SawTroll
Information Collector
So do I, and there are indications that the 555 (odd model number) will not have the revboost feature - time will tell....:msp_smile:
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562xp / 28" techlite bar / Fresh Youtube video
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So do I, and there are indications that the 555 (odd model number) will not have the revboost feature - time will tell....:msp_smile:
Tzed250
Addicted to ArboristSite
Hopefully not longer than just one more day :msp_biggrin:
SawTroll
Information Collector
As I said, I'm not interested in the 555, only the xp saws!
spike60
Addicted to ArboristSite
I'm sure you anticipated a reply like this, but...................
I agree that the 555 won't have the rev boost coil. Which is of course the case with EVERY other saw that any of us own. Revboost is a cool feature, but it's not as if any of us will be running our other saws and thinking, "Gee, I wish this thing had revboost."
The point I'm trying to make is this: Lack of revboost should not be considered much of a negative against the 555, or any saw for that matter. I've run it, and while you do notice it and it's nice, it's not "OH WOW!" nice.
Also, the way I understand it, Revboost doesn't make the saw spool up any faster. It just alllows you a short burst of extra RPM's at the top end for limbing. So, acceleration as we know it will not be all that different with or without the revboost. It's the lower weight of the rotating mass that should make for excellent acceleration in any of the saws in this family.
For the price that most think the 555 will hit in it will be a lot bigger seller than the 560/2xp. I'm more interested in the 555 than the other myself for the price I think they'll be at. I would rather spend a touch more and go get 70cc if it's over $600. I would want to run a large mount 20" 3/8s on whichever one they get over here.
wigglesworth
Booned
What exactly does a "revboost" coil do? I mean in real terms. Alter the timing? Is so, in what way?
SawTroll
Information Collector
Spike, that is how I understand it as well, but it doesn't change my attitude! 
i dont think it would advance the timing but increase the rpm with more fuel. maybe a 2nd step rev limit controlled by the onboard ecu.
mikefunaro
Addicted to ArboristSite
I still don't quite understand the point of revboost. Is it to enable faster acceleration in a very short term sense or to enable a period (say several minutes) of high rpm limbing?
This is what was written by whomever does their PR, but I still don't get it:
n the engine, which creates less gyration and more control. The 562 XP also has Husqvarna’s Revboost feature, which allows for acceleration in chain speed over short periods to increase efficiency during cutting, specifically in de-limbing applications. Revboost is controlled by the ignition and enables users to increase to maximum rpm for about two seconds. It is designed to provide an optimum ratio of power to rpm without having the engine run wide open for extended periods of time.
If it increases maximum rpm for two seconds, then it can only help in getting to top rpm faster?
This is what was written by whomever does their PR, but I still don't get it:
n the engine, which creates less gyration and more control. The 562 XP also has Husqvarna’s Revboost feature, which allows for acceleration in chain speed over short periods to increase efficiency during cutting, specifically in de-limbing applications. Revboost is controlled by the ignition and enables users to increase to maximum rpm for about two seconds. It is designed to provide an optimum ratio of power to rpm without having the engine run wide open for extended periods of time.
If it increases maximum rpm for two seconds, then it can only help in getting to top rpm faster?
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SawTroll
Information Collector
Two seconds is often enough to make a difference during limbing - but I really need to use one, before I can comment more on this.....
Terry Syd
Addicted to ArboristSite
It looks like the revboost allows a higher rev limiter of a couple of seconds, say from 13,000 to 14,500. If so, I don't see it being a big deal, that would only be an 11% difference in speed with that example, IF, there was no decrease in RPM for loading.
So you get two seconds of extra speed, which at its optimum allows you to just cut through a branch in two seconds, instead of 2.22 seconds without the revboost.
When I first heard about the revboost feature, I figured it would allow someone to set their carburetor a bit easier as they would have two seconds before the engine would settle into the limiter - then I realised that the engines had autotune so that was out.
The revboost sounds like another sells gimick - just like the 'air injection' (I've blocked mine off to provide more cooling air to the cylinder and to keep the fine dust out of the air box).
So you get two seconds of extra speed, which at its optimum allows you to just cut through a branch in two seconds, instead of 2.22 seconds without the revboost.
When I first heard about the revboost feature, I figured it would allow someone to set their carburetor a bit easier as they would have two seconds before the engine would settle into the limiter - then I realised that the engines had autotune so that was out.
