Chainsaw dynometer build.
- Thread starter chadihman
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chadihman
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Alright men I'm out for a while. Going to cut some squish and base on the lathe. Got two MS 460's that I wanna get done.
chadihman
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I finaly got some time this morning to work on the dyno build. I had surgery and finaly made it back to work two weeks ago. Work has been crazy and had some long hours and was just to pooped to work on the dyno in the evenings. I'm going to work at it some more tonight.
LegDeLimber
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Chadihman, Darn delighted to see you're able to get things together!
(surgery?...)
Quote Originally Posted by dynodave
"..Again my $7000 dyno has no flowmeter and does both torque and HP read out with only hydraulic pressure and pump speed.
Since mine it is a chassis dyno, all the power goes through the rear wheel to a drum directly connected to a pump, and 3000psi(torque) @ 100MPH(speed) = 100hp where 100mph or a lesser portion will mathamtically convert back to engine RPM. This would basically be the same as your chain reduction ratio. "
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The pump is the flow meter in this setup.
Take a known displacement and drive it against a known load, figure the internal leakage
and other energy losses...
and there's your power output.
Just remember that proportionally, the saw test is working against a much lower ratio
of loss to power input.
i.e. the system uses say 4 tenths HP to run at 8000 rpm
that's not a serious significant number for a 100 hp motor under test
but it's pretty noteworthy portion of a 5 HP motors output.
(surgery?...)
Quote Originally Posted by dynodave
"..Again my $7000 dyno has no flowmeter and does both torque and HP read out with only hydraulic pressure and pump speed.
Since mine it is a chassis dyno, all the power goes through the rear wheel to a drum directly connected to a pump, and 3000psi(torque) @ 100MPH(speed) = 100hp where 100mph or a lesser portion will mathamtically convert back to engine RPM. This would basically be the same as your chain reduction ratio. "
-
The pump is the flow meter in this setup.
Take a known displacement and drive it against a known load, figure the internal leakage
and other energy losses...
and there's your power output.
Just remember that proportionally, the saw test is working against a much lower ratio
of loss to power input.
i.e. the system uses say 4 tenths HP to run at 8000 rpm
that's not a serious significant number for a 100 hp motor under test
but it's pretty noteworthy portion of a 5 HP motors output.
Nitroman
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The point in building a dyno is to learn if you are making power, and how much. If you just want to listen to it, go out in the woods and rip a log.
chadihman
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My dyno is going to be used for checking power changes after making changes to the saw like port timing or ignition advance. A brake style dyno like the one I'm building should be nice for pulling the saw to different rpms and testing the torque at any rpm. This dyno should be the cheapest way to find the #'s I'm looking for.
034avsuper
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dieselfitter
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Chadihman, did you make or purchase that driven sprocket?I finaly got some time this morning to work on the dyno build. I had surgery and finaly made it back to work two weeks ago. Work has been crazy and had some long hours and was just to pooped to work on the dyno in the evenings. I'm going to work at it some more tonight.
Why the lovejoy coupler and pump in a box? Does it provide an advantage to just hanging the pump on the shaft? Please don't get defensive. I am not criticizing your work. I've been following thread and prefer your approach to this project compared to other strategies offered. I am just hoping to gain some insight. Thanks, DF
chadihman
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A vid of how it going together[video=youtube_share;tkB9Q_hz__I]http://youtu.be/tkB9Q_hz__I[/video]
On your scales, there will be considerable vibration whereby you will need to interpolate the average reading. It is easy enough even with a digital scale after you get used to it.
You may want to consider a buffer - if you are using digital input into a computer, for example?
You may want to consider a buffer - if you are using digital input into a computer, for example?
