Tree Monkey MS462 - PART 2

tree monkey · Dec 12, 2018

huskihl said:
Are you still on the original 462? Cole's?

yes

huskihl said:
Wanted to make sure Scott understands the context of this post. I was only wondering if he was still finding improvements in the original 462

i'm working on other saws right now.

yes i'm still getting gains, smaller but still gains

tree monkey · Dec 12, 2018

I was hopping for some input from brad, but he don't wanna talk

huskihl · Dec 12, 2018

tree monkey said:
yes

i'm working on other saws right now.

yes i'm still getting gains, smaller but still gains

Thanks. Thats what I was wondering

retro · Dec 12, 2018

Atmospheric pressure is the only available force to supply air for the motor. The piston does very little of the required work for filling during the intake stroke. The existing atmosphere does most of that work.

Some of you guys might think I'm nitpicking semantics, but this is important to understand properly in order to keep our thinking & understanding honest.

The motor does not function by drawing (or sucking) any air inside, this assumption is what tricks a lot of folks into wrongly thinking that they must primarily optimize the mechanical pumping efficiencies of their "pump" in order to get more torque production. When in fact there is no stinkin' pump... there is only a constant external pressure pushing in varying densities of air. The piston performs most of its work while compressing the air that has been supplied by the atmospheric pressure. Thinking about things backwards can lead a person to attempt all sorts of voodoo nonsense that cannot ever work.... just sayin'.

And yeah, yer dead wrong in most of your assumptions Brad. Tree Monkey is dead right, and a good teacher, as usual.

tree monkey · Dec 12, 2018

retro said:
Atmospheric pressure is the only available force to supply air for the motor. The piston does very little of the required work for filling during the intake stroke. The existing atmosphere does most of that work.

Some of you guys might think I'm nitpicking semantics, but this is important to understand properly in order to keep our thinking & understanding honest.

The motor does not function by drawing (or sucking) any air inside, this assumption is what tricks a lot of folks into wrongly thinking that they must primarily optimize the mechanical pumping efficiencies of their "pump" in order to get more torque production. When in fact there is no stinkin' pump... there is only a constant external pressure pushing in varying densities of air. The piston performs most of its work while compressing the air that has been supplied by the atmospheric pressure. Thinking about things backwards can lead a person to attempt all sorts of voodoo nonsense that cannot ever work.... just sayin'.

And yeah, yer dead wrong in most of your assumptions Brad. Tree Monkey is dead right, and a good teacher, as usual.

very well sad sir.

drf256 · Dec 12, 2018

retro said:
Atmospheric pressure is the only available force to supply air for the motor. The piston does very little of the required work for filling during the intake stroke. The existing atmosphere does most of that work.

Some of you guys might think I'm nitpicking semantics, but this is important to understand properly in order to keep our thinking & understanding honest.

The motor does not function by drawing (or sucking) any air inside, this assumption is what tricks a lot of folks into wrongly thinking that they must primarily optimize the mechanical pumping efficiencies of their "pump" in order to get more torque production. When in fact there is no stinkin' pump... there is only a constant external pressure pushing in varying densities of air. The piston performs most of its work while compressing the air that has been supplied by the atmospheric pressure. Thinking about things backwards can lead a person to attempt all sorts of voodoo nonsense that cannot ever work.... just sayin'.

And yeah, yer dead wrong in most of your assumptions Brad. Tree Monkey is dead right, and a good teacher, as usual.

There still has to be a pressure gradient for atmospheric pressure to “fill” something. That’s where wind comes from.

Most people think the stratos are pushing charge into the cylinder before the transfers open, but they are not. They short circuit into the transfers and changes in pressure allow the charge in the tunnels to back fill with fresh air from them. The charge in the tunnel now has a layer of fresh air on top of it that enters the cylinder first. The charge is “stratified” like adding some Guinness stout on top of a Bass Ale for the classic Black and Tan. It will mix if stirred, but if you take a sip, you’ll get the Guinness first (which floats from lower density nitrogen charge).

