bikemike
loud pipes save lives
Good talkin about cool stuff like saws again
Will Strato charged motors be less reliable long term?
- Thread starter bwalker
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I checked the website this afternoon. They never specifically claim that the 461 is a strato but do claim that it has some sort of low emission engine. Has anyone seen a 461 carb? Does it have two throttles, one for fresh air? I suspect that Stihl can't employ strato technology without paying royalties to Husqvarna or some other company that holds patents, and that Stihl's "technology" for achieving low emissions in the 461 is running them really lean. Doesn't Tanaka use some sort of reflected wave in the muffler to stuff unburned hydrocarbons back into the combustion chamber?
Better fuel economy means less oil being ran through the motor. Simple math...
STIHLTHEDEERE
This is Koty
Can you enlighten us? I see the same mix going into the motor, it just does a better job of burning it?? I.E. a more efficient engine???
Chris-PA
Where the Wild Things Are
The 461 has no obvious features that would make it do exhaust delayed scavenging any more than any other saw does - except for that deflector under the piston which I understood to be for cooling. It's just speculation that it is related to any delayed scavenging though.
The muffler you are thinking of was from Dolamr, which has given it up in favor of a reed valve strato system. The Tanaka was shown in a recent post about one of their string trimmers. It uses long narrow transfers exiting from the bottom of the case and feeding much higher area/volume upper transfers. The intent is clearly to fill the larger upper transfers with exhaust but prevent it from traveling back to the case due to the higher velocity in the lower transfer runners. The fresh charge will be delayed until the exhaust gets pushed out of the upper transfers.
Yes, but there is no evidence that this is a problem. The ratio of oil to fuel in the case at any given time is the same, it's just moving though more slowly and the oil does not wear out in there.
so what i'm hearing is that the tanaka uses a strato system that injects burnt exhaust gasses, instead of fresh air, in front of the new charge. sounds like it might work but exhaust gasses are hot and dirty. actually i suppose a good expansion chamber does the same thing.
I can not answer that but I have read they have invested quite a bit in some research facility somewhere in the middle of the USA. How about the 4 mix like my pole saw is that late enough or did they purchase that innovation?
How about looking at it this way. Do you believe oil which dissolves in gasoline essentially condenses out in the lower end of a two cycle engine. If you believe that then more oil will condense out to do a given task (number of revolutions essentially) with the less effecient design. Then perhaps add in the heat of vaporization I noted earlier.
STIHLTHEDEERE
This is Koty
Well there is 4 mix, as many love it as hate it, m-tronic that actually works well, and a few DI two strokes. I wonder what argument all the critics will have when the the pro saws all go to DI? one thing Stihl prides themselves heavily on is continually evolving/improving on the products they have. Some say they are behind in product development. I can one thing they don't do, is push a product to market years before it is ready. The 661 is a perfect example. It was years in the making. The first few on the market were pulled and immediately replaced due to a vendor issue. ALL who purchased 661's had the option to have the saw replaced until the issue was delt with. Do you think that would happen with any other brand? I can tell you this first hand, right or wrong, you don't want to be on the receiving end of a phone call from VA Beach where a customer has contact ed customer service because they feel they were not treated fairly.
Chris-PA
Where the Wild Things Are
Thank you for proving my point, as well as a few other people's points.
Stihl has never sold a 4-mix chainsaw, nor have they ever sold a saw with fuel injection (and I'd be surprised if they ever do). Also their fuel injection is not direct injection, just an injector into the case (which accomplishes little if anything). And I do not believe the M-tronic system is their development either.
Its pretty simple. Saw x runs for 2 hours and burns a gallon of fuel with 4 ounces of oil in it. Saw Y runs for two hours and burns a half gallon of fuel with 2 ounces of oil in it. Saw Y had half the amount of lubrication as saw X. Of course this is a simplification for educational purposes.
A good expansion chamber is tuned such that it rams fresh charge back into the cylinder, not exhaust.
How fast the oil moves through is dictated by rpm. Maxima actually did an oil resonance time study years ago that used radioactive isotopes to determine how fast oil traveled through a running motor at a given rpm.
The fact of the matter is the strato engines are operating on less lubrication.
Chris-PA
Where the Wild Things Are
Define lubrication. From the point of view of the bearings in the case for example - they were continually bathed in the same mix ratio the whole time on both saws. Does it matter if that mix is moving through the case as fast? I'll grant that the lower flow rate of mix may effect evaporative cooling of some parts, but that is different from lubrication.
No matter how you look at it there is less oil in the motor at a given time because less oil is being admitted to the motor. As mentioned earlier the time it takes for oil to migrate through the motor is based on rpm and is unchanged.
bikemike
loud pipes save lives
Yes someone understands that most people think it just sucks exhaust out. No they also raise compression from a rebound pressure waves
Which is why an agressive pipe with a high compression motor can drive you into detonation pretty quick.
bikemike
loud pipes save lives
I do know the stihl ts500i concrete saw is a injection saw fuel is pumped by crank case pressure going to a diaphragm and check system like all pumped carbs. But it is metered by temp to tune the fuel ot air ratio. It is very convenient without a choke it does start easy at 0* temp. And is responsive cold start or or properly warmed up. But it isnt a chainsaw
bikemike
loud pipes save lives
Yep. The high comp is what kills the bottom end and seized rings. Thats also why i think saws are not like a moto x bike and built way less powerful so they can get the longevity out of the engine
STIHLTHEDEERE
This is Koty
Be prepared to be surprised then. FI is well on its way. 4 mix is their design/innovation. No matter where mtronic has come from, it is patent and it is now their's, and like it or not, it works, and works well. You ask for technology/innovation, and that is what I have for you. If you ever went to VA Beach to see the plant, I think you would be impressed by the RD dept, as well as the whole operation. Stihl has a lot invested in the US operations, and they feed a lot of families here as well. Sorry if some here see me as brand biased/ or a fanboy, but we have a lot invested with Stihl, and they have always done right by us. That is worth a bunch to my families' business.
