torque arm. As the needle valve is closed the pressure increases and loads the saw. The pump tries to twist because its mounted in bearings and pushes on the torque arm and I get a reading on the digital scale. The torque carm is 18" long so I multiply whatever is on the scale by 1.5 and that's ft-lbs. I measure the shaft rpm.
Torque x rpm/5252= Hp
chadihman
Addicted to ArboristSite
chadihman
Addicted to ArboristSite
Something wrong with his #s
Now we're on the same page. Thanks for the explanation. 
MasterMech
ArboristSite Operative
Had it ever been shown that a saw will pick up another 15% in power output during break in? That's a pretty big swing, and one would think the 15cc advantage would at least make the 660 marginally stronger. Broken in or not. If it hasn't picked up noticeably after 4-5 tanks, I'm not sure it ever will.
one.man.band
ArboristSite Guru
think you mean these numbers.
one.man.band
ArboristSite Guru
tried to help.......
message 1:
hey chadiham
hope the following will help:
-the attached file is a complete dyno graph of an older 066. i do not have references for an MS461, other than the numbers i posted in the thread.
-some of the posts made in the thread, had some good ideas for you to consider:
heat of the motor can sway results. monitoring temps can stabilze results. the longer the tests take to complete, the less power/TQ the motor will show... just the nature of 2ST's. after about 20 minutes of testing, power/TQ values will differ, decreasing up to 20%.
don't know if you keeping throttle pinned during the tests. be careful, if you are modulating the throttle at the same time turning the valve, it can sway the numbers.
like what you are trying to accomplish here. wish you the best and most accurate results possible.
-----------------------------------
message 2:
looking at the TQ values you posted, they are between 2.2 and 2.5 times
greater than the kwf and dlg values for these saws.
have a suspicion it may be due to the math you are using.
if i am off-base here please disregard, and may be telling you
what you already know, sorry.
don't know how long your torque arm is on your dyno.
maybe your values need to be divided by the torque arm length,
instead of multiplied.
you can easily tell if this is the case.
an easy check of this is to place a known weight directly on the scale.
then suspend it off your arm.
the suspended weight off of the arm,should end up being equal
the weight the scale see when the math is done.
one other thing comes to mind. you have up to 2% loss for each
gear the saw spins. so your reading on the scale now would in
actuality be low for the motor itself. but because the chainsaw spins
a chain with gears, it's a wash, and closer to reality.
another thing is atmospheric corection for weather.don't have time
to give you those tonight, but will give you those if you want them.
hard to do, but make sure your tach is acurate. trigger position is
solid. as mentioned before, it will effect the math.
usually the #'s read are averaged over a few or many tests.
hope it helps.
regards
-------------------------------------
message 1:
hey chadiham
hope the following will help:
-the attached file is a complete dyno graph of an older 066. i do not have references for an MS461, other than the numbers i posted in the thread.
-some of the posts made in the thread, had some good ideas for you to consider:
heat of the motor can sway results. monitoring temps can stabilze results. the longer the tests take to complete, the less power/TQ the motor will show... just the nature of 2ST's. after about 20 minutes of testing, power/TQ values will differ, decreasing up to 20%.
don't know if you keeping throttle pinned during the tests. be careful, if you are modulating the throttle at the same time turning the valve, it can sway the numbers.
like what you are trying to accomplish here. wish you the best and most accurate results possible.
-----------------------------------
message 2:
looking at the TQ values you posted, they are between 2.2 and 2.5 times
greater than the kwf and dlg values for these saws.
have a suspicion it may be due to the math you are using.
if i am off-base here please disregard, and may be telling you
what you already know, sorry.
don't know how long your torque arm is on your dyno.
maybe your values need to be divided by the torque arm length,
instead of multiplied.
you can easily tell if this is the case.
an easy check of this is to place a known weight directly on the scale.
then suspend it off your arm.
the suspended weight off of the arm,should end up being equal
the weight the scale see when the math is done.
one other thing comes to mind. you have up to 2% loss for each
gear the saw spins. so your reading on the scale now would in
actuality be low for the motor itself. but because the chainsaw spins
a chain with gears, it's a wash, and closer to reality.
another thing is atmospheric corection for weather.don't have time
to give you those tonight, but will give you those if you want them.
hard to do, but make sure your tach is acurate. trigger position is
solid. as mentioned before, it will effect the math.
usually the #'s read are averaged over a few or many tests.
hope it helps.
regards
-------------------------------------
one.man.band
ArboristSite Guru
good luck.
Proof is in the pudding. Here's an MS660 with a 36" bar and a cottonwood. The sawyer shown here is my logger buddy. He's just under 6' tall, has lots of hours on an 046, but he tends to like his 660 better for his work.
weedkilla
Ain't no guru of nuthin'
Chadihman, I'm not going to bite on the merits of the beloved 660, you have shown the data that you collected from the saws you have and I'm grateful for that.
I'm curious if you've tried using the dyno as a fuel tuning tool yet? I'd imagine that if you tune your saw by ear, and consider this the leanest point you are willing to run the saw, are there any points in the rev range you can pick up some power with a richer tune? I have a feeling that the answer will vary for every saw that runs on the dyno, but i'd be happy to be wrong!
This - to me - is the best use of a dyno, as a tuning tool. Whenever two engines are dynoed someone gets butthurt. Whenever a dyno is used to develop one engine - there is a happy person at the end.
Again, thanks for sharing what you find.
I'm curious if you've tried using the dyno as a fuel tuning tool yet? I'd imagine that if you tune your saw by ear, and consider this the leanest point you are willing to run the saw, are there any points in the rev range you can pick up some power with a richer tune? I have a feeling that the answer will vary for every saw that runs on the dyno, but i'd be happy to be wrong!
This - to me - is the best use of a dyno, as a tuning tool. Whenever two engines are dynoed someone gets butthurt. Whenever a dyno is used to develop one engine - there is a happy person at the end.
Again, thanks for sharing what you find.
chadihman
Addicted to ArboristSite
Sorry I was wrong. I have greater torque because the pump shaft is only spinning 1/3 of the saw speed. Shaft rpm x torque/5252 = hp
weedkilla
Ain't no guru of nuthin'
Can I say - comparing numbers from two dynos is always fraught with danger. Even on production dynos from the same manufacturer. Just consider the numbers from your dyno relevant to the other numbers from your dyno - and with time you will get a feel for what the likely variation is between different runs on different days on your setup.
With no knowledge of the exact setup and spec of the saws that go to dlg and kwf or the way stihl choose to generate the numbers that they show in their spec sheets (advertising material) none of that is any way relevant to what is being shown here.
chadihman
Addicted to ArboristSite
No I haven't used it to tune a saw yet. I. Can slowly load the saw and hear the four stroke to two stroke change.
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