Porting - Performance Measured?
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Hydraulic dynamometers have been around for a very long time, and they have proven very effective, and are easiest to manufacture and use, and can very easily be manipulated to vary loads. There is no reason to reinvent the wheel there. The nice thing about a dyno is wood, chain type and sharpening, bar length, etc make no difference. But they also rely heavily on how the dyno is tuned and used, how the results are interpreted and compared, ambient weather recorded and calibrated for, etc etc.
There are down sides to all forms of testing - whether wood or dyno. However, we are talking chainsaws here, not F1 race cars. A ballpark figure gives one a good idea of what performance one can expect. Some builders are afraid dyno numbers, like any form of statistics, can be used for evil just as well as good, perhaps slighting whatever efforts they may make in front of an internet crowd they intend to sell to; and this doesn't only end with chainsaw builders - bike builders are exactly the same way. Your average person isn't going to understand the inherent limitations of a particular set up whether wood or dyno. A good example is when Chad dyno'd a 461 VS a 660. The vast majority of members following the thread were completely oblivious to the important fact the 660 could not be stopped by the dyno, yet posted similar HP numbers to the 461 in that particular method, and so were excited about the 461 when they should have been far more impressed with that 660 - which many labelled a dog by comparison in the thread immediately thereafter. This is where one can tell by dyno that a 660 can easily pull more bar than a 461, regardless of how much HP the dyno stated either had, which is precisely the 660's raison d'etre. Another example was the testing between a standard current make and older make dual port vs single port muffler on Chad's dyno. Almost no one noticed, because Chad didn't really state it outright, that there was a 20% difference in power tested between the two mufflers alone. That was a very significant finding.
This also brings up another point - people are rather easily manipulated. They will often blindly follow someone they feel is an authority, even if they themselves have few means by which to authenticate such authority. Whether attached to an individual or a dyno, the mob can easily be swayed depending upon how the information is presented to them - and just as importantly, by which information is withheld from them.
To address the OP's original query - what you need to do is use a ported saw for yourself. It will answer a lot of questions.
There are down sides to all forms of testing - whether wood or dyno. However, we are talking chainsaws here, not F1 race cars. A ballpark figure gives one a good idea of what performance one can expect. Some builders are afraid dyno numbers, like any form of statistics, can be used for evil just as well as good, perhaps slighting whatever efforts they may make in front of an internet crowd they intend to sell to; and this doesn't only end with chainsaw builders - bike builders are exactly the same way. Your average person isn't going to understand the inherent limitations of a particular set up whether wood or dyno. A good example is when Chad dyno'd a 461 VS a 660. The vast majority of members following the thread were completely oblivious to the important fact the 660 could not be stopped by the dyno, yet posted similar HP numbers to the 461 in that particular method, and so were excited about the 461 when they should have been far more impressed with that 660 - which many labelled a dog by comparison in the thread immediately thereafter. This is where one can tell by dyno that a 660 can easily pull more bar than a 461, regardless of how much HP the dyno stated either had, which is precisely the 660's raison d'etre. Another example was the testing between a standard current make and older make dual port vs single port muffler on Chad's dyno. Almost no one noticed, because Chad didn't really state it outright, that there was a 20% difference in power tested between the two mufflers alone. That was a very significant finding.
This also brings up another point - people are rather easily manipulated. They will often blindly follow someone they feel is an authority, even if they themselves have few means by which to authenticate such authority. Whether attached to an individual or a dyno, the mob can easily be swayed depending upon how the information is presented to them - and just as importantly, by which information is withheld from them.
To address the OP's original query - what you need to do is use a ported saw for yourself. It will answer a lot of questions.
Chris-PA
Where the Wild Things Are
I'm 50, and I've been shifting for a while. I can do a heel-toe double clutch downshift that you will barely feel, and I don't need to look at the tach to shift. On the other hand, I know the hp and torque curves of my engine, and yes I do shift by the tach - that is how one gets the maximum performance or economy.
I'm of two minds on this topic. It is way too easy to have confirmation bias and to convince yourself that something is improved when it is all subjective. Yet max hp or torque numbers are of little use in real world application. It is actually the hp & torque curve vs. rpm that matter. A chainsaw is an engine running a chain that you hold in your hands, and really you do get a very good sense of how it runs that way over the long term. Short term, there are a lot of variables, including the chain and the wood.
Last, the little secret is that it doesn't matter for the vast majority of users, as almost any saw (of reasonably appropriate size) will get the job done. It's all about how it feels and how that makes you feel - and that is the real reason for porting a saw.
old-cat
Fir Man
The way to measure whatever increase there might be, is the amount of work done at the end of the day.
