Thanks Chadiham. And he'll have much to say I hope, and obviously sees potentials at least, even if only as an aid to what he's garnered through experience, but maybe much more. Like I said earlier, I don't have a dog in the fight, never even meant to suggest it's an either/or proposition. And lots a folk like their decisions supported with numbers/data, and no "rightly" or "wrongly" about it. I can even see how Randy might push other builders into using dynos simply b/c customers will come to want/expect numbers for their money. Also suppose many will decide either according to operating one, or seeing them (YouTube) in comparison cuts, and that the added readings could be a deal-maker. I do know that, had I known earlier what I know now, I'd rather have spent our 445 money on a port job for the 365. Kudos on your build, BTW. Glad it's gonna be put to good use.
Porting - Performance Measured?
- Thread starter Ron660
- Start date
Help Support Arborist Forum:
procarbine2k1
Addicted to ArboristSite
I have never heard a reputable builder say that port work extends the life of a saw. I am all for ported saws, but call a spade a spade. I only replied to this post in hopes that a random reader will not buy into your misinformation, not to bust your balls. Under your theory... why aren't gas race saws getting even better service life than a traditional woods port?
You make claims that are physically impossible, and when someone dares say different you ask them to prove otherwise. How about you take a muffler modded woods ported saw, and a muffler modded stock saw (to eliminate the variable with a baffled muffler) and see what kind of operating temperature differences you see? You aren't going to make more psi, and more rpms and run cooler. If you are going to make a saw run cooler, it is going to be because of the muffler- or the tune (more fuel, under the same rpm and load).
Eddy_t
ArboristSite Operative
I was using nice rounded numbers, and more isn't always more! As I said, you have higher speeds to contend with, regardless of more oil, parts still wear, otherwise motorbike clutches would never wear out. Whilst the compression may not be increases by much, rather than 50psi I used as an example, I most certainly try to get as much as possible when porting.
Sent from my iPhone using Tapatalk
M
moody
Guest
I never said anything about lasting long so don't put words in my mouth. I simply said reduced heat. Take that however you want but don't call it misinformation until you have proof that I'm wrong.
Sent from my SM-N900V using Tapatalk
procarbine2k1
Addicted to ArboristSite
Yes you did, more than once outside of this thread. I definitely don't have the interest to dig, but I can if the issue needs to be pushed.
How bout swapping out ceramic bearings in a port job? Would it be cost-prohibitive?
M
moody
Guest
I'm not talking about outside of this thread. You were accusing my above post of being misinformation. And when you come up with proof to show me otherwise I will keep saying that. Stock saws last guys around here 4-6 months. I started doing saws for loggers here last July and I haven't had a single failure. Sounds like pretty good proof or do you need to see the log piles ?
Sent from my SM-N900V using Tapatalk
Eddy_t
ArboristSite Operative
What's the point? Ceramics aren't proven to last that much longer, besides those bearings and the little end can be replaced anyway! It's only the big end that can't.
And by the time the saw is knackered, you'll have bought a newer one and had that ported too!
Sent from my iPhone using Tapatalk
Chris-PA
Where the Wild Things Are
Again it isn't an either/or proposition. The original designers had a set constraints they had to meet, and the porters don't have to meet the same constraints. Some of those things had to do with sound levels, emission, tolerances for production variation, etc. So there are some things a porter can change that may indeed make the saw run cooler and/or last longer (or not change it) - at the sacrifice of other parameters that may not matter to the owner. In general more power means more force applied to parts, which means they wear out faster, but this is only looking at it from one set of variables when the porter is generally changing a whole bunch of things at the same time. And you don't know how close to the design limit each of those parts was operating to begin with.
Eddy_t
ArboristSite Operative
Mate, you made a point of questioning my statement about a shortened lifespan of a ported saw compared to stock saws, which suggests you believe contrary, and I have yet to hear from another saw builder/modder that supports that statement
Sent from my iPhone using Tapatalk
procarbine2k1
Addicted to ArboristSite
Lol. Is that a serious question? I could care less about your port work, you know that. My gripe here wasn't about ported saws in the slightest, just the bs- and you know that too. I wish all the guys here trying to make a living doing whatever they do with saws the best, and that isn't part of my argument. If you have never had a failure, you either aren't taking them real far (which I think is ok too), or don't have too many saws in the woods yet. Everybody will, and there is nothing wrong with that either.
