Modding and Porting Fundamentals

[Real1shepherd]

I don't see comparing cuts as valid data. Even subconsciously, you could be leaning in harder with a modified saw...expecting more. Too much human factor there....too many variables. Measuring RPM is fine, but I don't know how you can keep the 'cut' part honest or induce a 'control' of some sort.

Kevin

 

[Moparmyway]

I don't see comparing cuts as valid data. Even subconsciously, you could be leaning in harder with a modified saw...expecting more. Too much human factor there....too many variables. Measuring RPM is fine, but I don't know how you can keep the 'cut' part honest or induce a 'control' of some sort.

Kevin

I dont agree ...........
I can stop a chain on a stock saw by pushing down or dogging in.
My ported ones - you cant stop the chain no matter how hard you push down, you MUST use the dogs to stop the chain

Good sharp chains self feed in the cut, requiring no pressure.
Self feed a stocker and then self feed a ported saw ............. HUGE difference

 

[blsnelling]

Any saw can be stopped in the cut.

 

[nmurph]

Any saw can be stopped in the cut.

Absolutely. Some are harder than others though!!!!!

 

[blsnelling]

For sure. My 090 you have to really get up on it to stop it, unless using the dawgs. Then it's a piece of cake to stop anything.

 

[Real1shepherd]

I dont agree ...........
I can stop a chain on a stock saw by pushing down or dogging in.
My ported ones - you cant stop the chain no matter how hard you push down.

Good sharp chains self feed in the cut, requiring no pressure.
Self feed a stocker and then self feed a ported saw ............. HUGE difference

I don't agree, especially if you're talking seconds difference. Give two people the same race saw(or stock saw) and they will have different times into the cut. It's knowing how hard to push a saw listening to the RPM. Now, the differences between two saws say one modded properly and one stock, may be greatly apparent dogging into the cut. My point is the human factor will change from operator to operator and so timing cuts is not the definitive answer alone. Especially if you're talking about small mods to a work saw wherein the operator can fudge the results by 'cut' tests. Obviously, the difference between a full race saw and a work saw will be remarkable.

Kevin

 

[moody]

Two piece cylinder and head, and external boost ports are beyond my paygrade and my cutomers willingness to pay. Now, back down to earth, the 2-3 deg taper, I have questions? Is this from edge of bore to end of interior of the squish band? If so, do you start, lets say at .020 squish and end at .024? This would depend on the depth of your band, but for conversation lets say its true. This would be easy to do with the lathe cross slide with set wat 2-3. Have you done this and whats your thoughts, engine heat, hp etc. Very interesting.

I've played with the taper. And my best results have been from a flat squish band and a 2* bevel on the piston. Not that it's a noticeable difference. I've messed around with squish and saws with .025-.030 idle a lot smoother. All I can tell you for certain is that textured aluminum dissipates heat faster than a polished surface.

 

[Moparmyway]

Any saw can be stopped in the cut.

Only if the bar is big enough to overcome the power that particular saw puts out.

I can stop my ported 046 with a 36" B&C ............ however if I put a 16" B&C on it, King Kong wouldnt be able to dog it in and slow it to a stop

 

[Moparmyway]

I don't agree, especially if you're talking seconds difference. Give two people the same race saw(or stock saw) and they will have different times into the cut. It's knowing how hard to push a saw listening to the RPM. Now, the differences between two saws say one modded properly and one stock, may be greatly apparent dogging into the cut. My point is the human factor will change from operator to operator and so timing cuts is not the definitive answer alone. Especially if you're talking about small mods to a work saw wherein the operator can fudge the results by 'cut' tests. Obviously, the difference between a full race saw and a work saw will be remarkable.

Kevin

When Sandy came through here, I had 3 trees bucked in the time another neighbor had 1. Both running 046's ......... mine ported, his stock. The very next day his saw was in my Barn and loosing some weight. A few days later we were both "moving down the street" getting the road and driveways cleared and he was keeping up with me all day. I also did his 2 other saws in the following weeks, and he threw about 15 saws my way from his friends. They all cant believe the time difference to do the same work.

Have you ran a properly ported saw of the same variety to compare to a stock saw ?
If you did and didnt see the difference, maybe it wasnt ported properly. I have seen some real hack jobs in person and in pictures on this forum. The "Blue goo wonder kid, named Tyrell" comes to mind
http://www.arboristsite.com/community/threads/we-have-a-little-problem.242728/

 

[shootingarts]

The "time in cut" not being an accurate measure has a lot of validity actually. Not trying to measure the difference between a stock and modified saw, but when trying to measure smaller amounts. two 460's modded by two top builders for example. If owner A in one part of the country runs one saw a second or two faster than owner B in another part of the country it doesn't really tell us a thing. When two saws are within a few percentage points of each other's time in the cut then the difference can be something other than raw saw output too.

Ideally to use time in the cut there would be a test fixture with an adjustable weight to control pressure, same chain and bar on both saws, and alternate which saw is used first in a series of tests. The toughest part of the test is what do you cut? Cookies from a log are a horrible thing to judge speed. pi x radius squared = area. A 28" section of log has 615.75 square inches of area. A 30" log section has 706.86 square inches of area. That is almost a fifteen percent difference in the amount of wood cut without considering any inconsistencies in the wood shape or hardness. I often see noticeable tapers in logs people are using to compare times in cuts and of course often people are comparing different logs.

Cutting squares would make things more consistent, maybe cutting squares of just heartwood would be the best wood to cut. If there was serious money behind the people doing the testing it would probably be better to select something other than natural wood to use as a test material.

