7sleeper
Addicted to ArboristSite
I will correct you the first mentions of stratified three valve system with a patent is supposed to be from 1918! Of course they were never like the system implied today in two strokes, but the principle has already been existant for quite some time!And here I must disagree on several technical points my friend. Both AT and strato are new technologies and are specifically related to either 2-stroke engines or these all-position fuel systems on o p e. Zenoah's unfortunately named strato has nothing to do with the stratified charge systems employed on 4-stroke automobiles in the 1970's. With those the fuel mixture was "stratified", or non-mixed, at the time of combustion. These stratos keep the fuel separated from the air in order to delay the arrival of fuel into the combustion chamber as long as possible, reducing losses out the open exhaust port, but the mixture is supposed to be well mixed at the time of ignition.
And here again I am much more critical! We are talking about multi millionen dollar companies with, I am convinsed, pretty large lab complexes. And these companies are supposed to be unable to produce a sufficient product? I am sorry but that is for me unacceptable and I will tell you why. I have friends in buisnesses where products are designed and produced and the procedure is quite simple. Simpilfied first the managment detects the need for a new product, then they determine what a product must be able to perform and then they deside how fast it has to come to the market and last they deside what it can cost. After all these steps the product is launched and problems are a clear indication of cheapo short cuts! This has nothing to do with the engineers but completely with the number crunchers.I think Husqvarna blundered into several unintended consequence in their attempt to gather several new technologies and solve some very long standing major emissions problems concerning 2-strokes and these lousy fuel systems. The industry had been stagnant for decades, and there were bound to be some problems playing catch up at that pace. First, I think they didn't realize just what all the effects of all that excess fuel hanging around were (i.e. cooling). Second, I think they lost sight of the reality that even the AT fuel system is still crude and grossly inaccurate when not in closed loop, and that's a large part of the time - and they tried to dial it down too tight. Last, I think they misjudged the problems involved with rolling out the first new technology in many decades to the dealer and service network. Still, I give them credit for actually trying to solve the problems, with what are simple and elegant technical solutions - rather than just slapping on a cat.
Further if we have the chance for a seldom glimpse of real world lab results, I believe they should not be ignored! I undersand that most of our discussions are strictly theoreticle so I like quoting this publication.
http://www.shindaiwa.de/presse/motorsaegentest.pdf
These great new technologies are sometimes a bit overblown in my eyes. Why do I say this? Because in above publication the classic stupid two stroke dolmar 420 consumes less fuel than the strato husqvarna 445 and extremely close to the strato stihl 251. So what is going on here? I have no idea but I have the impression that at least a company is trying to get the most out of existing technology.
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