Author Topic: bsfc vs. rpm  (Read 156 times)

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Offline 1manband

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Re: bsfc vs. rpm
« Reply #10 on: December 25, 2014, 06:09:11 pm »
here's a working file of the toy.

surprisingly accurate.  hahaha.  put in some numbers to see the fuels effect on power.

the true rolloff on these motors resembles something else though............ after peak tq.

see if it can be modeled?  hahaha.

test is to post the true curve if you can.

have some Christmas fun y'all

regards
-joe


works in openoffice program, or m$ equivalent.  some of the graphing gets lost in the language translation between the two programs.
hopefully this one will open?
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Offline 1manband

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Re: bsfc vs. rpm
« Reply #11 on: December 31, 2014, 08:24:18 pm »
effect of lower - average- higher bsfc
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Offline 1manband

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Re: bsfc vs. rpm
« Reply #12 on: December 31, 2014, 08:27:35 pm »
smaller 40cc motor effect of lower - average - higher bsfc
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Offline 1manband

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Re: bsfc vs. rpm
« Reply #13 on: December 31, 2014, 08:33:35 pm »
deleted the english horsepower and torque lines off of these graphs to get a clearer view with just metric.

the kW and Nm cross at 9549 rpm.  clearer for high rpm motors, imo.


the age old 6,7 hp 75cc motor vs. the 6.7 hp 90cc motor trick.

not the same?

is HP a good way to compare?
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Offline aclarke

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Re: bsfc vs. rpm
« Reply #14 on: December 31, 2014, 10:07:27 pm »
Joe, neat stuff.

Why would the 066 be have higher bfsc/kw vs the smaller motor?


Offline 1manband

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Re: bsfc vs. rpm
« Reply #15 on: January 01, 2015, 05:48:40 am »
bsfc is directly (edit:inversely) dependent on how thermally efficient a motor is.  motor size only plays a very small role, if any.

edit: compare the 'average' graphs of the 40cc to the 91.6cc motors.  the bsfc's used were exactly the same for each graph.  (on the graph, bsfc is the lowest line).

somewhere on here in another thread, made a chart that shows how therm eff each motor is.  there you can see what i mean.
edit: found the link http://chainsawrepair.createaforum.com/ported-saws/saw-motor-data-technical-chart-(things-mfg's-don't-tell-you)/?message=44955

what's interesting to me however, is the effect of fuel on the small vs. big motor.





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Offline 1manband

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Re: bsfc vs. rpm
« Reply #16 on: January 03, 2015, 09:30:16 am »
one last graph. thank goodness right?!

1 hp  60cc motor

had to make the numbers small to show what this particular bsfc curve looks like close up.

the lowest curve is bsfc.  the torque and bmep (pressure) curves are above.

bsfc curve flipped = torque and bmep

realize that this is not the forum for this kind of thing.
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Offline 1manband

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Re: bsfc vs. rpm
« Reply #17 on: July 08, 2016, 07:44:14 pm »
cfm info: http://www.asia.donaldson.com/en/exhaust/support/datalibrary/1053747.pdf

goes hand in hand with bsfc and A/F ratio.

(just putting it here, so i don't forget where i found it).
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