4 stroke saws coming?

[Rleonard]

Since Stihl and others are marketing 4 stroke engines in trimmers and blowers, how soon do you thing that this will migrate into saws? Will emission regs force it? Advances in engine technology?

The power to weight ratio certainly is a factor but this has been overcome in many applications. Other markets have moved this way. Outboard motors, snowmobiles, personal watercraft, and MX bikes are a few examples that come to mind.

I am just curious on your thoughts & insight. No alterior motive.

Bob

 

[Canyon Angler]

It seems like the way people turn chainsaws sideways, upside-down, etc., would make 4-stroke motors impractical for that application because the crankcase oil would be going all over the place. You say they're making 4-stroke trimmers nowadays?

 

[Rleonard]

Yes, there is the Stihl 4-Mix series that is used on several applications. Ryobi has one and even Briggs has a trimmer engine. All are 4 cycle.

Bob

 

[stckciv]

The Stihl uses w-cycle mix still. Honda has the best 4-cycle engine out for a trimmer, you can run it upside down all day and still lubricate everything.

Dolmar has made a 4 stroke unit PS-500v that uses 2-cycle mix like the Stihl. Someone said they worked with Porsche on the engine of this machine. (not sure on that) No word yet on specific date for release of that saw.

 

[JeffHK454]

I hope some the insiders will chime in on this topic as I would like to know what's coming down the pike in the 4 stroke saw development.

I don't know if 4 stroke power plants are advanced enough yet to get the power to weight you would need in a saw like a 066/395 or other pro models.

The illusion that 4 stroke MX bikes are competitive with the 2 strokers is a sales ploy that was made necessary by the EPA and strong-armed onto manufacturers. I can't believe they still call the classes 250 and 125 when all the bikes in the 125 class are 250 cc and the 250s are 450cc.

When they can get a 4stroke that makes a stock 7+ hp out of a 16 lb. package and will last 2,000 hours before it's first rebuild I will be interisted!

It's going to happen I just don't know when.

JH

 

[spacemule]

4 stroke engines have some interesting features that may allow them to be competitive with 2 strokes given the proper development. Sure, they only have half as many power cycles, but think of the ability to supercharge the engine with very few parts.

The pumping action of the piston on the exhaust cycle can be used to pressurize the air above atmospheric and be forced into the intake, thus giving a supercharging effect. This requires very little weight increase.

Also, remember that 4 strokes effectively use the entire piston stroke from bdc to tcd to create compression, whereas 2 strokes only use from closing of intake to tdc. 4 strokes can therefore be effectively used with much higher compression ratios. All of this equates to increased power per stroke and given enough development makes them comparable in power and weight to 2 strokes.

 

[JeffHK454]

Yeah but with squeeze comes heat and the necessity for larger more rigid pistons/cases/rods ...etc. Then you add in valves..springs..rockers..timing gear/belt and the thing is getting heavy and fast.


I do think that what Space said was on the money though .... how about a chainsaw with blower whine


JH

 

[IchWarriorMkII]

Im not sure how little 4 stroke motors are, but in the snowmobile world, the 4 stroke sleds just cant compete with 2 strokers. Too much weight not enough power, in a world that makes or breaks sleds by the pound and horsepower.

Definatly need some positive pressure on the intake... Turbo'd sleds are the only way to get good power... I wonder what the turbo lag is on a chainsaw

 

[Cut4fun]

4 stroke chainsaw thread

Past thread on 4 stroke chainsaws. Just type in 4 stroke or cycle in the search and you will find the past threads on the subject. Here's one to get you started. http://www.arboristsite.com/showthread.php?t=26148&highlight=dolmar+stroke

 

[hamradio]

It seems like the way people turn chainsaws sideways, upside-down, etc., would make 4-stroke motors impractical for that application because the crankcase oil would be going all over the place. You say they're making 4-stroke trimmers nowadays?

What version of OS X? I'm using 10.2.8 on an iBook 12" G3 800.

 

[Husky137]

What version of OS X? I'm using 10.2.8 on an iBook 12" G3 800.

Is that a 4-stroke ibook?

 

[JONSSTIHL]

as far as i know the stihl 4-mix engines are still two stroke engines you still have to mix the oil with the gas, the fuel air mix still goes thru the crank case before it goes into the cylinder the only difference is that valves control its entry into the cylinder. atleast that is what I learned from the stihl website

 

[Lakeside53]

as far as i know the stihl 4-mix engines are still two stroke engines you still have to mix the oil with the gas, the fuel air mix still goes thru the crank case before it goes into the cylinder the only difference is that valves control its entry into the cylinder. atleast that is what I learned from the stihl website

Oil in the gas has nothing to do with an engine being a 2 or 4 stroke... The 4 mix engines are definitely 4 stokes. The mix is so the crank case is so the engine does not need the complexity of and oil pump with a dry sump system - allows use in any attitude.

 

[bwalker]

With Husky's acquiringing redmax and their technology I dont think you will see a four stroke saw from them for some time.
I would think Stihl would have a 4-mix saw in the works and we know Dolmar has both Strato charged two cycle and four cycle saws in the works.

 

[hamradio]

Is that a 4-stroke ibook?

No, his signature says OS X, and I like macs. I'm looking at buying an iMac, too. (getting sick of my Windows desktops)

 

[Husky137]

No, his signature says OS X, and I like macs. I'm looking at buying an iMac, too. (getting sick of my Windows desktops)

Uhhh, yeah, I was uhhh, being sarcastic.

 

[shokidq]

Since Stihl and others are marketing 4 stroke engines in trimmers and blowers, how soon do you thing that this will migrate into saws? Will emission regs force it? Advances in engine technology?

The power to weight ratio certainly is a factor but this has been overcome in many applications. Other markets have moved this way. Outboard motors, snowmobiles, personal watercraft, and MX bikes are a few examples that come to mind.

I am just curious on your thoughts & insight. No alterior motive.

Bob

Here's a link to an article including Makita's four stroke chainsaw DCS500V

October chainsaw review 2006

http://www.forestmachinejournal.com/