Have read that if the ceramic is silicon nitride the advantages are real for weight, thermal, smoothness, lubrication, and hardness. That their life can be anywhere from 5x-20x longer than steel, depending probably upon the application? And yeah, I was referring to the main/bottom bearings. However, the fact that this isn't being done seems telling, suggesting (if not insisting) that port work isn't adding unreasonable strains. Yes?
M
moody
Guest
Well let him say that unless you have proof of anything different. And yes I questioned your statement because I don't believe that the numbers that you gave were anywhere near the truth. But yiu guys can have this thread. I offered my proof obviously you have none but things you've heard. Have a great day guy's I enjoyed this thread.
Sent from my SM-N900V using Tapatalk
Eddy_t
ArboristSite Operative
Hang on? Which numbers? The ones I made up to make maths easier, or the actual stihl power ratings I obtained from stihl resources?
Sent from my iPhone using Tapatalk
Eddy_t
ArboristSite Operative
Not much really to the bearings, the heat increase from ignition and the added fuel tends to case-harden steel parts, coupled with the absorption of carbon matrices from the oil into the bearing surfaces. The cylinder and piston tends to wear out first, being the softer metal
Sent from my iPhone using Tapatalk
chadihman
Addicted to ArboristSite
I'd love to put a stock saw vs a ported work saw on the dyno and run them loaded at 8500 rpms or so constantly until they blow. I think a couple stock saws and a couple ported saws would have to be run to be sure of fair findings. Who wants to donate some saws to blow up? Not me!
I really have no answer for weather a ported work saw will last longer or not. I would think that a muffler modded saw that flows more air would last longer than a stock saw and a ported saw. I would think higher compression would load the bearings more and the more cylinder that's removed the more piston and ring wear would be seen. Just my opinion. Opinions are like azz holes.... We all have one and they all stink.
Eddy_t
ArboristSite Operative
That is exactly what I would expect, it's already been shown on here that a muffler mod decreases temperature of the cylinder, but uses more fuel due to a decreased back pressure, but the porting extracts a lot more from the saw, which effectively shock loads the saw, after all, it's a bigger explosion in the cylinder!
Sent from my iPhone using Tapatalk
But...higher compression slows the piston more as it nears the squish band...another variable...and more air/fuel flows through larger ports and that fresh fuel is what provides most of the cooling in a two-stroke engine.
Ultimately what determines saw longevity is the maintenance it receives. Ironically, a lot of people here are concerned about saw life but they don't use their saws enough to ever really wear them out. Professional fallers rotate saws out before they're completely shot. Logging companies and tree services are the only entities that wear saws out on a regular basis. 99% of the guys on this site will trade or sell a powerhead off before it has given its total service life (or the saws will get smashed/run over/burned up due to operator error.)
We'll just do a 365-to-372 conversion and add the MM, especially if the latter will contribute to cooling. Not as concerned about fuel efficiency. This has turned into a pretty decent thread. Thanks to everyone. Plenty of lil ol homeowners/landowners here or visiting who find themselves in big wood at least every other weekend, even if just for firewood. And plenty who contract CAD one way or another and just wanna get the most outa their saw and total experience. Seems "natural" enough, which is why we got what we did, knowing it can be upgraded...and this was within a week of usin a harmless 445. "Rationality" went out the window almost immediately, but also learned very quickly that this isn't such a rare thing. Just seems to be sumthin about chainsaws...
Eddy_t
ArboristSite Operative
I am part of a tree service company, and I am partial to modding saws, but only my own. If I were to mod company saws, they'd last about 5 minutes, although they did buy my modded 200t, and a 394xp I did the transfers on whilst replacing a piston (rude not to!)
Sent from my iPhone using Tapatalk