More production = more $$$$
More production = more $$$$
Guess I'm off point now and on rant, but there can be a tyranny to numbers when they're regarded as the trumping authority to all other indices, phenomena, etc. Orwell warned how political speech was capable of making idiots of us all by using more words to say less, or by re-rendering extant nuance as cold, disembodied "facts." This is why Buddhism has 10 (or 14, depending) questions it refuses to address, b/c this ontological theorizing into an abstract "objectivity" has us all torturing ourselves over non-realities that we invent or buy into. What's really happening is we're having to fill in for lack of experience and firsthand knowledge. How often do we hear, "Where's the proof," as though the world is a courtroom? Or, "Science is the only legitimate method for ascertaining...umm...anything?" We built a large binocular telescope, but the astronomers kept doing their calculations to "prove" that a cost-benefit analysis didn't justify it. Well it does, provided you do ENOUGH calculations the right way, but even then these don't adequately convey the REAL gains. Honestly, I'm worried that we're devolving, but so be it. Nature creates evolutionary dead ends all the time.
old-cat
Fir Man
Dead on Wes!
ChrisPA...
NUANCE...He didn't ask me if I ONLY shift by tach...his point was to reintroduce NUANCE...to remind me that I use other things for a tach now, like hearing, feel, speed for a given gear, etc. You know...intimacies. This is the sorta dumbing down that has me worried. Sometimes it's people who don't read well, other times its folk who can't listen well enough to hear, other times its just ego needing to try to sound right and willing even to mischaracterize others to do it...whatever the case, there's a loss of nuance. Tell ya what, take a dyno reading...it still won't mean nearly as much to us as it will to Brad or Moody or Terry or Stumpy or anyone else I'm leaving out. That's nuance. That's subjectivity informing objectivity if ya wanna play that game. Wish you didn't use yer tach so much tho...probly as dangerous as texting and driving...or did I misunderstand you?
NUANCE...He didn't ask me if I ONLY shift by tach...his point was to reintroduce NUANCE...to remind me that I use other things for a tach now, like hearing, feel, speed for a given gear, etc. You know...intimacies. This is the sorta dumbing down that has me worried. Sometimes it's people who don't read well, other times its folk who can't listen well enough to hear, other times its just ego needing to try to sound right and willing even to mischaracterize others to do it...whatever the case, there's a loss of nuance. Tell ya what, take a dyno reading...it still won't mean nearly as much to us as it will to Brad or Moody or Terry or Stumpy or anyone else I'm leaving out. That's nuance. That's subjectivity informing objectivity if ya wanna play that game. Wish you didn't use yer tach so much tho...probly as dangerous as texting and driving...or did I misunderstand you?
Chris-PA
Where the Wild Things Are
LOL - and if you read more carefully, you would have understood that I don't always use the tach. And while perhaps an engine output plot is something you don't fully understand, your assumption that this applies to everyone is false. Also false is your assumption that everything I do is objective based solely on one short web forum comment - and rather arrogant too, as you do not know me and I surely don't need you to provide a philosophy on how to live. In fact I strive for a balance between subjective and objective, which you might perhaps have grasped if you had not stopped reading after my first paragraph.
VA-Sawyer
Addicted to ArboristSite
Off topic..... Grandpa called my brother and said he had stripped the spark plug hole on his riding mower. Mike goes over and puts in a heli-coil. About 6 weeks later Grandpa has again stripped out the spark plug. Mike ends up having to replace the head that time. So Mike asks Grandpa what he was using to put the spark plug in with. Grandpa proudly shows him a 1/2" Breaker bar and socket. Mike grabbed it and threw it as far out in the field as he could. Then Mike told him to never let that tool within 10' of the mower again. That solved the stripped spark plug problem!
Just for the record.... I have been turning wrenches for half a century now, and I still use a torque wrench putting a spark plug in an aluminum head. Not so much on mowers and chainsaws, but every time without fail on airplanes!
I now return you to your regularly scheduled program...
Just for the record.... I have been turning wrenches for half a century now, and I still use a torque wrench putting a spark plug in an aluminum head. Not so much on mowers and chainsaws, but every time without fail on airplanes!
I now return you to your regularly scheduled program...
Sorry chris-PA,
I didn't assume anything, but you certainly have, lastly, but not least, to say for whom it does and doesn't matter. All I did was to provide a larger context for which it can matter to those interested. For the rest, all I was doing with you was taking back my own words from having them hijacked out of context. It was an analogy, and a good enough one for some to find some value in, which you then tried to literalize. As for anyone saying "how to live," where in the world does that come from? You say you're of two minds...bring them to me and we'll have a look, see if we can't get them to agree. I've read plenty of your posts here, and always thought they were high caliber, but I take care in what I say and how I say it...don't like folks taking a hammer to my machine screws. If I was wrong to try to salvage my original meaning, so be it. And if you take literally my joke about your driving by tach as though text messaging, and don't see that I was giving tit for tat to illustrate the absurdity of expropriating someone's analogy for literal use to pontificate that most of us don't need the benefits of a port job, then maybe I should assume most of us don't need a tach? I bow to your superiority and will fire off a letter post haste to General Motors.
