::: Power vs Torque :::

[Jonsered2095]

It seems to me almost everyone quotes Hp as the only relevant measure of a saws engine [or cutting] performance.

So, whats your preference?



Its a fairly black or white poll, but I am interested to know the general consensus: please vote and/or state your preference and why. :chainsawguy:

 

[pbtree]

Torque is probably more relevant in a larger saw, but most seem to focus on horsepower...

 

[Lakeside53]

without torque, there is no HPopcorn:

As this thread will fill with endless arguments about the same, here's a baseline to argue from

http://en.wikipedia.org/wiki/Horsepower

 

[Jonsered2095]

without torque, there is no HPopcorn:

As this thread will fill with endless agruments about the same, here's a baseline to argue from

http://en.wikipedia.org/wiki/Horsepower

:bang: :blush:

 

[OLY-JIM]

In truth, the two are extremely symbiotic. However, in large DBH wood; I'll take an advantage in torque any day in order to nut it out. In firewood cutting; I'd opt for an advantage in HP where rapid completion is tantamount to profitability and filling the wood shed!

 

[kevlar]

Torque!

 

[windthrown]

From my physics books...

Its power that drives a chainsaw chain to cut through wood. Torque is just one factor in the calculation of power, and without rotational speed (RPMs) there is no cutting with a chain. So torque is only half of the equation, rotation speed is the other half, and from that you get POWER.

Power = Torque x Rotational Speed

and why chainsaws are rated by horsepower, and not torque.

 

[Lakeside53]

..and it starts..

O.K. CHOWDOZER, whip out and dust off your prior arguments.

 

[Jonsered2095]

..and it starts..

O.K. CHOWDOZER, whip out and dust off your prior arguments.

No riots please!

 

[Ironbark]

Power 'cause I don't really know what torques are :hmm3grin2orange:

 

[stevethekiwi]

Power 'cause I don't really know what torques are :hmm3grin2orange:

both torque and power are relative, you cant screw around with one without affecting the other. think of torque as turning force.


diesel engines are a good example of torque. not a quick sprint on the 1/4 mile, but put that 6000bhp top fuel drag car against a 3000bhp diesel, load em up with 600 tonne of weight, and see who gets to the finish first!

without power there is no torque. with zero torque there no power input... see where im going. ideally i want high torque and high power!

realisticly, if your chain / engine speed is the same, and your engine sizes are similar etc etc, an engine with slighly higher torque will cut faster than an engine with slightly higher power. consider higher torque a resistance to change. it is easier for a higher torque engine to maintain the perfect cutting speed, where higher power wants to spin the chain faster but doesnt like the extra load. people pump tonnes of power into their saws when modding i agree, but they are also increasing torque (allthough not at the same rate.... x2 power = < x2 torque). you can increase torque with more weight on the flywheel piston crank, port timing blah blah, but you need more power to get the engine up to speed to get the torque benefit. zzzzzzzz. there is lots more too it but im tired and boozed.

IMO there is no substitution for displacement. put all the power you want in to your small saws with your muffler mods and porting and jet fuel turbo charged whizz bang expansion chamber big carb tin pot. yeah, they will plough through an 18" log in no time. whop de do, i love cutting 18" logs as fast as i can. ill put my 3120 against your modded 359 which may have the same power output and have tonnes of $$$ spent on it - but the race will be on a 66" mill cutting up red gum with .404 chain. ill wait for you at the finish!

goodnight, you all

steve

 

[Ironbark]

without power there is no torque. with zero torque there no power input... see where im going. ideally i want high torque and high power!

realisticly, if your chain / engine speed is the same, and your engine sizes are similar etc etc, an engine with slighly higher torque will cut faster than an engine with slightly higher power.

steve

But that's what I don't understand. To cut your piece of wood requires a certain amount of work to be done on it. If power is the rate of doing work, then surely more power equals a faster cut?

 

[Scooterbum]

This is like do you prefer voltage or amperage?
You can't have one without the other.









now my head hurts

 

[Andyshine77]

torque and HP are in fact symbiotic. The best formula is to have both torque and HP = over a the entire rev band, from idle to max rpm. However for now a short stroke engine typically has high rpm's and hp, but low torque, and vice versa. That gap however is closing rapidly.

An abundance of one or the other can overcome ones shortcomings. For instance A light vehicle with high hp, but low torque can still be a fast vehicle. However a heavy vehicle with high hp but low torque, will be a slow vehicle off the line. In the end that heavey vehicle may end up fast, But is this what you need in a truck? No. You need torque more than hp. it all depends on what is needed. A balance of both is however optimal.

 

[oneoldbanjo]

This is a difficult topic to understand and/or explain - or to get someone to change their opinion about. A chainsaw needs both horsepower and torgue in adequate amounts - and generally bigger is better as long as both numbers are kept in balance. Torque is the measure of the ability to pull the chain through the wood - and horsepower is the measure of how quickly you can pull that given load through the wood. If you increase the load on the chain (bigger chain or increased pressure) you will need torque to overcome the load increase - or if you increase chain speed at the same load you will be increasing the horsepower requirements.

When you are using your chainsaw and the engine bogs down - it is because the imposed loads have exceeded the engines torque - so torque is very important. If you want to be able to move the chain quickly so the cuts can be made faster - you need horsepower.

A good working chainsaw will have a good balance of torque and horsepower and I believe that just looking at numbers won't provide a good idea of where the good balance is - you need to pick up that saw and use it to see if the balance between torque and horsepower is right for you. A small limbing saw can be a little higher strung and doesn't need to have a huge amount of torque to pull a short picco chain and it will probably have a pretty narrow powerband and need to be "wound up" to work well - whereas a saw pulling a long chain will need a good amount of torque and flexibility to handle the changing loads that occur when cutting big wood.

 

[Andyshine77]

I think that's what I just said, or am I just crazy. :crazy1:

 

[oneoldbanjo]

Andy.....I believe we were typing at the same time.....you just hit your send button before I did. We agree on the issue......I don't know if any others do.

 

[Andyshine77]

Your good, no worries.

 

[Knotdodger]

Don't no about mathematics to well. Unless It involves Money!!!
I will take what ever don't bog down in large Ash... opcorn:

 

[WRW]

Poke a similar sized hole in the lower side of both containers and see which shoots a farther stream. LOL

Max HP is the figure that manufacturers give, so that's what people can go by. Overlapping power and torque curves would give a better idea of performance.