Gutting them makes zero sense, at least to me. Can gutting them be a way to overcome improper porting or situations where the factory makes it unable to optimize port timing for performance? Possibly. But it’s air, not fuel, that’s the rate limiting step to performance.

XP_Slinger · Dec 12, 2018

I think where Stihl made a BIG improvement is the tight crank case on the 462. In my limited experience a lot of strato saws have relatively low intake area when compared to their non-stratified kin (ie 372OE vs X-Torq). Not to go off the rails too much with huskie, but they made no change to the X-Torq crankcase to accommodate the smaller, higher velocity intake tract. Gutting the stratos completely (filter holder to the boot) can be viewed as a way of gaining intake area but as seen in this thread, through the function of the strato design that extra mix is pretty much just flying out the exhaust.

Back to the 462, the tighter crank case is just a flat out win in terms of optimizing the intake In my hack opinion. In my head, it helps create a stronger intake pulse which moves a lot of air through the small intake and also obviously better case compression.

Maybe it’s too early for me to be thinking about this but as of now, the crank case design is what I see as the game changer on the 462.

RI Chevy · Dec 12, 2018

You NEED one if these Stihl 462s Josh. Lol

XP_Slinger · Dec 12, 2018

RI Chevy said:
You NEED one if these Stihl 462s Josh. Lol

I’d be lying if I said I didn’t want one Jeff. Could paint it orange and no one would ever know the difference

Would have to change muh handle to XP_Stihler lol

blsnelling · Dec 12, 2018

tree monkey said:
I was hopping for some input from brad, but he don't wanna talk

I'm here, just don't have much to say about the theory, and don't yet have another saw to do comparisons/changes with.

BTW, I fully respect your ideas and opinions. I have to see them work for myself though. Not everything works the same for everybody. I've tried other people's methods before and not had them work for me. I hope to port another 462 and leave the stratos intact. I will report what I find no matter the results.

Gary Courtney · Dec 12, 2018

retro said:
The motor does not function by drawing (or sucking) any air inside, this assumption is what tricks a lot of folks into wrongly thinking that they must primarily optimize the mechanical pumping efficiencies of their "pump" in order to get more torque production. When in fact there is no stinkin' pump... there is only a constant external pressure pushing in varying densities of air. The piston performs most of its work while compressing the air that has been supplied by the atmospheric pressure. Thinking about things backwards can lead a person to attempt all sorts of voodoo nonsense that cannot ever work.... just sayin'.

This is what a fire truck pumper does. It does not "pump" water when it drafts. It creates a negative pressure in the pump and the atmospheric pressure of 14.6# fills the void created.

RedGas · Dec 12, 2018

tree monkey said:
so why make a big hole in front of a small hole, makes no sense to me.

Dunno, maybe ask Julia?

Wood Chopper · Dec 12, 2018

our lungs too. Nothing sucks. Diaphram drops and lowers pressure.

cus_deluxe · Dec 12, 2018

retro said:
Atmospheric pressure is the only available force to supply air for the motor. The piston does very little of the required work for filling during the intake stroke. The existing atmosphere does most of that work.

Some of you guys might think I'm nitpicking semantics, but this is important to understand properly in order to keep our thinking & understanding honest.

The motor does not function by drawing (or sucking) any air inside, this assumption is what tricks a lot of folks into wrongly thinking that they must primarily optimize the mechanical pumping efficiencies of their "pump" in order to get more torque production. When in fact there is no stinkin' pump... there is only a constant external pressure pushing in varying densities of air. The piston performs most of its work while compressing the air that has been supplied by the atmospheric pressure. Thinking about things backwards can lead a person to attempt all sorts of voodoo nonsense that cannot ever work.... just sayin'.

And yeah, yer dead wrong in most of your assumptions Brad. Tree Monkey is dead right, and a good teacher, as usual.

