Chainsaw Dyno bring saws to there knees. Build from start to end with video

[watsonr]

Try a quick test and hook up some shop air from the compressor to the carb,like a mock turbo.Set a regulator for a few pounds,and increase i gradually and see what happens.
Thomas

Probably lean the motor out, we know what happens to lean engines. Could we use your saw first?

 

[chadihman]

Probably lean the motor out, we know what happens to lean engines. Could we use your saw first?

Yeah if blowing charged air in the carb won't blow it up I could inject nitro

 

[drkptt]

Why is the torque arm so long? Scale maxes out?

 

[LegDeLimber]

a shorter torque bar would reduce (*usable?) sensitivity and make it harder
to "see" small changes in the power output.

* i believe the reasons are somewhere
in the math of signal to noise & mechanical ratios,
But but pills for my knees are trowing my brain to pain ratios off for now.

 

[drkptt]

a shorter torque bar would reduce (*usable?) sensitivity and make it harder
to "see" small changes in the power output.

...

A shorter torque arm increases resolution and makes it easier to see small changes in torque.

 

[half_full]

Very cool! can't wait to see more mod results. As stated, who cares about actual HP accuracy when you can measure gains/losses for each mod.

 

[PogoInTheWoods]

....who cares about actual HP accuracy when you can measure gains/losses for each mod.

Uhhh..., compared to what?

I'd be sorta upset too if I built one of these and it told me my MS460 was only puttin' out 3.x HP, but it sure as hell woke up when I removed the air filter. So what? My Mantis does that.

Baselines are required for any of it to have much meaning.

And I disagree with the statement that HP ratings aren't relevant to the process. That's sorta what dyno's do and how gains and losses are determined, again, given baselines and accurate calibration against known standards.

Otherwise, just grab a stopwatch and go cut some cookies for more "scientific" results.

This has serious possibilities if refined. Just being satisfied with relative averages seems like a wasted effort to me considering how much has already been put into the project. Ya can get the same "relative gain and loss averages" just using a tach if RPM's are all you care about.

But don't get me wrong... I'm not trying to be a dark cloud raining on the parade. Quite the opposite, and would strongly encourage more refinement of an already seriously awesome effort.

 

[7sleeper]

I also find this a fantastic project! :msp_thumbsup: I would like to rep all participents but this stupid rep system is kind of restrictive.:msp_thumbdn:

I have a question about the ¨power loss¨. We have often read by sawtroll that echo has horrible hp numbers compared to the others. Then again the myth has it that echo measures hp numbers at the bar tip compared to the others. Do we now see a similar ¨power loss¨?

7

 

[lesorubcheek]

chadihman, you've done an incredible job! You You're an inspiration showing what can be done if one wants to accomplish something. Sure all the details will come in time. Key is you now have a foundation to build upon with endless possibilities (data logging / recording, calibration, comparitive analysis, sensitivity refinement....) Door is now wide open for all kinds of things to answer questions with measurment instead of just guessing and speculating. Really wish I had the sense and time to make one. Gets my vote for one of the best saw related threads on AS in all time. Can't wait to see what follows.

Dan

 

[LegDeLimber]

well crap, I'm thinking about the amount of movement at the end of a long bar
But seems I was still was reversed like using a wrench about the actual work.

Sorry for throwing in inaccurate thoughts and cluttering the thread guys,
Dang pain meds and broken up sleep make things get a bit fuzzy at times.

 

[Moparmyway]

A shorter torque arm increases resolution and makes it easier to see small changes in torque.

I am gunna dis-agree with this ....... a longer arm will give higher numbers, allowing math to be more accurate. The question arises about max scale readings, but if the scale can handle it, a 10 foot bar would show the smallest change in torque, or a 100 foot bar for that matter (Molson XXX talking there) !!

 

[Rudolf73]

The way I see it, you are measuring "at the wheel" hp, which means results will always be lower than actual hp numbers.

