Show them numbers!!!

[Fruecrue]

Its almost like your quoting a plumbers contract.

Are you a plumber?

Put up your dukes.

 

[Fruecrue]

Bingo

It all comes down to physics. Compression adds energy in the form of heat to the combustion chamber. We have all felt a compressor tank get warm after it fills and then get cool upon emptying. Also how refrigeration works.

But energy is never created, it only can change forms. So it takes energy to make the heat from compression.

One wants the charge that’s in the combustion chamber to have the fullest fastest burn possible. Preheating it (compression) helps that. Too much and you will get detonation (so perfect that it will fire before you want it to).

So you have to figure out if the parasitic losses of compression are overcome by the power increases.

The higher the compression, the more heat the cylinder will generate. The high compression saws definitely get hotter and don’t hold tune as well as lower compression. The OEM know that, but they also have those tiny muffler outlets that maintain heat as well. Higher compression also slows down max rpm and spoolup.

Small bores like more because they tend to have much more cooling area vs bore size. If you put an 036 and 044 jug on a bench they are indistinguishable at quick glance.

This is also why it’s easier for a cold saw to fire without the decomp pressed in.

The point is that, like all else, it has to be matched to what one wants in a saw. There is no perfect combo. I tailor it to what the end user has in mind for the saw.

Good morning Al.
Agreed on all but the refrigeration point (because I’m a stickler for detail and an RC). Heat of compression is a factor in the compressor as suction vapor is compressed and becomes discharge vapor but not “how refrigeration works”.
Refrigeration principle relies upon the change of state of a substance, the latent heat that is absorbed and rejected during a phase change is the lion’s share of the heat transfer.
Latent heat numbers are high. It takes 1 btu to change the temperature of 1 lb. of water 1 degree F but takes 970 btu to change the state of 1 lb. of water to steam and it can be measured at 212 degrees both before and after adding all that heat. 970 btu added and it didn’t even change 1 degree but the enthalpy, or embodied heat is much higher.
I’m done now, carry on.

And @Redfin , please read above to see that I ain’t no damn plumber. GFY.

 

[drf256]

Good morning Al.
Agreed on all but the refrigeration point (because I’m a stickler for detail and an RC). Heat of compression is a factor in the compressor as suction vapor is compressed and becomes discharge vapor but not “how refrigeration works”.
Refrigeration principle relies upon the change of state of a substance, the latent heat that is absorbed and rejected during a phase change is the lion’s share of the heat transfer.
Latent heat numbers are high. It takes 1 btu to change the temperature of 1 lb. of water 1 degree F but takes 970 btu to change the state of 1 lb. of water to steam and it can be measured at 212 degrees both before and after adding all that heat. 970 btu added and it didn’t even change 1 degree but the enthalpy, or embodied heat is much higher.
I’m done now, carry on.

And @Redfin , please read above to see that I ain’t no damn plumber. GFY.

It still has to do with creating potential from kinetic energy and the basic principle is the same, at least to me.

Plus, there is no suck thing as a compressor, did you forget? It’s just cycling atmospheric pressure and the atmosphere does it all.

 

[Fruecrue]

It still has to do with creating potential from kinetic energy and the basic principle is the same, at least to me.

Plus, there is no suck thing as a compressor, did you forget? It’s just cycling atmospheric pressure and the atmosphere does it all.

I remember!
I’ve yet to cut down a tree using only the atmosphere.
#imsoweak

 

[Deets066]

Put up your dukes.

I fuggin got no dukes man, I’m a goat

 

[Mastermind]

I fuggin got no dukes man, I’m a goat

Images?

 

[Deets066]

Images?

 

[Fruecrue]

I fuggin got no dukes man, I’m a goat

Come closer, I cannot see you.

 

[Deets066]

Come closer, I cannot see you.

Brilliance

 

[Fruecrue]

Brilliance

I feel bad for all who don’t know what we’re talking about.

 

[MustangMike]

OK, I'd like to enter this compression discussion (I'll leave the goats and stuff to others) …

Doc, you mention changing the squish band on a "milling saw" to lower compression. Isn't it sometimes more effective to leave the squish at .020 but just raise the exhaust a bit?

On my 660s I find it makes them much easier to start and they often seem to run stronger, but I still keep the squish at .020. IMO it results in a much more user friendly saw. (Note: I also enlarged/lowered the intake and added bridge ports to these saws).

Next I'm going to see if I can get a Hybrid to run stronger with a lower exhaust (I know the longer 660 stroke had something to do with the results). My thought is the more you improve the flow of the air fuel mixture, the less low RPM compression you need to make power … almost like forced induction engines benefit from lower compression (and it is not just from the size of the compression chamber, cam timing has effects it).

Comments welcome.

 

[Mastermind]

OK, I'd like to enter this compression discussion (I'll leave the goats and stuff to others) …

Doc, you mention changing the squish band on a "milling saw" to lower compression. Isn't it sometimes more effective to leave the squish at .020 but just raise the exhaust a bit?

On my 660s I find it makes them much easier to start and they often seem to run stronger, but I still keep the squish at .020. IMO it results in a much more user friendly saw. (Note: I also enlarged/lowered the intake and added bridge ports to these saws).

Next I'm going to see if I can get a Hybrid to run stronger with a lower exhaust (I know the longer 660 stroke had something to do with the results). My thought is the more you improve the flow of the air fuel mixture, the less low RPM compression you need to make power … almost like forced induction engines benefit from lower compression (and it is not just from the size of the compression chamber, cam timing has effects it).

Comments welcome.

Are you a goat too?

 

[MustangMike]

Keep on topic or I'll have to ban ya!

 

[Mastermind]

Keep on topic or I'll have to ban ya!

My sorry.

What exactly was the topic?

 

[MustangMike]

Turtles … It was all about Turtles!!!

 

[Mastermind]

Turtles … It was all about Turtles!!!

Oh. I like turtles.

 

[Deets066]

Turtles … It was all about Turtles!!!

It’s about the GOAT!

Fack me in the goat asss

 

[MustangMike]

Let's move DEETS to the Outdoor Power Beastiality site and we can move on here!

 

[Mastermind]

Let's move DEETS to the Outdoor Power Beastiality site and we can move on here!

There's really a site like that?

Wow.

 

[deye223]

I'm a goat Greatest Of All Time