Design, Fabrication, and Testing of a Small Engine Dynamomete
http://www.hastings.edu/downloads/DEasterly.pdf
several on craigslist $500-$850 range
-=
CL baltimore all for sale / wanted tools - by owner
[email protected] [?]
flag [?] : miscategorized prohibited spam best of
Posted: 2013-04-15, 11:14PM EDT
small engine Dyno - $850 (Odenton)
I have a small engine Dyno for sale. For any Q. CALL Tim at 240-565-4458
http://www.hastings.edu/downloads/DEasterly.pdf
several on craigslist $500-$850 range
-=
CL baltimore all for sale / wanted tools - by owner
[email protected] [?]
flag [?] : miscategorized prohibited spam best of
Posted: 2013-04-15, 11:14PM EDT
small engine Dyno - $850 (Odenton)
I have a small engine Dyno for sale. For any Q. CALL Tim at 240-565-4458
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Nitroman
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Exactly. You can do the very same thing with a wheel. Hope it works as well as it is beginning to look. This is an interesting project.
chadihman
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Could you please explain how you can determine torque at any rpm with a flywheel dyno? I'm guessing it takes an expensive monitoring system. Am I right in saying a flywheel dyno uses a heavy flywheel and the saw is timed on how long it takes the saw to get the heavy mass to a certain rpm. I guess that works for power testing but what im looking for. Changes could be made to the saw as its running the test with my style dyno. Air flow or carb adjustments would be nice to test underload.
Here's a dyno video of an engine blowing up on a dyno. Don't want this to happen to a freshly built chainsaw on the dyno. [video=youtube_share;aUkXriHjQeI]http://youtu.be/aUkXriHjQeI[/video]
Nitroman
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That is an expensive video to watch!
Yes, using the hardware and software from Performance Trends Dyno DataMite you spin up the wheel and the graph of hp and torque versus rpm is displayed on your computer screen. You can add sensors to measure and correct for temperature humidity, show EGT, O2 and many more. A basic setup would run about $800.00.
Obviously you'd have to bring the wheel stationary to make a change, then spin it back up to see what the change accomplished. You could overlay the graphs to track the changes.
Here is a screen-sot that shows the output:
Yes, using the hardware and software from Performance Trends Dyno DataMite you spin up the wheel and the graph of hp and torque versus rpm is displayed on your computer screen. You can add sensors to measure and correct for temperature humidity, show EGT, O2 and many more. A basic setup would run about $800.00.
Obviously you'd have to bring the wheel stationary to make a change, then spin it back up to see what the change accomplished. You could overlay the graphs to track the changes.
Here is a screen-sot that shows the output:
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The wheel's incremental encoder is time measured between successive clocks, then compared to the previous count. The shorter time is due to increase in rpm/speed of the wheel directly caused by torque applied to the wheel. All high school math after that.
Without brake dyno you don't get heat soak. But we've been over that before...... :bang:
LegDeLimber
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pardon my derailing a bit here but thought it was interesting to watch
the heating of the individual pipes of this engine.
you can see where the hot gasses hit the pipe walls
in all the curves.
I'm calling from left to right here:
#4 tube shape gets it really close to the block fast (notice the shape of that pipe and exit angle).
#3 has an interesting lag in it's glow.
should provide a little something to think of when you're pondering those porting cuts
and the gas flows.
Exhaust on fire (Dyno) - YouTube
the heating of the individual pipes of this engine.
you can see where the hot gasses hit the pipe walls
in all the curves.
I'm calling from left to right here:
#4 tube shape gets it really close to the block fast (notice the shape of that pipe and exit angle).
#3 has an interesting lag in it's glow.
should provide a little something to think of when you're pondering those porting cuts
and the gas flows.
Exhaust on fire (Dyno) - YouTube
chadihman
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I'm hoping that vibration is not to much of an issue. I've given this some thought and decided that I'm going to tap threads into the center of the end of the pump housing pivot. I'll then attach a cylindrical mount isolater to the end of the shaft and the torque arm to the isolater. This will hopefully reduce the vibration and make it easier to read the torque.
chadihman
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I found a little more time to work on the Dyno again. I got the bearing mount plates all welded in place. I spent a good bit of time welding it all up as I wanted everything nice and square and in line. I bolted all the bearings tight and locked the bearing collars and love joy set screws. I used a straight coupler to get the mating shafts lined up. I removed the coupler and installed the love joys. I tapped the bearings and shaft and used a fealer guage to check the gap all the way around the love joy. Everything spins freely. I cut out a 24"x24" 3/8" thick steel base. I used some casters off a snap on tool box that I removed the wheels to put the box in my service truck. I plan to get some time this week to get it finished up. I'll have a video of the first chainsaw run.
Very Interesting and look forward to your first run.
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