IMO it would be good to have some kind of idea on the loses and therefore an estimated engine hp value. You could then run any saw on the dyno and have an idea how close it is to stock numbers, especially if you don't plan on modding it etc.

 

[Moparmyway]

Uhhh..., compared to what?

I'd be sorta upset too if I built one of these and it told me my MS460 was only puttin' out 3.x HP, but it sure as hell woke up when I removed the air filter. So what? My Mantis does that.

Baselines are required for any of it to have much meaning.

His 460 was ported and admittantly not as good as at least one other stock saw. So his port job didnt produce the numbers he wished for, it aint the first time, and probably wont be the second time someone ported something without stellar results. The whole purpose of removing the AF was to see if the setup would show a difference, and it did !!! Someone should buy Chad a beer !! His baseline should have been at the RPM's that Stihl rated the saw at .......... any other RPM isnt a fair comparison. His invention will show what RPM has the most power ........ thats all we need !! Show me where my saw produces the most power, and I can aim for those RPM's in the cut ........ where is the downside ?? Show me how a MM improves usable torque (no matter if its calibrated or not, an increase is an increase!!)

Baseline for each saw, and then I agree ......... but baseline for "X" saw vs baseline for "Y" saw, whats the difference ??

I said it before and I will say it again ........ AWESOME invention and AWESOME results Chad !!!!

 

[Motorsen]

Dynos is all about calibration and friction. What you are measuring on your scale is force created by friction in your pump. Next step is to determine losses in setup. Take a stock saw, tune to max performance and call that a benchmark on that given day. X weight on scale equals Y Kw. Then you have to look into airpressure, humidity, temperature to correct your measurements. You made a really great dyno now you have to fine tune it.
This is the best bet on an uncomplicated contruction to measure power I have seen for a very long time. Sharing this with us is priceless.

Regards

Motorsen

 

[drkptt]

I am gunna dis-agree with this ....... a longer arm will give higher numbers, allowing math to be more accurate. The question arises about max scale readings, but if the scale can handle it, a 10 foot bar would show the smallest change in torque, or a 100 foot bar for that matter (Molson XXX talking there) !!

Try again. If the saw is making 1 lb-ft of torque the scale would measure 1 lb if the torque arm is 1 ft long. It would display 0.1 lb if the arm was 10 ft, and 0.01 lb if the arm was 100 feet long.

 

[LowVolt]

Not smart enough to comment but you did a hell of a job.

 

[ozflea]

Try again. If the saw is making 1 lb-ft of torque the scale would measure 1 lb if the torque arm is 1 ft long. It would display 0.1 lb if the arm was 10 ft, and 0.01 lb if the arm was 100 feet long.

But wouldn't the weight of the 100' arm have to be allowed for ?

 

[chadihman]

The torque arm was made 18" long because my scales had a limit.
Every dyno ever built has some drag and had to be calibrated to make accurate. A chainsaw dyno looks bad because its really low torque numbers. This will for sure work for testing small gains or losses. I only used the air filter demonstration to prove a point on how it easily picked up on the gain.

 

[Moparmyway]

Try again. If the saw is making 1 lb-ft of torque the scale would measure 1 lb if the torque arm is 1 ft long. It would display 0.1 lb if the arm was 10 ft, and 0.01 lb if the arm was 100 feet long.

Dude, I dont think you even realize it, but you just prooved my point !!
@ 100 feet, the resolution would be within +/- 0.01
@ 1 foot, the resolution is +/- 01.0

Its WAY more accurate with a longer arm, its just a pain in the rump to move around with a 100 foot arm if his scale can handle the load !!!!!!

 

[Karl Robbers]

But wouldn't the weight of the 100' arm have to be allowed for ?

Sure would, but only in initial set up. IE. everything set up and at rest, press the tare or zero button on your scale and there you have it. Thereafter and reading on the scale is that produced by the saw.
We could of course in theory place a 100' arm hanging in the opposite direction to counteract the weight and balance the assembly, but then we would definitely need a bigger shed to put our dyno in