Chainsaw RPM's (Frankie gets the last word)

[Frankie]

Over here in USA EPA established regulation in 1995. If you look at design of my 1990 064 cylinder the port timing , shape and size are excellent to produce more torque, same idea with 044 - both designs lend themselves to make power. Contrast that with 2020 462c or 572xp , much more difficult to coax power because of design. 044 5.4hp stock 70.7cc , 462c 72.2cc but 5.9hp, 372xp 5.3hp 70.7cc vs 572xp 70.6 but 5.8hp. I say the difference in design between 372xp ,044 cylinder vs 462c,572xp is like comparing Apple to orange

 

[Magnus]

There was EPA regulations long before that the manufacturers had in consideration when building saws, just like now but not as stupid. They changed a lot over the years and make less sense everytime.
Look on saws in 80's. Thats the reason we got different models and versions on export saws made here.

 

[Frankie]

My oldest saw is 1990 all the rest are 2016 or newer so I do not have/been inside/built any older versions than the 064 . I think the old saws do not give as much performance from stock but can be made very powerful. Newer saws like 462c,572xp give user more power stock , almost like ported/modded saw of old right from the factory ! But, cylinder design, piston is much different because of additional ports , like a controlled air-leak where raw air is introduced to cylinder via piston

 

[Nutball]

I disagree with that analysis, Frankie, the Husky 262xp is a prime example of what high compression can do for a saw, 60cc saw with 70cc power. To fight heat you add more fuel.
The two saws I have left, Husky 350 and Dolmar 5100s, are both running without base gaskets and .018" squish, that's as tight as I like it, but it's a big jump in compression, I run good fuel and better two stroke mix and run them a little fat. I can tune either to run stupid rpm's, but they wont cut anything but small limbs, they just bog down in wood. Fatten them up, they rip.
Raj, be careful with that tach, it may not be able to register the difference between a two and four stroke engine, I've been burnt by this one once.

Good to read you again. My guess is a 4 stroke fires the spark as often as a 2 stroke to keep the ignition system simple. Obviously the rpm it read on the 4 stroke was right near the usual 3600.

 

[Nutball]

High compression makes more powa no doubt , also puts more stress on the bottom end , also creates more heat (fuel cools , oil lubes: right-0) also enhances low-mid power at expense of top-end rev. Lotta ways to build a strong saw - high compression ain’t the only way , especially if a guy/gal wants the saw to last as long as a stocker. I’m from the school of “let them run” instead of “make them run” especially with these newer offerings. The golden era of chainsaws has came and went. I’ve got a Hotwoods ported 1990 064 that will whoop ass on these newer saws and it’s 31years old! Cannot compare pre epa saw today’s versions , apple and orange. I doubt folk in the future will be extolling the virtues of the 500i in 2052 😎

How many hours on the 064? From what I've heard, there's little, if any, noticable difference in life of high compression ported saws run by loggers, and they are the ones who see many a saw to the end of it's life because they put way more hours per day on them than firewood cutters and tree removers. Lots of people will out torque Frankie if you don't up the compression.

 

[Frankie]

From what I’ve seen (not heard from another) with my own 2eyes differs from your narrative. You see , if you set the squish at .020 or less and don’t clean the carbon out the combustion chamber and off the top of the piston regularly you will start hearing noises out the top end and hammer the heck outta the lower end , it’s saw building 101bro , ... If you get cute and exceed the ML you will start whacking the top of the band with the piston - not good ... Sad that the “competition” can’t out-torque Ol’ Frankie even with the “lady’s’ aid” of high compression - I don’t “make them run” ... I “let” them run , HUGE difference! Best combo for power /longevity is .025-.035squish: Hotwoods 462c and Torque monster 572xp use stock squish. Most stock saws are a little higher from the factory. You think you are smarter/more clever than the engineers that designed/ built the saw? I assure you , you are not ... You want to argue then fine ... do your way ... I don’t really give a rats ass ...

