Why do the old saws make more torque?

[Stihl 041S]

Bagwan Lake; I ask what would be a good bar length to play with the 90cc saws, 32,36? We await your words.
Rob

 

[superfire]

uh boyz

i think it boils down to engine design. newer engines more vertical. old sawz were mostly horizontal. horizontal enginez have better push and pull on each engine stroke. vertical enginez have weaker push and pull on each engine stroke.


just my hung over opinion

 

[Peacock]

i think it boils down to engine design. newer engines more vertical. old sawz were mostly horizontal. horizontal enginez have better push and pull on each engine stroke. vertical enginez have weaker push and pull on each engine stroke.


just my hung over opinion

That doesn't make any sense.

What if you turn you modern, vertical cylinder saw, vertically? Does it gain torque? What if I turn an 041 vertically? Does it lose torque?

 

[funky sawman]

:agree2: :agree2: :agree2:

That doesn't make any sense.

What if you turn you modern, vertical cylinder saw, vertically? Does it gain torque? What if I turn an 041 vertically? Does it lose torque?

 

[Tzed250]

Torque is a function of cylinder filling efficiency. Older saws have small ports and reed valves, great for low RPM cylinder scavenging.

Horsepower is a function of torque.

 

[superfire]

which is easier lifting a heavy weight or pushing it?????????? that is what i am describing . basic physics sayz it is easier to push a object then to lift it
opcorn:

 

[lesorubcheek]

i think it boils down to engine design. newer engines more vertical. old sawz were mostly horizontal. horizontal enginez have better push and pull on each engine stroke. vertical enginez have weaker push and pull on each engine stroke.


just my hung over opinion

Uh... maybe ya need to cruise Mr. Acres site a bit. Yep, plenty of saws in the late 60, and throughout 70s with horizontal, but step back a little further. Think its safe to say most saws of the 50's and early 60s were vertical. The vertical->horizontal->vertical transition is a question I've yet to get an answer on.

Dan

 

[thomas72]

I believe the main reason for the fly wheel is for rotating mass to get the crank, rod, and piston through a stroke. I like reed valves and in my opinion they are better than a piston ported engine, and just because it has reed valves does not mean the engine is only good for lower rpms, and a reed valve engine cost more to produce than a piston ported engine. I like the older higher torque saws, and that is why I run a McCulloch SP125.

 

[maico490]

which is easier lifting a heavy weight or pushing it?????????? that is what i am describing . basic physics sayz it is easier to push a object then to lift it
opcorn:

So if you rocked the saw up and down in time with the piston motion,thus ensuring it was always going downhill,you would be able to outcut just about anything.




IMHO it makes no difference if the cylinder is upright,horizontal,upside down or anywhere else short of inside out.

 

[heimannm]

Help please

Hey Andy,

In reference to your post #18, can you give a little more direction to find the old thread?

I am now more curious that ever as my first reaction (stroke) does not seem to be the whole answer.

Help me out a bit here please...

Mark

 

[ShoerFast]

So if you rocked the saw up and down in time with the piston motion,thus ensuring it was always going downhill,you would be able to outcut just about anything.




IMHO it makes no difference if the cylinder is upright,horizontal,upside down or anywhere else short of inside out.

Your right.

The gravity the piston gains going down is lost when it gose up.

Try a vertical engine in a vertical cut,(making the piston work vertical) it cuts the same, as with trying a horizontal engine in a horizontal cut(making the piston work vertical) no change.

 

[JohnL]

I think that the older reed engines were better runners across the entire rpm band, where as piston ported machines are designed to run and make power at a smaller rpm range, mainly at the top end. I don't understand the dynamics of why this is, but notice that most (all?) modern saw engines are piston ported, and rev much higher than the older reed engines.

 

[ShoerFast]

Compression has been mentioned, needing to cut 'NOX' emissions is easy, by controlling the pressure*, cutting the pressure the engine runs at cuts NOX, cutting power(work) also.

Cutting the pressure/temperature Nox can't form, EGR valves cut NOX by decreasing fire temp. Restricted muffs are saws EGR valve.

Just look at how many new saws get performance gains by opening the muffs and decreasing squish (raising compression) ?

Trust that there now making NOX like an engine should.

 

[rms61moparman]

All other things being equal, longer stroke ALWAYS means more power.

The difference is determined by TIME IN DWELL ( the length of time that the explosion is pushing down on the top of the piston) and simple leverage.

Longer lever means more force is produced at the driven end at the same force at the driving end.

Volumetric efficiency is the measure of how efficiently the cylinder fills with air/fuel mixture with each intake stroke (this is why the Hemi engine still dominates every motorsport even 60 years after its original development by Chrysler) and is why the disparity isn't a lot worse than it is.

Mike

 

[kevin j]

Q All other things being equal, longer stroke ALWAYS means more power.

The difference is determined by TIME IN DWELL ( the length of time that the explosion is pushing down on the top of the piston) and simple leverage.

Longer lever means more force is produced at the driven end at the same force at the driving end Q



not.......

kcj

 

[ShoerFast]

Racing NHRA engines

Longer strock also works more leverage on the crank, pure TQ , longer burn times.

CSB engines had the 327, an over bored engine, drag racers really liked them back when gear-slapper's benefited.

Come the fuel crunch/stiffer emmisions and a need to clean the CSB up, Chevy came up with an under bored engine to meet fleet emissions, cheaper to build the 305 was a natural stroker.

When automatic transmissions started to rule NHRA , tossing 400 CSB cranks into 350's/388's made huge success. stroking a 350 makes some huge bottom end power, automatics love the TQ.

Engine makes for years knew how to build TQ into the engines, some off-set the wrist-pin at more angle to the crank to steel extra TQ, at the price of more cylinder-piston ware.

 

[rms61moparman]

Q All other things being equal, longer stroke ALWAYS means more power.

The difference is determined by TIME IN DWELL ( the length of time that the explosion is pushing down on the top of the piston) and simple leverage.

Longer lever means more force is produced at the driven end at the same force at the driving end Q



not.......

kcj

What's not?????

 

[Rookie1]

What about Fuel efficiency? Torque motor or hi rev motor burns more?

 

[Stihl 041S]

What about Fuel efficiency? Torque motor or hi rev motor burns more?

Are you holding the cylinder horizontal or vertical?

 

[ShoerFast]

Are you holding the cylinder horizontal or vertical?

Or rocking it real fast so the piston would be falling with gravity, both ways?