The revboost sounds like another sells gimick - just like the 'air injection' (I've blocked mine off to provide more cooling air to the cylinder and to keep the fine dust out of the air box).
mikefunaro
Addicted to ArboristSite
I guess my question then is: is the point of its going higher to actually go to higher rpms, or to get to the rpms where it would have gone sooner? Or both? If it cuts out after 2 seconds i understand how it's ok for really small limbs but...
SawTroll
Information Collector
:
:monkey::monkey::help:
How can your saws run well, after doing that - where does the air come from???
:monkey::monkey::help:
How can your saws run well, after doing that - where does the air come from???
Terry Syd
Addicted to ArboristSite
Hmm, I wonder if the computer system for the carb uses the max RPM of the revboost to set the mixture strength for the cutting speed. I'd love to see the logic diagram for the carb system.
Perhaps the factory had an extra burst of revs for setting the mixture that marketing wonks spun into a 'special feature'. That would be easier to sell to an owner than the fact that their saw acted really weird when it first revved up.
In any case, we'll soon find out how useful it is.
Perhaps the factory had an extra burst of revs for setting the mixture that marketing wonks spun into a 'special feature'. That would be easier to sell to an owner than the fact that their saw acted really weird when it first revved up.
In any case, we'll soon find out how useful it is.
Terry Syd
Addicted to ArboristSite
ST, I have two holes I drilled in the back of the air box lid just above the handle.
Timberwolf did some research on the heating of the air by the compression of the flywheel and found that there could be up to 10F increase in the air temperature coming off the air injection system. That is a slight drop in air density that I don't have to worry about now.
The air injection system works well for keeping the big chunks out of the airbox, but it is the 'fines' that get sucked into the filter system. I got a graphic demonstration of how the air injection system actually increases the fines to the air box.
I was cutting up a burnt stump that had a fair bit of charcoal on it. The front of the saw was black with the dust from the charcoal - HOWEVER, it was the black coating down the left side and into the front of the flywheel cover that showed the flow of the charcoal dust into the air injection system.
If someone was cutting green wood it wouldn't be a problem, but over here in Oz the dry hardwood (and termite litter) creates a lot of fine dust - dust which would get sucked into the front of the flywheel cover.
My running temps also dropped quite significantly after blocking of the air injection. The more I modded the engine to increase the flow, the more air I was removing from the cylinder fins. In other words, I was making the engine produce more power (and heat) at the same time I was removing cooling air.
Timberwolf did some research on the heating of the air by the compression of the flywheel and found that there could be up to 10F increase in the air temperature coming off the air injection system. That is a slight drop in air density that I don't have to worry about now.
The air injection system works well for keeping the big chunks out of the airbox, but it is the 'fines' that get sucked into the filter system. I got a graphic demonstration of how the air injection system actually increases the fines to the air box.
I was cutting up a burnt stump that had a fair bit of charcoal on it. The front of the saw was black with the dust from the charcoal - HOWEVER, it was the black coating down the left side and into the front of the flywheel cover that showed the flow of the charcoal dust into the air injection system.
If someone was cutting green wood it wouldn't be a problem, but over here in Oz the dry hardwood (and termite litter) creates a lot of fine dust - dust which would get sucked into the front of the flywheel cover.
My running temps also dropped quite significantly after blocking of the air injection. The more I modded the engine to increase the flow, the more air I was removing from the cylinder fins. In other words, I was making the engine produce more power (and heat) at the same time I was removing cooling air.
So you're saying you run an EGT on your saw to monitor running temps (if not then how are you doing this monitoring?)? And in blocking off the air injection you were able to measure an increase in power? How did you measure that?
SawTroll
Information Collector
It sounds like you are increasing the amount of chips that get into the filter area - what saw models did you do that to?
spike60
Addicted to ArboristSite
That's pretty much the explanation right there. The coil allows a 2 second burst of additional max RPM's to help you blow through branches when limbing. It doesn't sound to me like it has anything to do with acceleration from idle, which goes back to the lighter rotating mass, carburation and porting.
But this is all new to me too, so who knows? But......... I'll be running one tomorrow, so we'll see the 555 does in the acceleration department. :msp_biggrin:
spike60
Addicted to ArboristSite
Spike, that is how I understand it as well, but it doesn't change my attitude!
HAHA!!!
I didn't think it would, and it shouldn't anyway. I agree that it makes more sense for you to get the XP version. I'd do the same thing if I was only going to get one of them, and like you I hardly need another saw. My main point was that the 555 should not be dismissed as just a watered down version of the top saw in the family as often happens to other "little brothers" like the 365 and 353.
