Case Compression, Let's Talk About It

[rogue60]

Plumb this sucker into the intake of a 500i lol

 

[Dolkitafreak]

That would be true, but those are temporary power adders.

You’re right, but guys complain about a pound difference in saws already, they would have a stroke thinking about the size and weight of a turbo! Not to mention making it fit in a work chassis.

 

[farminkarman]

You’re right, but guys complain about a pound difference in saws already, they would have a stroke thinking about the size and weight of a turbo! Not to mention making it fit in a work chassis.

Not to mention the part of the whole tuned pipe in front of said turbo...

 

[Wanab]

Plumb this sucker into the intake of a 500i lol
View attachment 322040

Can you say hand grenade?

 

[Ketchup]

The biggest unaddressed issue with the MS201 is the poor fit of the transfer covers. After a little squish cut, a tossed out base gasket, and some fine tuning of the ports.....the little saw becomes a completely different animal.

I still haven’t managed to pry one of those covers off. The way it juts into the transfer upper is very irritating. Do you grind that or just leave it alone? I’m not convinced grinding helps much.

I just wanna add something about weight, the 201 is heavier than the 200. It may ripass. but Now every one is raving about the super light 2511 up in the tree,
Lightness up tree really counts

but your right about case compression, it would be interesting to know the volume difference between the 200\201. I know it won’t be a lot but it will be significant.

The weight difference between a 200 and 201 is less than the difference between a 14” and 16” bar. I would prefer lighter but it’s not enough for me to fuss over. The 2511 is a little more than HALF the weight of a 35cc top handle. That keeps the 201 on the ground most days.

2511 addresses case volume in some goofy ways. I’m of a mind to try fabricating crank stuffers for one. The transfer stuffer doesn’t bother me much, but the cylinder flange is super constrictive for the transfer lowers. I want to open it up like a 346, but if you add too much volume…

 

[Al Smith]

The entire conversation is based on theory and conjecture unless it's proven .Again related to to how the cat is skinned .

 

[Dieselshawn]

You’re right, but guys complain about a pound difference in saws already, they would have a stroke thinking about the size and weight of a turbo! Not to mention making it fit in a work chassis.

Logic states that is true too. Having power gets heavier.

 

[Mastermind]

I still haven’t managed to pry one of those covers off. The way it juts into the transfer upper is very irritating. Do you grind that or just leave it alone? I’m not convinced grinding helps much.

I've never attempted to take the covers off. After I cut the squish band, I find the highest point of the upper transfers, then cut them all to that height. I use a small burr, and work back into the passage so that the insert is matched to my ports. Makes a difference.

 

[Stump Shot]

Can you say hand grenade?

Naw, it would just push any potential boost right out the exhaust port.

 

[Dieselshawn]

You’re right, but guys complain about a pound difference in saws already, they would have a stroke thinking about the size and weight of a turbo! Not to mention making it fit in a work chassis.

It’s funny how a pound of weight difference can make a huge negative opinion to a lot of people.

Loggers of the past would carry the IEL Super Twin 52 saw around while guys of now would throw a fit at carrying more than a MS260.

 

[Ketchup]

It’s funny how a pound of weight difference can make a huge negative opinion to a lot of people.

Loggers of the past would carry the IEL Super Twin 52 saw around while guys of now would throw a fit at carrying more than a MS260.

I remember my Dad thought he would get strong by holding a 12lb cannon ball straight out for 10 minutes every three days or so. He tore a deltoid about two weeks in and couldn’t couldn’t lift his arm above his head for three months. I think about that every time I one hand a 201 (roughly 12lbs full with the bar and chain). Mostly now I use the 2511 and think Dad should have tried a 6 pound ball.

I really like light saws.

 

[Dieselshawn]

I remember my Dad thought he would get strong by holding a 12lb cannon ball straight out for 10 minutes every three days or so. He tore a deltoid about two weeks in and couldn’t couldn’t lift his arm above his head for three months. I think about that every time I one hand a 201 (roughly 12lbs full with the bar and chain). Mostly now I use the 2511 and think Dad should have tried a 6 pound ball.

I really like light saws.

I have light saws, but I still prefer my MMWS 660 over them.

Some people aren’t meant to do certain things which ends up hurting them while others do the same thing just fine.

I know of a father and son logger that are like that. Father easily spends everyday carrying an 088 in the bush felling trees for years. His son used a 661 for a few years and ended up requiring surgery to fix his shoulder. He’s downgraded to 500i since.

 

[telejed]

So taking volume away will give it more movement up though the transfer passages because less time is wasted compressing mixture that will never leave the crankcase anyhow.

Hey Randy, I've been reading and watching videos but that statement is something that I've been thinking about. Mainly the volume of the charge that you have to work with is the volume change of the piston.

Too much intake duration and spit back occurs. . . or wasted fuel.

If I have a stock saw that spits back does increasing case volume help? Or opening up lower transfers?

 

[Mastermind]

Mainly the volume of the charge that you have to work with is the volume change of the piston.

The displacement of the volume change is what you can move......and some inertia perhaps.

If I have a stock saw that spits back does increasing case volume help? Or opening up lower transfers?

I don't think it would. Shortening the intake duration, or using a velocity stack would be two ways to help it.

 

[Maintenance Chief]

I think the ten series McCulloch is a good example of case volume and how flexible it can be ? Just about everything from 54cc to 82cc being close to the same case volume.
When I was reading about the 36/044 hybrids someone questioned if the bigger cylinder would be starved because of case volume not being able to support the cylinder? I thought did McCulloch consider this going from the SP60 to the SP81? Same case ,both great saws. Or am I confused about this?

 

[Mastermind]

I think the ten series McCulloch is a good example of case volume and how flexible it can be ? Just about everything from 54cc to 82cc being close to the same case volume.
When I was reading about the 36/044 hybrids someone questioned if the bigger cylinder would be starved because of case volume not being able to support the cylinder? I thought did McCulloch consider this going from the SP60 to the SP81? Same case ,both great saws. Or am I confused about this?

Case volume does change when displacement increases though. Everything under the piston when it is at tdc is case volume. If you increase bore, or stroke, you added volume and displacement to the area above, and below the piston.

 

[Ketchup]

The transfer volume matters a lot too.

 

[Stump Shot]

The transfer volume matters a lot too.

Also a part of case volume.

 

[Ketchup]

Also a part of case volume.

Ed Zachary.

 

[Wanab]

Port work increases volume but can make more power. Larger volume also increases the volume of the charge as well. A balancing act and back to skinning the cat I guess.