I didn't assume anything, but you certainly have, lastly, but not least, to say for whom it does and doesn't matter. All I did was to provide a larger context for which it can matter to those interested. For the rest, all I was doing with you was taking back my own words from having them hijacked out of context. It was an analogy, and a good enough one for some to find some value in, which you then tried to literalize. As for anyone saying "how to live," where in the world does that come from? You say you're of two minds...bring them to me and we'll have a look, see if we can't get them to agree. I've read plenty of your posts here, and always thought they were high caliber, but I take care in what I say and how I say it...don't like folks taking a hammer to my machine screws. If I was wrong to try to salvage my original meaning, so be it. And if you take literally my joke about your driving by tach as though text messaging, and don't see that I was giving tit for tat to illustrate the absurdity of expropriating someone's analogy for literal use to pontificate that most of us don't need the benefits of a port job, then maybe I should assume most of us don't need a tach? I bow to your superiority and will fire off a letter post haste to General Motors.
mweba
Addicted to ArboristSite
Cut times with same cutting equipment in the same wood at relatively the same atmospheric conditions is the best you're going to get from most builders. Personally, I'd argue an honest timed test is efficient enough as most guys in the market are looking for a return on their investment in terms of production. Reducing a single cut time from let's say one minute to forty seconds or better is exactly what they want to see, not necessarily some numbers on a chart. Don't get me wrong, I love that stuff too.
Chris-PA
Where the Wild Things Are
Thanks but no thanks. That kind of analysis does not interest me, especially on an arborist forum. I'm perfectly comfortable with the two different views and do not need them resolved further - you will note that my original conclusion is that the reason to port a saw is to make one feel good, and that I agree with you that no one needs a ported saw.
Please also note that I totally ignored your comments about driving by the tach and text messaging, so you have no way of knowing if I took it literally or otherwise.
Let's just forget it try again on some other thread?
This is weird. Where did I say nobody needs a port job? Yer kidding, right?
"I've given you an answer. I am not obliged [thankfully] to give you an understanding."
But sure, lets get back to the field. So you posted first to say that you drive by tach, then to toss "confirmation bias" into a mix of what chainsaws do (loosely speaking), all evidently from a divided mind and just to say that most people don't need them, that it's about feel and how it makes someone feel about how it feels, or some such. Maybe like a tach. But since you use your tach to measure performance, then maybe you "benefit" from a port job while the rest of us are jerking off? I'm with ya. Hell, I'd even agree, to a point, and leaving aside that each person can legitimately fill in their justification blank, whether they live by their saw or no. But yeah, let's get back to the field. I'm lookin at the "likes" Reindeer received, and the "likes" you, erm, ... are gonna receive. My guess is Reindeer actually spoke to the issue, while you were maybe a little dismissive of the whole proposition. Maybe a little unnuanced. Could be an older fella would gain more from a port job than would a logger. After all, money isn't everything. Sorry again. Guess it just irked me, that if I was gonna have one short sentence lifted outa an entire narrative, I'd want it to be in the service of better material. You've definitely had better posts.
"I've given you an answer. I am not obliged [thankfully] to give you an understanding."
But sure, lets get back to the field. So you posted first to say that you drive by tach, then to toss "confirmation bias" into a mix of what chainsaws do (loosely speaking), all evidently from a divided mind and just to say that most people don't need them, that it's about feel and how it makes someone feel about how it feels, or some such. Maybe like a tach. But since you use your tach to measure performance, then maybe you "benefit" from a port job while the rest of us are jerking off? I'm with ya. Hell, I'd even agree, to a point, and leaving aside that each person can legitimately fill in their justification blank, whether they live by their saw or no. But yeah, let's get back to the field. I'm lookin at the "likes" Reindeer received, and the "likes" you, erm, ... are gonna receive. My guess is Reindeer actually spoke to the issue, while you were maybe a little dismissive of the whole proposition. Maybe a little unnuanced. Could be an older fella would gain more from a port job than would a logger. After all, money isn't everything. Sorry again. Guess it just irked me, that if I was gonna have one short sentence lifted outa an entire narrative, I'd want it to be in the service of better material. You've definitely had better posts.
Eddy_t
ArboristSite Operative
Dyno tests can be manipulated easily either way, likewise so can cut times, for example, the stihl 880 vs 090
Power:
090 is 6.3kW
880 is 6.4kW
Torque:
090 is 7.0ft/lb
880 is 5.9ft/lb
Likewise the chain speed can be manipulated:
090 is 16.7m/s
880 is 23.9m/s
So the 880 is the more powerful saw... until you add the rpm's!
