what is "strato charged"

PES+ · Apr 7, 2008

Ypsilanti is hot in the summer man.......

drkptt · Apr 8, 2008

CWI chainsaws have been on the market for almost 3 years

Emak has been manufacturing compression-wave injected chainsaws since the 2005 model year badged as John Deere CS36LE and CS40LE. They also sell them under their own label (Efco MT3700 and MT4000).

German forestry institute award:
http://www.emak.us/Sezione.jsp?idSezione=591&idSezioneRif=623

1Alpha1 · Apr 3, 2015

So.....are more Stihl engines Strato Charged than not?

Or.....does it take a certain # of cc's for it to be effective? Or......does the engine size even matter?

stihlaficionado · Apr 3, 2015

2123 said:
So.....are more Stihl engines Strato Charged than not?

Or.....does it take a certain # of cc's for it to be effective? Or......does the engine size even matter?

I do believe the 193 top handle is a strato

1Alpha1 · Apr 4, 2015

A dealer told me that strato-charging is more or less, an EPA thing more than anything else. He implied that it's a bit more fuel effective, and of course, reduces emissions to some degree.

I was just curious if ALL Stihl saws are strato charged? If I'm not getting all this right, or misinterpreting it, I'd appreciate it if someone would school me a bit on it. And......just to muddy the waters a bit more, are string trimmers, pole saws, blowers, etc. strato-charged?

theoldwizard1 · Sep 19, 2015

THALL10326 said:
Now tell us if this is true. A little birdie told me, well one about 6'3 235 lbs named Kevin, that fuel injection is on the way. He esitmated within 10 years but it is being put on the drawing board now and is being considered and he felt it would be on small power equipment when all is said and done.

Well it is not quite 10 years so I guess they have a few more years to get that FI (or should I say Direct Fuel Injection) on "small" single cylinder 2 stroke engine !

First, The "strato" term is obviously a "marketing name". Any two gaseous volumes not separated by some physical barrier will not stay "stratified" very long, less if pressures above atmospheric are involved. That is just the physical properties of gases. The key to the technology is get "fresh" air into the cylinder BEFORE the air/fuel mixture to push the exhaust out. There is some "stratification" of the air and air/fuel mixture in the transfer port but calling it "stratified" is kind of an exaggeration. (Look up Honda CVCC technology or Ford PROCO and EcoBoost)

Second, the current "leader" in DFI for 2 stroke is BRC/Evinrude with their ETEC technology. Back in the 90s, OMc worked with a German (Austrian?) company name Ficht to develop a direct injector for 2 stroke applications knowing that if only air came through the transfer port there would be less unburned fuel (lower emissions and better fuel economy) going out the exhaust. OMC bought the patents from Ficht. OMC was bought by Bombardier (now BRC). The first generation Ficht engine had more than their share of problems. BRC made many improvements to the injector design and the electronic controls and rename it ETEC. All 2 stroke Evinrude engines now have been using the ETEC DFI system for over 10 years now.

Now this where it get interesting. BRC wanted 100% of the Evinrude lineup to use ETEC, but it was just not cost effective ! First, their DFI injector is quite large compared to a typical gasoline injector. Being large, it is hard to package on a small 1 or 2 cylinder engine. Then of course there is the electronics and sensors. Consequently all "small" Evinrude engines are 4 stroke (actually Tahatsu with white paint).

So if "strato-charged" works why would you want EFI/DFI with all the extra weight and cost ? Both technologies use the same "technology" (clear the cylinder with "fresh" air not air/fuel), they just do it differently (as did Mercury's now discontinued OptiMax.) Glad to see small 2 stroke engine are "not dead yet !"