 

[Magnus]

Saws today run hotter, with more rpms and less runtime/saw.
If you look at the saws made in 80's and early 90's they had 2-4 times more runtime in them doing same work/performance.

If you look at the environmental impact calculation a saw make, its a vast difference if if it runs 500 hrs or 2000hrs.
Making them is same affects, recycling the same, but the gain in environmental aspect is not to use more natural resources than needed to get the job done. In manufacturing, transports etc is were the bad stuff happen.
It is not more environmentally correct as its new and uses a decilitre less fuel in a day.

 

[Frankie]

The newer saws feature a “metered air leak” where raw air is introduced into the cylinder in an effort to make the saw burn cleaner - EPA. Rpm is higher in cut than older versions and because of design a guy/gal better be using the best mix oil /fuel he can afford if he/she wants his saw to last. I do not doubt for one second that longevity is reduced in comparison to older versions, this is why I stay away from high compression on these new saws. More “built” saw blowing up nowadays in less than 50 tanks of fuel because the builder is ignorant of how new design works and uses .020 squish , runs like a raped ape for awhile then kaboom - good for them , let them do their way and deal with the grenade 😀... seems a stretch to say the old saw last 4 times as long but if that is your experience then so be it - Even if we agree 1/2 as long than you need to produce 2 saws and considering the costs of raw materials, transport etc it is false economy

 

[Nutball]

I guess one could argue more rpm = faster wear, but compensating with higher torque at lower rpm could do the same. It's a disposable tool to those who put lots of time on them in just a few years. That's why some want the pleasure of the most power in the least weight for as long as they have to wield it. Customer's choice, and as usual people can figure things out for themselves. Maybe someone doesn't notice a decrease in life because there may be none, maybe they value ease and speed of work over longevity of the tool. I don't think there's a right or wrong answer here considering the amount of personal preference. It is an unfortunate fact that modern tech often has a shorter life, but at least it can be more of a pleasure to use in some ways: less refilling, less weight, more stock power.

 

[Frankie]

No argument here - More compression = more power. Never claimed to the contrary. However, in this life ain’t nothin for free especially with these new model controlled air leak saws and jacking up compression is a big no-no IF ya want longevity out of them. This is not just my personal opinion but the opinion of FAR more knowledgeable individuals. You see “talk” is one thing ... Actually doing the work/testing and seeing the results is what separates fact from fiction. This way YOU have the knowledge ... and I think that’s wonderful 😀 Here is an example for your enjoyment. A “Tennessee” 395xp high compression ported saw vs a Hotwoods 064 with stock compression NO machine work ... As you can see the 064 wins the race. Were I to tighten the squish on the 064 then margin of victory would increase. Oh ... it’s also 94cc 395 vs 85cc 064 just in case you are wondering ... See ya ✌️...

 

[Frankie]

Lots of people will out torque Frankie if you don't up the compression.

No builder from Tennessee is out-torquing Frankie 😀

 

[Magnus]

They run lean. Its not the fresh air in cylinder that cause issues as I see it its the lack of fuel/oil mix in crankcase.
Its like punching a 6mm hole in case...

Here we fight air leaks for decades and they think its a bright idea to design it in the saws?
It did not work in 1924 when Rinco had it in their saw engines and not now either...
But they do sell more saws/logger. And loggers get new saws more frequently.
So what if it mean a bit more stress on environment... Its not in the immediate environment so no one cares...

 

[Magnus]

There is no need for high rpm's above 12 000. Put another cog on the wheel or two instead if you need chainspeeds higher than 21m/sek.

 

[Frankie]

They run lean. Its not the fresh air in cylinder that cause issues as I see it its the lack of fuel/oil mix in crankcase.
Its like punching a 6mm hole in case...