Max speed for an 090 is 8000rpm, so the speed and power are given at 7500 rpm and the torque at 5000
The 880 on the other hand is 11000 as max permissible rpm, the power and torque readings are tested at higher rpm's than the 090 (8500, 6000 and 11000 respectively).
Cut times can be manipulated with theses saws too, the 880 has a much higher rpm range, so the saw with a lower load will outcut the 090 easily, lean hard and dog in and the 090 will win. Try it with a ported saw comparison and once again the results can be manipulated! The same model of saw can be modified by 2 different guys to get a different result, the one who raises the exhaust port more will get a higher rpm range at the sacrifice of torque and power, but it'll win in a cut race when the saws are being left to cut, rather than loaded up and vice versa, at the end of the day, it's down to the individual users methods and needs
Sent from my iPhone using Tapatalk
Power:
090 is 6.3kW
880 is 6.4kW
Torque:
090 is 7.0ft/lb
880 is 5.9ft/lb
Likewise the chain speed can be manipulated:
090 is 16.7m/s
880 is 23.9m/s
So the 880 is the more powerful saw... until you add the rpm's!
Max speed for an 090 is 8000rpm, so the speed and power are given at 7500 rpm and the torque at 5000
The 880 on the other hand is 11000 as max permissible rpm, the power and torque readings are tested at higher rpm's than the 090 (8500, 6000 and 11000 respectively).
Cut times can be manipulated with theses saws too, the 880 has a much higher rpm range, so the saw with a lower load will outcut the 090 easily, lean hard and dog in and the 090 will win. Try it with a ported saw comparison and once again the results can be manipulated! The same model of saw can be modified by 2 different guys to get a different result, the one who raises the exhaust port more will get a higher rpm range at the sacrifice of torque and power, but it'll win in a cut race when the saws are being left to cut, rather than loaded up and vice versa, at the end of the day, it's down to the individual users methods and needs
Sent from my iPhone using Tapatalk
chadihman
Addicted to ArboristSite
Most of my ported saws hit the wood before the dyno....It's fun doing both. Hp means nothing to me. I care about the torque curve the most.
Chris-PA
Where the Wild Things Are
Pardon me if I got that wrong. Just in case you are wondering, I really don't have much idea of what you actually were trying to say and I bet I'm not alone in that, but I no longer have much interest.
I disagreed with your "experienced mechanic" analogy, and still do. Sometimes using the torque wrench is critical, and sometimes not. Sometimes shifting at the correct rpm matters and sometimes not, depending on what you are trying to accomplish.
Bingo - and every time I torque a wheel nut. It's knowing when it matters that matters. Experience doesn't mean we can forget about doing things the right way, it allows us to know when it is important.
Chris-PA
Where the Wild Things Are
That is wise - also the spread between the torque and hp peak.
VA-Sawyer
Addicted to ArboristSite
Yep, I get out the torque wrench for lug nuts too. I clean rust off the hub and both sides of the brake rotor as well. A chunk of rust between the hub and rotor can cause a pulse in the brake pedal. It takes more time, but not as much as doing it again!
After all these years, I have learned that sometimes it is the small details that makes the performance difference. I'm going to guess that is most of the difference between the good saw builders and the port-a-putzes.
After all these years, I have learned that sometimes it is the small details that makes the performance difference. I'm going to guess that is most of the difference between the good saw builders and the port-a-putzes.
This is surreal. I never said, "Don't read a tach," nor did I say, "Don't use a torque wrench." Truly bizarre. And lug nuts? LMAO
This thread has been interesting apart from the ego spat in the middle which was not very 'dyno' related. Often de-tuning can also improve an engines usability. For example a race bike tuned for max hp down the straights in a long circut will lack low down power and produce max hp at high rpm. This bike may not be that pleasurable to ride on a shorter circut with alot more turns and requires a higher level of rider to maximise its power. If de-tuned it would have more low end power & be far more fun to ride as the torque is better accellerating out of corners and riders of lesser ability can actually utilise the hp availible. Unless very experienced in riding often a de-tuned bike will yield better lap times and be much more fun to ride. l'd rather the hp be accessable in the area where l spend 95% of the time riding rather than have more hp where l only use 5% of the time. l see some ported saws that make huge rpms but when they hit wood have to be lighty
feathered through the cut. This for the trained hotsaw racer may produce the fastest cookie times however for the average user would be a very unpleasant saw to use. When your hot, sweaty, tired and have a job to complete this saw is the last thing you want in your hands.
feathered through the cut. This for the trained hotsaw racer may produce the fastest cookie times however for the average user would be a very unpleasant saw to use. When your hot, sweaty, tired and have a job to complete this saw is the last thing you want in your hands.
