Saw Dyno

[malk315]

Ill put the links for mine here when I get to my computer

Kevin's 066 and 661 link is here:

http://slice.bvwireless.net/dyno/auto_run_data.cgi?dataset=moparmyway_597f72f65967f9c1

 

[Mastermind]

Ported saws are silly.

 

[paragonbuilder]

Ported saws are silly.

They sure are! That's why I've had a silly grin on my face for a long time now!!! [emoji12]

 

[jmssaws]

Ported saws are silly.

Wtf is a ported saw?
It sounds silly

 

[Mastermind]

Wtf is a ported saw?
It sounds silly

See?

I just want a tuna fish sammich.

 

[jmssaws]

See?

I just want a tuna fish sammich.

That does sound good

 

[MustangMike]

Kevin, IMO, your 661 dyno #1 is right in there with the best of em, and the 660 has a very broad power band.

My 460s touched a few 8s, but not as many!

 

[Moparmyway]

Kevin, IMO, your 661 dyno #1 is right in there with the best of em, and the 660 has a very broad power band.

My 460s touched a few 8s, but not as many!

Thanks Mike !
I think that 066 would have shown better tuned to 14,000 .......... I didn't really have time to re-adjust it from its working weekend

 

[malk315]

@malk315 Go ahead and send me the data via PM. I'll run some analysis on it and place some graphs in this thread. From the graph I would guess the noise is around 25Hz.

Hey Shaun -- haven't forgot about this.

I noticed a bunch of points missing from the data -- I tried to get fancy Saturday when I hacked the code to show the raw load cell every 5ms w/ microsecond resolution timestamp and had it only logging when load cell is above 0.5. Well the noise band is large enough there are many points below 0.5 and those are all missing. I wanted to get the same points that contributed to a run instead of all points to sift through later -- we start the run when load exceeds a threshold -- of the filtered data which is cleaned up -- that's a big doh on my part applying same check on unfiltered since that data is all over the place.

However -- there is a swath in the data later on where all of it is above 0.5 (when the saw is pulling pretty well on the load cell and keeping all of the data in the whole band above 0.5) and it may be enough for you to characterize the frequency.

If not I'll collect more next time I get together with Bill for testing.

I'm absolutely beat tonight -- so tomorrow I'll get together the data that is good and PM you the good data and the entire swath (which has some missing points -- easy to tell by time stamps more than 5ms apart) I'll do that tomorrow after work.

Thanks again for offering to take a look. I'll be psyched to try a different filter setting if you come up with something that is better than the current 30 point setup we're using.

 

[srcarr52]

Yikes. That's a large error band. I was looking at the graphs and I noticed you must be hitting a resonance of the brake around 9250-9500. With all the saws I noticed a dip or spike in your data here which indicated that the noise band is larger there then elsewhere. The actual torque generated from the normal force on the brake can shift the frequency slightly and that is why you see it at slightly different RPM for different saws.

I wonder if you can't use a less stiff with more damping material behind the brake pad to help with the noise in the data. Often brakes have an extra shim which is used to offset two eigen modes of the system such that they don't ring off each other.

 

[Deets066]

 

[malk315]

We've gone back to a rigid attachment for the load cell so we can once again try weight on the torque arm. Damping right at the pads is a great idea. Will have to see Bills thoughts when he reads this.

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[Deets066]

We've gone back to a rigid attachment for the load cell so we can once again try weight on the torque arm. Damping right at the pads is a great idea. Will have to see Bills thoughts when he reads this.

Sent from my XT1080 using Tapatalk

Get her dialed in so my saw reads higher than Jason's!

 

[MustangMike]

Guys, I have only done analysis on two of my saws, but I am getting some consistent #s even with very different looking charts.

I look for a minimum of 7 consecutive usable data points, but often use as many as 12 consecutive data points, then compute an average.

Here is what I have been coming up with so far (which IMO validates the #s):

MS460/046-D Ported by Al for Run #s 94, 95 & 96 ... 8.142 Hp, 7.787 Hp and 7.98 Hp for an average of the 3 runs of 7.969 (we will call it 8 Hp) Al.

MS440 for Run # 100 and 101-1 and 101-2 ... 6.76 Hp, 6.67 Hp and 6.7 Hp for an average of 6.71 Hp.

I'm amazed at how consistent the #s are for these 2 saws, we will see if it continues.

I admittedly am using some judgement here, based on where to start and stop, based on how the chart looks, but it seems to be generating consistent results so far.

If anyone wants more details on what I am doing, or how I am doing it, just let me know.

 

[Time's Standing Stihl]

Should the rpm on the graph be switched? If not these are some low end monsters

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[MustangMike]

Oh well, it did not continue. My 362 had one low # run, my MMWS 044 had 2 runs that were much lower than the third, and my stock 044 had one run that was much lower than the other 2.

I still think the method of using at least 7 continuous data points from the best part of your best runs gives you a good idea of what your saw is doing.

Time to turn in, more tomorrow!

 

[malk315]

Mike hopefully we will make more improvements to the dyno so next time your saws can get a good look under the magnifying glass.

We can also do a more deep dive with stock saws. We shoulda run Dans bone stock 460 for several samples to characterize. Towards the end Bill started noticing better numbers when saw 4 stroke / 2 Stoke transitions were at certain points... Perhaps the more rich saws 4 stroking here and there while getting into the load cause different vibrations or affect brake grabbiness. I'm hoping to have higher sample rates so we can do better noise elimination in software too.

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[malk315]

Should the rpm on the graph be switched? If not these are some low end monsters

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It should. It's backwards because we bring it from WOT down as brake is applied. I can reverse it for graph display. Also need to setup fixed scales on left and right.

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[paragonbuilder]

Oh well, it did not continue. My 362 had one low # run, my MMWS 044 had 2 runs that were much lower than the third, and my stock 044 had one run that was much lower than the other 2.

I still think the method of using at least 7 continuous data points from the best part of your best runs gives you a good idea of what your saw is doing.

Time to turn in, more tomorrow!

I still think that the best run is probably most accurate. We are still working on getting the load constant and giving the saw enough time as it comes down through the rpm to stabilize. But if the saw can keep the numbers up for a duration, that is real power created. If it's lower its just a bad run. IMHO

 

[paragonbuilder]

It should. It's backwards because we bring it from WOT down as brake is applied. I can reverse it for graph display. Also need to setup fixed scales on left and right.

Sent from my XT1080 using Tapatalk

I think equal scales would be good so it's less confusing. Then the lines will track each other better too.
Those graphs are easier for me to read.