As al said above, there has to be a pressure gradient inside and outside the engine (this is what is used to operate the diaphragm carbs in saws). If there was no vacuum in the crankcase when the intake port opened, then no air would move. Im not saying atmospheric pressure isnt involved, just saying that the existence of alternating case pressure and case vaccuum is certainly a part of what makes the whole thing go round. A case w piston at bottom dead center has X volume, meanwhile (in theory) fresh charge is being scavenged by outgoing exhaust yes? Say the port timing of this engine is 100-120-80, that would mean that the piston would move move up 40 degrees after the transfers close, but before the intake opens right? That 40 degrees of travel increases the physical volume of the case at that point, while the actual volume of fresh charge ( assuming piston and ring(s) are sealing things properly) stays the same as it was when the transfers were sealed. that has to lead to a vacuum of some sort in the case when the intake port opens? Hopefully im not way off lol.

00wyk · Dec 12, 2018

Geziz Christmas, folks. I mean. Wow.

And Merry Christmas, too.

A pump, by definition, is a device that either uses suction OR pressure to move liquids or gases. So, absolutely, ALL 2 strokes operate like a pump(as well as many other mechanisms folks here are saying are not pumps or vacuums), and they all act as though they are supercharged on the transfer intake side. If a device uses standard air pressure to fill it's cavity, it still is using suction as, by definition, it only has to produce a partial vacuum VS an absolute vacuum to be called suction. A partial vacuum simply means it has less pressure than the air around it. If there were no pressure differential, then no fuel, mix, or air will exchange. At least not in a timely manner(which is how it can be painful it to operate a saw at very high altitudes). You need a pump to create that pressure differential. Thus, even though it is using 14.6psi at sea level to help move the charge, it is still using suction. It's just not supercharging the mix on the intake side. Without behaving like a pump, there would be no pressure differential. And without being a pump, neither air nor fuel nor oil nor strato nor whatever would move through the engine. A good hint is the fact that two of the strokes of a 2t engine are called a 'compression stroke'. Another hint is the fact the freaking thing has a piston in it. According to the 'Two Stroke Tuner's Handbook", average crankcase compression is 1.5bar on most modern two stroke engines - supercharging a fuel mix means more than 1bar of pressure. Thus, the intake phase for the transfers is supercharged unless they open too early. That is probably where the confusions about pumping and sucking comes from. A charge does not need to be supercharged to be pumped...or sucked. And once that mix that's been all pumpy pumped and sucky sucked explodes, it starts to create it's own pressure as well, shoving the piston down. Since that piston goes both down AND up, it will definitely displace volume that will be filled with an incoming charge as it races back up, creating a partial vacuum, aka a pressure differential, AKA suckin' or suction.

So there's more pumping and sucking going on in your average 2 stroke than a first year college dormitory.

This is how stratos work; It takes the deference in pressure to fill the top of the transfers to help with scavenging. It doesn't supercharge that strato charge, though. Otherwise you'd end up with too much air and too little mix. At least how the ports are currently designed.[/B]

Redbull661 · Dec 12, 2018

Deets066 · Dec 12, 2018

00wyk said:
Geziz Christmas, folks. I mean. Wow.

And Merry Christmas, too.

A pump, by definition, is a device that either uses suction OR pressure to move liquids or gases. So, absolutely, ALL 2 strokes operate like a pump(as well as many other mechanisms folks here are saying are not pumps or vacuums), and they all act as though they are supercharged on the transfer intake side. If a device uses standard air pressure to fill it's cavity, it still is using suction as, by definition, it only has to produce a partial vacuum VS an absolute vacuum to be called suction. A partial vacuum simply means it has less pressure than the air around it. If there were no pressure differential, then no fuel, mix, or air will exchange. At least not in a timely manner(which is how it can be painful it to operate a saw at very high altitudes). You need a pump to create that pressure differential. Thus, even though it is using 14.6psi at sea level to help move the charge, it is still using suction. It's just not supercharging the mix on the intake side. Without behaving like a pump, there would be no pressure differential. And without being a pump, neither air nor fuel nor oil nor strato nor whatever would move through the engine. A good hint is the fact that two of the strokes of a 2t engine are called a 'compression stroke'. Another hint is the fact the freaking thing has a piston in it. According to the 'Two Stroke Tuner's Handbook", average crankcase compression is 1.5bar on most modern two stroke engines - supercharging a fuel mix means more than 1bar of pressure. Thus, the intake phase for the transfers is supercharged unless they open too early. That is probably where the confusions about pumping and sucking comes from. A charge does not need to be supercharged to be pumped...or sucked. And once that mix that's been all pumpy pumped and sucky sucked explodes, it starts to create it's own pressure as well, shoving the piston down. Since that piston goes both down AND up, it will definitely displace volume that will be filled with an incoming charge as it races back up, creating a partial vacuum, aka a pressure differential, AKA suckin' or suction.