Time in the cut is the most relevant test we have available in my opinion, other than maybe Chad's dyno and some experience interpreting what it is saying. Most of us won't have access to the dyno so time in the cut is the best we can do. We do need to exercise a good bit of care interpreting what we learn from those cuts though. Aside from anything else, optimum set-up and technique may be different for two saws. We all know that a higher RPM saw will kick butt on a big slow saw with both pulling a small bar and light chain. Put a big bar and heavy chain on the saws and the situation reverses. Sometimes it is just a matter of pressure. One saw cuts quicker with very light pressure, the other with more pressure.

Right now my saw is set up for speed, I'm pulling an eight pin rim with a twenty inch bar and very sharp RS chain. Thing cuts like a wild child letting it mostly feed itself into the cut and turning as much as 12,000 in the cut with sixteen or eighteen inch very hard wood. Lean on it and I would probably curse it mightily. Change sprockets, tune a little different, and it would cut faster with heavier pressure than the very light pressure I use now.

A lot of experience track testing circle track cars years ago and then I spent a little time in R&D. Very easy for even highly trained people to misinterpret results, scientists with PhDs do it all the time. We shouldn't put too much weight in small differences shown in one time testing. Large differences yes, small differences consistent over a longer test period, yes.

Hu

 

[moody]

I think some people over think the fuel mileage on ported saws. Yes they use more fuel buy a properly ported saw will put that fuel to use. Say that you use 10% more fuel but your production is increased 40%. You still see 30% more in the truck. To some that's more heat and to others that's a bigger check. Am I saying that everyone needs a ported saw? Not at all. A lot of logging happens in my area. And one log is $300ish veneers are quite a bit higher. Say that you get on Average of 30 logs a day with a stock saw. A 30% increase in production will yield 9 more logs a day. That's $2700 increase in pay. Tell me where $250 is a waste of money? This is not me ranting just a little food for thought is all

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[Philbert]

There can be a lot of variation in these home-brew tests. But they can give us some subjective feedback, especially when there are big differences in performance, and are easy to do.

That is why I asked about tach readings - these are easier for most of us to measure than power output.

Philbert

 

[Philbert]

I think some people over think the fuel mileage on ported saws.

I like to be environmentally conscious, and not waste money. But if I use half a gallon of gas a day, and my consumption goes up by 50% . . . . .

Philbert

 

[moody]

I like to be environmentally conscious, and not waste money. But if I use half a gallon of gas a day, and my consumption goes up by 50% . . . . .

Philbert

The mileage isn't that horrible. I'd be willing to bet that in most cases you may lose 5-7 minutes run time. I've ported saws that didn't have a noticeable difference in run time. It's not easy to get mileage but there are ways to get power without losing run time. Now if you run a 660 you're jus SOL they're thirsty

 

[moody]

There can be a lot of variation in these home-brew tests. But they can give us some subjective feedback, especially when there are big differences in performance, and are easy to do.

That is why I asked about tach readings - these are easier for most of us to measure than power output.

Philbert

Tach readings can be misleading. Say you were to run a saw that turns 10,500 in the cut there's faster saws than that for sure right? Now you take that saw and bury it to the dawg and give it some leverage in Hedge. And it's still turning 10,500 where most saws would fall on their face it's still pulling.

 

[Philbert]

Tach readings can be misleading.

I get that. But it is one more piece of information. Are you keeping RPMs close when comparing cuts? Does the saw 'feel' like it hits max power at a different speed? Is the chain turning faster, or is the muffler just louder? Etc. In your example, above, it can be used to compare the performance btw 2 saws in the same conditions (e.g. Saw 1 maintained it speed, while Saw 2 slowed down a measurable, objective amount).

Philbert

 

[Heilman181]

Everyone is different. Different strokes for different folks - that what keeps things interesting. If you want to port a saw or pay someone to port a saw then please feel free to do so. If porting is not your flavor then run whatever you like.

I am willing to bet that those complaining about the "fuel economy" of a ported saw probably drive above the posted freeway speed limits in their cars/trucks. The harder you push most engines the more fuel you are going to use.

 

[moody]

I get that. But it is one more piece of information. Are you keeping RPMs close when comparing cuts? Does the saw 'feel' like it hits max power at a different speed? Is the chain turning faster, or is the muffler just louder? Etc. In your example, above, it can be used to compare the performance btw 2 saws in the same conditions (e.g. Saw 1 maintained it speed, while Saw 2 slowed down a measurable, objective amount).

Philbert

But you can't accurately measure the load put on both saws. Saws are funny critters. The only way to judge performance is in the cut. Dyno won't do anything but show ratings but are those ratings user friendly during operation?

 

[Philbert]

If you want to port a saw or pay someone to port a saw then please feel free to do so.

The purpose of this thread was to help understand the specific goals/benefits/effects/results from specific mods independently. The right place to fit fuel economy into this discussion would be with the associated modification.

For example, I assume that increasing the size of the muffler opening and exhaust port would increase fuel use somewhat, but mods to increase compression would not noticeably increase fuel use on their own.

Whether or not the costs or benefits of these mods are worth it has always been up to the saw owner/operator.

Philbert

 

[KenJax Tree]

I don't really see a big jump in production in tree service. I can see it in logging and cutting firewood off a pile of logs. If i
had a ported saw that was 40% faster than stock its still not gonna turn a 10 hour day into a 6 hour day. And if it does i'm losing over $600 in wages because i get paid hourly.


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