Here we fight air leaks for decades and they think its a bright idea to design it in the saws?
It did not work in 1924 when Rinco had it in their saw engines and not now either...
But they do sell more saws/logger. And loggers get new saws more frequently.
So what if it mean a bit more stress on environment... Its not in the immediate environment so no one cares...

Definitely run leaner and hotter than older versions - injecting raw air into cylinder is a contributing factor to this. I recommend motomix to all my customers ... mix is critical on these new saws - I use stock squish and stay away from high compression on these models and get my performance increase thru airflow and precise port-timing. At 10000rpm in cut piston is cycling 166.666667/ sec - not much time for port to be open - get it right saw throws chips and operator smiles - get it wrong and you have a turd that is slower than stock ... when the hammer drops , the bullshit stops

 

[Magnus]

If you want good emissions high rpm's is not the way to go. We known this for 100 years.
Faster revs give less complete combustion.
So they run them leaner and leaner, cat's in muffler and very good fuel and ignition systems to help get rpm's up more.
Why?
They don't last longer or run cheaper... Chainspeed might be higher, but if you put it in a log they drop pretty quick so whats the use?
Runtime in saw is less, It holds up worse....
Chainspeed is good for limbing, but thats on smaller saws. Bigger saws you need the umpf in them to pull, keep cool and last.

 

[Frankie]

Torque wins races ... Horsepower sells cars (or in this case saws). Take what the manufacturer gives you and make it flow better! More AIR=More TORQUE. With stock compression, muffler flow mods and precise port-work along with other mods (piston mod to increase intake duration , bore carb .010 for more flow etc) a stock saw can be made 20-25% stronger and last as long as a stocker. High-compression, Making ports wider to keep timing but increase flow high rpm etc to me are “race saw” techniques- Every time piston goes up / down ring bulge into wider port ... eventually failure occurs. I see more and more newer stratos-charged “built saw” not lasting 50 tank of fuel before grenading! If you are building saws for profit for others you want power yes but not expense of longevity!

 

[Frankie]

...Example: 572xp torque monster - excellent blend of power , fuel economy and longevity ... Can I make saw cut faster by additional modifications? Yes but saw will drink considerably more fuel and will not last as long. Buy once,cry once and call me when you need new set of rings !

 

[Magnus]

You need fuel to generate power. Grab a can of air and measure how much torque you get from it...
Decreasing compression space is in my head just dumb. Better to fill it up with suff that can generate power.
Fuel is not enough you need air as well or rather oxygen, but in an appropriate mix it will generate more power than if its lean or rich. Fuel has its limits...
Emissions are measured after how fully burnt the fuel air mix is. Higher rpm's = worse results, especially if not under load.

 

[Frankie]

Yes you need fuel to generate power @Magnus but must be at proper ratio ... Ported saw can actually make more power and get almost same mileage as stock because fuel is being burned more efficiently! I’m not decreasing compression at all , Just using the stock gasket or if customer wants higher compression a thinner base gasket - If you look at 2-stroke race bike / street bike you will find race bike has lower compression! Street model 7.5:1 , Race 6.6:1 - street make 60hp , race make 90hp ... hmm 🤔 maybe higher RPM on race bike no ?

 

[Marc-Antoine]

What is the issue if we plug the fresh air intake in the cylinder ?
Beside making EPA angry...

 

[Frankie]

... Excellent video showing modern “EPA compliant” stratos-charged saw ... If you plug fresh air intake you have made a nice paperweight 😂

 

[Frankie]

.... If you are making clocks then this saw for you

 

[Nutball]

Are you trying to sell something? I thought we already had a saw video thread...

... your saw video thread.

 

[Frankie]

Yeppers ... high compression chainsaws are just a silly fad anyway 😃. Hey Aren’t you from Tennessee?

 

[Nutball]

What does Tennessee or my location have to do with anything?

Peeps already know I port power-heads, so no need to pester and pressure them with pesky posts promoting products and personal pride in my porting performance prowess.