So there's more pumping and sucking going on in your average 2 stroke than a first year college dormitory.

This is how stratos work; It takes the deference in pressure to fill the top of the transfers to help with scavenging. It doesn't supercharge that strato charge, though. Otherwise you'd end up with too much air and too little mix. At least how the ports are currently designed.[/B]

Tl;dr

XP_Slinger · Dec 12, 2018

00wyk said:
Geziz Christmas, folks. I mean. Wow.

And Merry Christmas, too.

A pump, by definition, is a device that either uses suction OR pressure to move liquids or gases. So, absolutely, ALL 2 strokes operate like a pump(as well as many other mechanisms folks here are saying are not pumps or vacuums), and they all act as though they are supercharged on the transfer intake side. If a device uses standard air pressure to fill it's cavity, it still is using suction as, by definition, it only has to produce a partial vacuum VS an absolute vacuum to be called suction. A partial vacuum simply means it has less pressure than the air around it. If there were no pressure differential, then no fuel, mix, or air will exchange. At least not in a timely manner(which is how it can be painful it to operate a saw at very high altitudes). You need a pump to create that pressure differential. Thus, even though it is using 14.6psi at sea level to help move the charge, it is still using suction. It's just not supercharging the mix on the intake side. Without behaving like a pump, there would be no pressure differential. And without being a pump, neither air nor fuel nor oil nor strato nor whatever would move through the engine. A good hint is the fact that two of the strokes of a 2t engine are called a 'compression stroke'. Another hint is the fact the freaking thing has a piston in it. According to the 'Two Stroke Tuner's Handbook", average crankcase compression is 1.5bar on most modern two stroke engines - supercharging a fuel mix means more than 1bar of pressure. Thus, the intake phase for the transfers is supercharged unless they open too early. That is probably where the confusions about pumping and sucking comes from. A charge does not need to be supercharged to be pumped...or sucked. And once that mix that's been all pumpy pumped and sucky sucked explodes, it starts to create it's own pressure as well, shoving the piston down. Since that piston goes both down AND up, it will definitely displace volume that will be filled with an incoming charge as it races back up, creating a partial vacuum, aka a pressure differential, AKA suckin' or suction.

So there's more pumping and sucking going on in your average 2 stroke than a first year college dormitory.

This is how stratos work; It takes the deference in pressure to fill the top of the transfers to help with scavenging. It doesn't supercharge that strato charge, though. Otherwise you'd end up with too much air and too little mix. At least how the ports are currently designed.[/B]

Agreed, just didn’t have the desire to put thumb to keyboard this morning.

XP_Slinger · Dec 12, 2018

Redbull661 said:

Mega Maid! Lmao!

XP_Slinger · Dec 12, 2018

Gary Courtney said:
This is what a fire truck pumper does. It does not "pump" water when it drafts. It creates a negative pressure in the pump and the atmospheric pressure of 14.6# fills the void created.

And the strength of the negative pressure (vacuum, suction) dictates the speed at which a given volume is filled by ambient pressure. Both lines of thinking are correct IMO. Different ways to arrive at the same conclusion...chainsaws suck. Lol!

Tree Monkey MS462 - PART 2

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