Is compression king?

[jmssaws]

Only saws I've built that are over 200 and tune past 15 are 026 and 346's

 

[Stump Shot]

As far as the cool dense air thing goes, when we ran snowmobiles the motors ran best the colder it got. At -20F to -30F they would just scream, would be the fastest you could go for sure.

 

[Deets066]

Send it to Tennessee, maybe Deets can haul it down. Send your gauge too please.

I think he's comin down Joey

 

[RI Chevy]

So Jason, my thinking is backwards?

 

[Redfin]

Send it to Tennessee, maybe Deets can haul it down. Send your gauge too please.

I plan on coming Joey, I look foward to meeting you.

I wasnt planning on bringing anything but my rear but since you asked nicely.

 

[Deets066]

So Jason, my thinking is backwards?

Higher octane resists combustion, that's why it can run cooler in high compression engines

 

[Stihlbro]

Adding oil to fuel changes the burn rate too....

 

[exSW]

As far as the cool dense air thing goes, when we ran snowmobiles the motors ran best the colder it got. At -20F to -30F they would just scream, would be the fastest you could go for sure.

I know large two stroke diesels like to pull better in the cool night air.

 

[Red97]

This one was 240 psi

But only 50cc

60cc 170 psi range

Just like anything. Engine related, if you get all the variables in line at 175 psi it is going to be stronger than a hodge podge at 215 psi

I have been on both ends of the scale, still searching for a sweet spot on the models I have been doing.

Best I can do is try something, if it works great, then try something else and see lol.

I know nothing, just ask I'll tell ya

 

[Stihlbro]

I know large two stroke diesels like to pull better in the cool night air.

You wouldn't speaking of turbo charged 710 gb3'S would you? 70ace or 90mac would you? Governor or emdec?

 

[drf256]

Supercharged engines generally run a little lower than normal compression due to the higher RPM's and the air being forced in.
Helps prevent bent connector rods.

They run lower STATIC compression because the boost fills the cylinder under pressure. So it's actually compressing more volume than the cylinder has into the same chamber.

And there is your proofff.

I would like to know the "why" smaller bores dont mind the higher comps.

Follow my thinking, the larger bores compress more volume to a certain psi that a smaller bore would but...

The larger bore also has a larger centripital mass to carry the piston around back up to tdc to repeat the process.

I think it's heat disappation John. The smaller the bore, the more surface area of fins relative to the bore size.

I'm not very good with words on the internet, my post don't always come out right , but I know thru experience cranking compression can be misleading. The internet tell you you more is better. I'm a believer there is more of a formula to determine what you need.

1.) What is your elevation?
2.) What are you cutting?
3.) What kind of chain you using? Bar length?
4.) How you operate a saw?
5.) What are your physical limitations?

Most saws that are factory hot rods are harder to get gains out of versus the typical pro rated saw. They generally have more cranking compression. In other words, if you tell me you got 200 plus compression and are four stroking at 15k plus, then bring the saw to Mastermind in December and let me run it.

I often relate saw experiences to automotive scenarios. I remember the day of the 5.0 mustangs and lingo and how it changed thru that era. I've been thru the truck scenes too. The moral of this as we all want a truck that pulls like a Mack, rides like a Cadillac but run like a Super charged mustang. We saw enthusiast what a small saw that pull like ole home lite, speed of a race saw but yet handle like limbing saw.

Ok, I may have ranted for a bit but to answer the question of cranking compression, in all my experiences the more compression is not always most powerful.

Lower comp saws rev higher for sure, at least for me.

Definitive Daves 260 is running 260 psi and easily 4 strokes over 15k.

 

[jmssaws]

Kool dense air makes power.

 

[Red97]

Well what allows a saw to 4 stroke up high??

Carb? Fuel? Intake? Exhaust? Transfers?

The more I think I understand, the less my saws seem perform.

Think I'm just gonna go back to "winging" it, or "meh" that outta work approach. lol

Or I just need to run some stock saws.......

 

[Deets066]

Ok, I'll bring it

It's a fuzz over 15,000 in the vid and way fat

 

[drf256]

Well what allows a saw to 4 stroke up high??

Carb? Fuel? Intake? Exhaust? Transfers?

The more I think I understand, the less my saws seem perform.

Think I'm just gonna go back to "winging" it, or "meh" that outta work approach. lol

Or I just need to run some stock saws.......

Great quaestions Joe.

Agree, feel like I'm going backwards at times.

I think it's compression and transfer design that makes rpm Joe.

 

[exSW]

You wouldn't speaking of turbo charged 710 gb3'S would you? 70ace or 90mac would you? Governor or emdec?

More the old 40's , 45's,50's and some 60's. Most of our newer stuff has the nuts cut off for fuel economy.

 

[mdavlee]

This one was a touch over 200 and was around 15k in the video.

 

[P.M.P.]

These

 

[Stihlbro]

It's a fuzz over 15,000 in the vid and way fat

You made two cuts, great! Bring that one.

More the old 40's , 45's,50's and some 60's. Most of our newer stuff has the nuts cut off for fuel economy.

Hard to beat the 40-2 stuff. Emd still uses the same engine excpept fuel injected and more traction adhesion. Simple the old way, wheel slip meant one thing.

This one was a touch over 200 and was around 15k in the video.

Again, you made two cuts and had to rock the saw to make cut. That saw needs a chain.

 

[Deets066]

You made two cuts, great! Bring that one.



Hard to beat the 40-2 stuff. Emd still uses the same engine excpept fuel injected and more traction adhesion. Simple the old way, wheel slip meant one thing.


Again, you made two cuts and had to rock the saw to make cut. That saw needs a chain.

What you gettin at Joey? I could make a 20 minute video of the saw cuttin but would get kinda boring to watch